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Sample records for actual observed spectral

  1. Which spectral distortions does ΛCDM actually predict?

    NASA Astrophysics Data System (ADS)

    Chluba, Jens

    2016-04-01

    Ever refined cosmological measurements have established the ΛCDM concordance model, with the key cosmological parameters being determined to percent-level precision today. This allows us to make explicit predictions for the spectral distortions of the cosmic microwave background (CMB) created by various processes occurring in the early Universe. Here, we summarize all guaranteed CMB distortions and assess their total uncertainty within ΛCDM. We also compare simple methods for approximating them, highlighting some of the subtle aspects when it comes to interpreting future distortion measurements. Under simplified assumptions, we briefly study how well a PIXIE-like experiment may measure the main distortion parameters (i.e., μ and y). Next generation CMB spectrometers are expected to detect the distortion caused by reionization and structure formation at extremely high significance. They will also be able to constrain the small-scale power spectrum through the associated μ-distortion, improving limits on running of the spectral index. Distortions from the recombination era, adiabatic cooling of matter relative to the CMB and dark matter annihilation require a higher sensitivity than PIXIE in its current design. The crucial next step is an improved modeling of foregrounds and instrumental aspects, as we briefly discuss here.

  2. Which spectral distortions does ΛCDM actually predict?

    NASA Astrophysics Data System (ADS)

    Chluba, Jens

    2016-07-01

    Ever refined cosmological measurements have established the ΛCDM concordance model, with the key cosmological parameters being determined to per cent-level precision today. This allows us to make explicit predictions for the spectral distortions of the cosmic microwave background (CMB) created by various processes occurring in the early Universe. Here, we summarize all guaranteed CMB distortions and assess their total uncertainty within ΛCDM. We also compare simple methods for approximating them, highlighting some of the subtle aspects when it comes to interpreting future distortion measurements. Under simplified assumptions, we briefly study how well a PIXIE-like experiment may measure the main distortion parameters (i.e. μ and y). Next-generation CMB spectrometers are expected to detect the distortion caused by reionization and structure formation at extremely high significance. They will also be able to constrain the small-scale power spectrum through the associated μ-distortion, improving limits on running of the spectral index. Distortions from the recombination era, adiabatic cooling of matter relative to the CMB and dark matter annihilation require a higher sensitivity than PIXIE in its current design. The crucial next step is an improved modelling of foregrounds and instrumental aspects, as we briefly discuss here.

  3. Galileo 243 Ida System Spectral Observations Revisited

    NASA Astrophysics Data System (ADS)

    Granahan, J. C.

    2001-11-01

    On August 28, 1993 the Galileo spacecraft encountered the asteroid 243 Ida and its moon Dactyl. A variety of observations of this asteroid system were collected including visible wavelength (0.4-1.0 microns) imagery with the Solid State Imager (SSI) instrument and infrared wavelength (0.7-5.2 microns) with the Near Infrared Mapping Spectrometer (NIMS). A new analysis of these observations has been conducted using band area analysis, band center measurement, and spectral similarity value measurement using the BAE SYSTEMS Hyperspectral Tool Kit. This abstract reports the initial results of this research effort. These data indicate that 243 Ida has an orthopyroxene/(orthopyroxene + olivine) ratio of about 0.28, a value consistent with that of LL chondrites. The ratio does not vary significantly for the portions of 243 Ida observed by the Galileo NIMS instrument. 243 Ida is a SIV subtype of the S type asteroid population. At least two spectral units were identified in a combined SSI and NIMS spectral data set. The primary difference is the amount of red slope present in the two spectral units. A larger red slope corresponds to regions of 243 Ida where ejecta from the crater Azurra are present. This evidence suggests that impacts enhance the red components of the 243 Ida spectrum, perhaps enhancing the NiFe content. Dactyl has a relatively deep absorption centered approximately at 0.97 microns with no significant two micron absorption features. This is a possible indicator of clinopyroxene and suggests partial melting or fractional crystallization processes occurred on Dactyl. Dactyl appears to be an SII subtype S type asteroid and is spectrally different from 243 Ida. Dactyl may have been produced by partial melting within the Koronis parent body while the 243 Ida region escaped such igneous processing. This study was made possible through support from NASA's Planetary Geology and Geophysics program.

  4. Orbiter glow observations at high spectral resolution

    NASA Technical Reports Server (NTRS)

    Kendall, D. J. W.; Mende, S. B.; Yn, E. J. ADMCDADE, I. C. AEMENDE, S. B.

    1985-01-01

    An experiment flow on mission STS 41-G as part of the Canadian complement of experiments was designed to obtain relatively high resolution spectra of the Orbiter glow phenomenon over limited spectral regions centered on prominent upper atmospheric emissions. Observations were carried out successfully at altitudes of 360 km and 230 km although those at the lower altitude were limited by degradation of the image intensifier. Definitive glow results were obtained at the end of a thruster firing which showed the spectrum to be a continuum at a resolution of approximately 0.4 nm centered at a wavelength of 360 nm. Results at other wavelengths in the absence of any firings strongly suggest that the Orbiter glow is a continuum throughout the spectral region 550 nm to 760 nm. A discussion is presented that considers the reaction NO + O2 as being a possible candidate for the mechanism producing the shuttle glow.

  5. Apparent and Actual Use of Observational Frameworks by Experienced Teachers.

    ERIC Educational Resources Information Center

    Satern, Miriam N.

    This study investigated observational strategies that were used by six experienced physical education teachers when viewing a videotape of motor skills (standing vertical jump, overarm throw, tennis serve, basketball jump shot and dance sequence). Four observational frameworks were proposed as being representative of subdisciplinary knowledge…

  6. SHIELD II: WSRT HI Spectral Line Observations

    NASA Astrophysics Data System (ADS)

    Gordon, Alex Jonah Robert; Cannon, John M.; Adams, Elizabeth A.; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We present new results from WSRT HI spectral line observations of 22 galaxies in the SHIELD II sample. We explore the morphology and kinematics by comparing images of the HI surface densities and the intensity weighted velocity fields with optical images from HST, SDSS, and WIYN. In most cases the HI and stellar populations are cospatial; projected rotation velocities range from less than 10 km/s to roughly 30 km/s.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College, and by NASA through grant GO-13750 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

  7. SHIELD II: VLA HI Spectral Line Observations

    NASA Astrophysics Data System (ADS)

    Lee, Eojin; Cannon, John M.; McNichols, Andrew; Teich, Yaron; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We present new results from low-resolution D-configuration VLA HI spectral line observations of 6 galaxies in the SHIELD II sample. We explore the morphology and kinematics by comparing images of the HI surface densities and the intensity weighted velocity fields with optical images from SDSS and WIYN. These data allow us to localize the HI gas and to study the bulk neutral gas kinematics.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College.

  8. Shortwave spectral radiative forcing of cumulus clouds from surface observations

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J.; Berg, L. K.; Long, C. N.; Flynn, C.

    2011-04-01

    The spectral changes of the shortwave total, direct and diffuse cloud radiative forcing (CRF) at surface are examined for the first time using spectrally resolved all-sky flux observations and clear-sky fluxes. The latter are computed applying a physically based approach, which accounts for the spectral changes of aerosol optical properties and surface albedo. Application of this approach to 13 summertime days with single-layer continental cumuli demonstrates: (i) the substantial contribution of the diffuse component to the total CRF, (ii) the well-defined spectral variations of total CRF in the visible spectral region, and (iii) the strong statistical relationship between spectral (500 nm) and shortwave broadband values of total CRF. Our results suggest that the framework based on the visible narrowband fluxes can provide important radiative quantities for rigorous evaluation of radiative transfer parameterizations and also can be applied for estimation of the shortwave broadband CRF.

  9. Remote sensing cloud properties from high spectral resolution infrared observations

    NASA Technical Reports Server (NTRS)

    Smith, William L.; Ma, Xia L.; Ackerman, Steven A.; Revercomb, H. E.; Knuteson, R. O.

    1993-01-01

    A technique for estimating cloud radiative properties (spectral emissivity and reflectivity) in the IR is developed based on observations at a spectral resolution of approximately 0.5/cm. The algorithm uses spectral radiance observations and theoretical calculations of the IR spectra for clear and cloudy conditions along with lidar-determined cloud-base and cloud-top pressure. An advantage of the high spectral resolution observations is that the absorption effects of atmospheric gases are minimized by analyzing between gaseous absorption lines. The technique is applicable to both ground-based and aircraft-based platforms and derives the effective particle size and associated cloud water content required to satisfy, theoretically, the observed cloud IR spectra. The algorithm is tested using theoretical simulations and applied to observations made with the University of Wisconsin's ground-based and NASA ER-2 aircraft High-Resolution Infrared Spectrometer instruments.

  10. Actual defect observation results of an extreme-ultraviolet blank mask by coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Harada, Tetsuo; Hashimoto, Hiraku; Amano, Tsuyoshi; Kinoshita, Hiroo; Watanabe, Takeo

    2016-03-01

    Extreme-ultraviolet (EUV) lithography poses a number of challenges, one of which is the production of a defect-free mask. To observe the defects on an EUV mask in a quantitative phase image, we have developed a microcoherent EUV scatterometry microscope. The intensity and phase images of the defects are reconstructed using ptychography. We observe four actual defects on an EUV blank mask using the microscope. The reconstructed shapes of the actual defects correspond well to those measured by atomic force microscopy (AFM). Our microscope should therefore function as an essential review tool in characterizing defects.

  11. Lyman alpha solar spectral irradiance line profile observations and models

    NASA Astrophysics Data System (ADS)

    Snow, Martin; Machol, Janet; Quemerais, Eric; Curdt, Werner; Kretschmar, Matthieu; Haberreiter, Margit

    2016-04-01

    Solar lyman alpha solar spectral irradiance measurements are available on a daily basis, but only the 1-nm integrated flux is typically published. The International Space Science Institute (ISSI) in Bern, Switzerland has sponsored a team to make higher spectral resolution data available to the community. Using a combination of SORCE/SOLSTICE and SOHO/SUMER observations plus empirical and semi-empirical modeling, we will produce a dataset of the line profile. Our poster will describe progress towards this goal.

  12. Infrared Spectral Observations While Drilling into a Frozen Lunar Simulant

    NASA Astrophysics Data System (ADS)

    Roush, T. L.; Colaprete, A.; Thompson, S.; Cook, A.; Kleinhenz, J.

    2014-12-01

    Past and continuing observations indicate an enrichment of volatile materials in lunar polar regions. While these volatiles may be located near the surface, access to them will likely require subsurface sampling, during which it is desirable to monitor the volatile content. In a simulation of such activities, a multilayer lunar simulant was prepared with differing water content, and placed inside a thermal vacuum chamber at Glenn Research Center (GRC). The soil profile was cooled using liquid nitrogen. In addition to the soil, a drill and infrared (IR) spectrometer (~1600-3400 nm) were also located in the GRC chamber. We report the spectral observations obtained during a sequence where the drill was repeatedly inserted and extracted, to different depths, at the same location. We observe an overall increase in the spectral signature of water ice over the duration of the test. Additionally, we observe variations in the water ice spectral signature as the drill encounters different layers.

  13. Infrared Spectral Observations While Drilling into a Frozen Lunar Simulant

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Colaprete, Anthony; Thompson, Sarah; Cook, Amanda; Kleinhenz, Julie

    2014-01-01

    Past and continuing observations indicate an enrichment of volatile materials in lunar polar regions. While these volatiles may be located near the surface, access to them will likely require subsurface sampling, during which it is desirable to monitor the volatile content. In a simulation of such activities, a multilayer lunar simulant was prepared with differing water content, and placed inside a thermal vacuum chamber at Glenn Research Center (GRC). The soil profile was cooled using liquid nitrogen. In addition to the soil, a drill and infrared (IR) spectrometer (1600-3400 nm) were also located in the GRC chamber. We report the spectral observations obtained during a sequence where the drill was repeatedly inserted and extracted, to different depths, at the same location. We observe an overall increase in the spectral signature of water ice over the duration of the test. Additionally, we observe variations in the water ice spectral signature as the drill encounters different layers.

  14. Solar Spectral Irradiance Observations from the PICARD/PREMOS Radiometer

    NASA Astrophysics Data System (ADS)

    Cessateur, G.; Schöll, M.; Schmutz, W. K.; Wehrli, C.; Groebner, J.; Haberreiter, M.; Kretzschmar, M.; Shapiro, A.; Thuillier, G. O.; Finsterle, W.; Fox, N.; Hochedez, J. F.; Koller, S.; Meftah, M.; Nyeki, S.; Pfiffner, D.; Roth, H.; Rouze, M.; Spescha, M.; Tagirov, R.; Werner, L.; Wyss, J.

    2015-12-01

    Space weather and space climate studies require accurate Solar Spectral Irradiance (SSI) observations. The PREcision Monitoring Sensor (PREMOS) instrument aboard the PICARD satellite acquired solar irradiance measurements in specific spectral windows in the UV, visible and near infrared from October 2010 to March 2014. This contribution aims at presenting the Level 3 data, corrected for non solar features as well as for degradation. These level 3 data has been tested over different scientific cases, such as observations during the Venus transit and the presence of the p-mode signature within high-cadence data. The PREMOS Level 3 data have also been compared to others data sets, namely the SOLSTICE and SIM instruments aboard SORCE, for nearly 3 and half years. An excellent correlation has been found for the UV spectral ranges. We have also found a rather good correlation for visible and near-infrared observations for short-term variations, for which an error of about 200 ppm has been estimated within PREMOS visible and near-infrared observations. The PREMOS data could also be used to address several scientific topics, i.e. for validating semi-empirical models of the solar irradiance. We will emphasize about our new irradiance model, COSIR for Code of Solar Irradiance Reconstruction, which is successful at reproducing the solar modulation as seen in the PREMOS, SoHO/Virgo and SORCE data.

  15. Smearing of Observables and Spectral Measures on Quantum Structures

    NASA Astrophysics Data System (ADS)

    Dvurečenskij, Anatolij

    2013-02-01

    An observable on a quantum structure is any σ-homomorphism of quantum structures from the Borel σ-algebra of the real line into the quantum structure which is in our case a monotone σ-complete effect algebra with the Riesz Decomposition Property. We show that every observable is a smearing of a sharp observable which takes values from a Boolean σ-subalgebra of the effect algebra, and we prove that for every element of the effect algebra there corresponds a spectral measure.

  16. Ion spectral structures observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Ferradas, C.; Zhang, J.; Spence, H. E.; Kistler, L. M.; Larsen, B.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.

    2015-12-01

    During the last decades several missions have recorded the presence of dynamic spectral features of energetic ions in the inner magnetosphere. Previous studies have reported single "nose-like" structures occurring alone and simultaneous nose-like structures (up to three). These ion structures are named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. They constitute the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. The HOPE mass spectrometer onboard the Van Allen Probes measures energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet, where these ion structures are observed. We present a statistical study of nose-like structures, using 2-years measurements from the HOPE instrument. The results provide important details about the spatial distribution (dependence on geocentric distance), spectral features of the structures (differences among species), and geomagnetic conditions under which these structures occur.

  17. Observation of the optical and spectral characteristics of ball lightning.

    PubMed

    Cen, Jianyong; Yuan, Ping; Xue, Simin

    2014-01-24

    Ball lightning (BL) has been observed with two slitless spectrographs at a distance of 0.9 km. The BL is generated by a cloud-to-ground lightning strike. It moves horizontally during the luminous duration. The evolution of size, color, and light intensity is reported in detail. The spectral analysis indicates that the radiation from soil elements is present for the entire lifetime of the BL. PMID:24484145

  18. Observation of the Optical and Spectral Characteristics of Ball Lightning

    NASA Astrophysics Data System (ADS)

    Cen, Jianyong; Yuan, Ping; Xue, Simin

    2014-01-01

    Ball lightning (BL) has been observed with two slitless spectrographs at a distance of 0.9 km. The BL is generated by a cloud-to-ground lightning strike. It moves horizontally during the luminous duration. The evolution of size, color, and light intensity is reported in detail. The spectral analysis indicates that the radiation from soil elements is present for the entire lifetime of the BL.

  19. Spectral and polarization analysis of micropulsations observed at ATS-1

    NASA Technical Reports Server (NTRS)

    Morris, W.; Cummings, W. D.; Mcpherron, R. L.

    1972-01-01

    Results are reported for an analysis of low frequency oscillations in the earth's magnetic field as observed at the synchronous orbit by the magnetometer experiment on board ATS 1. Oscillations in the range .002 f .02 H3 for the period Dec. 1966 through Dec. 1967 were studied. The analysis combines a detailed, computer-processed, spectral analysis of selected events with a less detailed manual analysis of all events in the two year time interval from Dec. 1966 to Dec. 1968. The computer analysis revealed that a given event is often characterized by a dominat, narrow, spectral peak whose associated oscillations are almost entirely limited to a plane, together with several minor peaks. Dynamic spectral analyses revealed that minor spectral peaks appear as short isolated bursts. The sense of rotation of the perturbation vector tends to change from right-handed elliptical at the beginning of a burst to left-handed elliptical at the end. The major axis of the polarization ellipse is inclined by typically 30 deg east of radial.

  20. Hyperspectral imagery for observing spectral signature change in Aspergillus flavus

    NASA Astrophysics Data System (ADS)

    DiCrispino, Kevin; Yao, Haibo; Hruska, Zuzana; Brabham, Kori; Lewis, David; Beach, Jim; Brown, Robert L.; Cleveland, Thomas E.

    2005-11-01

    Aflatoxin contaminated corn is dangerous for domestic animals when used as feed and cause liver cancer when consumed by human beings. Therefore, the ability to detect A. flavus and its toxic metabolite, aflatoxin, is important. The objective of this study is to measure A. flavus growth using hyperspectral technology and develop spectral signatures for A. flavus. Based on the research group's previous experiments using hyperspectral imaging techniques, it has been confirmed that the spectral signature of A. flavus is unique and readily identifiable against any background or surrounding surface and among other fungal strains. This study focused on observing changes in the A. flavus spectral signature over an eight-day growth period. The study used a visible-near-infrared hyperspectral image system for data acquisition. This image system uses focal plane pushbroom scanning for high spatial and high spectral resolution imaging. Procedures previously developed by the research group were used for image calibration and image processing. The results showed that while A. flavus gradually progressed along the experiment timeline, the day-to-day surface reflectance of A. flavus displayed significant difference in discreet regions of the wavelength spectrum. External disturbance due to environmental changes also altered the growth and subsequently changed the reflectance patterns of A. flavus.

  1. High solar cycle spectral variations inconsistent with stratospheric ozone observations

    NASA Astrophysics Data System (ADS)

    Ball, W. T.; Haigh, J. D.; Rozanov, E. V.; Kuchar, A.; Sukhodolov, T.; Tummon, F.; Shapiro, A. V.; Schmutz, W.

    2016-03-01

    Solar variability can influence surface climate, for example by affecting the mid-to-high-latitude surface pressure gradient associated with the North Atlantic Oscillation. One key mechanism behind such an influence is the absorption of solar ultraviolet (UV) radiation by ozone in the tropical stratosphere, a process that modifies temperature and wind patterns and hence wave propagation and atmospheric circulation. The amplitude of UV variability is uncertain, yet it directly affects the magnitude of the climate response: observations from the SOlar Radiation and Climate Experiment (SORCE) satellite show broadband changes up to three times larger than previous measurements. Here we present estimates of the stratospheric ozone variability during the solar cycle. Specifically, we estimate the photolytic response of stratospheric ozone to changes in spectral solar irradiance by calculating the difference between a reference chemistry-climate model simulation of ozone variability driven only by transport (with no changes in solar irradiance) and observations of ozone concentrations. Subtracting the reference from simulations with time-varying irradiance, we can evaluate different data sets of measured and modelled spectral irradiance. We find that at altitudes above pressure levels of 5 hPa, the ozone response to solar variability simulated using the SORCE spectral solar irradiance data are inconsistent with the observations.

  2. Is Ecosystem-Atmosphere Observation in Long-Term Networks actually Science?

    NASA Astrophysics Data System (ADS)

    Schmid, H. P. E.

    2015-12-01

    Science uses observations to build knowledge by testable explanations and predictions. The "scientific method" requires controlled systematic observation to examine questions, hypotheses and predictions. Thus, enquiry along the scientific method responds to questions of the type "what if …?" In contrast, long-term observation programs follow a different strategy: we commonly take great care to minimize our influence on the environment of our measurements, with the aim to maximize their external validity. We observe what we think are key variables for ecosystem-atmosphere exchange and ask questions such as "what happens next?" or "how did this happen?" This apparent deviation from the scientific method begs the question whether any explanations we come up with for the phenomena we observe are actually contributing to testable knowledge, or whether their value remains purely anecdotal. Here, we present examples to argue that, under certain conditions, data from long-term observations and observation networks can have equivalent or even higher scientific validity than controlled experiments. Internal validity is particularly enhanced if observations are combined with modeling. Long-term observations of ecosystem-atmosphere fluxes identify trends and temporal scales of variability. Observation networks reveal spatial patterns and variations, and long-term observation networks combine both aspects. A necessary condition for such observations to gain validity beyond the anecdotal is the requirement that the data are comparable: a comparison of two measured values, separated in time or space, must inform us objectively whether (e.g.) one value is larger than the other. In turn, a necessary condition for the comparability of data is the compatibility of the sensors and procedures used to generate them. Compatibility ensures that we compare "apples to apples": that measurements conducted in identical conditions give the same values (within suitable uncertainty intervals

  3. Wind wave spectral observations in Currituck Sound, North Carolina

    NASA Astrophysics Data System (ADS)

    Long, Charles E.; Resio, Donald T.

    2007-05-01

    We examine a set of 1626 high-resolution frequency-direction wind wave spectra and collocated winds collected during a 7-month period at a site in Currituck Sound, North Carolina, in terms of one-dimensional spectral structure and directional distribution functions. The data set includes cases of shore-normal winds in broad-fetch conditions as well as winds oblique to the basin geometry, with all fetches of order 10 km or less. Using equilibrium-range scaling, all one-dimensional spectra have a spectral peak region, an equilibrium range of finite bandwidth following an f-4 slope at slightly higher frequencies, and a high-frequency tail that falls off more rapidly than f-4. For shore-normal winds, spectral peakedness appears to be high and approximately constant for young waves, low and approximately constant for old waves, and steeply graded for intermediate inverse wave ages in the range 1.0 < u10/cp < 1.7. Equilibrium-range bandwidth seems to be narrow for young waves and increases with increasing wave age. Directional distribution functions in shore-normal winds are symmetric about the wind direction, narrow at spectral peaks, and broad at high frequencies with distinct directionally bimodal peaks, consistent with other observations. In oblique-wind cases, directional distribution functions are asymmetric and directionally sheared in spectral peak regions, with peak directions aligned with longer fetch directions. At high frequencies, directional distributions are more nearly symmetric about the wind direction. One-dimensional spectra tend to have reduced spectral peakedness and highly variable equilibrium-range bandwidths in oblique-wind conditions, clearly indicating a more complex balance of source terms in these cases than in the more elementary situation of shore-normal winds. These complications are not without consequence in wave modeling, as any bounded or semibounded lake or estuary will be subject to oblique winds, and current operational models do not

  4. Spectral changes associated with rain on Titan: observations by VIMS

    NASA Astrophysics Data System (ADS)

    Buratti, B. J.; Dalba, P. A.; Barnes, J.; Baines, K. H.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.; Sotin, C.

    2012-04-01

    Titan has an erosional cycle similar to that on the Earth, with solid, liquid, and gaseous methane taking the place of the Earth’s water. Lakes and ponds, drainage and fluvial features, and clouds all suggest that rain is falling on Titan. A darkening event near clouds covering the Huygens landing site, followed by a return to the previous state, strongly suggested rainfall followed by evaporation (Turtle et al., 2011). The Cassini Visual infrared Mapping Spectrometer (VIMS) obtains medium resolution spectra in the 0.35-5.1 μm spectral region, which includes several atmospheric “windows” that offer glimpses of Titan’s surface. The albedo of the surface can be measured in these windows, and some compositional information, including changes through time, can be derived. VIMS observed an area near 15º south latitude and 330º longitude at two separate times: in August 2009 during T61 and in May 2011 during T76. A spectral analysis of this region, including compensation for varying atmospheric path lengths, shows substantial spectral changes in the two and five micron atmospheric windows. A comparison of the changes with that expected from the deposition and later evaporation of liquid methane or another hydrocarbon shows them to be consistent with rain on Titan. Ackowledgements: This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration. Copyright 2012 all rights reserved. References: Turtle, E. P. et al. (2011) Science 331, 1414.

  5. Improving a Spectral Bin Microphysical Scheme Using TRMM Satellite Observations

    NASA Technical Reports Server (NTRS)

    Li, Xiaowen; Tao, Wei-Kuo; Matsui, Toshihisa; Liu, Chuntao; Masunaga, Hirohiko

    2010-01-01

    Comparisons between cloud model simulations and observations are crucial in validating model performance and improving physical processes represented in the mod Tel.hese modeled physical processes are idealized representations and almost always have large rooms for improvements. In this study, we use data from two different sensors onboard TRMM (Tropical Rainfall Measurement Mission) satellite to improve the microphysical scheme in the Goddard Cumulus Ensemble (GCE) model. TRMM observed mature-stage squall lines during late spring, early summer in central US over a 9-year period are compiled and compared with a case simulation by GCE model. A unique aspect of the GCE model is that it has a state-of-the-art spectral bin microphysical scheme, which uses 33 different bins to represent particle size distribution of each of the seven hydrometeor species. A forward radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity and TRMM Microwave Imager (TMI) 85 GHz brightness temperatures from simulated particle size distributions. Comparisons between model outputs and observations reveal that the model overestimates sizes of snow/aggregates in the stratiform region of the squall line. After adjusting temperature-dependent collection coefficients among ice-phase particles, PR comparisons become good while TMI comparisons worsen. Further investigations show that the partitioning between graupel (a high-density form of aggregate), and snow (a low-density form of aggregate) needs to be adjusted in order to have good comparisons in both PR reflectivity and TMI brightness temperature. This study shows that long-term satellite observations, especially those with multiple sensors, can be very useful in constraining model microphysics. It is also the first study in validating and improving a sophisticated spectral bin microphysical scheme according to long-term satellite observations.

  6. An overview of the CILBO spectral observation program

    NASA Astrophysics Data System (ADS)

    Rudawska, R.; Zender, J.; Koschny, D.

    2016-01-01

    The video equipment can be easily adopted with a spectral grating to obtain spectral information from meteors. Therefore, in recent years spectroscopic observations of meteors have become quite popular. The Meteor Research Group (MRG) of the European Space Agency has been working on upgrating the analysis of meteor spectra as well, operating image-intensified camera with objective grating (ICC8). ICC8 is located on Tenerife station of the double-station camera setup CILBO (Canary Island Long-Baseline Observatory). The pipeline software processes data with the standard calibration procedure (dark current, flat field, lens distortion corrections). While using the position of a meteor recorded by ICC7 camera (zero order), the position of the 1st order spectrum as a function of wavelength is computed Moreover, thanks to the double meteor observations carried by ICC7 (Tenerife) and ICC9 (La Palma), trajectory of a meteor and its orbit is determined. Which merged with simultaneously measurement of meteor spectrum from ICC8, allow us to identify the source of the meteoroid. Here, we report on preliminary results from a sample of meteor spectra collected by CILBO-ICC8 camera since 2012.

  7. First Radio Burst Imaging Observation From Mingantu Ultrawide Spectral Radioheliograph

    NASA Astrophysics Data System (ADS)

    Yan, Yihua; Chen, Linjie; Yu, Sijie; CSRH Team

    2015-08-01

    Radio imaging spectroscopy over wide range wavelength in dm/cm-bands will open new windows on solar flares and coronal mass ejections by tracing the radio emissions from accelerated electrons. The Chinese Spectral Radioheliograph (CSRH) with two arrays in 400MHz-2GHz /2-15GHz ranges with 64/532 frequency channels have been established in Mingantu Observing Station, Inner Mongolia of China, since 2013 and is in test observations now. CSRH is renamed as MUSER (Mingantu Ultrawide SpEctral Radioheliograph) after it's accomplishment We will introduce the progress and current status of CSRH. Some preliminary results of CSRH will be presented.On 11 Nov2014, the first burst event was registered by MUSER-I array at 400MHz-2GHz waveband. According to SGD event list there was a C-class flare peaked at 04:49UT in the disk center and the radio bursts around 04:22-04:24UT was attributed to this flare. However, MUSER-I image observation of the burst indicates that the radio burst peaked around 04:22UT was due to the eruption at the east limb of the Sun and connected to a CME appeared in that direction about 1 hour later. This demonstrate the importance of the spectroscopy observation of the solar radio burst.Acknowledgement: The CSRH team includes Wei Wang, Zhijun Chen, Fei Liu, Lihong Geng and Jian Zhang and CSRH project is supported by National Major Scientific Equipment R&D Project ZDYZ2009-3. The research was also supported by NSFC grants (11433006, 11221063), MOST grant (MOST2011CB811401), CAS Pilot-B Project (XDB09000000) and Marie Curie PIRSES- GA-295272-RADIOSUN.

  8. Numerical observer for atherosclerotic plaque classification in spectral computed tomography.

    PubMed

    Lorsakul, Auranuch; Fakhri, Georges El; Worstell, William; Ouyang, Jinsong; Rakvongthai, Yothin; Laine, Andrew F; Li, Quanzheng

    2016-07-01

    Spectral computed tomography (SCT) generates better image quality than conventional computed tomography (CT). It has overcome several limitations for imaging atherosclerotic plaque. However, the literature evaluating the performance of SCT based on objective image assessment is very limited for the task of discriminating plaques. We developed a numerical-observer method and used it to assess performance on discrimination vulnerable-plaque features and compared the performance among multienergy CT (MECT), dual-energy CT (DECT), and conventional CT methods. Our numerical observer was designed to incorporate all spectral information and comprised two-processing stages. First, each energy-window domain was preprocessed by a set of localized channelized Hotelling observers (CHO). In this step, the spectral image in each energy bin was decorrelated using localized prewhitening and matched filtering with a set of Laguerre-Gaussian channel functions. Second, the series of the intermediate scores computed from all the CHOs were integrated by a Hotelling observer with an additional prewhitening and matched filter. The overall signal-to-noise ratio (SNR) and the area under the receiver operating characteristic curve (AUC) were obtained, yielding an overall discrimination performance metric. The performance of our new observer was evaluated for the particular binary classification task of differentiating between alternative plaque characterizations in carotid arteries. A clinically realistic model of signal variability was also included in our simulation of the discrimination tasks. The inclusion of signal variation is a key to applying the proposed observer method to spectral CT data. Hence, the task-based approaches based on the signal-known-exactly/background-known-exactly (SKE/BKE) framework and the clinical-relevant signal-known-statistically/background-known-exactly (SKS/BKE) framework were applied for analytical computation of figures of merit (FOM). Simulated data of a

  9. Divergence of actual and reference evapotranspiration observations for irrigated sugarcane with windy tropical conditions

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Wang, D.; Tirado-Corbalá, R.; Zhang, H.; Ayars, J. E.

    2015-01-01

    Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical environments. We measured ET (ETEC) using eddy covariance (EC) towers at two irrigated sugarcane fields on the leeward (dry) side of Maui, Hawaii, USA in contrasting climates. We calculated reference ET at the fields using the short (ET0) and tall (ETr) vegetation versions of the American Society for Civil Engineers (ASCE) equation. The ASCE equations were compared to the Priestley-Taylor ET (ETPT) and ETEC. Reference ET from the ASCE approaches exceeded ETEC during the mid-period (when vegetation coefficients suggest ETEC should exceed reference ET). At the windier tower site, cumulative ETr exceeded ETEC by 854 mm over the course of the mid-period (267 days). At the less windy site, mid-period ETr still exceeded ETEC, but the difference was smaller (443 mm). At both sites, ETPT approximated mid-period ETEC more closely than the ASCE equations ((ETPT-ETEC) < 170 mm). Analysis of applied water and precipitation, soil moisture, leaf stomatal resistance, and canopy cover suggest that the lower observed ETEC was not the result of water stress or reduced vegetation cover. Use of a custom-calibrated bulk canopy resistance improved the reference ET estimate and reduced seasonal ET discrepancy relative to ETPT and ETEC in the less windy field and had mixed performance in the windier field. These divergences suggest that modifications to reference ET equations may be warranted in some tropical regions.

  10. CASSIS, a software package to analyse high spectral resolution observations

    NASA Astrophysics Data System (ADS)

    Caux, E.; Bottinelli, S.; Vastel, C.; Glorian, J. M.

    2011-05-01

    CASSIS (Centre d'Analyse Scientifique de Spectres Infrarouges et Submillimetriques) is a software package aimed to speed-up the scientific analysis of high spectral resolution observations, particularly suited for broad-band spectral surveys. CASSIS is written in Java and can be ran on any platform. It has been extensively tested on Mac OSX, Linux and Windows operating systems. CASSIS is regularly enhanced, and can be easily installed and updated on any modern laptop. It uses a fast Sql-lite access to a local spectroscopic database made of the two molecular spectroscopic databases JPL and CDMS, as well as the atomic spectroscopic database NIST. The tools available in the currently distributed version (2.6) include a LTE model and the RADEX model connected to the LAMDA molecular collisional database. A module allows to build a line list fitting the various transitions of a given species and to directly produce rotational diagrams from these lists. CASSIS has been recently fully integrated into HIPE, the Herschel Interactive Processing Environment, as a plug-in (from version 5.1).

  11. Simultaneous Spectral and Timing Observations of Accreting Neuron Stars

    NASA Technical Reports Server (NTRS)

    Kaaret, P.; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The goal of this proposal is to perform simultaneous x-ray spectral and millisecond timing observations of accreting neutron stars to further our understanding of their accretion dynamics and in the hope of using these systems as probes of the physics of strong gravitational fields. NAG5-9104 is the successor grant to NAG5-8408. Observations using the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAX were performed of 4U1702-429, 4U1735-44, and Cyg X-2. Unfortunately, only a small fraction of the approved observing time was obtained for the first two targets and the data are of limited scientific value. Data analysis has been completed on the observations of Cyg X-2. We discovered a correlation between the frequency of the horizontal branch oscillations (HBO) and a soft, thermal component of the x-ray spectrum likely associated with emission from the accretion disk. This correlation may place constraints on models of the oscillations. A paper based on these results appeared in the Astrophysical Journal.

  12. Simultaneous Spectral and Timing Observations of Accreting Neuron Stars

    NASA Astrophysics Data System (ADS)

    Kaaret, P.

    2002-07-01

    The goal of this proposal is to perform simultaneous x-ray spectral and millisecond timing observations of accreting neutron stars to further our understanding of their accretion dynamics and in the hope of using these systems as probes of the physics of strong gravitational fields. NAG5-9104 is the successor grant to NAG5-8408. Observations using the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAX were performed of 4U1702-429, 4U1735-44, and Cyg X-2. Unfortunately, only a small fraction of the approved observing time was obtained for the first two targets and the data are of limited scientific value. Data analysis has been completed on the observations of Cyg X-2. We discovered a correlation between the frequency of the horizontal branch oscillations (HBO) and a soft, thermal component of the x-ray spectrum likely associated with emission from the accretion disk. This correlation may place constraints on models of the oscillations. A paper based on these results appeared in the Astrophysical Journal.

  13. Spectral observations of the extreme ultraviolet astronomical background radiation

    NASA Technical Reports Server (NTRS)

    Labov, S.; Bowyer, S.

    1988-01-01

    Observations in the FUV and soft X-ray bands suggest that the ISM contains several components of high-temperature gas (100,000-1 million K). If large volumes of local interstellar space are filled with this hot plasma, emission lines will be produced in the EUV. Diffuse EUV radiation, however, has only been detected with photometric instruments; no spectral measurements exist below 520 A. A unique grazing-incidence spectrometer to study the diffuse emission between 80 and 650 A with resolution 10-30 A was successfully flown on a sounding rocket in April 1986, and a preliminary analysis reveals several features. In addition to the expected interplanetary He I 584 A emission and the geocoronal He II 304 A emission, other features appear which may orginate in the hot ionized interstellar gas.

  14. X, E, M, and P-Type Asteroid Spectral Observations

    NASA Astrophysics Data System (ADS)

    Clark, B. E.; Rivkin, A. S.; Bus, S. J.; Sanders, J.

    2003-05-01

    What are the X-types made of? How would knowledge of their composition change our picture of the geological structure of the asteroid regions? X-types are important in the main belt, yet we do not understand their composition or meteorite linkage. This is an outstanding problem in asteroid-meteorite studies, because X-types comprise approximately 20% of the inner main belt (Tholen and Barucci 1989; Bus 1999). We have conducted a program of infrared (0.8-2.5microns) observations aimed at determining mineralogy without albedo information. Because X-types are spectrally like E, M, and P-type asteroids, we observed 18 X-types, 5 E-types, 8 M-types, and 4 P-types. This is the first focused study of XEMP asteroids. In this paper, we present a compositional analysis of the new spectral data. What we call XEMPs are asteroids identified as ambiguous on the basis of their visible spectral properties only (Zellner et al. 1985; Tholen 1984; Bus and Binzel 2002). By convention (Bowell et al. 1978; Tholen and Barucci 1989), X-types with measured geometric albedos are classified into E, M, or P-types, where E-types (designated ``E" based on their possible link with enstatite meteorites) are high-albedo objects, P-types are low-albedo objects (there are no meteorite analogs for these objects), and M-types (designated ``M" based on their possible link with metallic meteorites) are intermediate. Bus and Binzel (2002) found subtle features in X-class spectra in a high resolution survey. We have regrouped XEMP spectra for a reanalysis of the extended wavelength coverage now available (0.3-2.5 microns). When continuum slope is removed, we find distinct 0.9 micron bands at the level of 2-5% in many of our XEMP objects. We also find consistent wavelength maxima near 1.5 microns, and hints of 2.0 micron bands in some objects. Our preliminary findings suggest that new mineralogy-based groupings may be called for, breaking down the old albedo-based E, M, and P-type designations. We

  15. Actual and prescribed energy and protein intakes for very low birth weight infants: An observational study

    NASA Astrophysics Data System (ADS)

    Allevato, Anthony J.

    Objectives: To determine (1) whether prescribed and delivered energy and protein intakes during the first two weeks of life met Ziegler's estimated requirements for Very Low Birth Weight (VLBW) infants, (2) if actual energy during the first week of life correlated with time to regain birth weight and reach full enteral nutrition (EN) defined as 100 kcal/kg/day, (3) if growth velocity from time to reach full EN to 36 weeks' postmenstrual age (PMA) met Ziegler's estimated fetal growth velocity (16 g/kg/day), and (4) growth outcomes at 36 weeks' PMA. Study design: Observational study of feeding, early nutrition and early growth of 40 VLBW infants <30 weeks GA at birth in three newborn intensive care units NICUs. Results: During the first week of life, the percentages of prescribed and delivered energy (69% [65 kcal/kg/day]) and protein (89% [3.1 g/kg/day]) were significantly less than theoretical estimated requirements. Delivered intakes were 15% less than prescribed because of numerous interruptions in delivery and medical complications. During the second week, the delivered intakes of energy (90% [86 kcal/kg/day]) and protein (102% [3.5 g/kg/day]) improved although the differences between prescribed and delivered were consistently 15%. Energy but not protein intake during the first week was significantly related to time to reach full EN. Neither energy nor protein intake significantly correlated with days to return to birth weight. The average growth velocity from the age that full EN was attained to 36 weeks' PMA (15 g/kg/day) was significantly less than the theoretical estimated fetal growth velocity (16 g/kg/day) (p<0.03). A difference of 1 g/kg/day represents a total deficit of 42 - 54 grams over the course of a month. At 36 weeks' PMA, 53% of the VLBW infants had extrauterine growth restriction, or EUGR (<10th percentile) on the Fenton growth grid and 34% had EUGR on the Lubchenco growth grid. Conclusions: The delivered nutrient intakes were consistently less

  16. Divergence of actual and reference evapotranspiration observations for irrigated sugarcane with windy tropical conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in more humid environments. We measured ET (ETEC) using Eddy Covariance (EC) towers a...

  17. Seyfert Spectral Database: 10 Years Of Rxte Observations

    NASA Astrophysics Data System (ADS)

    Mattson, Barbara; Weaver, K.; Reynolds, C.

    2008-05-01

    What does the core of an active galactic nucleus truly look like? Do all Seyfert 2s have a Seyfert 1 at their core? How does the environment of their central regions affect our view of the central engine? We explore these questions with a systematic X-ray spectral study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE). We develop a database of spectral fits of 821 time-resolved spectra from 39 Seyfert galaxies fitted to a standard model including the effects of a power-law X-ray spectrum reprocessed and absorbed by material around the black hole. We find a complex relationship between the iron line equivalent width (EW) and the underlying power law index (Γ) in the Seyfert 1 sample, which may be caused by dilution of a disk spectrum (which includes the narrow iron line) by a beamed jet component and, hence, could be used as a diagnostic of jet-dominance. The same relationship does not hold for the Seyfert 2 sample, and may indicate that these sources show more complex environments. We also see the X-ray Baldwin effect (an anti-correlation between the 2-10 keV X-ray luminosity and EW) for the Seyfert 1 sample and Seyfert 1 sub-classifications, but not for each individual galaxy. In addition, our sample shows a strong correlation between R and Γ for all spectra in the sample, but we find that it is likely the result of a modeling degeneracy.

  18. Simultaneous Spectral and Timing Observations of Accreting Neuron Stars

    NASA Technical Reports Server (NTRS)

    Kaaret, P.; West, Donald K. (Technical Monitor)

    2001-01-01

    The goal of this proposal was to perform simultaneous x-ray spectral and millisecond timing observations of accreting neutron stars to further our understanding of their accretion dynamics and in the hope of using these systems as probes of the physics of strong gravitational fields. Observations of the neutron star binaries 4U0614+091, 4U1728-34, 4U1820-30, and Cyg X-2 were carried out with RXTE and BeppoSAX, ASCA, and Chandra (not all simultaneously). In addition, archival data were analyzed for 4U0614+091 and 4U1820-30. This investigation led to publication of three papers in peer-reviewed journals. These are listed below. In addition, the results were presented at several meetings including the two poster presentations listed below. Dr. Santina Piraino visited SAO for 4 months during 2000 to collaborate on analysis of the data from NAG5-8408 and NAG5-9104.

  19. A new X-ray spectral observation of NGC 1068

    NASA Technical Reports Server (NTRS)

    Marshall, F. E.; Netzer, H.; Arnaud, K. A.; Boldt, E. A.; Holt, S. S.; Jahoda, K. M.; Kelley, R.; Mushotzky, R. F.; Petre, R.; Serlemitsos, P. J.

    1993-01-01

    A new X-ray observation of NGC 1068, in which improved spectral resolution (R is approximately equal to 40) and broad energy range provide important new constraints on models for this galaxy, is reported. The observed X-ray continuum of NGC 1068 from 0.3 to 10 keV is well fitted as the sum of two power-law spectra with no evidence for absorption intrinsic to the source. Strong Fe K emission lines with a total equivalent width of 2700 eV were detected due to iron less ionized than Fe XX and to iron more ionized than Fe XXIII. No evidence was seen for lines due to the recombination of highly ionized oxygen with an upper limit for the O Ly-alpha emission line of 40 eV. The discovery of multiple Fe K and Fe L emission lines indicates a broad range of ionization states for this gas. The X-ray emission from the two components is modeled for various geometries using a photoionization code that calculates the temperature and ionization state of the gas. Typical model parameters are a total Compton depth of a few percent, an inner boundary of the hot component of about 1 pc, and an inner boundary of the warm component of about 20 pc.

  20. [Contradiction and intention of actual situation and statistical observation on home custody of mental patients].

    PubMed

    Kanekawa, Hideo

    2012-01-01

    Actual Situation and Statistical Observation on Home Custody of Mental Patients (1918) by Kure and Kashida has diverse content but contains many contradictions. This book is a record of investigations performed by 15 psychiatrists regarding home custody of mental patients in 15 prefectures between 1910 and 1916. The book is written in archaic Japanese and contains a mixture of old Kanji characters and Katakana, so few people have read the entire book in recent years. We thoroughly read the book over 2 years, and presented the results of our investigation and analysis. The contents were initially published in Tokyo Journal of Medical Sciences as a series of 4 articles, and published as a book in 1918. The Department of the Interior distributed 100 copies of the book to relevant personnel. Until its dissolution in 1947, the Department of the Interior included the Police Department and had a great deal of authority. The Health and Welfare Ministry became independent from the Department of the Interior in 1938. Therefore, mental institutions were under the supervision of the police force for many years. At the time, an important task for police officers was to search for infectious disease patients and to seclude and restrain them. Thus, home custody for mental patients was also supervised under the direction of the Police Department. This book is a record of an external investigation performed by psychiatrists on home custody supervised by the police. When investigating the conditions, one of the psychiatrists obtained a copy of "Documents for mental patients under confinement" at the local police station. The contents of these documents included records of hearings by the police, as well as applications for confinement submitted by family members, as well as detailed specifications and drawings of the confinement room. With a local photographer, they traveled deep into the mountains to investigate the conditions under which mental patients were living. The book

  1. Observed Variability of the Solar Mg II h Spectral Line

    NASA Astrophysics Data System (ADS)

    Schmit, D.; Bryans, P.; De Pontieu, B.; McIntosh, S.; Leenaarts, J.; Carlsson, M.

    2015-10-01

    The Mg ii h&k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the photosphere to the upper chromosphere. We use a double-Gaussian model to fit the Mg ii h profile for a full-Sun mosaic data set taken on 2014 August 24. We use the ensemble of high-quality profile fits to conduct a statistical study on the variability of the line profile as it relates the magnetic structure, dynamics, and center-to-limb viewing angle. The average internetwork profile contains a deeply reversed core and is weakly asymmetric at h2. In the internetwork, we find a strong correlation between h3 wavelength and profile asymmetry as well as h1 width and h2 width. The average reversal depth of the h3 core is inversely related to the magnetic field. Plage and sunspots exhibit many profiles that do not contain a reversal. These profiles also occur infrequently in the internetwork. We see indications of magnetically aligned structures in plage and network in statistics associated with the line core, but these structures are not clear or extended in the internetwork. The center-to-limb variations are compared to predictions of semi-empirical model atmospheres. We measure a pronounced limb darkening in the line core that is not predicted by the model. The aim of this work is to provide a comprehensive measurement baseline and preliminary analysis on the observed structure and formation of the Mg ii profiles observed by IRIS.

  2. New results of the spectral observations of CP stars

    NASA Astrophysics Data System (ADS)

    Polosukhina, N. S.; Shavrina, A. V.; Drake, N. A.; Kudryavtsev, D. O.; Smirnova, M. A.

    2010-04-01

    The lithium problem in Ap-CP stars has been, for a long time, a subject of debate. Individual characteristics of CP stars, such as high abundance of the rare-earth elements presence of magnetic fields, complicate structure of the surface distribution of chemical elements, rapid oscillations of some CP-stars, make the detection of the lithium lines and the determination of the lithium abundance, a difficult task. During the International Meeting in Slovakia in 1996, the lithium problem in Ap-CP stars was discussed. The results of the Li study carried out in CrAO Polosukhina (1973-1976), the works of Hack & Faraggiana (1963), Wallerstein & Hack (1964), Faraggiana et al. (1992-1996) formed the basis of the International project ‘Lithium in the cool CP-stars with magnetic fields’. The main goal of the project was, using systematical observations of Ap-CP stars with phase rotation in the spectral regions of the resonance doublet Li I 6708 Å and subordinate 6104 Å lithium lines with different telescopes, to create a database, which will permit to explain the physical origin of anomalous Li abundance in the atmospheres of these stars.

  3. OBSERVATION AND SPECTRAL MEASUREMENTS OF THE CRAB NEBULA WITH MILAGRO

    SciTech Connect

    Abdo, A. A.; Allen, B. T.; Chen, C.; Atkins, R.; Aune, T.; Benbow, W.; Coyne, D. G.; Dorfan, D. E.; Berley, D.; Blaufuss, E.; Bussons, J.; Bonamente, E.; Galbraith-Frew, J.; Christopher, G. E.; Fleysher, L.; Fleysher, R.; DeYoung, T.; Falcone, A.; Dingus, B. L.; Ellsworth, R. W.; and others

    2012-05-01

    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV-100 TeV gamma-ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between {approx}1 and {approx}100 TeV. The TeV emission is believed to be caused by inverse-Compton upscattering of ambient photons by an energetic electron population. The location of a TeV steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fitted. The differential photon energy spectrum, including the statistical errors from the fit, obtained using a simple power-law hypothesis for data between 2005 September and 2008 March is (6.5 {+-} 0.4) Multiplication-Sign 10{sup -14}(E/10 TeV){sup -3.1{+-}0.1}(cm{sup 2} s TeV ){sup -1} between {approx}1 TeV and {approx}100 TeV. Allowing for a possible exponential cutoff, the photon energy spectrum is fitted as (2.5{sup +0.7}{sub -0.4}) Multiplication-Sign 10{sup -12}(E/3 TeV){sup -2.5{+-}0.4}exp (- E/32{sup +39}{sub -18} TeV) (cm{sup 2} s TeV){sup -1}. The results are subject to an {approx}30% systematic uncertainty in the overall flux and an {approx}0.1 systematic uncertainty in the power-law indices quoted. Uncertainty in the overall energy scale has been absorbed into these errors. Fixing the spectral index to values that have been measured below 1 TeV by IACT experiments (2.4-2.6), the fit to the Milagro data suggests that Crab exhibits a

  4. Spectral models for early time SN 2011fe observations

    NASA Astrophysics Data System (ADS)

    Baron, E.; Hoeflich, P.; Friesen, Brian; Sullivan, M.; Hsiao, E.; Ellis, R. S.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Dominguez, I.; Krisciunas, K.; Phillips, M. M.; Suntzeff, N.; Wang, L.; Thomas, R. C.

    2015-12-01

    We use observed UV through near-IR spectra to examine whether SN 2011fe can be understood in the framework of Branch-normal Type Ia supernovae (SNe Ia) and to examine its individual peculiarities. As a benchmark, we use a delayed-detonation model with a progenitor metallicity of Z⊙/20. We study the sensitivity of features to variations in progenitor metallicity, the outer density profile, and the distribution of radioactive nickel. The effect of metallicity variations in the progenitor have a relatively small effect on the synthetic spectra. We also find that the abundance stratification of SN 2011fe resembles closely that of a delayed-detonation model with a transition density that has been fit to other Branch-normal SNe Ia. At early times, the model photosphere is formed in material with velocities that are too high, indicating that the photosphere recedes too slowly or that SN 2011fe has a lower specific energy in the outer ≈0.1 M⊙ than does the model. We discuss several explanations for the discrepancies. Finally, we examine variations in both the spectral energy distribution and in the colours due to variations in the progenitor metallicity, which suggests that colours are only weak indicators for the progenitor metallicity, in the particular explosion model that we have studied. We do find that the flux in the U band is significantly higher at maximum light in the solar metallicity model than in the lower metallicity model and the lower metallicity model much better matches the observed spectrum.

  5. A rapid retrieval methodology based on the spectrally integrated Voigt function for space observation spectral radiance data

    NASA Astrophysics Data System (ADS)

    Quine, Brendan M.; Abrarov, Sanjar M.; Jagpal, Raj K.

    2014-06-01

    In our recent publication, we proposed the application of the spectrally integrated Voigt function (SIVF) to a line-by-line (LBL) radiative transfer modelling1. We applied the GENSPECT LBL radiative transfer model that utilizes the HITRAN database to generate synthetic spectral data due to thermal or solar radiation of the Earth or planetary atmosphere2. It has been shown that the SIVF methodology enables the computation of a LBL radiative transfer at reduced spectral resolution model without loss in accuracy. In contrast to the traditional method of computation, the SIVF implementation accounts for the area under the Voigt function between adjacent grid points resulting in well-preserved shape of a spectral radiance even at low spectral resolution. This significant advantage of the SIVF methodology can be applied in the rapid retrieval of the space observation data, required for real-time control and decision making in future generation of the Argus3 remote-sensing microspectrometers. The spectrally integrated methodology can be generalized to other linebroadening profiles, such as Galatry, Rautian-Sobelman or speed dependent profiles, to prevent underestimation of the spectral radiance that always occurs at reduced spectral resolution1 in any LBL radiative transfer model using a traditional method of computation.

  6. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  7. Observation and Modeling of the Solar Transition Region. 1; Multi-Spectral Solar Telescope Array Observations

    NASA Technical Reports Server (NTRS)

    Oluseyi, Hakeem M.; Walker, A. B. C., II; Porter, Jason; Hoover, Richard B.; Barbee, Troy W., Jr.

    1999-01-01

    We report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.

  8. Spectral Observations and Analyses of Low-Redshift Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey Michael

    , SNe Ia that show strong evidence for interaction with circumstellar material or an aspherical explosion are found to have the largest near-maximum expansion velocities and pEWs, possibly linking extreme values of spectral observables with specific progenitor or explosion scenarios. The fourth Chapter of this Thesis presents comparisons of spectral feature measurements to photometric properties of 115 low-redshift (z < 0.1) SNe Ia with optical spectra within 5 d of maximum brightness. The spectral data come from the BSNIP sample described in Chapter 2, and the photometric data come mainly from the Lick Observatory Supernova Search (LOSS) and are published by Ganeshalingam et al. (2010). The spectral measurements come from BSNIP II (Chapter 3 of this Thesis) and the light-curve fits and photometric parameters can be found in Ganeshalingam et al. (in preparation). A variety of previously proposed correlations between spectral and photometric parameters are investigated using the large and self-consistent BSNIP dataset. We also use a combination of light-curve parameters (specifically the SALT2 stretch and color parameters x1 and c) and spectral measurements to calculate distance moduli. The residuals from these models is then compared to the standard model which only uses light-curve stretch and color. The pEW of Si II lambda4000 is found to be a good indicator of light-curve width and the pEWs of the Mg II and Fe II complexes are relatively good proxies for color. Chapter 5 presents and analyzes optical photometry and spectra of the extremely luminous and slowly evolving Type Ia SN 2009dc, and offers evidence that it is a super-Chandrasekhar mass (SC) SN Ia and thus had a SC white dwarf (WD) progenitor. I calculate a lower limit to the peak bolometric luminosity of ˜2.4x1043 erg s-1, though the actual value is likely almost 40% larger. The high luminosity and low expansion velocities of SN 2009dc lead to a derived WD progenitor mass of more than 2 MSun and a 56Ni mass

  9. Spectral Invariance Principles Observed in Spectral Radiation Measurements of the Transition Zone

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander

    2011-01-01

    The main theme for our research is the understanding and closure of the surface spectral shortwave radiation problem in fully 3D cloud situations by combining the new ARM scanning radars, shortwave spectrometers, and microwave radiometers with the arsenal of radiative transfer tools developed by our group. In particular, we define first a large number of cloudy test cases spanning all 3D possibilities not just the customary uniform-overcast ones. Second, for each case, we define a "Best Estimate of Clouds That Affect Shortwave Radiation" using all relevant ARM instruments, notably the new scanning radars, and contribute this to the ARM Archive. Third, we test the ASR-signature radiative transfer model RRTMG_SW for those cases, focusing on the near-IR because of long-standing problems in this spectral region, and work with the developers to improve RRTMG_SW in order to increase its penetration into the modeling community.

  10. Simultaneous Spectral and Timing Observations of Accreting Neutron Stars

    NASA Technical Reports Server (NTRS)

    Kaaret, P.

    2000-01-01

    All six Rossi Timing Explorer (RXTE) observations approved for this proposal were car- ried out. Four of the observations were simultaneous with BeppoSAX (two of the source 4Ul820-30, and one each of 4U1636-536 and 4U0614+091) and two were simultaneous with ASCA (of 4Ul636-536 and of 4U0614+091). RXTE experienced a single event upset and went into a safe hold mode during the first 4U0614+091 observation and remained in safe hold until after the scheduled start of the second 4U0614+091 observation. An additional observation of 4U0614+091 was performed with RXTE to make up for the lost time. However, it was not possible to arrange for simultaneous observations with either BeppoSAX or ASCA. Our work has led to three papers directly related to observations made - one paper for each source observed - and one additional paper summarizing our progress in this field. In addition, several reports on these results were made at various conferences.

  11. Observed Differences in Spectral Microphysical Retrievals from MODIS

    NASA Technical Reports Server (NTRS)

    Platnick, Steven E.; Zhang, Zhibo; Maddox, Brent; Ackeman, Steven A.

    2010-01-01

    The microphysical structure of clouds is of fundamental importance for understanding a variety of cloud radiation and physical processes. With the advent of MODIS (Moderate Resolution Imaging Spectroradiometer) on the NASA EOS Terra and Aqua platforms, simultaneous global/daily 1km retrievals of cloud effective particle size are available using the heritage 3.7 an band from AVHRR as well as the 1.6 and 2.1 m shortwave IR bands. The MODIS cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate effective radii results using each of these spectral bands. It has been found that significant differences can occur between the three size retrievals, mainly for liquid water marine boundary layer clouds and especially in broken (low cloud fraction) regimes. In particular, for such regimes, effective radii derived from the MODIS 2.1 lim band can be substantially larger than retrievals from the Heritage 3.7 lam band. In this paper, we present global and regional results of the differences, including correlations, view angle dependencies, and algorithm sensitivities for the existing MODIS Collection 5 product.

  12. Spitzer spectral observations of the deep impact ejecta.

    PubMed

    Lisse, C M; Vancleve, J; Adams, A C; A'hearn, M F; Fernández, Y R; Farnham, T L; Armus, L; Grillmair, C J; Ingalls, J; Belton, M J S; Groussin, O; McFadden, L A; Meech, K J; Schultz, P H; Clark, B C; Feaga, L M; Sunshine, J M

    2006-08-01

    Spitzer Space Telescope imaging spectrometer observations of comet 9P/Tempel 1 during the Deep Impact encounter returned detailed, highly structured, 5- to 35-micrometer spectra of the ejecta. Emission signatures due to amorphous and crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas and ice, and sulfides were found. Good agreement is seen between the ejecta spectra and the material emitted from comet C/1995 O1 (Hale-Bopp) and the circumstellar material around the young stellar object HD100546. The atomic abundance of the observed material is consistent with solar and C1 chondritic abundances, and the dust-to-gas ratio was determined to be greater than or equal to 1.3. The presence of the observed mix of materials requires efficient methods of annealing amorphous silicates and mixing of high- and low-temperature phases over large distances in the early protosolar nebula. PMID:16840662

  13. Spectral lag features of GRB 060814 from swift bat and Suzaku observations

    SciTech Connect

    Roychoudhury, Arundhati; Sarkar, Samir K.; Bhadra, Arunava E-mail: samirksarkar@rediffmail.com

    2014-02-20

    This work reports a study on the spectral lag of the prompt emission spectrum of a multi-pulse gamma-ray burst (GRB) GRB 060814 (z = 0.84) using the observations of the Swift Burst Alert Telescope and the Suzaku Wide Area Monitor. We found that the spectral lag for GRB 060814 is positive for the first two and the fourth pulses, while the third pulse exhibits negative lag. However, the time variation of the E {sub peak} of all the stated pulses shows a similar trend. The leading models for spectral lags in GRBs are thus found inadequate to explain the observed spectral lag features of GRB 060814. Probable causes of the spectral lag characteristics of GRB 060814 are discussed.

  14. Late-Time Spectral Observations of Type IIP Supernovae

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Pickett, Stephanie; Wheeler, J. Craig; Filippenko, Alexei

    2016-01-01

    Type II-Plateau supernovae (SNe IIP) are H-rich explosions that come from red supergiant (RSG) progenitors. Despite the fact that they are the most common subtype of SN, little work has been done on late-time observations of SNe IIP owing to their relative faintness at these epochs. We analyze 91 late-time (older than about 100 days past explosion) optical spectra of 38 SNe IIP, making this the largest sample of SN IIP nebular spectra ever studied. Quantitative criteria from the spectra themselves are employed to determine if an observation is truly nebular, and thus should be included in the study. We measure the fluxes, shapes, and velocities of various emission lines and investigate their temporal evolution. These values are also compared to photometric data in order to search for correlations that may allow us to gain insight into the RSG progenitors of SNe IIP and learn more about the details of the explosion itself.

  15. Thermal-infrared spectral observations of geologic materials in emission

    NASA Technical Reports Server (NTRS)

    Christensen, Philip R.; Luth, Sharon J.

    1987-01-01

    The thermal-infrared spectra of geologic materials in emission were studied using the prototype Thermal Emission Spectrometer (TES). A variety of of processes and surface modifications that may influence or alter the spectra of primary rock materials were studied. It was confirmed that thermal emission spectra contain the same absorption features as those observed in transmission and reflection spectra. It was confirmed that the TES instrument can be used to obtain relevant spectra for analysis of rock and mineral composition.

  16. Modeling Spectral Turnovers in Interplanetary Shocks Observed by ULYSSES

    NASA Astrophysics Data System (ADS)

    Summerlin, E. J.; Baring, M. G.

    2009-12-01

    Interplanetary shocks in the heliosphere provide excellent test cases for the simulation and theory of particle acceleration at shocks thanks to the presence of in-situ measurements and a relatively well understood initial particle distribution. The Monte-Carlo test particle simulation employed in this work has been previously used to study injection and acceleration from thermal energies into the high energy power-law tail at co-rotating interaction regions (CIRs) in the heliosphere presuming a steady state planar shock (Summerlin & Baring, 2006, Baring and Summerlin, 2008). These simulated power-spectra compare favorably with in-situ measurements from the ULYSSES spacecraft below 60 keV. However, to effectively model the high energy exponential cutoff at energies above 60 keV observed in these distributions, simulations must apply spatial or temporal constraints to the acceleration process. This work studies the effects of a variety of temporal and spatial co! nstraints (including spatial constraints on the turbulent region around the shock as determined by magnetometer data, spatial constraints related to the scale size of the shock and constraints on the acceleration time based on the known limits for the shock's lifetime) on the high energy cut-off and compares simulated particle spectra to those observed by the ULYSSES HI-SCALE instrument in an effort to determine which constraint is creating the cut-off and using that constraining parameter to determine additional information about the shock that can not, normally, be determined by a single data point, such as the spatial extent of the shock or how long the shock has been propagating through the heliosphere before it encounters the spacecraft. Shocks observed by multiple spacecraft will be of particular interest as their parameters will be better constrained than shocks observed by only one spacecraft. To achieve these goals, the simulation will be modified to include the re! trodictive approach of Jones

  17. Late-time Spectral Observations of Type IIP Supernovae

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey Michael; Pickett, Stephanie; Wheeler, J. Craig; Filippenko, Alex

    2015-08-01

    We analyse late-time (older than about 150 days past explosion) optical spectra of Type II-Plateau (IIP) supernovae (SNe), which are H-rich SNe that come from red supergiant (RSG) progenitors. The dataset includes over 100 spectra of about 50 objects, making this the largest sample of SN IIP nebular spectra ever investigated. Quantitative criteria from within the spectra themselves are employed to determine if an observation is truly nebular, and thus should be included in the study. We present the temporal evolution of the fluxes, shapes, and velocities of various emission lines. These measured values are also compared to photometric data in order to search for correlations that can allow us to gain insight into the diversity of RSG progenitors and learn more about the details of the explosion itself.

  18. RXTE observation of Cygnus X-1 - I. Spectral analysis

    NASA Astrophysics Data System (ADS)

    Dove, James B.; Wilms, Jörn; Nowak, Michael A.; Vaughan, Brian A.; Begelman, Mitchell C.

    1998-08-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200keV, using data from a 10-ks observation by the Rossi X-ray Timing Explorer (RXTE). The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Γ=1.45+0.01-0.02 (a value considerably harder than is typically found), e-folding energy Ef=162+9-8keV, plus a deviation from a power law that formally can be modelled as a thermal blackbody with temperature kTbb=1.2+0.0-0.1keV. Although the 3-30 keV portion of the spectrum can be fitted with a reflected power law with Γ=1.81+/-0.01 and covering fraction f=0.35+/-0.02, the quality of the fit is significantly reduced when the HEXTE data in the 30-100 keV range are included, as there is no observed softening in the power law within this energy range. As a physical description of this system, we apply the accretion disc corona models of Dove, Wilms &38 Begelman, in which the temperature of the corona is determined self-consistently. A spherical corona with a total optical depth τ=1.6+/-0.1 and an average temperature kTc=87+/-5keV, surrounded by an exterior cold disc, does provide a good description of the data (χ2red=1.55). These models deviate from the data by up to 7 per cent in the 5-10keV range, and we discuss possible reasons for these discrepancies. However, considering how successfully the spherical corona reproduces the 10-200keV data, such `photon-starved' coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  19. RXTE Observation of Cygnus X-1. 1; Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Dove, James B.; Wilms, Joern; Nowak, Michael A.; Vaughan, Brian A.; Begelman, Mitchell C.

    1998-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Gamma = 1.45(+0.01 -0.02) (a value considerably harder 0.02 than typically found), e-folding energy E(sub f) = 162(+9 -8) keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody with temperature kT(sub bb) = 1.2(+0.0 -0.1) keV. Although the 3-30 keV portion of the spectrum can be fit with a reflected power law with Gamma = 1.81 + or - 0.01 and covering fraction f = 0.35 + or - 0.02, the quality of the fit is significantly reduced when the HEXTE data in the 30-100 keV range is included, as there is no observed hardening in the power law within this energy range. As a physical description of this system, we apply the accretion disc corona models of Dove, Wilms & Begelman (1997a) - where the temperature of the corona is determined self-consistently. A spherical corona with a total optical depth pi = 1.6 + or - 0.1 and an average temperature kT(sub c) = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X(exp 2 sub red) = 1.55). These models deviate from red the data by up to 7% in the 5 - 10 keV range, and we discuss possible reasons for these discrepancies. However, considering bow successfully the spherical corona reproduces the 10 - 200 keV data, such "pboton-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  20. RXTE observation of Cygnus X-1: spectral analysis

    NASA Astrophysics Data System (ADS)

    Dove, J. B.; Wilms, Jörn; Nowak, M. A.; Vaughan, B. A.; Begelman, M. C.

    1999-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200keV, using data from a 10ksec observation by the Rossi X-ray Timing Explorer. Although the spectrum can be well described phenomenologically by an exponentially cut-off power law (photon index Γ=1.45+0.01-0.02, e-folding energy Ef=162+9-8keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody with temperature kTBB=1.2+0.0-0.1keV), the inclusion of a reflection component does not improve the fit. As a physical description of this system, we apply the accretion disc corona (ADC0 models of Dove, Wilms & Begelman [1]). A slab-geometry ADC model is unable to describe the data. However, a spherical corona, with a total optical depth τ=1.6+/-0.1 and an average temperature kTC=87+/-5keV, surrounded by an exterior cold disc, does provide a good description of the data (χ2red=1.55). These models deviate from the data by up to 7% in the 5-10keV range. However, considering how successfully the spherical corona reproduces the 10-200keV data, such ``photon-starved'' coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  1. GBT spectral monitoring observations of megamaser disk systems

    NASA Astrophysics Data System (ADS)

    Pesce, Dominic; Braatz, James A.; Condon, James J.; Gao, Feng; Henkel, Christian; Litzinger, Eugenia; Lo, Fred K. Y.; Reid, Mark J.; Megamaser Cosmology Project

    2016-01-01

    We use single-dish radio spectra of known 22 GHz H2O megamasers, primarily gathered from the large data set observed by the Megamaser Cosmology Project, to investigate various aspects of the accretion disk physics. We characterize the several classes of variability present in the megamaser spectra, which have different timescales and presumed underlying physical causes. In doing so, we found rapid intra-day variability in the maser spectrum of ESO 558-G009 that is likely the result of interstellar scintillation, for which we favor a nearby (D~70 pc) scattering screen. We also set limits on the magnetic field strengths in seven sources, using strong flaring events to check for the presence of Zeeman splitting. These limits are typically 200-300 mG (1σ), but our most stringent limit reaches 73 mG for the galaxy NGC 1194. These measurements begin to probe the regime where the magnetic pressure becomes comparable to the gas pressure in the disk, thereby placing constraints on the vertical support mechanism.

  2. Observation and Spectral Measurements of the Crab Nebula with Milagro

    NASA Technical Reports Server (NTRS)

    Abdo, A. A.; Allen, B. T.; Aune, T.; Benbow, W.; Berley, D.; Chen, C.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Falcone, A.; Fleysher, L.; Fleysher, R.; Gonzalez, M. M.; Goodman, J. A.; Gordo, J. B.; Hays, E.; Hoffman, C. M.; Huntemeyer, P. H.; Kolterman, B. E.; Linnemann, J. T.; McEnery, J. E.; Morgan, T.; Mincer, A. I.; Nemethy, P.

    2011-01-01

    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV - 100 TeV gamma ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between 1 and 100 TeV. The TeV emission is believed to be caused by inverse-Compton up-scattering scattering of ambient photons by an energetic electron population. The location of a Te V steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fit.

  3. Spectral Analysis of Velocities in Quiescent Prominences Observed with Hinode

    NASA Astrophysics Data System (ADS)

    McKenzie, David; Freed, Michael

    2015-04-01

    High-resolution observations of solar prominences, especially with the Solar Optical Telescope (SOT) on Hinode, reveal the presence of upward and downward flows consistent with convection, at length scales that were not accessible with previous telescopes. Since prominences are magnetic structures, the strength and arrangement of their magnetic fields are crucial for determining whether a given prominence will erupt into a coronal mass ejection. Convective flows can twist and tangle those magnetic fields. However, the magnetic fields within the prominences are extremely difficult to measure; therefore measurements of the dynamics of the magnetized plasma in prominences, and the balance between magnetic and gas-pressure forces, are valuable for understanding how these apparently stable structures can evolve to become suddenly eruptive. We will show our findings from analysis of the dynamics in a few solar prominences using local correlation tracking, and make estimates of the kinetic energy, diffusivity, and vorticity.This work is supported by NASA under contract NNM07AB07C with the Smithsonian Astrophysical Observatory.

  4. RXTE Observation of Cygnus X-1 Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Dove, J. B.; Wilms, Joern; Nowak, M. A.; Vaughan, B. A.; Begelman, M. C.

    1998-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. Although the spectrum can be well described phenomenologically by an exponentially cut-off power law (photon index Gamma = 1.45+0.01 -0.02 , e-folding energy e(sub f) = 162+9 -8 keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody, with temperature kT(sub BB) = 1.2 +0.0 -0.1 keV), the inclusion of a reflection component does not improve the fit. As a physical description of this system, we apply the accretion disc corona (ADC) models. A slab-geometry ADC model is unable to describe the data. However, a spherical corona, with a total optical depth tau- = 1.6 + or - 0.1 and an average temperature kTc = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X red (exp 2) = 1.55). These models deviate from the data bv up to 7% in the 5-10 keV range. However, considering how successfully the spherical corona reproduces the 10-200 keV data, such "photon-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  5. The Atmospheric Infrared Sounder on the Earth Observing System - In-orbit spectral calibration

    NASA Technical Reports Server (NTRS)

    Aumann, H. H.

    1991-01-01

    The Atmospheric Infrared Sounder (AIRS) is a facility instrument on the Earth Observing System (EOS). The ability of AIRS to provide accurate temperature and moisture soundings with high vertical resolution depends critically on a very accurate spectral calibration. The routine in-orbit spectral calibration is accomplished with a Fabry-Perot plate with a fixed spacing of 360 microns. This paper discusses design, Signal-to-Noise, and temperature and alignment stability constraints which have to be met to achieve the required spectral calibration accuracy.

  6. Global patterns of annual actual evapotranspiration with land-cover type: knowledge gained from a new observation-based database

    NASA Astrophysics Data System (ADS)

    Ambrose, S. M.; Sterling, S. M.

    2014-10-01

    The process of evapotranspiration (ET) plays a critical role in the earth system, driving key land-surface processes in the energy, water and carbon cycles. Land-cover (LC) exerts multiple controls on ET, yet the global distribution of ET by LC and the related physical variables are poorly understood. The lack of quantitative understanding of global ET variation with LC begets considerable uncertainties regarding how ET and key land-surface processes will change alongside ongoing anthropogenic LC transformations. Here we apply statistical analysis and models to a new global ET database to advance our understanding of how annual actual ET varies with LC type. We derive global fields for each LC using linear mixed effect models (LMMs) that use geographical and meteorological variables as possible independent regression variables. Our inventory of ET observations reveals important gaps in spatial coverage that overlie hotpots of global change. There is a spatial bias of observations towards the mid latitudes, and LCs with large areas in the high latitudes (lakes, wetlands and barren land) are poorly represented. From the distribution of points as well as the uncertainty analysis completed by bootstrapping we identify high priority regions in need of more data collection. Our analysis of the new database provides new insights into how ET varies globally, providing more robust estimates of global ET rates for a broad range of LC types. Results reveal that different LC types have distinct global patterns of ET. Furthermore, zonal ET means among LCs reveal new patterns: ET rates in low latitudinal bands are more sensitive to LC change than in higher latitude bands; LCs with a higher evaporation component show higher variability of ET at the global scale; and LCs with dispersed rather than contiguous global locations have a higher variability of ET at the global scale. Results from this study indicate two major advancements are required to improve our ability to predict

  7. Inference of Surface Chemical and Physical Properties Using Mid-Infrared (MIR) Spectral Observations

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.

    2016-01-01

    Reflected or emitted energy from solid surfaces in the solar system can provide insight into thermo-physical and chemical properties of the surface materials. Measurements have been obtained from instruments located on Earth-based telescopes and carried on several space missions. The characteristic spectral features commonly observed in Mid-Infrared (MIR) spectra of minerals will be reviewed, along with methods used for compositional interpretations of MIR emission spectra. The influence of surface grain size, and space weathering processes on MIR emissivity spectra will also be discussed. Methods used for estimating surface temperature, emissivity, and thermal inertias from MIR spectral observations will be reviewed.

  8. New spectral observations of Callisto and leading/trailing hemisphere distinctions

    NASA Technical Reports Server (NTRS)

    Calvin, W. M.; Clark, R. N.; King, T. V. V.

    1991-01-01

    In December 1989 and January 1990, new observations of the leading and trailing edges of Callisto were made from the NASA Infrared Telescope Facility on Mauna Kea in Hawaii. Using the Cool Grating Array Spectrometer, spectral coverage was obtained from 1.89 to 2.46 microns and from 2.8 to 4.2 microns for both the leading and trailing hemispheres. In addition, spectral coverage of the leading hemisphere was obtained from 1.30 to 2.55 microns and from 4.2 to 4.8 microns. Interpretations of the data are given.

  9. What Do Millimeter Continuum and Spectral Line Observations Tell Us about Solar System Bodies?

    NASA Technical Reports Server (NTRS)

    Milam, Stefanie N.

    2013-01-01

    Solar system objects are generally cold and radiate at low frequencies and tend to have strong molecular rotational transitions. Millimeter continuum and spectral line observations provide detailed information for nearly all solar system bodies. At these wavelengths, details of the bulk physical composition of icy surfaces, the size and albedo of small objects, the composition of planetary atmospheres can be measured as well as monitoring of time variable phenomena for extended periods (not restricted to nighttime observations), etc. Major issues in solar system science can be addressed by observations in the millimeter/sub-millimeter regime such as the origin of the solar system (isotope ratios, composition) and the evolution of solar system objects (dynamics, atmospheric constituents, etc). ALMA s exceptional sensitivity, large spectral bandwidth, high spectral resolution, and angular resolution (down to 10 milliarcsec) will enable researchers for the first time to better resolve the smallest bodies in the solar system and provide detailed maps of the larger objects. Additionally, measurements with nearly 8 GHz of instantaneous bandwidth to fully characterize solar system object s spectrum and detect trace species. The spatial information and line profiles can be obtained over 800 GHz of bandwidth in 8 receiver bands to not only assist in the identification of spectral lines and emission components for a given species but also to help elucidate the chemistry of the extraterrestrial bodies closest to us.

  10. Spectral distinctions between the leading and trailing hemispheres of Callisto - New observations

    NASA Technical Reports Server (NTRS)

    Calvin, Wendy M.; Clark, Roger N.

    1993-01-01

    Recent spectral observations of both the leading and trailing hemispheres of Callisto confirm the conclusions of Calvin and Clark (1991) that the water ice is typically large-grained, and the general spectral trend from 3 to 43 microns is caused by an adsorbed water band associated with hydrous minerals. On the leading hemisphere, a broad absorption near 3.4 microns was definitively identified and interpreted as being caused by fine-grained water ice. This band, coupled with the slope in the region from 2 to 2.5 microns, is indicative of a small amount, on the order of 1 to 2 percent, of fine-grained ice on the leading side. It is suggested that in the longer wavelength spectral region on the leading hemisphere an additional band correlated with NH4-bearing clays may be indicated.

  11. RXTE Observations of A1744-361: Correlated Spectral and Timing Behavior

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Sudip; Strohmayer, Tod E.; Swank, Jean H.; Markwardt, Craig B.

    2007-01-01

    We analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data of the transient low mass X-ray binary (LMXB) system A1744-361. We explore the X-ray intensity and spectral evolution of the source, perform timing analysis, and find that A1744-361 is a weak LMXB, that shows atoll behavior at high intensity states. The color-color diagram indicates that this LMXB was observed in a low intensity spectrally hard (low-hard) state and in a high intensity banana state. The low-hard state shows a horizontal pattern in the color-color diagram, and the previously reported dipper QPO appears only during this state. We also perform energy spectral analyses, and report the first detection of broad iron emission line and iron absorption edge from A1744-361.

  12. Spectral formation in black hole and neutron star binaries: theory vs observations

    NASA Astrophysics Data System (ADS)

    Gilfanov, Marat

    2016-07-01

    I will discuss spectral formation in X-ray binaries with particular emphasis on the dichotomy between black holes and neutron stars. Predictions of theoretical models will be confronted with observations of compact X-ray sources in the Milky Way and beyond. I will discuss how the difference in the nature of the compact object leads to observable differences between accreting neutron stars and black holes and how accretion regimes change across the mass accretion rate range. This will be illustrated with observations of X-ray binaries in the Milky Way and external galaxies, the latter providing us with a unique possibility to explore accretion at its extremities.

  13. Design of multivariable feedback control systems via spectral assignment using reduced-order models and reduced-order observers

    NASA Technical Reports Server (NTRS)

    Mielke, R. R.; Tung, L. J.; Carraway, P. I., III

    1984-01-01

    The feasibility of using reduced order models and reduced order observers with eigenvalue/eigenvector assignment procedures is investigated. A review of spectral assignment synthesis procedures is presented. Then, a reduced order model which retains essential system characteristics is formulated. A constant state feedback matrix which assigns desired closed loop eigenvalues and approximates specified closed loop eigenvectors is calculated for the reduced order model. It is shown that the eigenvalue and eigenvector assignments made in the reduced order system are retained when the feedback matrix is implemented about the full order system. In addition, those modes and associated eigenvectors which are not included in the reduced order model remain unchanged in the closed loop full order system. The full state feedback design is then implemented by using a reduced order observer. It is shown that the eigenvalue and eigenvector assignments of the closed loop full order system rmain unchanged when a reduced order observer is used. The design procedure is illustrated by an actual design problem.

  14. Design of multivariable feedback control systems via spectral assignment using reduced-order models and reduced-order observers

    NASA Technical Reports Server (NTRS)

    Mielke, R. R.; Tung, L. J.; Carraway, P. I., III

    1985-01-01

    The feasibility of using reduced order models and reduced order observers with eigenvalue/eigenvector assignment procedures is investigated. A review of spectral assignment synthesis procedures is presented. Then, a reduced order model which retains essential system characteristics is formulated. A constant state feedback matrix which assigns desired closed loop eigenvalues and approximates specified closed loop eigenvectors is calculated for the reduced order model. It is shown that the eigenvalue and eigenvector assignments made in the reduced order system are retained when the feedback matrix is implemented about the full order system. In addition, those modes and associated eigenvectors which are not included in the reduced order model remain unchanged in the closed loop full order system. The fulll state feedback design is then implemented by using a reduced order observer. It is shown that the eigenvalue and eigenvector assignments of the closed loop full order system remain unchanged when a reduced order observer is used. The design procedure is illustrated by an actual design problem.

  15. Seasonality of spectral albedo and transmittance as observed in the Arctic Transpolar Drift in 2007

    NASA Astrophysics Data System (ADS)

    Nicolaus, Marcel; Gerland, Sebastian; Hudson, Stephen R.; Hanson, Susanne; Haapala, Jari; Perovich, Donald K.

    2010-11-01

    The first continuous and high temporal resolution record of spectral albedo and transmittance of snow and sea ice in the Arctic Ocean over an entire summer season is presented. Measurements were performed at a manned station on multiyear sea ice in the Transpolar Drift during the drift of the schooner Tara from April to September 2007. Concurrent autonomous measurements of ice mass balance and weekly observations of snow and sea-ice properties complement the data set. The seasonality of physical and biological processes of snow and sea ice is characterized, including quantification of melt onset (10 June), melt season duration, and freeze onset (15 August). Over one year, approximately two thirds of the transmitted energy reached the ocean during the 66-day-long melt season. During the second half of July, transmitted irradiance decreased by 90% and absorption in and directly under the ice increased, significantly affecting the vertical partitioning of irradiance. The spectral radiation time series suggests that high biomass abundance in or below the sea ice caused this decrease. Comparing the spectral data set with broadband albedo data measured at the same location shows that 90% of the temporal variability of broadband albedo can be explained by variability in spectral albedo integrated over the limited wavelength range. The combination of spectral radiation and ice mass balance measurements allows a comprehensive description, and quantification, of snow and sea-ice processes, even with minimal additional in situ observations, suggesting such data sets can be collected autonomously to provide insight into the physical and biological processes on sea ice.

  16. Stochastic analysis of multiple-passband spectral classifications systems affected by observation errors

    NASA Technical Reports Server (NTRS)

    Tsokos, C. P.

    1980-01-01

    The classification of targets viewed by a pushbroom type multiple band spectral scanner by algorithms suitable for implementation in high speed online digital circuits is considered. A class of algorithms suitable for use with a pipelined classifier is investigated through simulations based on observed data from agricultural targets. It is shown that time distribution of target types is an important determining factor in classification efficiency.

  17. Understanding the Long-Term Spectral Variability of Cygnus X-1 from BATSE and ASM Observations

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Poutanen, Juri; Paciesas, William S.; Wen, Linqing; Six, N. Frank (Technical Monitor)

    2002-01-01

    We present a spectral analysis of observations of Cygnus X-1 by the RXTE/ASM (1.5-12 keV) and CGRO/BATSE (20-300 keV), including about 1200 days of simultaneous data. We find a number of correlations between intensities and hardnesses in different energy bands from 1.5 keV to 300 keV. In the hard (low) spectral state, there is a negative correlation between the ASM 1.5-12 keV flux and the hardness at any energy. In the soft (high) spectral state, the ASM flux is positively correlated with the ASM hardness (as previously reported) but uncorrelated with the BATSE hardness. In both spectral states, the BATSE hardness correlates with the flux above 100 keV, while it shows no correlation with the flux in the 20-100 keV range. At the same time, there is clear correlation between the BATSE fluxes below and above 100 keV. In the hard state, most of the variability can be explained by softening the overall spectrum with a pivot at approximately 50 keV. The observations show that there has to be another, independent variability pattern of lower amplitude where the spectral shape does not change when the luminosity changes. In the soft state, the variability is mostly caused by a variable hard (Comptonized) spectral component of a constant shape superimposed on a constant soft blackbody component. These variability patterns are in agreement with the dependence of the rms variability on the photon energy in the two states. We interpret the observed correlations in terms of theoretical Comptonization models. In the hard state, the variability appears to be driven mostly by changing flux in seed photons Comptonized in a hot thermal plasma cloud with an approximately constant power supply. In the soft state, the variability is consistent with flares of hybrid, thermal/nonthermal, plasma with variable power above a stable cold disk. Also, based on broadband pointed observations simultaneous with those of the ASM and BATSE, we find the intrinsic bolometric luminosity increases by a

  18. Spectral separation of wind sea and swell based on buoy observations

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Hao, Zengzhou; Gong, Fang; Wang, Tianyu; Chen, Jianyu

    2015-10-01

    Coexistence of swells from distant sources and wind seas generated by local wind field results in complex surface wave condition. Identification and separation analysis of wave components of the wind sea and swell provide a more realistic depiction of the sea state and is important for understanding of the mechanisms of climate variability in the wave field. Spectral separating is one of the most important methods in partitioning waves. Two separating methods including the initial wave steepness method (STPN) and modified wave steepness method (MSTPN) that proposed by the National Data Buoy Center (NDBC) are described in this paper. And the NDBC buoy observations are applied in this study to investigate STPN and MSTPN. Although MSTPN method is improved from the STPN method, it is still not fit for the swell effect. Considering limitations mentioned above, we use spectral energy proportion (SEP) to describe the swell effect and abstract the valid data according to this index. Finally, we give a description of correlation between significant wave height (SWH) and wind speed under the wind sea condition. From results, it is shown that SWH and wind speed of wind sea have a quasiquadratic fitting relationship. In addition, it shows that MSTPN is a better performance in application as expected. Our work for spectral partitioning algorithms could provide a reference for the future work in satellite spectral data. And a practical method for deriving the SWHs from wind speed of scatterometer will be realized on the basis of the empirical wind and sea relationship.

  19. Spectral irradiance variations: comparison between observations and the SATIRE model on solar rotation time scales

    NASA Astrophysics Data System (ADS)

    Unruh, Y. C.; Krivova, N. A.; Solanki, S. K.; Harder, J. W.; Kopp, G.

    2008-07-01

    Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance observations taken with SORCE/SIM, SoHO/VIRGO, and UARS/SUSIM. The calculations assume LTE and are based on the SATIRE (Spectral And Total Irradiance REconstruction) model. We analyse the variability as a function of wavelength and present time series in a number of selected wavelength regions covering the UV to the NIR. We also show the facular and spot contributions to the total calculated variability. Results: In most wavelength regions, the variability agrees well between all sets of observations and the model calculations. The model does particularly well between 400 and 1300 nm, but fails below 220 nm, as well as for some of the strong NUV lines. Our calculations clearly show the shift from faculae-dominated variability in the NUV to spot-dominated variability above approximately 400 nm. We also discuss some of the remaining problems, such as the low sensitivity of SUSIM and SORCE for wavelengths between approximately 310 and 350 nm, where currently the model calculations still provide the best estimates of solar variability.

  20. Far-infrared Spectral Radiance Observations and Modeling of Arctic Cirrus: Preliminary Results From RHUBC

    NASA Astrophysics Data System (ADS)

    Humpage, Neil; Green, Paul D.; Harries, John E.

    2009-03-01

    Recent studies have highlighted the important contribution of the far-infrared (electromagnetic radiation with wavelengths greater than 12 μm) to the Earth's radiative energy budget. In a cloud-free atmosphere, a significant fraction of the Earth's cooling to space from the mid- and upper troposphere takes place via the water vapor pure rotational band between 17 and 33 μm. Cirrus clouds also play an important role in the Earth's outgoing longwave radiation. The effect of cirrus on far-infrared radiation is of particular interest, since the refractive index of ice depends strongly on wavelength in this spectral region. The scattering properties of ice crystals are directly related to the refractive index, so consequently the spectral signature of cirrus measured in the FIR is sensitive to the cloud microphysical properties [1, 2]. By examining radiances measured at wavelengths between the strong water vapor absorption lines in the FIR, the understanding of the relationship between cirrus microphysics and the radiative transfer of thermal energy through cirrus may be improved. Until recently, very few observations of FIR spectral radiances had been made. The Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) was developed by Imperial College to address this lack of observational data. TAFTS observes both zenith and nadir radiances at 0.1 cm-1 resolution, between 80 and 600 cm-1. During February and March 2007, TAFTS was involved in RHUBC (the Radiative Heating in Under-explored Bands Campaign), an ARM funded field campaign based at the ACRF-North Slope of Alaska site near Barrow, situated at 71° latitude. Infrared zenith spectral observations were taken by both TAFTS and the AERI-ER (spectral range 400-3300 cm-1) from the ground during both cloud-free and cirrus conditions. A wide range of other instrumentation was also available at the site, including a micropulse lidar, 35 GHz radar and the University of Colorado/NOAA Ground-based Scanning Radiometer

  1. The Lockman Hole project: LOFAR observations and spectral index properties of low-frequency radio sources

    NASA Astrophysics Data System (ADS)

    Mahony, E. K.; Morganti, R.; Prandoni, I.; van Bemmel, I. M.; Shimwell, T. W.; Brienza, M.; Best, P. N.; Brüggen, M.; Rivera, G. Calistro; de Gasperin, F.; Hardcastle, M. J.; Harwood, J. J.; Heald, G.; Jarvis, M. J.; Mandal, S.; Miley, G. K.; Retana-Montenegro, E.; Röttgering, H. J. A.; Sabater, J.; Tasse, C.; van Velzen, S.; van Weeren, R. J.; Williams, W. L.; White, G. J.

    2016-09-01

    The Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterising the physical and evolutionary properties of the various source populations detected in deep radio fields (mainly star-forming galaxies and AGNs). In this paper we present new 150-MHz observations carried out with the LOw Frequency ARray (LOFAR), allowing us to explore a new spectral window for the faint radio source population. This 150-MHz image covers an area of 34.7 square degrees with a resolution of 18.6×14.7 arcsec and reaches an rms of 160 μJy beam-1 at the centre of the field. As expected for a low-frequency selected sample, the vast majority of sources exhibit steep spectra, with a median spectral index of α _{150}^{1400}=-0.78± 0.015. The median spectral index becomes slightly flatter (increasing from α _{150}^{1400}=-0.84 to α _{150}^{1400}=-0.75) with decreasing flux density down to S150 ˜10 mJy before flattening out and remaining constant below this flux level. For a bright subset of the 150-MHz selected sample we can trace the spectral properties down to lower frequencies using 60-MHz LOFAR observations, finding tentative evidence for sources to become flatter in spectrum between 60 and 150 MHz. Using the deep, multi-frequency data available in the Lockman Hole, we identify a sample of 100 Ultra-steep spectrum (USS) sources and 13 peaked spectrum sources. We estimate that up to 21 per cent of these could have z > 4 and are candidate high-z radio galaxies, but further follow-up observations are required to confirm the physical nature of these objects.

  2. Assessing Spectral Shortwave Cloud Observations at the Southern Great Plains Facility

    NASA Technical Reports Server (NTRS)

    McBride, P. J.; Marshak, A.; Wiscombe, W. J.; Flynn, C. J.; Vogelmann, A. M.

    2012-01-01

    The Atmospheric Radiation Measurement (ARM) program (now Atmospheric System Research) was established, in part, to improve radiation models so that they could be used reliably to compute radiation fluxes through the atmosphere, given knowledge of the surface albedo, atmospheric gases, and the aerosol and cloud properties. Despite years of observations, discrepancies still exist between radiative transfer models and observations, particularly in the presence of clouds. Progress has been made at closing discrepancies in the spectral region beyond 3 micron, but the progress lags at shorter wavelengths. Ratios of observed visible and near infrared cloud albedo from aircraft and satellite have shown both localized and global discrepancies between model and observations that are, thus far, unexplained. The capabilities of shortwave surface spectrometry have been improved in recent years at the Southern Great Plains facility (SGP) of the ARM Climate Research Facility through the addition of new instrumentation, the Shortwave Array Spectroradiometer, and upgrades to existing instrumentation, the Shortwave Spectroradiometer and the Rotating Shadowband Spectroradiometer. An airborne-based instrument, the HydroRad Spectroradiometer, was also deployed at the ARM site during the Routine ARM Aerial Facility Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign. Using the new and upgraded spectral observations along with radiative transfer models, cloud scenes at the SGP are presented with the goal of characterizing the instrumentation and the cloud fields themselves.

  3. Ground-based observations of the corona in the visible and NIR spectral ranges

    NASA Astrophysics Data System (ADS)

    Epple, Alexander; Schwenn, Rainer

    1995-06-01

    Since late 1993 we have been using a mirror coronagraph on Pic du Midi (PICO) to observe the solar emission corona in several spectral lines of (FE-X), (FE-XIII), and (FE-XIV). For good meteorological conditions the diffuse corona and coronal holes in between can be seen out to 1.2 solar mass for sun center. Active regions can be mapped to bond 1.5 solar mass in the green and infrared lines. Recent observations of PICO are presented.

  4. Ground-based observations of the corona in the visible and NIR spectral ranges

    NASA Technical Reports Server (NTRS)

    Epple, Alexander; Schwenn, Rainer

    1995-01-01

    Since late 1993 we have been using a mirror coronagraph on Pic du Midi (PICO) to observe the solar emission corona in several spectral lines of (FE-X), (FE-XIII), and (FE-XIV). For good meteorological conditions the diffuse corona and coronal holes in between can be seen out to 1.2 solar mass for sun center. Active regions can be mapped to bond 1.5 solar mass in the green and infrared lines. Recent observations of PICO are presented.

  5. A decade of Rossi X-ray Timing Explorer Seyfert observations: An RXTE Seyfert spectral database

    NASA Astrophysics Data System (ADS)

    Mattson, Barbara Jo

    2008-10-01

    With over forty years of X-ray observations, we should have a grasp on the X- ray nature of active galactic nuclei (AGN). The unification model of Antonucci and Miller (1985) offered a context for understanding observations by defining a "typical" AGN geometry, with observed spectral differences explained by line- of-sight effects. However, the emerging picture is that the central AGN is more complex than unification alone can describe. We explore the unified model with a systematic X-ray spectral study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE) over its first 10 years. We develop a spectral-fit database of 821 time-resolved spectra from 39 Seyfert galaxies fitted to a model describing the effects of an X-ray power-law spectrum reprocessed and absorbed by material in the central AGN region. We observe a relationship between radio and X-ray properties for Seyfert 1s, with the spectral parameters differing between radio-loud and radio-quiet Seyfert 1s. We also find a complex relationship between the Fe K equivalent width ( EW ) and the power-law photon index (Gamma) for the Seyfert 1s, with a correlation for the radio-loud sources and an anti-correlation for the radio- quiet sources. These results can be explained if X-rays from the relativistic jet in radio-loud sources contribute significantly to the observed spectrum. We observe scatter in the EW-Gamma relationship for the Seyfert 2s, suggesting complex environments that unification alone cannot explain. We see a strong correlation between Gamma and the reflection fraction ( R ) in the Seyfert 1 and 2 samples, but modeling degeneracies are present, so this relationship cannot be trusted as instructive of the AGN physics. For the Seyfert 1 sample, we find an anticorrelation between EW and the 2 to 10 keV luminosity ( L x ), also known as the X-ray Baldwin effect. This may suggest that higher luminosity sources contain less material or may be due to a time-lag effect. We do not

  6. Spectral Distinctions between the Leading and Trailing Hemispheres of Callisto: New Observations

    USGS Publications Warehouse

    Calvin, W.M.; Clark, R.N.

    1993-01-01

    An analysis of recent telescopic observations of Callisto results in new insights regarding spectral variations from the leading to the trailing hemisphere of Callisto. Examination of data in the wavelength range from 2.0 to 2.5 ??m indicates that previous suggestions of spectral differences are most likely the result of experimental uncertainty or error. Slight variations in the slope of this wavelength range are consistent with larger ice grain sizes on the trailing hemisphere. The new observations confirm the presence of an absorption feature centered on 3.4 ??m in the spectrum of the leading hemisphere. Theoretical spectral modeling indicates this feature is caused by small amounts of fine-grained water ice. Finally, an absorption feature near 3.1 ??m is indicated but cannot be confirmed due to the strong variation in the spectrum of water ice in this region. If this feature is real, rather than an artifact of the reflectance modeling, it is similar in location and bandwidth to a feature seen in the spectrum of Ceres, attributed to NH4-bearing clays. ?? 1993 Academic Press. All rights reserved.

  7. Spectral Order Automorphisms on Hilbert Space Effects and Observables: The 2-Dimensional Case

    NASA Astrophysics Data System (ADS)

    Molnár, Lajos; Nagy, Gergő

    2016-04-01

    In the earlier paper (Molnár and Šemrl in Lett Math Phys 80:239-255, 2007), we described the structure of all spectral order automorphisms of the sets of Hilbert space effects and bounded observables in the case where the dimension of the underlying Hilbert space is at least 3. The aim of this note is to present a complete description in the missing two-dimensional case. We will see that in that case there is a one-to-one correspondence between the set of all spectral order automorphisms and the set of all bijective maps of pure states together with the set of all strictly increasing bijections of the real unit interval or the real line.

  8. An Explanation for the Observed Spectral Contrast Reduction Between Field and Laboratory Infrared Measurements of Soils

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Lucey, P. G.; Horton, K. A.; Williams, T.; Winter, E. M.; Stocker, A. D.

    1996-03-01

    Comparison of emission spectra (7-14 m) of pristine soils in the field with bidirectional reflectance spectra of soils obtained in the laboratory shows that laboratory spectra tend to have less contrast than field spectra. We investigated this phenomenon by measuring emission spectra of both pristine (in situ) and sampled soils (prepared as if for transport to the laboratory). The sampled soils had much less spectral contrast than the pristine soils in the reststrahlen region near 9 m. We hypothesize that this effect is due to a difference in grainsize distribution of the optically active layer (i.e., fine particle coatings). This concept was proposed by Salisbury et al. to explain their observations that soils washed free of small particles adhering to larger grains exhibited greater spectral contrast than unwashed soils. Unrecognized, this phenomenon could influence interpretations of remote sensing data since it is a common practice to use spectra of materials obtained in the laboratory to interpret spectra obtained remotely.

  9. Analysis of far-infrared spectral radiance observations of the water vapor continuum in the Arctic

    NASA Astrophysics Data System (ADS)

    Fox, Cathryn; Green, Paul D.; Pickering, Juliet C.; Humpage, Neil

    2015-04-01

    The Radiative Heating in Underexplored Bands Campaign (RHUBC) took place in Barrow, Alaska, in February and March 2007. During RHUBC, high resolution far-infrared spectra were measured simultaneously and independently by two different spectrometers - the Imperial College Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) and the Atmospheric Radiation Measurement program (ARM) Atmospheric Emitted Radiance Interferometer - Extended Range (AERI-ER). Co-incidental far-infrared downwelling radiance measurements from the two instruments show good agreement within their overlapping wavenumber measurement range (400-550 cm-1). Radiance measurements taken using the TAFTS instrument are compared to the current Mlawer-Tobin-Clough-Kneizys-Davies (MT-CKD) version 2.5 water vapor continuum parameterization for the spectral range 350-500 cm-1 (20-29 μm). Simulated values agree with the TAFTS observations within uncertainties, enhancing confidence that MT-CKD 2.5 accurately represents the foreign-broadened water vapor continuum in this crucial spectral region.

  10. Observational constraints on the spectral index of the cosmological curvature perturbation

    NASA Astrophysics Data System (ADS)

    Lyth, David H.; Covi, Laura

    2000-11-01

    We evaluate the observational constraints on the spectral index n, in the context of the ΛCDM hypothesis which represents the simplest viable cosmology. We first take n to be practically scale independent. Ignoring reionization, we find at a nominal 2-σ level n~=1.0+/-0.1. If we make the more realistic assumption that reionization occurs when a fraction f~10-5 to 1 of the matter has collapsed, the 2-σ lower bound is unchanged while the 1-σ bound rises slightly. These constraints are compared with the prediction of various inflation models. Then we investigate the two-parameter scale-dependent spectral index, predicted by running-mass inflation models, and find that present data allow significant scale dependence of n, which occurs in a physically reasonable regime of parameter space.

  11. Comparison of clustering techniques for determining compositional units on Mercury from MESSENGER spectral observations

    NASA Astrophysics Data System (ADS)

    D'Amore, Mario; Helbert, Jorn; Maturilli, Alessandro; Marzo, Giuseppe A.; Roush, Ted L.; Hogan, Robert C.; Izenberg, Noam R.; Sprague, Ann L.; Holsclaw, Gregory M.; Head, James; McClintock, William; Solomon, Sean C.

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) obtained spectra of much of the surface of Mercury during the first two MESSENGER flybys of the planet. The resulting dataset is composed of several hundred reflectance spectra that have not yet been corrected for any effect due to observing geometry or to surface material phase curves. Our hypothesis is that the separation of surface signal from other contributions can be efficiently performed by the use of statistical techniques. We adopt principal component and clustering analyses to identify and characterize spectral units along the MASCS ground tracks. In order to extract the spectral shapes of the primary surface components exposed in the surface area an-alyzed, we applied an R-mode factor analysis, aiming to find an eigenvector set that minimizes data covariance. Identification of the different components and their abundances is accom-plished by principal component analysis together with an evaluation of the eigenvectors and eigenvalues of the covariance matrix (also called covariance matrix decomposition). A compar-ison of the results using only the near-infrared (NIR) and visible (VIS) portions of the spectra indicates that the NIR spectral range is carrying less information than the VIS portion. We also find that the eigenvectors are essentially unchanged if the full wavelength range is selected (VIS+NIR) rather than limiting observations to the VIS range. The full-range analysis shows that seven eigenvectors are needed to reconstruct the original spectrum to within the level of variability associated with the observational data. Each spectral eigenvector can be regarded as a representative of a distinct spectral class that varies in spatial abundance along the track. The first eigenvector always displays a strong positive or "red" slope, probably strongly linked to uncorrected effects associated with viewing geometry variations, and all eigenvectors show distinctive spectral signatures

  12. Spectral signatures of the ionospheric Alfvén resonator to be observed by low-Earth orbit satellite

    NASA Astrophysics Data System (ADS)

    Surkov, V. V.; Pilipenko, V. A.

    2016-03-01

    Interference of an incident and reflected Alfvén pulses propagating inside the ionospheric Alfvén resonator (IAR) is studied on the basis of a simple one-dimensional model. Particular emphasis has been placed on the analysis of spectral features of ultralow frequency (˜1-15 Hz) electric perturbations recently observed by Communications/Navigation Outage Forecasting System satellite. This "fingerprint" multiband spectral structure was observed when satellite descended in the terminator vicinity. Among factors affecting spectral structure the satellite position and distance from the IAR boundaries are most significant. It is concluded that the observed spectrograms exhibit modulation with "period" depending on propagation delay time of reflected Alfvén pulses in such a way that this effect can mask a spectral resonance structure resulted from excitation of IAR eigenmodes. The proposed interference effect is capable to produce a spectral pattern resembling a fingerprint which is compatible with the satellite observations.

  13. CO Spectral Line Energy Distributions in Orion Sources: Templates for Extragalactic Observations

    NASA Astrophysics Data System (ADS)

    Indriolo, Nick; Bergin, Edwin A.; Goicoechea, Javier; Schilke, Peter

    2016-01-01

    Relative populations in the excited rotational levels of CO are sensitive to conditions in the interstellar medium. Emission lines originating in these levels can thus be used in constraining parameters such as density, temperature, and radiation field. The Herschel Space Observatory has enabled the observation of CO emission lines arising from the J=4 through J=48 rotational levels, many of which are detected in different sources within the Orion star-forming region. We present observations of CO emission toward Orion KL, Orion H2 Peak 1, Orion South, and the Orion Bar, all of which show distinctive CO spectral line energy distributions (SLEDs) indicating the different excitation mechanisms at work. Using the high spectral resolution HIFI observations, we decompose emission line profiles into multiple components (e.g., shock, outflow, photodissociation region, ambient cloud) in order to characterize the CO SLED associated with each component. In doing so, we generate templates for the various excitation mechanisms that can be applied toward understanding the processes occurring in unresolved star-forming regions where CO observations have been made.

  14. Constraining parameters in marine pelagic ecosystem models - is it actually feasible with typical observations of standing stocks?

    NASA Astrophysics Data System (ADS)

    Löptien, U.; Dietze, H.

    2015-07-01

    In a changing climate, marine pelagic biogeochemistry may modulate the atmospheric concentrations of climate-relevant species such as CO2 and N2O. To date, projections rely on earth system models, featuring simple pelagic biogeochemical model components, embedded into 3-D ocean circulation models. Most of these biogeochemical model components rely on the hyperbolic Michaelis-Menten (MM) formulation which specifies the limiting effect of light and nutrients on carbon assimilation by autotrophic phytoplankton. The respective MM constants, along with other model parameters, of 3-D coupled biogeochemical ocean-circulation models are usually tuned; the parameters are changed until a "reasonable" similarity to observed standing stocks is achieved. Here, we explore with twin experiments (or synthetic "observations") the demands on observations that allow for a more objective estimation of model parameters. We start with parameter retrieval experiments based on "perfect" (synthetic) observations which we distort, step by step, by low-frequency noise to approach realistic conditions. Finally, we confirm our findings with real-world observations. In summary, we find that MM constants are especially hard to constrain because even modest noise (10 %) inherent to observations may hinder the parameter retrieval already. This is of concern since the MM parameters are key to the model's sensitivity to anticipated changes in the external conditions. Furthermore, we illustrate problems caused by high-order parameter dependencies when parameter estimation is based on sparse observations of standing stocks. Somewhat counter to intuition, we find that more observational data can sometimes degrade the ability to constrain certain parameters.

  15. A falsely fat curvaton with an observable running of the spectral tilt

    SciTech Connect

    Peloso, Marco; Sorbo, Lorenzo; Tasinato, Gianmassimo E-mail: sorbo@physics.umass.edu

    2014-06-01

    In slow roll inflation, the running of the spectral tilt is generically proportional to the square of the deviation from scale invariance, α{sub s}∝(n{sub s}−1){sup 2}, and is therefore currently undetectable. We present a mechanism able to generate a much larger running within slow roll. The mechanism is based on a curvaton field with a large mass term, and a time evolving normalization. This may happen for instance to the angular direction of a complex field in presence of an evolving radial direction. At the price of a single tuning between the mass term and the rate of change of the normalization, the curvaton can be made effectively light at the CMB scales, giving a spectral tilt in agreement with observations. The lightness is not preserved at later times, resulting in a detectable running of the spectral tilt. This mechanism shows that fields with a large mass term do not necessarily decouple from the inflationary physics, and provides a new tool for model building in inflation.

  16. X-RAY SPECTRAL COMPONENTS OBSERVED IN THE AFTERGLOW OF GRB 130925A

    SciTech Connect

    Bellm, Eric C.; Forster, Karl; Harrison, Fiona A.; Madsen, Kristin K.; Perley, Daniel A.; Rana, Vikram R.; Barrière, Nicolas M.; Boggs, Steven E.; Craig, William W.; Bhalerao, Varun; Cenko, S. Bradley; Christensen, Finn E.; Fryer, Chris L.; Hailey, Charles J.; Horesh, Assaf; Ofek, Eran O.; Kouveliotou, Chryssa; Reynolds, Stephen P.; Stern, Daniel; and others

    2014-04-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between two observation epochs at 2 × 10{sup 5} and 10{sup 6} s after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10{sup 8} cm), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  17. Multi-spectral CCD camera system for ocean water color and seacoast observation

    NASA Astrophysics Data System (ADS)

    Zhu, Min; Chen, Shiping; Wu, Yanlin; Huang, Qiaolin; Jin, Weiqi

    2001-10-01

    One of the earth observing instruments on HY-1 Satellite which will be launched in 2001, the multi-spectral CCD camera system, is developed by Beijing Institute of Space Mechanics & Electricity (BISME), Chinese Academy of Space Technology (CAST). In 798 km orbit, the system can provide images with 250 m ground resolution and a swath of 500 km. It is mainly used for coast zone dynamic mapping and oceanic watercolor monitoring, which include the pollution of offshore and coast zone, plant cover, watercolor, ice, terrain underwater, suspended sediment, mudflat, soil and vapor gross. The multi- spectral camera system is composed of four monocolor CCD cameras, which are line array-based, 'push-broom' scanning cameras, and responding for four spectral bands. The camera system adapts view field registration; that is, each camera scans the same region at the same moment. Each of them contains optics, focal plane assembly, electrical circuit, installation structure, calibration system, thermal control and so on. The primary features on the camera system are: (1) Offset of the central wavelength is better than 5 nm; (2) Degree of polarization is less than 0.5%; (3) Signal-to-noise ratio is about 1000; (4) Dynamic range is better than 2000:1; (5) Registration precision is better than 0.3 pixel; (6) Quantization value is 12 bit.

  18. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    NASA Technical Reports Server (NTRS)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  19. Water balance-based actual evapotranspiration reconstruction from ground and satellite observations over the conterminous United States

    NASA Astrophysics Data System (ADS)

    Wan, Zhanming; Zhang, Ke; Xue, Xianwu; Hong, Zhen; Hong, Yang; Gourley, Jonathan J.

    2015-08-01

    The objective of this study is to produce an observationally based monthly evapotranspiration (ET) product using the simple water balance equation across the conterminous United States (CONUS). We adopted the best quality ground and satellite-based observations of the water budget components, i.e., precipitation, runoff, and water storage change, while ET is computed as the residual. Precipitation data are provided by the bias-corrected PRISM observation-based precipitation data set, while runoff comes from observed monthly streamflow values at 592 USGS stream gauging stations that have been screened by strict quality controls. We developed a land surface model-based downscaling approach to disaggregate the monthly GRACE equivalent water thickness data to daily, 0.125° values. The derived ET computed as the residual from the water balance equation is evaluated against three sets of existing ET products. The similar spatial patterns and small differences between the reconstructed ET in this study and the other three products show the reliability of the observationally based approach. The new ET product and the disaggregated GRACE data provide a unique, important hydro-meteorological data set that can be used to evaluate the other ET products as a benchmark data set, assess recent hydrological and climatological changes, and terrestrial water and energy cycle dynamics across the CONUS. These products will also be valuable for studies and applications in drought assessment, water resources management, and climate change evaluation.

  20. A spectral analysis of HDE 269445 from optical and infrared observations.

    NASA Astrophysics Data System (ADS)

    Pasquali, A.; Schmutz, W.; Nota, A.; Origlia, L.

    1997-11-01

    We present new, near-IR spectroscopic observations of HDE 269445, which we combine with published HST and IUE ultraviolet data and optical high resolution spectra. We discuss the spectral morphology of the star from UV to near-IR wavelengths, concentrating on profile variations in the UV and optical H and He lines. From a spectroscopic analysis with non-LTE model atmospheres, we derive for HDE 269445: T_*_=34000K, R_*_=43Rsun_, log˙(M)(Msun_/yr)=-4.5 and He/H=0.4/0.6 by number. These parameters are in good agreement with those previously derived by Pasquali et al. (1997ApJ...478..340P) who used only ultraviolet and optical lines. Therefore, our analysis confirms that a combination of optical and infrared lines can be fruitfully used to determine stellar and wind properties when ultraviolet data are not available. Our model calculations only fit the broad component underneath a strong core emission. We interpret the discrepancy between the observed and the model line profiles as the effect of a non-spherical wind which has a hot, fast polar component and a cold, slow equatorial component. The time-variability detected in some H and He lines indicates that the wind geometry may be variable and the star has undergone changes in T_eff_ and ˙(M). These properties are similar to those observed for the galactic LBV AG Carinae by Leitherer et al. (1994ApJ...428..292L) and we may suspect that HDE 269445 is also a Luminous Blue Variable. This could explain why HDE 269445 has defied easy spectral classification, and, although originally classified as a Ofpe/WN9, it has always represented a peculiarity for this spectral type.

  1. First observational Evidence of Rossby Wave Signatures in Spectral Aerosol Optical Depths over Central Himalayas

    NASA Astrophysics Data System (ADS)

    Devulapalli, P. V.; Kondapalli, N. K.; Krishna, S.; Ratnam, M.; Naja, M. K.; Kishore, R.

    2013-12-01

    It is now well known that the atmospheric aerosols (both natural and anthropogenic) exhibit large spatial, temporal and spectral uncertainties due to the short residence time and the diverse aerosol types. For example, aerosol loading varies not only from year to year but also on higher frequency intra-seasonal time scales producing strong variability on local and regional scales. Considering the advancements in the morphology of aerosol layers and their contribution to earth's radiation budget, recent studies tried to understand the role of atmospheric waves in variability of AODs from fast moving gravity waves to slow moving planetary-scale waves. It is also evident from earlier reports that the planetary-scale waves are intense in winter in both the hemispheres and play vital role in transporting not only energy and momentum but also atmospheric trace species. Very few reports till date showed modulations in the spectral AODs, from the equatorial and tropical latitudes by Madden Julian Oscillation (MJO) which dominates the tropical variability on time scales of 30-70 days. However, there are no reports yet neither from mid- nor from high latitudes showing the effect of planetary scale waves on spectral AODs and their quantification of the aerosol radiative forcing due to long period modulations. Hence, it is very important to understand the variability of aerosols, and the spectral AODs in terms of atmospheric wave modulations. This could be an essential input to the global and regional aerosol models to assess the global and regional radiative forcing and subsequent climate impacts. For the first time, long period modulations in spectral Aerosol Optical Depths (AODs) over extra-tropical region, Manora Peak, Nainital (29.4oN; 79.2oE; 1957m AMSL) in Central Himalayas are presented. Power spectrum analysis of AODs showed the existence of dominant 25-45 day oscillation, apart from quasi-6.5 and quasi-16 day waves. The 25-45 day oscillations are also seen in MODIS

  2. A Compact Airborne High Spectral Resolution Lidar for Observations of Aerosol and Cloud Optical Properties

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris A.; Hair, John W.; Cook, Anthony L.

    2002-01-01

    We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical transport models. In this paper, we provide an overview of the instrument design and present the results of simulations showing the instrument's capability to accurately measure extinction and extinction-to-backscatter ratio.

  3. A source representation of microseisms constrained by HV spectral ratio observations

    NASA Astrophysics Data System (ADS)

    Dreger, D.; Rhie, J.

    2006-12-01

    The microseisms are generated by pressure variation on the sea floor caused by incident and reflected ocean waves, and dominant background noises at short periods. The observations of microseism wave fields in deep sedimentary basins (e.g., Santa Clara Valley) show that the maximum period of the horizontal to vertical (H/V) spectral ratio correlates with basin thickness. A similar correlation has been found in teleseismic arrival times and P-wave amplitude as well as local-earthquake S-wave relative amplification [Dolenc et al., 2005]. This observation infers that a study of microseism wave field, combined with other seismic data sets, can probably be used to invert for the velocity structures of the deep basins. To make this inversion possible, it is necessary to understand the excitation and propagation characteristics of microseisms. We will perform forward computations of microseism wave fields for source representations such as CLVDs and single-forces with the USGS 3D velocity model. Various spatial extensions as well as the frequency content of the source will be tested to match observed shifts in dominant H/V spectral ratio. The optimal source representation of the microseisms will be the first step to accomplish inversions for 3D seismic velocity structure in sedimentary basins using microseisms.

  4. Spectral lags of flaring events in LS I+61°303 from RXTE Observations

    NASA Astrophysics Data System (ADS)

    Sarkar, Tamal; Sarkar, Samir; Bhadra, Arunava

    2016-07-01

    This work reports the first discovery of (negative) spectral lags in X-ray emission below 10keV from the gamma ray binary LS I+61° 303 during large flaring episodes using Rossi X-ray Timing Explorer (RXTE) observations. It is found from the RXTE data that during the flares, low energy (3–5 keV) variations lead the higher energy (8–10 keV) variations by a few tens of seconds whereas no significant time lag is observed during the non-flaring states. The observed spectral lag features for flaring events suggest that inverse Compton scattering may be operating, at least in some part of the system. Another possibility is that the sites of particle acceleration may be different for flaring and non-flaring events such as in the microquasar model, in which the flaring radiation may come from hot spots sitting above the black hole while steady state emissions are due to the jets.

  5. Hyper-spectral observations of greenhouse gases in Three Gorges Reservoir Region, China

    NASA Astrophysics Data System (ADS)

    Wang, Ding Yi; Zhang, Chun-ming; Qin, Lin; Zhang, Lu; Wang, Xiang-hong; Li, Hong-qun; Yang, Fu-Mo; Chen, Gang-Cai; Wang, Shu-peng; Zhang, Xing-ying; Zhang, Peng

    The Three Gorges Reservoir (TGR) is the most ambitious hydroelectric and flood control project in human history. Its riparian zone has areas of ~300 km2 with water levels fluctuating between 175m above the sea in winter and 145m in summer, and is a special type of wetlands at the low water levels. These wetlands may release CO2 and CH4 with significantly spatial and temporal variations, and have been misleadingly described as a “methane menace” and caused a worldwide concern. A joint research program for TGR greenhouse gases monitoring is operated by several institutions and based at Yangtze Normal Univ. in Fuling of Chongqing. It is characterized by the combined satellite, airship, and ground-based hyper-spectral observations, which serve to simultaneously measure various eco-environmental parameters in a large area with high spatial and spectral resolutions, and to model the status and key dynamic processes of the TGR greenhouse gases. In this talk, the retrieval algorithm of the gas species from satellite near-infrared observations is discussed with special attentions paid to the mountainous and foggy TGR region. The distributions and variations of TGR greenhouse gases are studied by using the AIRS and SCIAMACHY monthly means of multiple years. The airship and ground-based observation system is outlined and expected to provide unique data needed to address the TGR environmental issues, and to evolve towards operational service.

  6. Co Spectral Line Energy Distributions in Orion Sources: Templates for Extragalactic Observations

    NASA Astrophysics Data System (ADS)

    Indriolo, Nick; Bergin, Edwin

    2015-06-01

    The Herschel Space Observatory has enabled the observation of CO emission lines originating in the J=5 through J=48 rotational levels. Surveys of active galaxies (e.g., starbursts, Seyferts, ULIRGs) detect emission from levels as high as J=30, but the precise excitation mechanisms responsible for producing the observed CO SLEDs (Spectral Line Energy Distribution) remain ambiguous. To better constrain the possible excitation mechanisms in extragalactic sources, we investigate the CO SLEDs arising from sources with known characteristics in the nearby Orion region. Targets include Orion-KL (high-mass star forming region containing a hot core, embedded protostars, outflows, and shocks), Orion South (high-mass star forming region containing embedded protostars, outflows, and a photodissociation region), Orion H_2 Peak 1 (molecular shock), and the Orion Bar (a photodissociation region). Emission lines from complex sources are decomposed using velocity information from high spectral resolution observations made with Herschel-HIFI (Heterodyne Instrument for the Far-Infrared). Each source and/or component is taken as a template for a particular excitation mechanism, and then applied to interpret excitation in more distant regions within the Galaxy, as well as external galaxies.

  7. New Ground-based Spectral Observations of Mercury and Comparison with the Moon

    NASA Technical Reports Server (NTRS)

    Blewett, D. T.; Warell, J.

    2003-01-01

    Spectroscopic observations (400-670 nm) of Mercury were made at La Palma with the Nordic Optical Telescope (NOT) in June and July of 2002. Extensive observations of solar analog standard stars and validation spectra of 7 Iris and a variety of locations on the Moon were also collected. The 2002 Mercury data were also combined with previous observations (520-970 nm) from the Swedish Solar Vacuum Telescope (SVST). A spectrum (400-970 nm) calibrated to standard bidirectional geometry (alpha=i=30deg, e=0deg) was constructed based on the spectral slopes from 2002. The combined spectrum permits analysis with the Lucey lunar abundance relations for FeO and TiO2.

  8. Development of quantitative diagnostic observables for age-related macular degeneration using Spectral Domain OCT

    NASA Astrophysics Data System (ADS)

    Bower, Bradley A.; Chiu, Stephanie J.; Davies, Emily; Davis, Anjul M.; Zawadzki, Robert J.; Fuller, Alfred R.; Wiley, David F.; Izatt, Joseph A.; Toth, Cynthia A.

    2007-02-01

    We report on the development of quantitative, reproducible diagnostic observables for age-related macular degeneration (AMD) based on high speed spectral domain optical coherence tomography (SDOCT). 3D SDOCT volumetric data sets (512 x 1000 x 100 voxels) were collected (5.7 seconds acquisition time) in over 50 patients with age-related macular degeneration and geographic atrophy using a state-of-the-art SDOCT scanner. Commercial and custom software utilities were used for manual and semi-automated segmentation of photoreceptor layer thickness, total drusen volume, and geographic atrophy cross-sectional area. In a preliminary test of reproducibility in segmentation of total drusen volume and geographic atrophy surface area, inter-observer error was less than 5%. Extracted volume and surface area of AMD-related drusen and geographic atrophy, respectively, may serve as useful observables for tracking disease state that were not accessible without the rapid 3D volumetric imaging capability unique to retinal SDOCT.

  9. Peak Flux Distributions of Solar Radio Type-i Bursts from Highly Resolved Spectral Observations

    NASA Astrophysics Data System (ADS)

    Iwai, K.; Masuda, S.; Miyoshi, Y.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2013-05-01

    Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the radio telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each type-I burst element from complex noise storm spectra that include numerous instances of radio frequency interference (RFI). This algorithm removes RFI from the observed radio spectra by applying a moving median filter along the frequency axis. Burst and continuum components are distinguished by a two-dimensional maximum and minimum search of the radio dynamic spectra. The analysis result shows that each type-I burst element has one peak flux without double counts or missed counts. The peak flux distribution of type-I bursts derived using this algorithm follows a power law with a spectral index between 4 and 5.

  10. PEAK FLUX DISTRIBUTIONS OF SOLAR RADIO TYPE-I BURSTS FROM HIGHLY RESOLVED SPECTRAL OBSERVATIONS

    SciTech Connect

    Iwai, K.; Masuda, S.; Miyoshi, Y.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2013-05-01

    Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the radio telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each type-I burst element from complex noise storm spectra that include numerous instances of radio frequency interference (RFI). This algorithm removes RFI from the observed radio spectra by applying a moving median filter along the frequency axis. Burst and continuum components are distinguished by a two-dimensional maximum and minimum search of the radio dynamic spectra. The analysis result shows that each type-I burst element has one peak flux without double counts or missed counts. The peak flux distribution of type-I bursts derived using this algorithm follows a power law with a spectral index between 4 and 5.

  11. Spectrally-resolved Soft X-ray Observations and the Temperature Structure of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Warren, Harry; McTiernan, James; Woods, Thomas N.

    2015-04-01

    Solar X-ray observations provide important diagnostics of plasma heating and particle acceleration, during solar flares and quiescent periods. How the corona is heated to its ~1-3 MK nominal temperature remains one of the fundamental unanswered questions of solar physics; heating of plasma to tens of MK during solar flares -- particularly to the hottest observed temperatures of up to ~50 MK -- is also still poorly understood. Soft X-ray emission (~0.1-10 keV; or ~0.1-10 nm) is particularly sensitive to hot coronal plasma and serves as a probe of the thermal processes driving coronal plasma heating. Spectrally- and temporally-resolved measurements are crucial for understanding these energetic processes, but there have historically been very few such observations. We present new solar soft X-ray spectra from the Amptek X123-SDD, measuring quiescent solar X-ray emission from ~0.5 to ~30 keV with ~0.15 keV FWHM resolution from two SDO/EVE calibration sounding rocket underflights in 2012 and 2013. Combined with observations from RHESSI, GOES/XRS, SDO/EVE, and SDO/AIA, the temperature distribution derived from these data suggest significant hot (5-10 MK) emission from active regions, and the 2013 spectra suggest a low-FIP enhancement of only ~1.6 relative to the photosphere, 40% of the usually-observed value from quiescent coronal plasma. We explore the implications of these findings on coronal heating. We discuss future missions for spectrally-resolved soft X-ray observations using the X123-SDD, including the upcoming MinXSS 3U CubeSat using the X123-SDD and scheduled for deployment in mid-2015, and the CubIXSS 6U CubeSat mission concept.

  12. New Spectral Reflectance Observations of Hayabusa 2 Near-Earth Asteroid Target 162173 1999 JU3

    NASA Astrophysics Data System (ADS)

    Vilas, Faith

    2012-10-01

    The successful visit of the spacecraft Hayabusa to near-Earth asteroid 25143 Itokawa, and the successful return of samples of the asteroid's material, have spurred the Japanese Space Agency (JAXA) to mount a second mission (Hayabusa 2) to Apollo asteroid 162173 1999 JU3. JAXA's objective is to sample an asteroid having an unaltered or barely altered composition (C or D class). Asteroid 162173 1999 JU3 is targeted both for its easy accessibility from the Earth (a low ΔV of 3.238 km s-1) and its spectral class. Spectral reflectance observations of 162173 during two apparitions in 2003 and 2007 are both tantalizing and potentially inconclusive, with the suggestion that mineralogical variegation is revealed on the asteroid's surface. A spectrum from July 2007 suggests the presence of an absorption feature centered near 0.7 µm. The strength of the absorption feature suggests that the material contributing to the spectrum is largely concentrated iron-bearing phyllosilicates, however, the SNR is limited. Other spectra do not show this feature, but could contain other subtle absorption features. During the final opportunity to observe 162173 before the proposed launch of Hayabusa 2, reflectance spectra were obtained of 162173 (V ˜ 18.5) using the facility ES2 spectrograph with a red-sensitive CCD at McDonald Observatory's 2.1-m telescope on UT June 12 and 13, 2012. A preliminary examination of these spectra suggests that absorption features could be present and the surface variegation is real, however, the SNR remains limited. These new spectral will be presented and discussed in the context of our prior knowledge of 162173 1999 JU3.

  13. Fine spectral structures in Jovian decametric radio emission observed by ground-based radio telescope.

    NASA Astrophysics Data System (ADS)

    Panchenko, M.; Brazhenko, A. I.; Shaposhnikov, V. E.; Konovalenko, A. A.; Rucker, H. O.

    2014-04-01

    Jupiter with the largest planetary magnetosphere in the solar system emits intense coherent non-thermal radio emission in a wide frequency range. This emission is a result of a complicated interaction between the dynamic Jovian magnetosphere and energetic particles supplying the free energy from planetary rotation and the interaction between Jupiter and the Galilean moons. Decametric radio emission (DAM) is the strongest component of Jovian radiation observed in a frequency range from few MHz up to 40 MHz. This emission is generated via cyclotron maser mechanism in sources located along Jovian magnetic field lines. Depending on the time scales the Jovian DAMexhibits different complex spectral structures. We present the observations of the Jovian decametric radio emission using the large ground-based radio telescope URAN- 2 (Poltava, Ukraine) operated in the decametric frequency range. This telescope is one of the largest low frequency telescopes in Europe equipped with high performance digital radio spectrometers. The antenna array of URAN-2 consists of 512 crossed dipoles with an effective area of 28 000m2 and beam pattern size of 3.5 x 7 deg. (at 25 MHz). The instrument enables continuous observations of the Jovian radio during long period of times. Jovian DAM was observed continuously since Sep. 2012 (depending on Jupiter visibility) with relatively high time-frequency resolution (4 kHz - 100ms) in the broad frequency range (8-32MHz). We have detected a big amount of the fine spectral structures in the dynamic spectra of DAM such as trains of S-bursts, quasi-continuous narrowband emission, narrow-band splitting events and zebra stripe-like patterns. We analyzed mainly the fine structures associated with non-Io controlled DAM. We discuss how the observed narrowband structures which most probably are related to the propagation of the decametric radiation in the Jupiter's ionosphere can be used to study the plasma parameters in the inner Jovian magnetosphere.

  14. RXTE Observations of LMC X-1 and LMC X-3 Spectral and Temporal Evolution

    NASA Technical Reports Server (NTRS)

    Wilms, Joern; Nowak, Michael A.; Dove, James B.; Heindl, William; Begelman, Mitchell C.

    1998-01-01

    Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. In the past year we have conducted a monitoring campaign with RXTE (Rossi X Ray Timing Explorer) to study the short and long term behavior of these two sources. In this poster we present results from 180 ksec of continuous RXTE observation of LMS X-1 and LMC X-3 made in December 1996. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power law. In addition to the results of the long observations we also present information on the long-term spectral behavior of LMC X-3 as derived from the monitoring campaign.

  15. Spectral evolution during a complex gamma ray burst observed with BATSE

    NASA Technical Reports Server (NTRS)

    Gruber, D. E.; Band, D. L.; Ford, L.; Matteson, J. L.; Meegan, C. L.; Wilson, R. B.; Fishman, G. J.; Paciesas, W. S.; Pendleton, G. N.; Schaefer, B.

    1992-01-01

    More than 270 gamma ray bursts have been observed to date with the BATSE (Burst and Transient Source Experiment) aboard the Compton Gamma Ray Observatory. Many have a duration of 10 seconds or more and complex structure with multiple peaks or spikes. Complex bursts in the energy range 30 keV to 1 MeV were systematically analyzed to determine the relations between intensity and spectral shape, or hardness. The burst hardness rises and falls in during spikes, but somewhat earlier than the intensity. A simple correlation between intensity and hardness is, therefore, not observed: the intensity lags instead. Results from one burst which shows evidence for longer lags in longer spikes are reported.

  16. High spectral resolution observations of fluorescent molecular hydrogen in molecular clouds

    NASA Technical Reports Server (NTRS)

    Burton, Michael G.; Geballe, T. R.; Brand, P. W. J. L.; Moorhouse, A.

    1990-01-01

    The 1-0 S(1) line of molecular hydrogen has been observed at high spectral resolution in several sources where the emission was suspected of being fluorescent. In NGC 2023, the Orion Bar, and Parsamyan 18, the S(1) line is unresolved, and the line center close to the rest velocity of the ambient molecular cloud. Such behavior is expected for UV-excited line emission. The H2 line widths in molecular clouds thus can serve as diagnostic for shocked and UV-excitation mechanisms. If the lines are broader than several km/s or velocity shifts are observed across a source it is likely that shocks are responsible for the excitation of the gas.

  17. P-MaNGA: full spectral fitting and stellar population maps from prototype observations

    NASA Astrophysics Data System (ADS)

    Wilkinson, David M.; Maraston, Claudia; Thomas, Daniel; Coccato, Lodovico; Tojeiro, Rita; Cappellari, Michele; Belfiore, Francesco; Bershady, Matthew; Blanton, Mike; Bundy, Kevin; Cales, Sabrina; Cherinka, Brian; Drory, Niv; Emsellem, Eric; Fu, Hai; Law, David; Li, Cheng; Maiolino, Roberto; Masters, Karen; Tremonti, Christy; Wake, David; Wang, Enci; Weijmans, Anne-Marie; Xiao, Ting; Yan, Renbin; Zhang, Kai; Bizyaev, Dmitry; Brinkmann, Jonathan; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Simmons, Audrey

    2015-05-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr SDSS-IV (Sloan Digital Sky Survey IV) survey that will obtain resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we derive spatially resolved stellar population properties and radial gradients by performing full spectral fitting of observed galaxy spectra from P-MaNGA, a prototype of the MaNGA instrument. These data include spectra for 18 galaxies, covering a large range of morphological type. We derive age, metallicity, dust, and stellar mass maps, and their radial gradients, using high spectral-resolution stellar population models, and assess the impact of varying the stellar library input to the models. We introduce a method to determine dust extinction which is able to give smooth stellar mass maps even in cases of high and spatially non-uniform dust attenuation. With the spectral fitting, we produce detailed maps of stellar population properties which allow us to identify galactic features among this diverse sample such as spiral structure, smooth radial profiles with little azimuthal structure in spheroidal galaxies, and spatially distinct galaxy sub-components. In agreement with the literature, we find the gradients for galaxies identified as early type to be on average flat in age, and negative (-0.15 dex/Re) in metallicity, whereas the gradients for late-type galaxies are on average negative in age (-0.39 dex/Re) and flat in metallicity. We demonstrate how different levels of data quality change the precision with which radial gradients can be measured. We show how this analysis, extended to the large numbers of MaNGA galaxies, will have the potential to shed light on galaxy structure and evolution.

  18. Spectral heterogeneity on Phobos and Deimos: HiRISE observations and comparisons to Mars Pathfinder results

    NASA Astrophysics Data System (ADS)

    Thomas, N.; Stelter, R.; Ivanov, A.; Bridges, N. T.; Herkenhoff, K. E.; McEwen, A. S.

    2011-10-01

    The High-Resolution Imaging Science Experiment (HiRISE) onboard Mars Reconnaissance Orbiter (MRO) has been used to observe Phobos and Deimos at spatial scales of around 6 and 20 m/px, respectively. HiRISE (McEwen et al., JGR, 112, CiteID E05S02, DOI: 10.1029/2005JE002605, 2007) has provided, for the first time, high-resolution colour images of the surfaces of the Martian moons. When processed, by the production of colour ratio images for example, the data show considerable small-scale heterogeneity, which might be attributable to fresh impacts exposing different materials otherwise largely hidden by a homogenous regolith. The bluer material that is draped over the south-eastern rim of the largest crater on Phobos, Stickney, has been perforated by an impact to reveal redder material and must therefore be relatively thin. A fresh impact with dark crater rays has been identified. Previously identified mass-wasting features in Stickney and Limtoc craters stand out strongly in colour. The interior deposits in Stickney appear more inhomogeneous than previously suspected. Several other local colour variations are also evident. Deimos is more uniform in colour but does show some small-scale inhomogeneity. The bright “streamers” (Thomas et al., Icarus, 123, 536-556,1996) are relatively blue. One crater to the south-west of Voltaire and its surroundings appear quite strongly reddened with respect to the rest of the surface. The reddening of the surroundings may be the result of ejecta from this impact. The spectral gradients at optical wavelengths observed for both Phobos and Deimos are quantitatively in good agreement with those found by unresolved photometric observations made by the Imager for Mars Pathfinder (IMP; Thomas et al., JGR, 104, 9055-9068, 1999). The spectral gradients of the blue and red units on Phobos bracket the results from IMP.

  19. Spectral heterogeneity on Phobos and Deimos: HiRISE observations and comparisons to Mars Pathfinder results

    USGS Publications Warehouse

    Thomas, N.; Stelter, R.; Ivanov, A.; Bridges, N.T.; Herkenhoff, K. E.; McEwen, A.S.

    2011-01-01

    The High-Resolution Imaging Science Experiment (HiRISE) onboard Mars Reconnaissance Orbiter (MRO) has been used to observe Phobos and Deimos at spatial scales of around 6 and 20 m/px, respectively. HiRISE (McEwen et al.; JGR, 112, CiteID E05S02, DOI: 10.1029/2005JE002605, 2007) has provided, for the first time, high-resolution colour images of the surfaces of the Martian moons. When processed, by the production of colour ratio images for example, the data show considerable small-scale heterogeneity, which might be attributable to fresh impacts exposing different materials otherwise largely hidden by a homogenous regolith. The bluer material that is draped over the south-eastern rim of the largest crater on Phobos, Stickney, has been perforated by an impact to reveal redder material and must therefore be relatively thin. A fresh impact with dark crater rays has been identified. Previously identified mass-wasting features in Stickney and Limtoc craters stand out strongly in colour. The interior deposits in Stickney appear more inhomogeneous than previously suspected. Several other local colour variations are also evident. Deimos is more uniform in colour but does show some small-scale inhomogeneity. The bright streamers (Thomas et al.; Icarus, 123, 536556,1996) are relatively blue. One crater to the south-west of Voltaire and its surroundings appear quite strongly reddened with respect to the rest of the surface. The reddening of the surroundings may be the result of ejecta from this impact. The spectral gradients at optical wavelengths observed for both Phobos and Deimos are quantitatively in good agreement with those found by unresolved photometric observations made by the Imager for Mars Pathfinder (IMP; Thomas et al.; JGR, 104, 90559068, 1999). The spectral gradients of the blue and red units on Phobos bracket the results from IMP. ?? 2010 Elsevier Ltd. All rights reserved.

  20. Wideband very large array observations of A2256. I. Continuum, rotation measure, and spectral imaging

    SciTech Connect

    Owen, Frazer N.; Rau, Urvashi; Bhatnagar, Sanjay; Kogan, Leonid; Rudnick, Lawrence; Jean Eilek

    2014-10-10

    We report new observations of A2256 with the Karl G. Jansky Very Large Array (VLA) at frequencies between 1 and 8 GHz. These observations take advantage of the 2:1 bandwidths available during a single observation to study the spectral index, polarization, and rotation measure as well as using the associated higher sensitivity per unit time to image total intensity features down to ∼0.''5 resolution. We find that the Large Relic, which dominates the cluster, is made up of a complex of filaments that show correlated distributions in intensity, spectral index, and fractional polarization. The rotation measure varies across the face of the Large Relic but is not well correlated with the other properties of the source. The shape of individual filaments suggests that the Large Relic is at least 25 kpc thick. We detect a low surface brightness arc connecting the Large Relic to the Halo and other radio structures, suggesting a physical connection between these features. The center of the F-complex is dominated by a very steep-spectrum, polarized, ring-like structure, F2, without an obvious optical identification, but the entire F-complex does have interesting morphological similarities to the radio structure of NGC 1265. Source C, the Long Tail, is unresolved in width near the galaxy core and is ≲ 100 pc in diameter there. This morphology suggests either that C is a one-sided jet or that the bending of the tails takes place very near the core, consistent with the parent galaxy having undergone extreme stripping. Overall it seems that many of the unusual phenomena can be understood in the context of A2256 being near the pericenter of a slightly off-axis merger between a cluster and a smaller group. Given the lack of evidence for a strong shock associated with the Large Relic, other models should be considered, such as reconnection between two large-scale magnetic domains.

  1. Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Petre, R.; Mushotzky, R. F.; Krolik, J. H.; Holt, S. S.

    1983-01-01

    Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The averager spectral index alpha is 0.66 + or - .36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N(H) 10 to the 22nd power/sq cm; the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0175-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium.

  2. Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Cessateur, G.; Shapiro, A. I.; Dominique, M.; Kretzschmar, M.; Krivova, N.; Shapiro, A. V.; Schmutz, W.; Schoell, M.; Solanki, S.; Tagirov, R.; Thuillier, G.; Wehrli, C.; Yeo, K. L.

    2012-04-01

    Total and Spectral Solar Irradiance are key input parameters to atmospheric/oceanic and space weather models. Both vary on time-scales ranging from days to millennia, although a complete picture of the solar irradiance variability is still missing. The recent launch of two European missions PROBA-2 with LYRA radiometer onboard and PICARD with PREMOS package onboard provides therefore valuable information and nourishes theoretical models. Both instruments covers the solar spectrum from the EUV to near-infrared. Here we present spectral solar irradiance data from these two recent missions. After a proper correction of the degradation and non-solar signatures, we compare these data with those from the VIRGO/SOHO and SOLSTICE+SIM/SORCE experiments. Both LYRA and PREMOS have also observed several solar eclipses, which allows us to accurately retrieve the center-to-limb variations (CLVs) of the quiet Sun's brightness at the wavelengths of the corresponding channels. CLVs play indeed an important role in modelling of the solar irradiance variability. We show that calculations with the published COde for Solar Irradiance (COSI) yield CLVs that are in good agreement with measurements. Finally we use COSI to model the variability of the irradiance, assuming that the latter is determined by the evolution of the solar surface magnetic field as seen with SDO/HMI data. These theoretical results are compared to PREMOS and LYRA measurements.

  3. Inference of Ice Cloud Properties from High-spectral Resolution Infrared Observations. Appendix 4

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Yang, Ping; Wei, Heli; Baum, Bryan A.; Hu, Yongxiang; Antonelli, Paolo; Ackerman, Steven A.

    2005-01-01

    The theoretical basis is explored for inferring the microphysical properties of ice crystal from high-spectral resolution infrared observations. A radiative transfer model is employed to simulate spectral radiances to address relevant issues. The extinction and absorption efficiencies of individual ice crystals, assumed as hexagonal columns for large particles and droxtals for small particles, are computed from a combination of the finite- difference time-domain (FDTD) technique and a composite method. The corresponding phase functions are computed from a combination of FDTD and an improved geometric optics method (IGOM). Bulk scattering properties are derived by averaging the single- scattering properties of individual particles for 30 particle size distributions developed from in situ measurements and for additional four analytical Gamma size distributions for small particles. The non-sphericity of ice crystals is shown to have a significant impact on the radiative signatures in the infrared (IR) spectrum; the spherical particle approximation for inferring ice cloud properties may result in an overest&ation of the optical thickness and an inaccurate retrieval of effective particle size. Furthermore, we show that the error associated with the use of the Henyey-Greenstein phase function can be as larger as 1 K in terms of brightness temperature for larger particle effective size at some strong scattering wavenumbers. For small particles, the difference between the two phase functions is much less, with brightness temperatures generally differing by less than 0.4 K. The simulations undertaken in this study show that the slope of the IR brightness temperature spectrum between 790-960/cm is sensitive to the effective particle size. Furthermore, a strong sensitivity of IR brightness temperature to cloud optical thickness is noted within the l050-1250/cm region. Based on this spectral feature, a technique is presented for the simultaneous retrieval of the visible

  4. Spectral characteristics of the Farley-Buneman instability: Simulations versus observations

    NASA Astrophysics Data System (ADS)

    Oppenheim, Meers; Otani, Niels

    1996-11-01

    The Farley-Buneman instability is a collisional two-stream instability observed in the E region ionosphere at altitudes in the range of 95-110 km. While linear theory predicts the dominant wavelengths, it cannot fully describe the behavior of this nonlinearly saturated instability as observed by radar and rocket measurements. We simulate the behavior of this instability in the plane perpendicular to the Earth's magnetic field, using a two-dimensional hybrid code which models electron dynamics as a fluid and ion dynamics with a particle-in-cell approach. The results show the growth, saturation, and nonlinear behavior of the instability for a much longer period of time than was possible with the pure particle codes used in previous studies. This paper describes the spectra from these simulations and compares them to the observed spectra. Both the simulations and observations show that (1) type I spectra result from saturated two-stream waves for a broad range of elevation angles, (2) the phase velocity of these waves is below that predicted by linear theory, (3) mode coupling leads to type II-like spectra without the presence of a plasma density gradient as often thought necessary, (4) longer wavelengths due to mode coupling develop, and (5) spectral power decreases at a rate of 0.3 dB/degree of elevation angle.

  5. Spectral Decay Characteristics in High Frequency Range of Observed Records from Crustal Large Earthquakes (Part 2)

    NASA Astrophysics Data System (ADS)

    Tsurugi, M.; Kagawa, T.; Irikura, K.

    2012-12-01

    Spectral decay characteristics in high frequency range of observed records from crustal large earthquakes occurred in Japan is examined. It is very important to make spectral decay characteristics clear in high frequency range for strong ground motion prediction in engineering purpose. The authors examined spectral decay characteristics in high frequency range of observed records among three events, the 2003 Miyagi-Ken Hokubu earthquake (Mw 6.1), the 2005 Fukuoka-Ken Seiho-oki earthquake (Mw 6.6), and the 2008 Iwate-Miyagi Nairiku earthquake (Mw 6.9) in previous study [Tsurugi et al.(2010)]. Target earthquakes in this study are two events shown below. *EQ No.1 Origin time: 2011/04/11 17:16, Location of hypocenter: East of Fukushima pref., Mj: 7.0, Mw: 6.6, Fault type: Normal fault *EQ No.2 Origin time: 2011/03/15 22:31, Location of hypocenter: East of Shizuoka pref., Mj: 6.4, Mw: 5.9, Fault type: Strike slip fault The borehole data of each event are used in the analysis. The Butterworth type high-cut filter with cut-off frequency, fmax and its power coefficient of high-frequency decay, s [Boore(1983)], are assumed to express the high-cut frequency characteristics of ground motions. The four parameters such as seismic moment, corner frequency, cut-off frequency and its power coefficient of high-frequency decay are estimated by comparing observed spectra at rock sites with theoretical spectra. The theoretical spectra are calculated based on the omega squared source characteristics convolved with propagation-path effects and high-cut filter shapes. In result, the fmax's of the records from the earthquakes are estimated 8.0Hz for EQ No.1 and 8.5Hz for EQ No.2. These values are almost same with those of other large crustal earthquakes occurred in Japan. The power coefficient, s, are estimated 0.78 for EQ No.1 and 1.65 for EQ No.2. The value for EQ No.2 is notably larger than those of other large crustal earthquakes. It is seems that the value of the power coefficient, s

  6. GREAT high spectral resolution [OI] 4.7 THz observations of protoplanetary disks and other sources

    NASA Astrophysics Data System (ADS)

    Sandell, Goran H. L.; GREAT Consortium

    2016-01-01

    I discuss velocity resolved atomic oxygen observations obtained with the GREAT (German Receiver for Astronomy at Terahertz Frequencies) high frequency channel (H-channel) receiver on SOFIA. The H-channel is an extremely sensitive hot electron bolometer mixer using a novel quantum cascade laser, which enables high spectral resolution (0.2 km/s) measurements of atomic oxygen [OI] at a frequency of 4.74 THz (63 micron). The [OI] 63 micron atomic fine structure line is known to be strong in photodissociation regions, where it traces denser gas than [CII], and also in shocks. It is the most sensitive gas tracer in protoplanetary disks. I show preliminary results of velocity-resolved [OI] in the two brightest protoplanetary disks in Taurus-Auriga: HL Tau and AB Aur, as well as other highlights from the commissioning and from cycle 3.

  7. Spectral observations of active region sources with RATAN-600 and WSRT. [Westerbork Synthesis Radio Telescope

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Gel'frejkh, G. B.; Borovik, V. N.; Korzhavin, A. N.; Bogod, V. M.; Nindos, A.; Kundu, M. R.

    1993-01-01

    We present spectral observations of neutral line and sunspot associated sources obtained with the RATAN-600 radio telescope and the WSRT in the wavelength range of 2 to 6 cm. Sources associated with large sunspots have flat spectra, while neutral line sources have very steep spectra. In the case of a large spot we estimated the magnetic field to be at least 2700 G at the base of the transition region and 1800 G in the low corona. We consider possible interpretations of the radio emission above the neutral lines. Gyroresonance emission at the fourth harmonic is inadequate, whereas emission from a small population of nonthermal electrons (total number 10 exp 30 to 10 exp 31) with a delta = 3 power law distribution seems to be sufficient.

  8. FERMI OBSERVATIONS OF GRB 090902B: A DISTINCT SPECTRAL COMPONENT IN THE PROMPT AND DELAYED EMISSION

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bhat, P. N.; Bissaldi, E.; Bonamente, E.

    2009-11-20

    We report on the observation of the bright, long gamma-ray burst (GRB), GRB 090902B, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory. This was one of the brightest GRBs to have been observed by the LAT, which detected several hundred photons during the prompt phase. With a redshift of z = 1.822, this burst is among the most luminous detected by Fermi. Time-resolved spectral analysis reveals a significant power-law component in the LAT data that is distinct from the usual Band model emission that is seen in the sub-MeV energy range. This power-law component appears to extrapolate from the GeV range to the lowest energies and is more intense than the Band component, both below approx50 keV and above 100 MeV. The Band component undergoes substantial spectral evolution over the entire course of the burst, while the photon index of the power-law component remains constant for most of the prompt phase, then hardens significantly toward the end. After the prompt phase, power-law emission persists in the LAT data as late as 1 ks post-trigger, with its flux declining as t {sup -1.5}. The LAT detected a photon with the highest energy so far measured from a GRB, 33.4{sup +2.7}{sub -3.5} GeV. This event arrived 82 s after the GBM trigger and approx50 s after the prompt phase emission had ended in the GBM band. We discuss the implications of these results for models of GRB emission and for constraints on models of the extragalactic background light.

  9. Swift and Suzaku observations of spectral evolution in the FRED type GRBs

    NASA Astrophysics Data System (ADS)

    Tashiro, Makoto; Ueno, H.; Enomoto, J.

    The energy dependence in light curves of gamma-ray bursts (GRBs) is a probe to study the underlying radiation mechanism. In particular, spectral evolution in the decay phase is expected to reflect the cooling process of accelerated electrons. Norris et al. systematically examined asymmetric pulses in the prompt emissions of GRBs and showed that the pulse widths have the energy dependence that is well approximated with a power-law with the energy index of -0.41 in average. Although they did not particularly mention about the decay phase, their result strongly suggests a universal radiation/cooling mechanism in the emission region of GRBs. In previous study with Suzaku/WAM, we sampled 6 bright GRBs; 7 well isolated pulses that showed no power-law decay but exhibiting exponential-decay (FRED) were detected in total, and found that the time constants evaluated for each energy band exhibited a power-law type energy dependence with the energy index of -0.3 to -0.5. Now our next step would be to investigate the radiation process in the GRB prompt emissions in wider energy bands beyond Suzaku/WAM. Here we report the results of our study of the three bright GRBs (GRB 060117, GRB 070917, GRB 080413B) that showed the FRED and were observed with both Swift/BAT and Suzaku/WAM. All of their exponential decays exhibit similar power-law type energy dependence. The distribution of the energy indices is consistent with the FREDs that were observed with WAM, as reported in Tashiro et al. Our detailed time-resolved spectral study reveals that the spectra of all the three FREDs are well reproduced with the Band GRB functions with decreasing turnover energy. In particular, the time evolution of two of the three FREDs are consistent with those expected in the fast synchrotron-cooling regime.

  10. Observational Signatures of Black Holes: Spectral and Temporal Features of XTE J1550-564

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Shrader, C. R.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    The theoretical predictions of the converging inflow, or Bulk-Motion Comptonization model are discussed and some predictions are compared to X- and gamma-ray observations of the high-soft state of Galactic black hole candidate XTE J1550+564. The approx. 10(exp 2)-Hz QPO phenomenon tends to be detected in the high-state at times when the bolometric luminosity surges and the hard-powerlaw spectral component is dominant. Furthermore, the power in these features increases with energy. We offer interpretation of this phenomenon, as oscillations of the innermost part of the accretion disk, which in turn supplies the seed photons for the converging inflow where the hard power-law is formed through Bulk Motion Comptonization (BMC). We further argue that the noted lack of coherence between intensity variations of the high-soft-state low and high energy bands is a natural consequence of our model, and that a natural explanation for the observed hard and soft lag phenomenon is offered. In addition, we address some criticisms of the BMC model supporting our claims with observational results.

  11. A NOVEL TECHNIQUE TO OBSERVE RAPIDLY PULSATING OBJECTS USING SPECTRAL WAVE-INTERACTION EFFECTS

    SciTech Connect

    Borra, Ermanno F.

    2010-05-20

    Conventional techniques that measure rapid time variations are inefficient or inadequate to discover and observe rapidly pulsating astronomical sources. It is therefore conceivable that there exist some classes of objects pulsating with extremely short periods that have not yet been discovered. This paper starts from the fact that rapid flux variations generate a spectral modulation that can be detected in the beat spectrum of the output current fluctuations of a quadratic detector. The telescope could observe at any frequency, although shorter frequencies would have the advantage of lower photon noise. The techniques would allow us to find and observe extremely fast time variations, opening up a new time window in astronomy. The current fluctuation technique, like intensity interferometers, uses second-order correlation effects and fits into the current renewal of interest in intensity interferometry. An interesting aspect it shares with intensity interferometry is that it can use inexpensive large telescopes that have low-quality mirrors, like Cherenkov telescopes. It has other advantages over conventional techniques that measure time variations, foremost of which is its simplicity. Consequently, it could be used for extended monitoring of astronomical sources, something that is difficult to do with conventional telescopes. Arguably, the most interesting scientific justification for the technique comes from Serendipity.

  12. Optimizing commensality of radio continuum and spectral line observations in the era of the SKA

    NASA Astrophysics Data System (ADS)

    Maddox, Natasha; Jarvis, M. J.; Oosterloo, T. A.

    2016-08-01

    The substantial decrease in star formation density from z=1 to the present day is curious given the relatively constant neutral gas density over the same epoch. Future radio astronomy facilities, including the SKA and pathfinder telescopes, will provide pioneering measures of both the gas content of galaxies and star formation activity over cosmological timescales. Here we investigate the commensalities between neutral atomic gas (HI) and radio continuum observations, as well as the complementarity of the data products. We start with the proposed HI and continuum surveys to be undertaken with the SKA precursor telescope MeerKAT, and building on this, explore optimal combinations of survey area coverage and depth of proposed HI and continuum surveys to be undertaken with the SKA1-MID instrument. Intelligent adjustment of these observational parameters results in a tiered strategy that minimises observation time while maximising the value of the dataset, both for HI and continuum science goals. We also find great complementarity between the HI and continuum datasets, with the spectral line HI data providing redshift measurements for gas-rich, star-forming galaxies with stellar masses Mstellar~10^9 Msun to z~0.3, a factor of three lower in stellar mass than would be feasible to reach with large optical spectroscopic campaigns.

  13. Optimizing commensality of radio continuum and spectral line observations in the era of the SKA

    NASA Astrophysics Data System (ADS)

    Maddox, Natasha; Jarvis, M. J.; Oosterloo, T. A.

    2016-08-01

    The substantial decrease in star formation density from z = 1 to the present day is curious given the relatively constant neutral gas density over the same epoch. Future radio astronomy facilities, including the Square Kilometre Array (SKA) and pathfinder telescopes, will provide pioneering measures of both the gas content of galaxies and star formation activity over cosmological time-scales. Here we investigate the commensalities between neutral atomic gas (H I) and radio continuum observations, as well as the complementarity of the data products. We start with the proposed H I and continuum surveys to be undertaken with the SKA precursor telescope MeerKAT, and building on this, explore optimal combinations of survey area coverage and depth of proposed H I and continuum surveys to be undertaken with the SKA1-MID instrument. Intelligent adjustment of these observational parameters results in a tiered strategy that minimizes observation time while maximizing the value of the data set, both for H I and continuum science goals. We also find great complementarity between the H I and continuum data sets, with the spectral line H I data providing redshift measurements for gas-rich, star-forming galaxies with stellar masses M* ˜ 109 M⊙ to z ˜ 0.3, a factor of 3 lower in stellar mass than would be feasible to reach with large optical spectroscopic campaigns.

  14. SPATIALLY AND SPECTRALLY RESOLVED OBSERVATIONS OF A ZEBRA PATTERN IN A SOLAR DECIMETRIC RADIO BURST

    SciTech Connect

    Chen Bin; Bastian, T. S.; Gary, D. E.; Jing Ju

    2011-07-20

    We present the first interferometric observation of a zebra-pattern radio burst with simultaneous high spectral ({approx}1 MHz) and high time (20 ms) resolution. The Frequency-Agile Solar Radiotelescope Subsystem Testbed (FST) and the Owens Valley Solar Array (OVSA) were used in parallel to observe the X1.5 flare on 2006 December 14. By using OVSA to calibrate the FST, the source position of the zebra pattern can be located on the solar disk. With the help of multi-wavelength observations and a nonlinear force-free field extrapolation, the zebra source is explored in relation to the magnetic field configuration. New constraints are placed on the source size and position as a function of frequency and time. We conclude that the zebra burst is consistent with a double-plasma resonance model in which the radio emission occurs in resonance layers where the upper-hybrid frequency is harmonically related to the electron cyclotron frequency in a coronal magnetic loop.

  15. Temporal and spectral characteristics of seismicity observed at Popocatepetl volcano, central Mexico

    USGS Publications Warehouse

    Arciniega-Ceballos, A.; Valdes-Gonzalez, C.; Dawson, P.

    2000-01-01

    Popocatepetl volcano entered an eruptive phase from December 21, 1994 to March 30, 1995, which was characterized by ash and fumarolic emissions. During this eruptive episode, the observed seismicity consisted of volcano-tectonic (VT) events, long-period (LP) events and sustained tremor. Before the initial eruption on December 21, VT seismicity exhibited no increase in number until a swarm of VT earthquakes was observed at 01:31 hours local time. Visual observations of the eruption occurred at dawn the next morning. LP activity increased from an average of 7 events a day in October 1994 to 22 events per day in December 1994. At the onset of the eruption, LP activity peaked at 49 events per day. LP activity declined until mid-January 1995 when no events were observed. Tremor was first observed about one day after the initial eruption and averaged 10 h per episode. By late February 1995, tremor episodes became more intermittent, lasting less than 5 min, and the number of LP events returned to pre-eruption levels (7 events per day). Using a spectral ratio technique, low-frequency oceanic microseismic noise with a predominant peak around 7 s was removed from the broadband seismic signal of tremor and LP events. Stacks of corrected tremor episodes and LP events show that both tremor and LP events contain similar frequency features with major peaks around 1.4 Hz. Frequency analyses of LP events and tremor suggest a shallow extended source with similar radiation pattern characteristics. The distribution of VT events (between 2.5 and 10 km) also points to a shallow source of the tremor and LP events located in the first 2500 m beneath the crater. Under the assumption that the frequency characteristics of the signals are representative of an oscillator we used a fluid-filled-crack model to infer the length of the resonator.

  16. GNSS-based Observations and Simulations of Spectral Scintillation Indices in the Arctic Ionosphere

    NASA Astrophysics Data System (ADS)

    Durgonics, T.; Hoeg, P.; von Benzon, H. H.; Komjathy, A.

    2015-12-01

    During disturbed times, ionospheric scintillations can be severe and adversely impact satellite-based positioning and radio transmissions. The scintillation occurs in the amplitude, phase, polarization, and angle of arrival of the signal. Precise observation, classification, modeling, forecasting, and development of data-driven methodologies to accurately localize ionospheric irregularities and simulate GNSS scintillation signals are highly desired. Ionospheric scintillations have traditionally been quantified by amplitude (S4) and phase scintillations (σφ). Our study focuses on the Arctic, where scintillations, especially phase scintillations, are prominent. We will present observations acquired from a network of Greenlandic GNSS stations, including 2D amplitude and phase scintillation index maps for representative calm and storm periods. In addition to the traditional indices described above, we are exploring a set of indices derived from the power spectra of the signals. The observed corner frequency of the power spectrum is a function of the Fresnel radius and the drift speed of the irregularities, while the slope of the power spectrum is related to the Fresnel oscillations. We will demonstrate how spectral characteristics of the scintillations act under large total electron content (TEC) gradients and how physical parameters can be extracted from the power spectra, and will present how these parameters of the corner frequencies and power spectra slopes vary during ionospheric storms. The observations will then be compared to properties of simulated GNSS signals computed by the Fast Scintillation Mode (FSM). The FSM was developed to simulate ionospheric scintillations under different geophysical conditions, and is used to simulate GNSS signals with known scintillation characteristics. This comparison could lead to a better understanding of the observed ionospheric state.

  17. Spatial resolution enhancement of hyperspectral image based on the combination of spectral mixing model and observation model

    NASA Astrophysics Data System (ADS)

    Zhang, Yifan

    2014-10-01

    To improve the spatial resolution of a hyperspectral (HS) observation of a scene with the aid of an auxiliary multispectral (MS) observation, a new spectral unmixing-based HS and MS image fusion approach is presented in this paper. In the proposed fusion approach, linear spectral unmixing with sparsity constraint is employed, by taking the impact of linear observation model on linear mixing model into consideration. Simulative experiment is employed for verification and comparison. It is illustrated that the proposed approach would be more promising for practical utilization compared to some state-of-the-art approaches, due to its good balance between fusion performance and calculation cost.

  18. Terrestrial kilometric radiation. III - Average spectral properties. [observations by IMP-6 and RAE-2 satellites

    NASA Technical Reports Server (NTRS)

    Kaiser, M. L.; Alexander, J. K.

    1977-01-01

    The spectral properties of terrestrial kilometric radiation (TKR) derived from observations made during radio-astronomy experiments on board the Imp 6 and Radio Astronomy Explorer 2 spacecraft are studied. As viewed from near the equatorial plane, TKR is most intense and most often observed in the 2100-2400 LT zone and is rarely seen in the 0900-1200 LT zone. The absolute flux levels in the 100- to 600-kHz TKR band increase significantly with increasing substorm activity as inferred from the auroral electrojet index (AE). In the late-evening sector the median power increases by about 3 orders of magnitude between quiet periods (AE less than 75 gammas) and disturbed periods (AE above 200 gammas). The peak flux density usually occurs near 250 kHz, although the frequency of the peak in the flux spectrum appears to vary inversely with AE from a maximum near 300 kHz during very quiet times to a minimum below 200 kHz during very disturbed times. The half-power bandwidth is typically 100% of the peak frequency. The variation of TKR flux density with apparent source altitude indicates that source strength decreases more rapidly than the inverse square of distance.

  19. Aerosol and Cloud Interaction Observed From High Spectral Resolution Lidar Data

    NASA Technical Reports Server (NTRS)

    Su, Wenying; Schuster, Gregory L.; Loeb, Norman G.; Rogers, Raymond R.; Ferrare, Richard A.; Hostetler, Chris A.; Hair, Johnathan W.; Obland, Michael D.

    2008-01-01

    Recent studies utilizing satellite retrievals have shown a strong correlation between aerosol optical depth (AOD) and cloud cover. However, these retrievals from passive sensors are subject to many limitations, including cloud adjacency (or 3D) effects, possible cloud contamination, uncertainty in the AOD retrieval. Some of these limitations do not exist in High Spectral Resolution Lidar (HSRL) observations; for instance, HSRL observations are not a ected by cloud adjacency effects, are less prone to cloud contamination, and offer accurate aerosol property measurements (backscatter coefficient, extinction coefficient, lidar ratio, backscatter Angstrom exponent,and aerosol optical depth) at a neospatial resolution (less than 100 m) in the vicinity of clouds. Hence, the HSRL provides an important dataset for studying aerosol and cloud interaction. In this study, we statistically analyze aircraft-based HSRL profiles according to their distance from the nearest cloud, assuring that all profile comparisons are subject to the same large-scale meteorological conditions. Our results indicate that AODs from HSRL are about 17% higher in the proximity of clouds (approximately 100 m) than far away from clouds (4.5 km), which is much smaller than the reported cloud 3D effect on AOD retrievals. The backscatter and extinction coefficients also systematically increase in the vicinity of clouds, which can be explained by aerosol swelling in the high relative humidity (RH) environment and/or aerosol growth through in cloud processing (albeit not conclusively). On the other hand, we do not observe a systematic trend in lidar ratio; we hypothesize that this is caused by the opposite effects of aerosol swelling and aerosol in-cloud processing on the lidar ratio. Finally, the observed backscatter Angstrom exponent (BAE) does not show a consistent trend because of the complicated relationship between BAE and RH. We demonstrate that BAE should not be used as a surrogate for Angstrom

  20. Light Scattering and Compositional Analysis of Saturn's Rings Using Cassini UVIS Spectral Observations

    NASA Astrophysics Data System (ADS)

    Bradley, E. T.; Colwell, J. E.; Esposito, L. W.

    2015-12-01

    Saturn's ring particles are roughly centimeter to several-meter-sized objects that are covered with a regolith of icy grains. In general the composition of the regolith of an object can be investigated by comparing photometric models to reflectance spectra of the surface. However, since the rings as a whole are not a solid surface and the A and B ring particles clump together into self-gravity wakes, the light scattering behavior of the rings has a complex dependence on the geometry of the observations. In order to deal with this we first determine the ring particle albedo for the A, B, and C rings and the Cassini Division at discrete far ultraviolet wavelengths across the water ice absorption edge at 165 nm. We next use the retrieved albedos to compare to spectral models that use available optical constants in the FUV for water ice and various plausible non-water-ice contaminants such as organic tholins, silicates, and other ices.. We retrieve the ring particle albedo by comparing observations of the lit face of the rings to a single scattering Chandrasekhar model. We then compare the observations to photometric models where we assume that the non-water-ice constituents are either embedded in water ice grains so that the effective optical constants are a linear combination of constituent optical constants or that the regolith consists of discrete grains of water ice and non-ice constituents. We find that the best fit of the compositional models to the ring particle albedo is for water ice abundances greater than 95% and water ice grain sizes of a few microns.

  1. Optical Spectral Observations of a Flickering White-light Kernel in a C1 Solar Flare

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam F.; Cauzzi, Gianna; Fletcher, Lyndsay

    2015-01-01

    We analyze optical spectra of a two-ribbon, long-duration C1.1 flare that occurred on 2011 August 18 within AR 11271 (SOL2011-08-18T15:15). The impulsive phase of the flare was observed with a comprehensive set of space-borne and ground-based instruments, which provide a range of unique diagnostics of the lower flaring atmosphere. Here we report the detection of enhanced continuum emission, observed in low-resolution spectra from 3600 Å to 4550 Å acquired with the Horizontal Spectrograph at the Dunn Solar Telescope. A small, <=0.''5 (1015 cm2) penumbral/umbral kernel brightens repeatedly in the optical continuum and chromospheric emission lines, similar to the temporal characteristics of the hard X-ray variation as detected by the Gamma-ray Burst Monitor on the Fermi spacecraft. Radiative-hydrodynamic flare models that employ a nonthermal electron beam energy flux high enough to produce the optical contrast in our flare spectra would predict a large Balmer jump in emission, indicative of hydrogen recombination radiation from the upper flare chromosphere. However, we find no evidence of such a Balmer jump in the bluemost spectral region of the continuum excess. Just redward of the expected Balmer jump, we find evidence of a "blue continuum bump" in the excess emission which may be indicative of the merging of the higher order Balmer lines. The large number of observational constraints provides a springboard for modeling the blue/optical emission for this particular flare with radiative-hydrodynamic codes, which are necessary to understand the opacity effects for the continuum and emission line radiation at these wavelengths.

  2. OPTICAL SPECTRAL OBSERVATIONS OF A FLICKERING WHITE-LIGHT KERNEL IN A C1 SOLAR FLARE

    SciTech Connect

    Kowalski, Adam F.; Cauzzi, Gianna; Fletcher, Lyndsay

    2015-01-10

    We analyze optical spectra of a two-ribbon, long-duration C1.1 flare that occurred on 2011 August 18 within AR 11271 (SOL2011-08-18T15:15). The impulsive phase of the flare was observed with a comprehensive set of space-borne and ground-based instruments, which provide a range of unique diagnostics of the lower flaring atmosphere. Here we report the detection of enhanced continuum emission, observed in low-resolution spectra from 3600 Å to 4550 Å acquired with the Horizontal Spectrograph at the Dunn Solar Telescope. A small, ≤0.''5 (10{sup 15} cm{sup 2}) penumbral/umbral kernel brightens repeatedly in the optical continuum and chromospheric emission lines, similar to the temporal characteristics of the hard X-ray variation as detected by the Gamma-ray Burst Monitor on the Fermi spacecraft. Radiative-hydrodynamic flare models that employ a nonthermal electron beam energy flux high enough to produce the optical contrast in our flare spectra would predict a large Balmer jump in emission, indicative of hydrogen recombination radiation from the upper flare chromosphere. However, we find no evidence of such a Balmer jump in the bluemost spectral region of the continuum excess. Just redward of the expected Balmer jump, we find evidence of a ''blue continuum bump'' in the excess emission which may be indicative of the merging of the higher order Balmer lines. The large number of observational constraints provides a springboard for modeling the blue/optical emission for this particular flare with radiative-hydrodynamic codes, which are necessary to understand the opacity effects for the continuum and emission line radiation at these wavelengths.

  3. Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations.

    PubMed

    Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D

    2013-09-01

    The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-(57)Fe-enriched [Fe4S4Cl4](=) and 10%-(57)Fe and 90%-(54)Fe labeled [Fe4S4Cl4](=) has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3-4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements. PMID:23955030

  4. Validation of CALIPSO Lidar Observations Using Data From the NASA Langley Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris; Hair, Johnathan; Liu, Zhaoyan; Ferrare, Rich; Harper, David; Cook, Anthony; Vaughan, Mark; Trepte, Chip; Winker, David

    2006-01-01

    This poster focuses on preliminary comparisons of data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft with data acquired by the NASA Langley Airborne High Spectral Resolution Lidar (HSRL). A series of 20 aircraft validation flights was conducted from 14 June through 27 September 2006, under both day and night lighting conditions and a variety of aerosol and cloud conditions. This poster presents comparisons of CALIOP measurements of attenuated backscatter at 532 and 1064 nm and depolarization at 532 nm with near coincident measurements from the Airborne HSRL as a preliminary assessment of CALIOP calibration accuracy. Note that the CALIOP data presented here are the pre-release version. These data have known artifacts in calibration which have been corrected in the December 8 CALIPSO data release which was not available at the time the comparisons were conducted for this poster. The HSRL data are also preliminary. No artifacts are known to exist; however, refinements in calibration and algorithms are likely to be implemented before validation comparisons are made final.

  5. Spectral analysis of temperature and Brunt-Vaisala frequency fluctuations observed by radiosondes

    NASA Technical Reports Server (NTRS)

    Tsuda, T.; Vanzandt, T. E.; Kato, S.; Fukao, S.; Sato, T.

    1989-01-01

    Recent studies have revealed that vertical wave number spectra of wind velocity and temperture fluctuations in the troposphere and the lower stratosphere are fairly well explained by a saturated gravity wave spectrum. But N(2) (N:Brunt-Vaisala (BV) frequency) spectra seem to be better for testing the scaling of the vertical wave number spectra in layers with different stratifications, beause its energy density is proportional only to the background value of N(2), while that for temperature depends on both the BV frequency and the potential temperature. From temperature profiles observed in June to August 1987 over the MU Observatory, Japan, by using a radiosonde with 30 m height resolution, N(2) spectra are determined in the 2 to 8.5 km (troposphere) and 18.5 to 25 km (lower stratosphere) ranges. Although individual spectra show fairly large day-by-day variability, the slope of the median of 34 spectra agrees reasonably with the theoretical value of -1 in the wave number range of 6 x 10(-4) similar to 3 x 10(-3) (c/m). The ratio of the spectral energy between these two height regions is about equal to the ratio of N(2), consistent with the prediction of saturated gravity wave theory.

  6. Spectral study of GX 339-4 with TCAF using Swift and NuSTAR observation

    NASA Astrophysics Data System (ADS)

    Mondal, Santanu; Chakrabarti, Sandip K.; Debnath, Dipak

    2016-09-01

    We fit spectra of galactic transient source GX 339-4 during its 2013 outburst using Two Component Advective Flow (TCAF) solution. For the first time, we are fitting combined NuSTAR and Swift observation with TCAF. We use TCAF to fit 0.8-9.0 keV Swift and 4-79 keV NuSTAR spectra along with the LAOR model. To fit the data we use disk accretion rate, halo accretion rate, size of the Compton cloud and the density jump of advective flows at this cloud boundary as model parameters. From TCAF fitted flow parameters, and energy spectral index we conclude that the source was in the hard state throughout this particular outburst. The present analysis also gives some idea about the broadening of Fe K_{α } with the accretion rate. Since TCAF does not include Fe line yet, we make use of the `LAOR model' as a phenomenological model and find an estimate of the Kerr parameter to be {˜} 0.99 for this candidate.

  7. Modeling spatially and spectrally resolved observations to diagnose the formation of elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory Frantz

    2013-03-01

    morphologies across cosmic time. In the final chapter, I outline an approach to build a "mock observatory" from cosmological hydrodynamical simulations, with which observations of all types, including at high spatial and spectral resolutions, can be brought to bear in directly constraining the physics of galaxy formation and evolution.

  8. Modeling and Retrieval of Cometary Gas Spectral Lines for Rosetta-MIRO Observations Of Comet 67p

    NASA Astrophysics Data System (ADS)

    Lee, Seungwon; von Allmen, P.; Gulkis, S.; Hofstadter, M.; Kamp, L.

    2012-10-01

    The Microwave Instrument for the Rosetta Orbiter (MIRO), on board the ESA Rosetta spacecraft, will observe spectral lines of water, carbon monoxide, ammonia, and methanol at submillimeter wavelengths from the coma of Comet 67P Churyumov-Gerasimenko. Realistic modeling of observations of the cometary gas spectral lines is critical in preparation and interpretation of the MIRO observations. In addition, a reliable and efficient inverse method to retrieve cometary parameters from the observed lines is needed to interprete the observation results and to refine the future observation planning. This paper reports the forward models and retrieval methods developed for the Rosetta-MIRO observations. The forward models start from a nucleus and coma surface condition to a coma profile, to a molecular level distribution, to MIRO spectral lines. A Direct-Simulation Monte Carlo (DSMC) technique is applied to model the gas kinetics in the cometary coma. The population distribution of the molecular levels is calculated using the accelerated Monte Carlo method. The retrieval problem that we faces with MIRO observation is (1) to retrieve coma profiles from the MIRO spectral lines and (2) to retrieve nucleus and coma surface conditions (jets, outgassing rate, outgassing velocity distribution) from the MIRO retrieved coma profile. The optimal estimation theory is applied for the MIRO retrieval problem. By using the forward models in combination, we studied the effect of the physical conditions of the comet nucleus and coma on the observations by MIRO at various observational conditions such as different heliocentric distances, local solar phases, observation distances to the comet nucleus, and viewing angles (e.g. nadir or limb). We also studied the behavior and performance of the retrieval method for various observational data and a priori knowledge. The study results are used to prepare the MIRO observations and refine the forward model and the retrieval scheme.

  9. Implication of the Observable Spectral Cutoff Energy Evolution in XTE J1550-564

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Shaposhnikov, Nikolai

    2010-01-01

    The physical mechanisms responsible for production of the non-thermal emission in accreting black holes should be imprinted in the observational appearances of the power law tails in the X-ray spectra from these objects. Variety of spectral states observed from galactic black hole binaries by it Rossi X-ray Timing Explorer (RXTE) allow examination of the photon upscattering under different accretion regimes. We revisit of RXTE data collected from the black hole X-ray binary XTE J1550-564 during two periods of X-ray activity in 1998 and 2000 focusing on the behavior of the high energy cutoff of the power law part of the spectrum. For the 1998 outburst the Iran- sition from the low-hard state to the intermediate state was accompanied by a gradual decrease in the cutoff energy which then showed a sharp reversal to a clear increasing trend during the further evolution towards the very high and high-soft states. However, the 2000 outburst showed only the decreasing part of this pattern. Notably, the photon indexes corresponding to the cutoff increase for the 1998 event are much higher than the index values reached during the 2000 rise transition. We attribute this difference in the cutoff' energy behav- for to the different partial contributions of the thermal and non-thermal (bulk motion) Comptonization in photon upscattering. Namely, during the 1998 event the higher accretion rate presumably provided more cooling to the Comptonizing media and thus reducing the effectiveness of the thermal upscattering process. Under these conditions the bulk motion takes a leading role in boosting the input soft photons. Monte Carlo simulations of the The physical mechanisms responsible for production of the non-thermal emission in accreting black holes should be imprinted in the observational apperances of the power law tails in the X-ray spectra from these objects. Variety of spectral states observed from galactic black hole binaries by it Rossi X-ray Timing Explorer (RXTE) allow

  10. Linear spectral modeling of ground-based observations of Europa (ESO/VLT/SINFONI)

    NASA Astrophysics Data System (ADS)

    Ligier, Nicolas; Poulet, François; Carter, John; Langevin, Yves; Dumas, Christophe; Gourgeot, Florian

    2015-11-01

    Jupiter’s moon Europa may harbor a global salty subsurface liquid water ocean (Kivelson et al. 2000), and its surface should contain important clues about its composition. However, debate still persists about the nature of the surface chemistry and the relative roles of exogenous versus endogenous processing. Recently, Roth et al. (2014) reported the presence of activity by the detection of plumes reinforcing Europa as a major target of interests of upcoming space missions such as the ESA L-class mission JUICE.To continue the investigation of the composition of the surface of Europa, a global mapping campaign of the satellite was performed between October 2011 and January 2012 with the integral field spectrograph SINFONI on the Very Large Telescope (VLT) in Chile. The high spectral binning of this instrument (0.5 nm) is suitable to detect any narrow signature in the wavelength range 1.45-2.45 μm. The spatially resolved spectra we obtained over five epochs nearly cover the entire surface of Europa with a pixel scale of 12.5 by 25 m.a.s (~35 by 70 km on Europa’s surface).We perform linear spectral modeling using 4 types of species : water-ice (both crystalline and amorphous), sulfuric acid hydrate, sulfate salts and Cl-rich salts. At first order, spectra on the leading side are, as expected, dominated by water-ice distorted and asymmetric absorption features, whereas sulfuric acid hydrate thought to originate from Iogenic sulfur ion bombardment is clearly predominant on the trailing side (Carlson et al. 2005).Salts are also required to fit any SINFONI spectrum with the following notable result: when Na/K-bearing chlorines instead of Mg-sulfates are used, the fits are improved whatever the region. The feature centered at ~2.07 µm previously associated to the magnesium sulfates (Brown et al. 2013) is also observed in the SINFONI spectra and can be reproduced by some chlorine salts. Global abundance maps will be presented, regional variations of abundances will be

  11. Quantifying Aerosol Direct Effects from Broadband Irradiance and Spectral Aerosol Optical Depth Observations

    SciTech Connect

    Creekmore, Torreon N.; Joseph, Everette; Long, Charles N.; Li, Siwei

    2014-05-16

    We outline a methodology using broadband and spectral irradiances to quantify aerosol direct effects on the surface diffuse shortwave (SW) irradiance. Best Estimate Flux data span a 13 year timeframe at the Department of Energy Atmospheric Radiation Measurement Program’s Southern Great Plains (SGP) site. Screened clear-sky irradiances and aerosol optical depth (AOD), for solar zenith angles ≤ 65°, are used to estimate clear-sky diffuse irradiances. We validate against detected clear-sky observations from SGP’s Basic Radiation System (BRS). BRS diffuse irradiances were in accordance with estimates, producing a root-mean-square error and mean bias errors of 4.0 W/m2 and -1.4 W/m2, respectively. Absolute differences show 99% of estimates within ±10 W/m2 (10%) of the mean BRS observations. Clear-sky diffuse estimates are used to derive quantitative estimates of aerosol radiative effects, represented as the aerosol diffuse irradiance (ADI). ADI is the contribution of diffuse SW to global SW, attributable to scattering of atmospheric transmission by natural plus anthropogenic aerosols. Estimated slope for the ADI as a function of AOD indicates an increase of ~22 W/m2 in diffuse SW for every 0.1 increase in AOD. Such significant increases in the diffuse fraction could possibly increase photosynthesis. Annual mean ADI is 28.2 W/m2, and heavy aerosol loading at SGP provides up to a maximum increase of 120 W/m2 in diffuse SW over background conditions. With regard to seasonal variation, the mean diffuse forcings are 17.2, 33.3, 39.0, and 23.6 W/m2 for winter, spring, summer, and fall, respectively.

  12. Subretinal Fluid in Eyes with Active Ocular Toxoplasmosis Observed Using Spectral Domain Optical Coherence Tomography

    PubMed Central

    Shao, Qing; Heussen, Florian M.; Keane, Pearse A.; Stübiger, Nicole; Sadda, Srinivas R.; Pleyer, Uwe

    2015-01-01

    Purpose To describe the clinical finding of subretinal fluid (SRF) in the posterior pole by spectral domain optical coherence tomography (SD-OCT) in eyes with active ocular toxoplasmosis (OT). Design Retrospective case series. Participants Thirty-eight eyes from 39 patients with active OT. Methods Eyes with active OT which underwent SD-OCT were reviewed. SRFs in the posterior pole were further analyzed. Main Outcome Measures Presence of SRF; its accompanying features, e.g. retinal necrosis, cystoid macular edema (CME), choroidal neovascularization (CNV); and longitudinal changes of SRF, including maximum height and total volume before and after treatment. Results SRF presented in 45.5% (or 15/33) of eyes with typical active OT and in 51.3% (or 20/39) of eyes with active OT. The mean maximum height and total volume of SRF were 161.0 (range: 23–478) µm and 0.47 (range: 0.005–4.12) mm3, respectively. For 12 eyes with SRF related to active retinal necrosis, SRF was observed with complete absorption after conventional anti-toxoplasmosis treatment. The mean duration for observation of SRF clearance was 33.8 (range: 7–84) days. The mean rate of SRF clearance was 0.0128 (range: 0.0002–0.0665) mm3/day. Conclusions SRF (i.e., serous retinal detachment) is a common feature in patients with active OT when SD-OCT is performed. The majority of SRF was associated with retinal necrosis and reacted well to conventional therapy, regardless of total fluid volume. However, SRF accompanying with CME or CNV responded less favorably or remained refractory to conventional or combined intravitreal treatment, even when the SRF was small in size. PMID:26010656

  13. Spectral Observations of Ellerman Bombs and Fitting with a Two-cloud Model

    NASA Astrophysics Data System (ADS)

    Hong, Jie; Ding, M. D.; Li, Ying; Fang, Cheng; Cao, Wenda

    2014-09-01

    We study the Hα and Ca II 8542 Å line spectra of four typical Ellerman bombs (EBs) in the active region NOAA 11765 on 2013 June 6, observed with the Fast Imaging Solar Spectrograph installed at the 1.6 m New Solar Telescope at Big Bear Solar Observatory. Considering that EBs may occur in a restricted region in the lower atmosphere, and that their spectral lines show particular features, we propose a two-cloud model to fit the observed line profiles. The lower cloud can account for the wing emission, and the upper cloud is mainly responsible for the absorption at line center. After choosing carefully the free parameters, we get satisfactory fitting results. As expected, the lower cloud shows an increase of the source function, corresponding to a temperature increase of 400-1000 K in EBs relative to the quiet Sun. This is consistent with previous results deduced from semi-empirical models and confirms that local heating occurs in the lower atmosphere during the appearance of EBs. We also find that the optical depths can increase to some extent in both the lower and upper clouds, which may result from either direct heating in the lower cloud, or illumination by an enhanced radiation on the upper cloud. The velocities derived from this method, however, are different from those obtained using the traditional bisector method, implying that one should be cautious when interpreting this parameter. The two-cloud model can thus be used as an efficient method to deduce the basic physical parameters of EBs.

  14. The spectral properties of low latitude daytime electric fields inferred from magnetometer observations

    NASA Astrophysics Data System (ADS)

    Nicolls, Michael J.; Kelley, Michael C.; Chau, Jorge L.; Veliz, Oscar; Anderson, David; Anghel, Adela

    2007-07-01

    Four years of magnetometer data from two locations in Peru, one at the equator and one off the equator, have been converted to electric fields and their frequency characteristics (fluctuation spectra) examined. In the frequency range from 0.1 to 30 cycles per hour, the average spectrum monotonically decreases. However, it deviates from a power law in the range 0.3 3 cycles per hour especially for high levels of activity. The integrated power above 0.15 cycles per hour is a strong function of K indicating that much of the fluctuations in the ionospheric equatorial field are of solar wind or magnetospheric origin. This result is in agreement with a previous power spectral study of low, middle, and high latitude fields using radars. The observed field strengths are lower than the ones observed in a previous study using balloon data at middle and high latitudes when the fields are projected to the equatorial plane. Simultaneous interplanetary electric field (IEF) data are compared to the equatorial field to determine how strong a relationship exists and to determine the amplitude and phase of their ratio as a function of frequency—an estimate of the average transfer function of the system. This function displays a bandpass-like form with a peak near 0.5 cycles per hour. This peak and evidence for a ringing of the time domain response suggests a weakly resonant system indicating some capacitance in addition to the inductance of the ring current and the resistance of the ionosphere. Case studies show that application of this function to IEF data yields good results and supports the notion that the response of the equatorial field to long-duration IEF polarities can last for many hours. Application of the function to test inputs such as pulses and triangle waves support this result. At high frequencies, we suggest that mapping of small-scale MHD turbulence is less effective than high frequency related transitions in the IEF.

  15. Spectral observations of Ellerman bombs and fitting with a two-cloud model

    SciTech Connect

    Hong, Jie; Ding, M. D.; Li, Ying; Fang, Cheng; Cao, Wenda

    2014-09-01

    We study the Hα and Ca II 8542 Å line spectra of four typical Ellerman bombs (EBs) in the active region NOAA 11765 on 2013 June 6, observed with the Fast Imaging Solar Spectrograph installed at the 1.6 m New Solar Telescope at Big Bear Solar Observatory. Considering that EBs may occur in a restricted region in the lower atmosphere, and that their spectral lines show particular features, we propose a two-cloud model to fit the observed line profiles. The lower cloud can account for the wing emission, and the upper cloud is mainly responsible for the absorption at line center. After choosing carefully the free parameters, we get satisfactory fitting results. As expected, the lower cloud shows an increase of the source function, corresponding to a temperature increase of 400-1000 K in EBs relative to the quiet Sun. This is consistent with previous results deduced from semi-empirical models and confirms that local heating occurs in the lower atmosphere during the appearance of EBs. We also find that the optical depths can increase to some extent in both the lower and upper clouds, which may result from either direct heating in the lower cloud, or illumination by an enhanced radiation on the upper cloud. The velocities derived from this method, however, are different from those obtained using the traditional bisector method, implying that one should be cautious when interpreting this parameter. The two-cloud model can thus be used as an efficient method to deduce the basic physical parameters of EBs.

  16. Martian Weathering Environments of the Amazonian Indicated by Correlated Morphologic and Spectral Observation in Acidalia Planitia

    NASA Astrophysics Data System (ADS)

    Kraft, M. D.; Rogers, D.; Fergason, R. L.; Michalski, J. R.; Sharp, T. G.

    2009-12-01

    While much attention has been given to chemical alteration and the state of water on early Mars, it remains important to understand aqueous processes throughout Martian history, including the recent geologic past. It has been suggested that the Amazonian was marked primarily by anhydrous, oxidative weathering because Amazonian surfaces, such as the northern plains, lack hydration features in near-infrared spectra [1]. But high-silica materials (Surface Type 2, ST2) discovered by the Thermal Emission Spectrometer [2] that occur in the northern plains attest to aqueous alteration of silicate minerals. The questions are when did this occur and by what process? ST2 correlates spatially with outflow sediments and high-silica materials may have formed in large amounts of water related to outflow flooding events of the late Hesperian [3,4]. ST2 also may correspond to global ice-rich mantles, indicating formation in icy environments related to geologically recent climate fluctuations [3]. Can these very different mechanisms and environments be discerned? In a global study of TES spectra, Rogers et al. (2007) [5] found significant spectral differences between ST2 surfaces in northern and southern Acidalia Planitia that occur near 40-50° N. Several geomorphic transitions occur across latitudes, and many of these are directly or potentially related to Amazonian periglacial activity and occur in the 40-50° N range. This potential link between composition and periglacial morphology needs further exploration. We examined this relationship from 40-50° N in Acidalia Planitia, using Thermal Emission Imaging System (THEMIS) multispectral data to measure the local spectral properties of the surface. We identified a boundary between two surface spectral types that match closely the spectra of north and south Acidalia derived by Rogers et al. [2007]. This boundary is diffuse, occurring between 47-48° N in our study region in western Acidalia, and correlates with observed

  17. Large-scale numerical simulations of star formation put to the test. Comparing synthetic images and actual observations for statistical samples of protostars

    NASA Astrophysics Data System (ADS)

    Frimann, S.; Jørgensen, J. K.; Haugbølle, T.

    2016-02-01

    Context. Both observations and simulations of embedded protostars have progressed rapidly in recent years. Bringing them together is an important step in advancing our knowledge about the earliest phases of star formation. Aims: To compare synthetic continuum images and spectral energy distributions (SEDs), calculated from large-scale numerical simulations, to observational studies, thereby aiding in both the interpretation of the observations and in testing the fidelity of the simulations. Methods: The adaptive mesh refinement code, RAMSES, is used to simulate the evolution of a 5 pc × 5 pc × 5 pc molecular cloud. The simulation has a maximum resolution of 8 AU, resolving simultaneously the molecular cloud on parsec scales and individual protostellar systems on AU scales. The simulation is post-processed with the radiative transfer code RADMC-3D, which is used to create synthetic continuum images and SEDs of the protostellar systems. In this way, more than 13 000 unique radiative transfer models, of a variety of different protostellar systems, are produced. Results: Over the course of 0.76 Myr the simulation forms more than 500 protostars, primarily within two sub-clusters. The synthetic SEDs are used to calculate evolutionary tracers Tbol and Lsmm/Lbol. It is shown that, while the observed distributions of the tracers are well matched by the simulation, they generally do a poor job of tracking the protostellar ages. Disks form early in the simulation, with 40% of the Class 0 protostars being encircled by one. The flux emission from the simulated disks is found to be, on average, a factor ~6 too low relative to real observations; an issue that can be traced back to numerical effects on the smallest scales in the simulation. The simulated distribution of protostellar luminosities spans more than three order of magnitudes, similar to the observed distribution. Cores and protostars are found to be closely associated with one another, with the distance distribution

  18. AGN spectral states from simultaneous UV and X-ray observations by XMM-Newton

    NASA Astrophysics Data System (ADS)

    Svoboda, J.; Guainazzi, M.; Merloni, A.

    2016-06-01

    The accretion on super-massive black holes is believed to be similar to the accretion on stellar-mass black holes. It has been suggested by Koerding et al. (2006) and Sobolewska et al. (2008) that different types of Active Galactic Nuclei (AGN) correspond to different spectral states of X-Ray Binaries. We extend previous works by comparing strictly simultaneous UV and X-ray measurements of AGN obtained by the XMM-Newton satellite. The thermal disc component is estimated from the UV flux while the non-thermal flux is constrained from the 2-10 keV X-ray luminosity. For sources with available radio-flux measurements, we investigate how the spectral hardness is related to their radio power, radio spectral slope and morphology. Our results suggest that the AGN may spectrally evolve in a similar way as X-ray binaries, however, several problems still remain unclear.

  19. LAMOST Observations in the Kepler Field: Spectral Classification with the MKCLASS Code

    NASA Astrophysics Data System (ADS)

    Gray, R. O.; Corbally, C. J.; De Cat, P.; Fu, J. N.; Ren, A. B.; Shi, J. R.; Luo, A. L.; Zhang, H. T.; Wu, Y.; Cao, Z.; Li, G.; Zhang, Y.; Hou, Y.; Wang, Y.

    2016-01-01

    The LAMOST-Kepler project was designed to obtain high-quality, low-resolution spectra of many of the stars in the Kepler field with the Large Sky Area Multi Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic telescope. To date 101,086 spectra of 80,447 objects over the entire Kepler field have been acquired. Physical parameters, radial velocities, and rotational velocities of these stars will be reported in other papers. In this paper we present MK spectral classifications for these spectra determined with the automatic classification code MKCLASS. We discuss the quality and reliability of the spectral types and present histograms showing the frequency of the spectral types in the main table organized according to luminosity class. Finally, as examples of the use of this spectral database, we compute the proportion of A-type stars that are Am stars, and identify 32 new barium dwarf candidates.

  20. The spectral archive of cosmic X-ray sources observed by the Einstein Observatory Focal Plane Crystal Spectrometer

    NASA Technical Reports Server (NTRS)

    Lum, Kenneth S. K.; Canizares, Claude R.; Clark, George W.; Coyne, Joan M.; Markert, Thomas H.; Saez, Pablo J.; Schattenburg, Mark L.; Winkler, P. F.

    1992-01-01

    The Einstein Observatory Focal Plane Crystal Spectrometer (FPCS) used the technique of Bragg spectroscopy to study cosmic X-ray sources in the 0.2-3 keV energy range. The high spectral resolving power (E/Delta-E is approximately equal to 100-1000) of this instrument allowed it to resolve closely spaced lines and study the structure of individual features in the spectra of 41 cosmic X-ray sources. An archival summary of the results is presented as a concise record the FPCS observations and a source of information for future analysis by the general astrophysics community. For each observation, the instrument configuration, background rate, X-ray flux or upper limit within the energy band observed, and spectral histograms are given. Examples of the contributions the FPCS observations have made to the understanding of the objects observed are discussed.

  1. The Spectral Signature of Accretion in Low-Mass Protostars: Observations and Non-LTE Modelling

    NASA Astrophysics Data System (ADS)

    Wiesemeyer, Helmut

    1997-06-01

    This work demonstrates the feasibility of a study bringing together theoretical concepts of the earliest phase of low-mass star formation and its observational evidence. Thus, two aspects have been considered: Observational evidence: In order to detect protostellar collapse by virtue of kinematical features in spectral line profiles, both optically thick and optically thin tracers are needed. According to Leung & Brown (1977, ApJ 214, L73), a protostellar envelope undergoing collapse exhibits a red-shifted self-absorption in a molecular line transition if the excitation gradient is negative. Optically thin emission (e.g. from the corresponding isotopomere's line) corroborates the conclusions by ruling out the case of independent components filling the observing beam. The nearby (d~200 pc) globular filament L 1082 (no. 9 from a catalog assembled by Schneider & Elmegreen, 1979, ApJS 41, 87) provides at least three candidates showing unambigeous footprints of protostellar collapse. By means of millimeter-interferometry (with the iram and bima interferometers Asz well as single dish spectroscopy and continuum imaging (using the iram 30 m telescope), these candidates were identified and characterized. As moderately optically thick high-density tracers, the CS (2,1), (3,2) and (5,4) transitions have been observed. The optically thin (2,1) lines of C34S and C18O were measured to confirm the evidence for collapse. Preliminary results from observations with isophot and isocam were used to better constrain the luminosity of one of the collapse candidates, which subsequently has been classified as an extreme Class 0 protostar. Theoretical concepts: For reasons evidenced by the observed column density distributions and by systematic shifts of the molecular line emission across the sources, spherically-symmetric collapse has to be ruled out. Instead, scenarios such as core formation in sheet-like clouds (as proposed by Hartmann et al., 1994, ApJ 430, L49) and magnetic accretion

  2. Assessment of the Spectral Stability of Libya 4, Libya 1, and Mauritania 2 Sites Using Earth Observing One Hyperion

    NASA Technical Reports Server (NTRS)

    Choi, Taeyoung; Xiong, Xiaoxiong; Angal, Amit; Chander, Gyanesh; Qu, John J.

    2014-01-01

    The objective of this paper is to formulate a methodology to assess the spectral stability of the Libya 4, Libya 1, and Mauritania 2 pseudo-invariant calibration sites (PICS) using Earth Observing One (EO-1) Hyperion sensor. All the available Hyperion collections, downloaded from the Earth Explorer website, were utilized for the three PICS. In each site, a reference spectrum is selected at a specific day in the vicinity of the region of interest (ROI) defined by Committee on Earth Observation Satellites (CEOS). A series of ROIs are predefined in the along-track direction with 196 spectral top-of-atmosphere reflectance values in each ROI. Based on the reference ROI spectrum, the spectral stability of these ROIs is evaluated by average deviations (ADs) and spectral angle mapper (SAM) methods in the specific ranges of time and geo-spatial locations. Time and ROI location-dependent SAM and AD results are very stable within +/- 2 deg and +/-1.7% of 1sigma standard deviations. Consequently, the Libya 4, Mauritania 2, and Libya 1 CEOS selected PICS are spectrally stable targets within the time and spatial swath ranges of the Hyperion collections.

  3. Implication of the Observed Spectral Cutoff Energy Evolution in XTE J1550-564

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Shaposhnikov, Nikolai

    2010-12-01

    The physical mechanisms responsible for the production of non-thermal emission in accreting black holes (BHs) should be imprinted in the observational appearances of the power-law tails in the X-ray spectra from these objects. Phenomenology of different spectral states exhibited by galactic BH binaries allows us to establish the physics of the photon upscattering under different accretion regimes. We revisit the data collected by the Rossi X-ray Timing Explorer from the BH X-ray binary XTE J1550-564 during two periods of X-ray activity in 1998 and 2000 focusing on the behavior of the high-energy cutoff of the power-law part of the spectrum. For the 1998 outburst, the transition from the low-hard state to the intermediate state was accompanied by a gradual decrease in the cutoff energy. This was followed by an extended minimum which then showed an abrupt reversal to a clear increasing trend as the source evolved to the very high and high-soft states. The 2000 outburst showed only the decreasing and extended minimum portions of this pattern. We attribute this difference in the cutoff energy behavior to the different partial contributions of the thermal and non-thermal (bulk motion) Comptonization. Namely, during the 1998 event the higher accretion rate presumably provided more cooling to the Comptonizing media and thus reducing the effectiveness of the thermal upscattering process. Under these conditions, the bulk motion takes a leading role in boosting the input soft photons. Recent Monte Carlo simulations by Laurent & Titarchuk strongly support this scenario.

  4. BATSE Observations of the Piccinotti Sample of AGN II: Variability and Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2001-01-01

    The Piccinotti sample is the hard x-ray-selected sample of active galactic nuclei (AGNs) best studied at energies below approximately 10 keV. It represents the only unbiased and complete high-energy survey of the sky down to a limiting flux of 3.1 x 10(exp -11) per square erg per second. As such, it has been used to study AGN properties such as X-ray spectral characteristics, log N-log S relation, and luminosity function. The BATSE data provide, for the first time, a systematic coverage of the whole sample at high energies. BATSE data from nearly four years of observations (1993 November - 1997 September) were analyzed using standard BATSE occultation analysis software to extract a signal from sources in the Piccinotti sample. Although the BATSE sensitivity for individual source measurements is relatively poor on short time scales, the near all-sky coverage and long CGRO lifetime allows us to improve our sensitivity considerably by sumrrng data over many years. This significantly reduces our statistical errors at the expense of loss of temporal information. However, the systematic errors associated with the summation of data over such a long period are not negligible, and the study of systematic effects was a major part of our effort. We evaluated two types of systematic error: those affecting the overall normalization (which are important for comparison with other instruments) and those affecting the size of the fluctuations (which are relevant for estimating the confidence level of a detection). The former was studied by comparison of BATSE data with other instruments, primarily CGRO/OSSE. The results indicate that our absolute flux values maybe overestimated by as much as 35% for some sources. However, since this does not affect our estimation of the detection confidence, we made no corrections to our flux estimates.

  5. Global morphology and spectral properties of EMIC waves derived from CRRES observations

    NASA Astrophysics Data System (ADS)

    Meredith, Nigel P.; Horne, Richard B.; Kersten, Tobias; Fraser, Brian J.; Grew, Russell S.

    2014-07-01

    Gyroresonant wave-particle interactions with electromagnetic ion cyclotron (EMIC) waves are a potentially important loss process for relativistic electrons in the Earth's radiation belts. Here we perform a statistical analysis of the EMIC waves observed by the Combined Release and Radiation Effects Satellite (CRRES) to determine the global morphology and spectral properties of the waves and to help assess their role in radiation belt dynamics. Helium band EMIC waves, with intensities, Bw2, greater than 0.1 nT2, are most prevalent during active conditions (AE> 300 nT), from 4 0.1 nT2 reported on here will contribute to relativistic electron loss in the Earth's radiation belts and should be included in radiation belt models.

  6. Temporal Spectral Analysis of Be stars observed with CoRoT satellite

    NASA Astrophysics Data System (ADS)

    Emilio, Marcelo; Janot Pacheco, Eduardo; Andrade, Laerte

    Classical Be stars are rapid rotators of spectral type late O to early A and luminosity class V-III, which exhibit Balmer emission lines and often a near infrared excess originating in an equatorially concentrated circumstellar envelope, both produced by sporadic mass ejection episodes. The causes of the abnormal mass loss (the so-called Be phenomenon) are as yet unknown. In spite of their high V sin i, rapid rotation alone cannot explain the ejection episodes as most Be stars do not rotate at their critical rotation rates. High-resolution, high signal-to-noise spectroscopic observations have been analyzed to demonstrate short-term variations are rather common among early-type Be. The observed line profile variability (LPV) is characterized by moving bumps traveling from blue to red across the line profile on timescales ranging from minutes to a few days. The phenomenon has also been observed in O stars and delta Sct variables, among others. Non-radial pulsations (NRP) have been proposed as an explanation of the LPV observed in hot stars. NRP produce LPV thanks to the combination of the Doppler displacement of stellar surface elements with their associated temperature variations due to the compression/expansion caused by the passage of waves through the photosphere. NRP could be the additional mechanism required for a rapidly rotating B star to become a Be star, that is to trigger the Be phenomenon by means of mass ejection. Indeed in mu Cen a correlation exists between mass ejection episodes and the beating pattern of the multiperiodicity. The finding of new cases of Be stars for which beating periods of multiperiodic NRPs coincide with matter ejections would help us to confirm this model. The periodic variability of the star has been reproduced in detail by NRP modeling. Short-periodic LPV of other Be stars have also been modeled using NRP. Observations with the MOST satellite showed that multiperiodicity due to NRP is a rather common phenomenon among Be stars

  7. Hubble Space Telescope UV spectral observations of Io passing into eclipse

    NASA Astrophysics Data System (ADS)

    Clarke, J. T.; Ajello, J.; Luhmann, J.; Schneider, N.; Kanik, I.

    1994-04-01

    Time-resolved spectra of Io have been obtained with the Faint Object Spectrograph on the Hubble Space Telescope in January 1992 at times centered on the passage of Io into Jupiter's shadow. Two different eclipse observations covered 1100-1600 A and 2250-3300 A. In the far ultraviolet(far-UV) range, emission lines of atomic sulfur and oxygen from Io's atmosphere (similar to those previously detected with the International Ultraviolet Explorer (IUE)) have been observed from Io in sunlight, and the spatial extent of the emitting region has been resolved for the first time: this is 0.5-1 Io radii (RIo) above the surface. The emission lines are typically 1kR in brightness while Io is in sunlight, and decrease to a few hundred Rayleighs within 20 min or less of Io's passing into shadow. If the emissions are produced in Io's ionosphere, the decrease in shadow appears consistent with the collisional slowing and recombination of photoelectrons in 100-1000 s, with recombination an important quenching process if the dominant ion is molecular (i.e., SO2(+)) condensation, with the residual emission in shadow due either to plasma impact of gas above the hot volcanic calderas or electron impact on S and O. In the near-UV range, we have not detected any airglow emissions from Io's atmosphere in shadow, with the main limitation being a high level of scattered light from Jupiter. We derive a 3 sigma upper limit to the 2560 A SO emission feature of 1 KR, which is close to what is expected from electron impact on SO2 based on the obs erved brightness of the FUV S and O lines in shadow. A high signal-to-noise spectrum of Io's albedo in sunlight reveals a spectral shape similar to laboratory spectra of SO2 frost reflectivity, and the relative albedo spectrum changed as Io passed into eclipse and part of the disk was in shadow. No specific SO2 gas absorption features appear in the albedo spectrum, although there could be substantial gas absorption near 2800 A if the individual lines are

  8. Late-time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx

    NASA Astrophysics Data System (ADS)

    Silverman, Jeffrey M.; Nugent, Peter E.; Gal-Yam, Avishay; Sullivan, Mark; Howell, D. Andrew; Filippenko, Alexei V.; Pan, Yen-Chen; Cenko, S. Bradley; Hook, Isobel M.

    2013-08-01

    PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption features, including saturated Ca II H and K lines that weakened and eventually went into emission. The strength of the emission component of Hα gradually increased, implying that the SN was undergoing significant interaction with its circumstellar medium (CSM). These features, and many others, were blueshifted slightly and showed a P-Cygni profile, likely indicating that the CSM was directly related to, and probably previously ejected by, the progenitor system itself. These and other observations led Dilday et al. to conclude that PTF11kx came from a symbiotic nova progenitor like RS Oph. In this work we extend the spectral coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. The late-time spectra of PTF11kx are dominated by Hα emission (with widths of full width at half-maximum intensity ≈2000 km s-1), strong Ca II emission features (~10,000 km s-1 wide), and a blue "quasi-continuum" due to many overlapping narrow lines of Fe II. Emission from oxygen, He I, and Balmer lines higher than Hα is weak or completely absent at all epochs, leading to large observed Hα/Hβ intensity ratios. The Hα emission appears to increase in strength with time for ~1 yr, but it subsequently decreases significantly along with the Ca II emission. Our latest spectrum also indicates the possibility of newly formed dust in the system as evidenced by a slight decrease in the red wing of Hα. During the same epochs, multiple narrow emission features from the CSM temporally vary in strength. The weakening of the Hα and Ca II emission at late times is possible evidence that the SN ejecta have overtaken the majority of the CSM and agrees with models of other strongly interacting SNe Ia. The varying narrow emission features, on the other hand, may indicate that the CSM is clumpy or consists of multiple thin shells.

  9. Hubble Space Telescope UV spectral observations of Io passing into eclipse

    NASA Technical Reports Server (NTRS)

    Clarke, John T.; Ajello, Joe; Luhmann, Janet; Schneider, Nick; Kanik, Isik

    1994-01-01

    Time-resolved spectra of Io have been obtained with the Faint Object Spectrograph on the Hubble Space Telescope in January 1992 at times centered on the passage of Io into Jupiter's shadow. Two different eclipse observations covered 1100-1600 A and 2250-3300 A. In the far ultraviolet(far-UV) range, emission lines of atomic sulfur and oxygen from Io's atmosphere (similar to those previously detected with the International Ultraviolet Explorer (IUE)) have been observed from Io in sunlight, and the spatial extent of the emitting region has been resolved for the first time: this is 0.5-1 Io radii (R(sub Io)) above the surface. The emission lines are typically 1kR in brightness while Io is in sunlight, and decrease to a few hundred Rayleighs within 20 min or less of Io's passing into shadow. If the emissions are produced in Io's ionosphere, the decrease in shadow appears consistent with the collisional slowing and recombination of photoelectrons in 100-1000 s, with recombination an important quenching process if the dominant ion is molecular (i.e., SO2(+)) condensation, with the residual emission in shadow due either to plasma impact of gas above the hot volcanic calderas or electron impact on S and O. In the near-UV range, we have not detected any airglow emissions from Io's atmosphere in shadow, with the main limitation being a high level of scattered light from Jupiter. We derive a 3 sigma upper limit to the 2560 A SO emission feature of 1 KR, which is close to what is expected from electron impact on SO2 based on the obs erved brightness of the FUV S and O lines in shadow. A high signal-to-noise spectrum of Io's albedo in sunlight reveals a spectral shape similar to laboratory spectra of SO2 frost reflectivity, and the relative albedo spectrum changed as Io passed into eclipse and part of the disk was in shadow. No specific SO2 gas absorption features appear in the albedo spectrum, although there could be substantial gas absorption near 2800 A if the individual

  10. TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

    SciTech Connect

    Saunders, C.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Kim, A. G.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Chotard, N.; Copin, Y.; Gangler, E.; and others

    2015-02-10

    We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a given supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.

  11. Multifrequency radio observations of Cygnus A - Spectral aging in powerful radio galaxies

    NASA Technical Reports Server (NTRS)

    Carilli, C. L.; Perley, R. A.; Dreher, J. W.; Leahy, J. P.

    1991-01-01

    A detailed analysis of the radio spectrum across the lobes of Cygnus A is presented in order to critically test the synchroton spectral aging theory. The results are in good agreement with the jet model for powerful radio galaxies, involving particle acceleration at the hot spots and outflow into the radio lobes, with subsequent energy loss due to synchrotron radiation. The hot spot spectra are well represented by a spectral aging model involving continuous injection of relativistic particles. Both hot spots have spectral break frequencies around 10 GHz. An injection index of 0.5 is found for both hot spots, consistent with diffusive shock acceleration at a strong nonrelativistic shock in a Newtonian fluid. The LF hot spot emission spectrum falls below the injected power law. This effect is isolated to the hot spots, and is best explained by a low-energy cutoff in the particle distribution.

  12. First observation of SASE radiation using the compact wide-spectral-range XUV spectrometer at FLASH2

    NASA Astrophysics Data System (ADS)

    Tanikawa, T.; Hage, A.; Kuhlmann, M.; Gonschior, J.; Grunewald, S.; Plönjes, E.; Düsterer, S.; Brenner, G.; Dziarzhytski, S.; Braune, M.; Brachmanski, M.; Yin, Z.; Siewert, F.; Dzelzainis, T.; Dromey, B.; Prandolini, M. J.; Tavella, F.; Zepf, M.; Faatz, B.

    2016-09-01

    The Free-electron LASer in Hamburg (FLASH) has been extended with a new undulator line FLASH2 in 2014. A compact grazing-incident wide-spectral-range spectrometer based on spherical-variable-line-spacing (SVLS) gratings in the extreme ultraviolet (XUV) region was constructed to optimize and characterize the free-electron laser (FEL) performance at FLASH2. The spectrometer is equipped with three different concave SVLS gratings covering a spectral range from 1 to 62 nm to analyze the spectral characteristics of the XUV radiation. Wavelength calibration and evaluation of the spectral resolution were performed at the plane grating monochromator beamline PG2 at FLASH1 before the installation at FLASH2, and compared with analytical simulations. The first light using self-amplified spontaneous emission from FLASH2 was observed by the spectrometer during a simultaneous operation of both undulator lines-FLASH1 and FLASH2. In addition, the spectral resolution of the spectrometer was evaluated by comparing the measured spectrum from FLASH2 with FEL simulations.

  13. VLA observations of unidentified Leiden-Berkeley Deep-Survey sources - Luminosity and redshift dependence of spectral properties

    NASA Technical Reports Server (NTRS)

    Kapahi, Vijay K.; Kulkarni, Vasant K.

    1990-01-01

    VLA observations of a complete subset of the Leiden-Berkeley Deep Survey sources that have S(1.4 GHz) greater than 10 mJy and are not optically identified down to F=22 mag are reported. By comparing the spectral and structural properties of the sources with samples from the literature, an attempt was made to disentangle the luminosity and redshift dependence of the spectral indices of extended emission in radio galaxies and of the incidence of compact steep-spectrum sources. It is found that the fraction of compact sources among those with a steep spectrum is related primarily to redshift, being much larger at high redshifts for sources of similar radio luminosity. Only a weak and marginally significant dependence of spectral indices of the extended sources on luminosity and redshift is found in samples selected at 1.4 and 2.7 GHz. It is pointed out that the much stronger correlation of spectral indices with luminosity may be arising partly from spectral curvature, and partly due to the preferential inclusion of very steep-spectrum sources from high redshift in low-frequency surveys.

  14. Power spectral estimation algorithms

    NASA Technical Reports Server (NTRS)

    Bhatia, Manjit S.

    1989-01-01

    Algorithms to estimate the power spectrum using Maximum Entropy Methods were developed. These algorithms were coded in FORTRAN 77 and were implemented on the VAX 780. The important considerations in this analysis are: (1) resolution, i.e., how close in frequency two spectral components can be spaced and still be identified; (2) dynamic range, i.e., how small a spectral peak can be, relative to the largest, and still be observed in the spectra; and (3) variance, i.e., how accurate the estimate of the spectra is to the actual spectra. The application of the algorithms based on Maximum Entropy Methods to a variety of data shows that these criteria are met quite well. Additional work in this direction would help confirm the findings. All of the software developed was turned over to the technical monitor. A copy of a typical program is included. Some of the actual data and graphs used on this data are also included.

  15. Land Surface Temperature Forecasting using spectral observations of MODIS and Modular Neural Networks

    NASA Astrophysics Data System (ADS)

    Taghavi, Farahnaz; Zargaran, Zahrah; Ahmadi, Abbas

    Land Surface Temperature (LST) is a significant parameter for many applications including numerical weather prediction, climate and environmental studies. The goal of this study is using a combination of Modular neural networks and satellite image as input to predict the LST in Tehran ,Iran.In this study, two MLP and RBF neural networks and an algorithm for calculating of LST based spectral observations of MODerate resolution Imaging Spectra-radiometer (MODIS) are used This algorithm include Brightness Temperature of channel 31(BT31) and 32(BT32) on thermal band of MODIS. The algorithm are written using Hierarchical Data Format (HDF) calibrated data which has the spatial resolution of 1km by ENVI (Environment for Visualizing Images) software, and output products are in HDF format. Initial results show that modular neural network helps to improve networks' generalization and learning speed and the main reason for selecting these networks is their good performance in this problem.The model has a modular learning and structure. Since the task decomposition at first and the combination of results to get the final prediction at the end are key and effective points on the performance of modular neural network, in this study we propose a new approach to this issue. This method uses the Self-Organizing Map (SOM) Neural Network and Particle Swarm Optimization(PSO) algorithm for task decomposition. The proposed model combines this neural networks and optimization algorithms. Results indicate that use of PSO algorithm has caused suitable distribution of clusters obtained from SOM algorithm. In addition to the use of satellite images has improved the performance of the proposed model. Finally, the results obtained from this model will be compared with some other methods with non-modular structure and learning and it is shown that this proposed model is able to produce accurate results. The result of this comparison show that training time of model in the forecasting of land

  16. Initial analyses of surface spectral radiance between observations and Line-By-Line calculations

    SciTech Connect

    Brown, P.D.; Clough, S.A.; Miller, N.E.; Shippert, T.R.; Turner, D.D.

    1996-04-01

    The evaluation an improvement of radiative transfer calculations are essential to attain improved performance of general circulation models (GCMs) for climate change applications. A Quality Measurement Experiment (QME) is being conducted to analyze the spectral residuals between the downwelling longwave radiance measured by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) and spectral radiance calculated by the Line-By-Line Radiative Transfer Model (LBLRTM). The three critical components of this study are (1) the assessment of the quality of the high resolution AERI measurements, (2) the assessment of the ability to define the atmospheric state in the radiating column, and (3) the evaluation of the capability of LBLRTM. Validations have been performed on spectral radiance data, obtained from April 1994 through July 1994, through the analysis of the spectral interval and physical process. The results are archived as a function of time, enabling the retrieval of specific data and facilitating investigations and diurnal effects, seasonal effects, and longer-term trends. While the initial focus is restricted to clear-sky analyses, efforts are under way to include the effects of clouds and aerosols. Plans are well formulated for the extension of the current approach to the shortwave. An overview of the concept of the QME is described by Miller et al. (1994), and a detailed description of this study is provided by Clough et al. (1994).

  17. Martian aerosols: Near-infrared spectral properties and effects on the observation of the surface

    NASA Technical Reports Server (NTRS)

    Erard, Stephane; Mustard, John; Murchie, Scott; Bibring, Jean-Pierre; Cerroni, Priscilla; Caradini, Angioletta

    1994-01-01

    Imaging sprectroscopic measurements (ISM) of Mars acquired by the ISM instrument on Phobos-2 are used to investigate the NIR spectral properties of aerosols and the effects of atmospheric scattering on inferred mineralogy of the surface. Estimates of aerosols spectra between 0.77 and 2.6 micrometers are derived above Tharsis and Ophir Planum. The spectral continua are consistent with the particle size distribution derived using data from the solar occultation experiment on-board the spacecraft (effective radius approximately = 1.2 micrometers, with an effective variance approximately = 0.2). The aerosols spectra contain water-ice absorption features and possibly absorptions due to clay and/or sulfates. The largest effect of the aerosols on surface spectra is in dark regions, where the continuum spectral slope becomes more negative and the 1-micrometers absorption due to Fe in pyroxene is shifted toward longer wavelengths. The effects of aerosols on spectra of bright regions are insufficiently large to change mineralogic interpretations based on ISM data, i.e., that bright regions in Tharsis are dominated spectrally by hematite, but that additional ferric minerals are probably present in other areas including Arabia.

  18. The Liege-balloon program. [balloon-borne instruments for high-spectral resolution observations of the sun

    NASA Technical Reports Server (NTRS)

    Zander, R.

    1974-01-01

    The Liege-balloon program is intended to make high-spectral resolution observations of the sun in the near- and intermediate infrared regions not accessible from the ground. A description of the equipment, followed by a summary of the data obtained till now is presented. Except for ozone whose maximum of concentration lies near 25 Km altitude, the residual mass distribution of the other mentioned molecules decreases with altitude. This is a self-explanatory argument for carrying out spectroscopic observations from platforms transcending the densest layers of the earth's atmosphere. The Liege balloon equipment is primarily intended for very high-resolution solar observations from about 27-30 Km altitude, in all spectral regions between 1.5 and 15.0 microns, not accessible from the ground.

  19. All-Sky Observational Evidence for An Inverse Correlation Between Dust Temperature and Emissivity Spectral Index

    NASA Technical Reports Server (NTRS)

    Liang, Z.; Fixsen, D. J.; Gold, B.

    2012-01-01

    We show that a one-component variable-emissivity-spectral-index model (the free- model) provides more physically motivated estimates of dust temperature at the Galactic polar caps than one- or two-component fixed-emissivity-spectral-index models (fixed- models) for interstellar dust thermal emission at far-infrared and millimeter wavelengths. For the comparison we have fit all-sky one-component dust models with fixed or variable emissivity spectral index to a new and improved version of the 210-channel dust spectra from the COBE-FIRAS, the 100-240 micrometer maps from the COBE-DIRBE and the 94 GHz dust map from the WMAP. The best model, the free-alpha model, is well constrained by data at 60-3000 GHz over 86 per cent of the total sky area. It predicts dust temperature (T(sub dust)) to be 13.7-22.7 (plus or minus 1.3) K, the emissivity spectral index (alpha) to be 1.2-3.1 (plus or minus 0.3) and the optical depth (tau) to range 0.6-46 x 10(exp -5) with a 23 per cent uncertainty. Using these estimates, we present all-sky evidence for an inverse correlation between the emissivity spectral index and dust temperature, which fits the relation alpha = 1/(delta + omega (raised dot) T(sub dust) with delta = -.0.510 plus or minus 0.011 and omega = 0.059 plus or minus 0.001. This best model will be useful to cosmic microwave background experiments for removing foreground dust contamination and it can serve as an all-sky extended-frequency reference for future higher resolution dust models.

  20. Spectral Invariant Behavior of Zenith Radiance Around Cloud Edges Observed by ARM SWS

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Knyazikhin, Y.; Chiu, J. C.; Wiscombe, W. J.

    2009-01-01

    The ARM Shortwave Spectrometer (SWS) measures zenith radiance at 418 wavelengths between 350 and 2170 nm. Because of its 1-sec sampling resolution, the SWS provides a unique capability to study the transition zone between cloudy and clear sky areas. A spectral invariant behavior is found between ratios of zenith radiance spectra during the transition from cloudy to cloud-free. This behavior suggests that the spectral signature of the transition zone is a linear mixture between the two extremes (definitely cloudy and definitely clear). The weighting function of the linear mixture is a wavelength-independent characteristic of the transition zone. It is shown that the transition zone spectrum is fully determined by this function and zenith radiance spectra of clear and cloudy regions. An important result of these discoveries is that high temporal resolution radiance measurements in the clear-to-cloud transition zone can be well approximated by lower temporal resolution measurements plus linear interpolation.

  1. New Instruments for Spectrally-Resolved Solar Soft X-ray Observations from CubeSats, and Larger Missions

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Shih, A.; Warren, H. P.; DeForest, C. E.; Woods, T. N.

    2015-12-01

    Solar soft X-ray (SXR) observations provide important diagnostics of plasma heating, during solar flares and quiescent times. Spectrally- and temporally-resolved measurements are crucial for understanding the dynamics and evolution of these energetic processes; spatially-resolved measurements are critical for understanding energy transport. A better understanding of the thermal plasma informs our interpretation of hard X-ray (HXR) observations of nonthermal particles, improving our understanding of the relationships between particle acceleration, plasma heating, and the underlying release of magnetic energy during reconnection. We introduce a new proposed mission, the CubeSat Imaging X-ray Solar Spectrometer (CubIXSS), to measure spectrally- and spatially-resolved SXRs from the quiescent and flaring Sun from a 6U CubeSat platform in low-Earth orbit during a nominal 1-year mission. CubIXSS includes the Amptek X123-SDD silicon drift detector, a low-noise, commercial off-the-shelf (COTS) instrument enabling solar SXR spectroscopy from ~0.5 to ~30 keV with ~0.15 keV FWHM spectral resolution with low power, mass, and volume requirements. An X123-CdTe cadmium-telluride detector is also included for ~5-100 keV HXR spectroscopy with ~0.5-1 keV FWHM resolution. CubIXSS also includes a novel spectro-spatial imager -- the first ever solar imager on a CubeSat -- utilizing a pinhole aperture and X-ray transmission diffraction grating to provide full-Sun imaging from ~0.1 to ~10 keV, with ~25 arcsec and ~0.1 Å FWHM spatial and spectral resolutions, respectively. We discuss scaled versions of these instruments, with greater sensitivity and dynamic range, and significantly improved spectral and spatial resolutions for the imager, for deployment on larger platforms such as Small Explorer missions.

  2. EXPANDED VERY LARGE ARRAY OBSERVATIONS OF GALACTIC SUPERNOVA REMNANTS: WIDE-FIELD CONTINUUM AND SPECTRAL-INDEX IMAGING

    SciTech Connect

    Bhatnagar, S.; Rau, U.; Rupen, M. P.; Green, D. A. E-mail: rurvashi@nrao.edu E-mail: dag9@cam.ac.uk

    2011-09-20

    The radio continuum emission from the Galaxy has a rich mix of thermal and non-thermal emission. This very richness makes its interpretation challenging since the low radio opacity means that a radio image represents the sum of all emission regions along the line of sight. These challenges make the existing narrowband radio surveys of the Galactic plane difficult to interpret: e.g., a small region of emission might be a supernova remnant (SNR) or an H II region, or a complex combination of both. Instantaneous wide bandwidth radio observations in combination with the capability for high-resolution spectral-index mapping can be directly used to disentangle these effects. Here we demonstrate simultaneous continuum and spectral-index imaging capability at the full continuum sensitivity and resolution using newly developed wide-band wide-field imaging algorithms. Observations were conducted in the L and C bands with a total bandwidth of 1 and 2 GHz, respectively. We present preliminary results in the form of a full-field continuum image covering the wide-band sensitivity pattern of the EVLA centered on a large but poorly studied SNR (G55.7 + 3.4) and relatively narrower field continuum and spectral-index maps of three fields containing SNR and diffused thermal emission. We demonstrate that spatially resolved spectral-index maps differentiate regions with emission of different physical origins (spectral-index variation across composite SNRs and separation of thermal and non-thermal emission), superimposed along the line of sight. The wide-field image centered on the SNR G55.7+3.4 also demonstrates the excellent wide-field wide-band imaging capability of the EVLA.

  3. Pancam and Microscopic Imager observations of dust on the Spirit Rover: Cleaning events, spectral properties, and aggregates

    USGS Publications Warehouse

    Vaughan, Alicia F.; Johnson, Jeffrey R.; Herkenhoff, Kenneth E.; Sullivan, Robert; Landis, Geoffrey A.; Goetz, Walter; Madsen, Morten B.

    2010-01-01

    This work describes dust deposits on the Spirit Rover over 2000 sols through examination of Pancam and Microscopic Imager observations of specific locations on the rover body, including portions of the solar array, Pancam and Mini-TES calibration targets, and the magnets. This data set reveals the three "cleaning events" experienced by Spirit to date, the spectral properties of dust, and the tendency of dust particles to form aggregates 100 um and larger.

  4. VIMS spectral mapping observations of Titan during the Cassini prime mission

    USGS Publications Warehouse

    Barnes, J.W.; Soderblom, J.M.; Brown, R.H.; Buratti, B.J.; Sotin, C.; Baines, K.H.; Clark, R.N.; Jaumann, R.; McCord, T.B.; Nelson, R.; Le, Mouelic S.; Rodriguez, S.; Griffith, C.; Penteado, P.; Tosi, F.; Pitman, K.M.; Soderblom, L.; Stephan, K.; Hayne, P.; Vixie, G.; Bibring, J.-P.; Bellucci, G.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Langevin, Y.; Matson, D.L.; Nicholson, P.D.; Sicardy, B.

    2009-01-01

    This is a data paper designed to facilitate the use of and comparisons to Cassini/visual and infrared mapping spectrometer (VIMS) spectral mapping data of Saturn's moon Titan. We present thumbnail orthographic projections of flyby mosaics from each Titan encounter during the Cassini prime mission, 2004 July 1 through 2008 June 30. For each flyby we also describe the encounter geometry, and we discuss the studies that have previously been published using the VIMS dataset. The resulting compliation of metadata provides a complementary big-picture overview of the VIMS data in the public archive, and should be a useful reference for future Titan studies. ?? 2009 Elsevier Ltd.

  5. Statistically Optimized Inversion Algorithm for Enhanced Retrieval of Aerosol Properties from Spectral Multi-Angle Polarimetric Satellite Observations

    NASA Technical Reports Server (NTRS)

    Dubovik, O; Herman, M.; Holdak, A.; Lapyonok, T.; Taure, D.; Deuze, J. L.; Ducos, F.; Sinyuk, A.

    2011-01-01

    The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns) that is not common in satellite observations. The POLDER imager on board the PARASOL microsatellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of all available angular observations obtained by the POLDER sensor in the window spectral channels where absorption by gas is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed at retrieval of extended set of parameters affecting measured radiation.

  6. Modeling of the Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Shapiro, A.; Cessateur, G.; Dominique, M.; Krivova, N. A.; Lachat, D.; Rozanov, E.; Schmutz, W. K.; Shapiro, A. V.; Tagirov, R. V.; Thuillier, G. O.; Wehrli, C.

    2011-12-01

    Measurements and modeling of the solar irradiance have gained an increased attention during the last few decades. Nevertheless a complete picture of the solar variability is still missing. Therefore a launch of every new space mission devoted to the measurements of the spectral solar irradiance provides a crucial piece of complementary information and nourishes the theoretical models. We present here spectral solar irradiance data from the recent European missions PROBA-2 (launched on November 2, 2009) and PICARD (launched on June 15, 2010) and their theoretical interpretation. The PREMOS package onboard PICARD comprises two experiments, one observing solar irradiance in five (two UV, one visible and two near infrared) spectral channels with filter radiometers the other measuring TSI with absolute radiometers. LYRA is a solar VUV radiometer onboard PROBA-2, which is a technologically oriented ESA micro-mission, and is observing the solar irradiance in two UV and two EUV spectral channels. The passbands of the UV channels in the both experiments were selected on the ground of relevance for the terrestrial ozone concentration. The PREMOS and LYRA measurements were carefully corrected for the degradation and cleaned for non-solar signatures. We provide a comparison with the VIRGO/SOHO and SOLSTICE+SIM/SORCE data. Both LYRA and PREMOS have observed several solar eclipses. The analysis of these observations allows us to accurately retrieve the center-to-limb variations (CLV) of the solar brightness, which play an important role in the modeling of the solar irradiance variability on the time scale of the solar rotation. We show that the calculations with the recently developed and published COde for Solar Irradiance (COSI) yield the CLV which are in a good agreement with the measurements. The irradiance in all channels shows a clear variability on time-scale of the solar rotation. The amplitude and the profile of the variability strongly depend on the wavelength. We use

  7. Relative spectra and spectral slopes of selected lunar craters from observations by SIR on board SMART-1

    NASA Astrophysics Data System (ADS)

    Vilenius, E.; Wiese, M.; Mall, U.

    2007-08-01

    The infrared point spectrometer SIR on board the European Space Agency's SMART- 1 mission was designed for the detailed remote spectral investigation of the lunar surface in the wavelength range 0.9 μm - 2.4 μm. The SIR instrument provides high spectral resolution with a footprint size of 330 m to 3 km from typical lunar orbits of 300 km to 3000 kilometers. Comprehensive lunar spectrophotometric studies with SIR will provide a characterization of the overall spectral slope in the near infrared, as well as the effect of absorption bands between 1 μm and 2 μm, which are widely used in lunar remote geochemical studies. There is an ongoing process of archiving the data of SIR and AMIE, the high resolution camera on SMART-1. Data measured by the SIR spectrometer are used to obtain relative spectral slopes for selected lunar sites. All spectra are corrected for bias and for the dark count rate, based on laboratory calibration, as well as for the measurement geometry using Shkuratov's semiempirical function for photometric correction. The spectra are calculated relative to a reference spectrum, which is an averaged spectrum of a selected uniform area from the same orbit as the spectra. In order to also observe low albedo areas reliably, the most sensitive pixels of the instrument are selected for this study, limiting the spectral range between 1.02 μm and 2.13 μm. A color index C (1.2 μm / 2.0 μm) is calculated and divided by the corresponding color index Cref of the reference spectrum. This can be compared to the color index obtained from Clementine NIR mosaics, which have a different calibration and data reduction process. Discrepancies in the compared values of SIR and Clementine could be explained by the very different photometric conditions which existed during the two surveys: There are almost no shadowed crater areas in the Clementine data set (nadir looking and illuminated) while the angle of incidence varied with SIR operating in a nadir pointing mode

  8. Making of a solar spectral irradiance dataset I: observations, uncertainties, and methods

    NASA Astrophysics Data System (ADS)

    Schöll, Micha; Dudok de Wit, Thierry; Kretzschmar, Matthieu; Haberreiter, Margit

    2016-03-01

    Context. Changes in the spectral solar irradiance (SSI) are a key driver of the variability of the Earth's environment, strongly affecting the upper atmosphere, but also impacting climate. However, its measurements have been sparse and of different quality. The "First European Comprehensive Solar Irradiance Data Exploitation project" (SOLID) aims at merging the complete set of European irradiance data, complemented by archive data that include data from non-European missions. Aims: As part of SOLID, we present all available space-based SSI measurements, reference spectra, and relevant proxies in a unified format with regular temporal re-gridding, interpolation, gap-filling as well as associated uncertainty estimations. Methods: We apply a coherent methodology to all available SSI datasets. Our pipeline approach consists of the pre-processing of the data, the interpolation of missing data by utilizing the spectral coherency of SSI, the temporal re-gridding of the data, an instrumental outlier detection routine, and a proxy-based interpolation for missing and flagged values. In particular, to detect instrumental outliers, we combine an autoregressive model with proxy data. We independently estimate the precision and stability of each individual dataset and flag all changes due to processing in an accompanying quality mask. Results: We present a unified database of solar activity records with accompanying meta-data and uncertainties. Conclusions: This dataset can be used for further investigations of the long-term trend of solar activity and the construction of a homogeneous SSI record.

  9. Observations of Solar Spectral Irradiance Change During Cycle 22 from NOAA-9 SBUV/2

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Cebula, Richard P.; Hilsenrath, Ernest

    2003-01-01

    The NOM-9 Solar Backscatter Ultraviolet, model 2 (SBUV/2) instrument is one of a series of instruments providing daily solar spectral irradiance measurements in the middle and near ultraviolet since 1978. The SBUV/2 instruments are primarily designed to measure stratospheric profile and total column ozone, using the directional albedo as the input to the ozone processing algorithm. As a result, the SBUV/2 instrument does not have onboard monitoring of all time-dependent response changes. We have applied internal comparisons and vicarious (external) comparisons to determine the long-term instrument characterization for NOAA-9 SBUV/2 to derive accurate solar spectral irradiances from March 1985 to May 1997 spanning two solar cycle minima with a single instrument. The NOAA-9 data show an amplitude of 9.3(+/- 2.3)% (81-day averaged) at 200-205 nm for solar cycle 22. This is consistent with the result of (Delta)F(sub 200-205) = 8.3(+/- 2.6)% for cycle 21 from Nimbus-7 SBUV and (Delta)F(sub 200-205) = 10(+/- 2)% (daily values) for cycle 23 from UARS SUSIM. NOAA-9 data at 245-250 nm show a solar cycle amplitude of (Delta)F(sub 245-250) = 5.7(+/- 1.8)%. NOAA-9 SBUV/2 data can be combined with other instruments to create a 25-year record of solar UV irradiance.

  10. Reaching the peak of the quasar spectral energy distribution - I. Observations and models

    NASA Astrophysics Data System (ADS)

    Collinson, James S.; Ward, Martin J.; Done, Chris; Landt, Hermine; Elvis, Martin; McDowell, Jonathan C.

    2015-05-01

    We perform a spectral analysis of a sample of 11 medium redshift (1.5 ≲ z ≲ 2.2) quasars. Our sample all have optical spectra from the SDSS, infrared spectra from GNIRS and TripleSpec, and X-ray spectra from XMM-Newton. We first analyse the Balmer broad emission line profiles which are shifted into the IR spectra to constrain black hole masses. Then we fit an energy-conserving, three component accretion model of the broad-band spectral energy distribution (SED) to our multiwavelength data. 5 out of the 11 quasars show evidence of an SED peak, allowing us to constrain their bolometric luminosity from these models and estimate their mass accretion rates. Based on our limited sample, we suggest that estimating bolometric luminosities from L_{5100 A} and L2-10 keV may be unreliable, as has been also noted for a low-redshift, X-ray selected active galactic nucleus sample.

  11. Long-term Spectral Peaks of EEJ amplitudes observed by MAGDAS/CPMN

    NASA Astrophysics Data System (ADS)

    Numata, Y.; Ueno, T.; Hirano, T.; Uozumi, T.; Yumoto, K.

    2008-12-01

    The ultimate goal of this study is to understand the couplings of, and independencies in, the Solar wind- Magnetosphere-Ionosphere-Atmosphere (S-M-I-A) system. For this goal, in this paper we analyze ground magnetometer data from the DAV, MUT and ANC stations. DAV (Davao, Philippines at GM lat.-1.37, GM lon.196.53). MUT (Muntinlupa, Philippines at GM lat.6.26, GM lon.192.22). ANC (Ancon, Peru at GM lat.3.05, GM lon.354.40). These are three stations of the MAGDAS/CPMN (MAGnetic Data Acquisition System/Circum- pan Pacific Magnetometer Network). The MAGDAS/CPMN network has been constructed by SERC, Kyushu University, and widely covers the world. DAV is located at the intersection of the 210 degree magnetic meridian and the magnetic equator. We examined the relationships among the EEJ (equatorial electrojet) amplitude, the F10.7 solar radiation flux and the cowling conductivity. The EEJ flows roughly between the altitudes of 90km and 130km in the ionosphere. The intensity of the EEJ increases especially around noon time between the geomagnetic latitudes of +3deg and -3deg. We newly defined "ethe EEJ amplitude"f by subtracting the H-component magnetic field at night time from the averaged H-component at daytime 10:30"'12:30LT. The F10.7 is the solar radiation flux (1 day data) measured at the Dominion Radio Astrophysical observatory, Canada [ftp://ftp.ngdc.noaa.gov/]. The cowling conductivity is estimated using the IRI model (International Reference Ionosphere 2007 [http://iri.gsfc.nasa.gov/]). We have analyzed spectral peaks of the EEJ amplitude at DAV, MUT and ANC and the F10.7 solar radiation flux during the period from Jan. 1, 1999 to Dec. 31, 2001. Long-term variations of the EEJ amplitude having the period of several months are focused, and compared those of with the F10.7 solar radiation flux. A strong spectral peak of the EEJ amplitude at semi-annual period is found to show higher harmonic structure. Other strong spectral peaks of the EEJ amplitude are also

  12. Snowfall measurements using a combination of high spectral resolution lidar and radar observations

    NASA Astrophysics Data System (ADS)

    Eloranta, E.

    2009-04-01

    Aerodynamic flow around gauges and the horizontal transport of windblown snow along the surface produce errors in snowfall measurements. Comparisons between various snow gauges with and without wind shields show as much as as a factor of two difference between measurements(Yang et al., 1999). These problems are particularly significant in the high Arctic where snowfall amount are very low and blowing snow is frequent. This paper describes a lidar-radar based technique to measure the downward flux of snow at an altitude of ~100m. When particles are small compared to the wavelength, radar reflectivity is proportional to the number of snowflakes times the square of the mass of the average snowflake. For particles large compared to the wavelength, the lidar extinction cross section is equal to two times the number of snowflakes times the projected average area of the snowflakes. Donovan and Lammeren(2001) show that the ratio of radar to lidar cross sections can be used to define an effective-diameter-prime, which is proportional to the fourth root of the average mass-squared over the average projected area of the snowflakes. If one assumes a crystal shape this can be converted into an effective-diameter which is the average mass over the average area of the flakes. Multiplying the lidar measured projected area times the effective-diameter yields the mass of the particles. The product of this mass and the radar measured vertical velocity then provides the vertical flux of water. In past work we have tested this measurement approach with data acquired in the high Arctic at Eureka, Canada(80 N,90W). Measurements from the University of Wisconsin High Spectral Resolution Lidar and the NOAA 35 GHz cloud radar were used to compute the time-integrated flux of water at 100 m above the surface. This result was compared with Nipper gauge measurements of snowfall acquired as part of the Eureka weather station record. Best agreement was achieved when the crystals where assumed to

  13. High spectral resolution ground-based observations of Venus in the 450-1250 cm sup-1 region

    NASA Technical Reports Server (NTRS)

    Kunde, V. G.; Hanel, R. A.; Herath, L. W.

    1976-01-01

    The thermal emission of Venus was recorded during the winter of 1970-1971, and in 1973 using the 2.7m telescope at McDonald Observatory. The double beam Michelson interferometer installed at the Coude focus was used. The spectrum was recorded between 400/cm and 1,400/cm. For the 1970 observations, the spectral resolution was 0.25/cm and the linear spatial resolution was 3/4 of the disk of Venus. In 1973 the spectral resolution was 0.20/cm with a spatial resolution 1/3 of the planetary disk. In addition to Venus, the moon, the sky adjacent to each object, and the zenith sky were recorded to help eliminate the absorption and emission effects of the earth's atmosphere.

  14. SUZAKU OBSERVATION OF THE BLACK HOLE CANDIDATE MAXI J1836-194 IN A HARD/INTERMEDIATE SPECTRAL STATE

    SciTech Connect

    Reis, R. C.; Miller, J. M.; Reynolds, M. T.; Fabian, A. C.; Walton, D. J.

    2012-05-20

    We report on a Suzaku observation of the newly discovered X-ray binary MAXI J1836-194. The source is found to be in the hard/intermediate spectral state and displays a clear and strong relativistically broadened iron emission line. We fit the spectra with a variety of phenomenological, as well as physically motivated disk reflection models, and find that the breadth and strength of the iron line are always characteristic of emission within a few gravitational radii around a black hole. This result is independent of the continuum used and strongly points toward the central object in MAXI J1836-194 being a stellar mass black hole rotating with a spin of a = 0.88 {+-} 0.03 (90% confidence). We discuss this result in the context of spectral state definitions, physical changes (or lack thereof) in the accretion disk, and on the potential importance of the accretion disk corona in state transitions.

  15. Application of model-based spectral analysis to wind-profiler radar observations

    NASA Astrophysics Data System (ADS)

    Boyer, E.; Petitdidier, M.; Corneil, W.; Adnet, C.; Larzabal, P.

    2001-08-01

    A classical way to reduce a radar’s data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometeor echo. . . ) exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunder-storms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar’s data.

  16. Spectral atmospheric observations at Nantucket Island, May 7-14, 1981

    NASA Technical Reports Server (NTRS)

    Talay, T. A.; Poole, L. R.

    1981-01-01

    An experiment was conducted by the National Langley Research Center to measure atmospheric optical conditions using a 10-channel solar spectral photometer system. This experiment was part of a larger series of multidisciplinary experiments performed in the area of Nantucket Shoals aimed at studying the dynamics of phytoplankton production processes. Analysis of the collected atmospheric data yield total and aerosol optical depths, transmittances, normalized sky radiance distributions, and total and sky irradiances. Results of this analysis may aid in atmospheric corrections of remote sensor data obtained by several sensors overflying the Nantucket Shoals area. Recommendations are presented concerning future experiments using the described solar photometer system and calibration and operational deficiencies uncovered during the experiment.

  17. Observed acoustic and aeroelastic spectral responses of a MOD-2 turbine blade to turbulence excitation

    NASA Technical Reports Server (NTRS)

    Kelley, N. D.; Mckenna, H. E.; Jacobs, E. W.

    1995-01-01

    Early results from a recent experiment designed to directly evaluate the aeroacoustic/elastic spectral responses of a MOD-2 turbine blade to turbulence-induced unsteady blade loads are discussed. The experimental procedure consisted of flying a hot-film anemometer from a tethered balloon in the turbine inflow and simultaneously measuring the fluctuating airload and aeroelastic response at two blade span stations (65% and 87% spans) using surface-mounted, subminiature pressure transducers and standard strain gage instrumentation. The radiated acoustic pressure field was measured with a triad of very-low-frequency microphones placed at ground level, 1.5 rotor diameters upwind of the disk. Initial transfer function estimates for acoustic radiation, blade normal forces, flapwise acceleration/displacement, and chord/flapwise moments are presented.

  18. Some observations about the components of transonic fan noise from narrow-band spectral analysis

    NASA Technical Reports Server (NTRS)

    Saule, A. V.

    1974-01-01

    Qualitative and quantitative spectral analyses are presented that give the broadband-noise, discrete-tone, and multiple-tone properties of the noise generated by a full-scale high-bypass single-stage axial-flow transonic fan (fan B, NASA Quiet Engine Program). The noise components were obtained from narrow-band spectra in conjunction with 1/3-octave-band spectra. Variations in the pressure levels of the noise components with fan speed, forward-quadrant azimuth angle, and frequency are presented and compared. The study shows that much of the apparent broadband noise on 1/3-octave-band plots consists of a complex system of shaft-order tones. The analyses also indicate the difficulties in determining or defining noise components, especially the broadband level under the discrete tones. The sources which may be associated with the noise components are discussed.

  19. High-speed spectral observations of a lightning negative stepped leader

    NASA Astrophysics Data System (ADS)

    Orville, R. E.; Warner, T. A.

    2010-12-01

    A cloud-to-ground lightning stroke has been recorded with a high-speed video spectrograph at a recording rate of 10,000 images per second (ips) at a distance of 0.6 km. Five sequential spectra were recorded with an exposure (integration) time of 99.6 μs each over a spectral range from 600 to 1050 nm as the leader approached the ground. The five spectra sequence was obtained immediately before the stepped leader contacted the ground. The spectral emissions in the near infrared are dominated by neutral nitrogen and oxygen emissions, and H-alpha, with only a few emission lines from singly ionized nitrogen. The emissions, which are integrated over the 99.6 μs exposure time, show no evidence of stepping. The ensuing negative return stroke was detected by the National Lightning Detection Network (NLDN) and had an estimated peak current of -15.2 kA. Two subsequent strokes were outside the field of view of the spectrograph. The flash occurred on September 11, 2009 near New Underwood, South Dakota, and the exact location of the first stroke is known because it struck a car traveling on Interstate 90. The stepped leader speed increased in the last four steps from 1.53 x 105 to 2.42 x 105 m/s with an average of 2.03 x 105 m/s. This is the first recording of sequential spectra of the stepped leader and its emissions in the near infrared region, 600 to 1050 nm.

  20. New Results of Spectral Observations of CP Stars in the Li I 6708 Å Spectral Region with the 6-m BTA Telescope

    NASA Astrophysics Data System (ADS)

    Polosukhina, N.; Shavrina, A.; Drake, N.; Kudryavtsev, D.; Smirnova, M.

    The lithium problem in Ap-CP stars has for a long time been a subject of debates. Individual characteristics of CP stars, such as a high abundance of rare-earth elements, the presence of magnetic fields, complex structures of the surface distribution of chemical elements, rapid oscillations of some CP stars, make the detection of lithium lines, and determination of lithium abundance a challenging task. The lithium problem in Ap-CP stars was discussed during the meeting in Slovakia in 1996. The results of the Li study, carried out in CrAO (Polosukhina, 1973 - 1976), the works of Faraggiana & Hack (1963), Wallerstein & Hack (1964), Faraggiana et al. (1992 - 1996) formed the basis of the international project, called Lithium in the Cool CP Stars with Magnetic Fields. The main goal of the project was, using systematical observations of Ap-CP stars with phase rotation in the spectral regions of the resonance doublet Li I 6708 Å and subordinate 6104 Å lithium lines with different telescopes, to create a database, which will permit to explain the physical origin of the anomalous Li abundance in the atmospheres of these stars.

  1. Spectrally Resolved Flux Derived from Collocated AIRS and CERES Observations and its Application in Model Validation. Part I; Clear-Sky Over the Tropic Oceans

    NASA Technical Reports Server (NTRS)

    Huang, Xianglei; Yang, Wenze; Loeb, Norman G.; Ramaswamy, V.

    2008-01-01

    Spectrally resolved outgoing IR flux, the integrand of the outgoing longwave radiation (OLR), has its unique value in evaluating model simulations. Here we describe an algorithm of deriving such clear-sky outgoing spectral flux through the whole IR region from the collocated Atmospheric Infrared Sounder (AIRS) and the Clouds & the Earth's Radiant Energy System (CERES) measurements over the tropical oceans. Based on the scene types and corresponding angular distribution models (ADMs) used in the CERES Single Satellite Footprint (SSF) dataset, spectrally-dependent ADMs are developed and used to estimate the spectral flux at each AIRS channel. A multivariate linear prediction scheme is then used to estimate spectral fluxes at frequencies not covered by the AIRS instrument. The whole algorithm is validated using synthetic spectra as well as the CERES OLR measurements. Using the GFDL AM2 model simulation as a case study, the application of the derived clear-sky outgoing spectral flux in model evaluation is illustrated. By comparing the observed and simulated spectral flux in 2004, compensating errors in the simulated OLR from different absorption bands can be revealed, so does the errors from frequencies within a given absorption band. Discrepancies between the simulated and observed spatial distributions and seasonal evolutions of the spectral fluxes at different spectral ranges are further discussed. The methodology described in this study can be applied to other surface types as well as cloudy-sky observations and corresponding model evaluations.

  2. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF MARKARIAN 421: THE MISSING PIECE OF ITS SPECTRAL ENERGY DISTRIBUTION

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Buehler, R.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Bastieri, D.; Bonamente, E.; Bouvier, A.; Brigida, M.; Bruel, P. E-mail: anita.reimer@uibk.ac.at E-mail: justin.finke@nrl.navy.mil

    2011-08-01

    We report on the {gamma}-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) {gamma}-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index {Gamma} = 1.78 {+-} 0.02 and average photon flux F(> 0.3 GeV) = (7.23 {+-} 0.16) x 10{sup -8} ph cm{sup -2} s{sup -1}. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor {approx}3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in {gamma}-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.

  3. Fermi Large Area Telescope Observations of Markarian 421: The Missing Piece of its Spectral Energy Distribution

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Fukuyama, T.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pavlidou, V.; Pearson, T. J.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Reyes, L. C.; Richards, J. L.; Ritz, S.; Roth, M.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Stevenson, M.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Yang, Z.; Yatsu, Y.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Fermi LAT Collaboration; Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Bordas, P.; Borla Tridon, D.; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Dazzi, F.; de Angelis, A.; De Cea del Pozo, E.; Delgado Mendez, C.; De Lotto, B.; De Maria, M.; De Sabata, F.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giavitto, G.; Godinovi, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; Krause, J.; La Barbera, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; López, M.; Lorenz, E.; Majumdar, P.; Makariev, E.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, J.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, T.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Struebig, J. C.; Suric, T.; Takalo, L. O.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; MAGIC Collaboration; Villata, M.; Raiteri, C.; Aller, H. D.; Aller, M. F.; Chen, W. P.; Jordan, B.; Koptelova, E.; Kurtanidze, O. M.; Lähteenmäki, A.; McBreen, B.; Larionov, V. M.; Lin, C. S.; Nikolashvili, M. G.; Reinthal, R.; Angelakis, E.; Capalbi, M.; Carramiñana, A.

    2011-08-01

    We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Γ = 1.78 ± 0.02 and average photon flux F(> 0.3 GeV) = (7.23 ± 0.16) × 10-8 ph cm-2 s-1. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor ~3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.

  4. Multiwavelength observations of the energetic GRB 080810: detailed mapping of the broad-band spectral evolution

    NASA Astrophysics Data System (ADS)

    Page, K. L.; Willingale, R.; Bissaldi, E.; Postigo, A. De Ugarte; Holland, S. T.; McBreen, S.; O'Brien, P. T.; Osborne, J. P.; Prochaska, J. X.; Rol, E.; Rykoff, E. S.; Starling, R. L. C.; Tanvir, N. R.; van der Horst, A. J.; Wiersema, K.; Zhang, B.; Aceituno, F. J.; Akerlof, C.; Beardmore, A. P.; Briggs, M. S.; Burrows, D. N.; Castro-Tirado, A. J.; Connaughton, V.; Evans, P. A.; Fynbo, J. P. U.; Gehrels, N.; Guidorzi, C.; Howard, A. W.; Kennea, J. A.; Kouveliotou, C.; Pagani, C.; Preece, R.; Perley, D.; Steele, I. A.; Yuan, F.

    2009-11-01

    GRB 080810 was one of the first bursts to trigger both Swift and the Fermi Gamma-ray Space Telescope. It was subsequently monitored over the X-ray and UV/optical bands by Swift, in the optical by Robotic Optical Transient Search Experiment (ROTSE) and a host of other telescopes, and was detected in the radio by the Very Large Array. The redshift of z = 3.355 +/- 0.005 was determined by Keck/High Resolution Echelle Spectrometer (HIRES) and confirmed by RTT150 and NOT. The prompt gamma/X-ray emission, detected over 0.3-103 keV, systematically softens over time, with Epeak moving from ~600 keV at the start to ~40 keV around 100s after the trigger; alternatively, this spectral evolution could be identified with the blackbody temperature of a quasi-thermal model shifting from ~60 to ~3keV over the same time interval. The first optical detection was made at 38s, but the smooth, featureless profile of the full optical coverage implies that this is originated from the afterglow component, not from the pulsed/flaring prompt emission. Broad-band optical and X-ray coverage of the afterglow at the start of the final X-ray decay (~8ks) reveals a spectral break between the optical and X-ray bands in the range of 1015-2 × 1016Hz. The decay profiles of the X-ray and optical bands show that this break initially migrates blueward to this frequency and then subsequently drifts redward to below the optical band by ~3 × 105s. GRB 080810 was very energetic, with an isotropic energy output for the prompt component of 3 × 1053 and 1.6 × 1052 erg for the afterglow; there is no evidence for a jet break in the afterglow up to 6d following the burst. This paper is dedicated to the memory of Professor Martin Turner, who sadly passed away during its writing. Martin was an influential figure in X-ray Astronomy and an excellent PhD supervisor. He will be greatly missed. E-mail: kpa@star.le.ac.uk ‡ NASA postdoctoral program fellow.

  5. Observation and theory of reorientation-induced spectral diffusion in polarization-selective 2D IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kramer, Patrick L.; Nishida, Jun; Giammanco, Chiara H.; Tamimi, Amr; Fayer, Michael D.

    2015-05-01

    In nearly all applications of ultrafast multidimensional infrared spectroscopy, the spectral degrees of freedom (e.g., transition frequency) and the orientation of the transition dipole are assumed to be decoupled. We present experimental results which confirm that frequency fluctuations can be caused by rotational motion and observed under appropriate conditions. A theory of the frequency-frequency correlation function (FFCF) observable under various polarization conditions is introduced, and model calculations are found to reproduce the qualitative trends in FFCF rates. The FFCF determined with polarization-selective two-dimensional infrared (2D IR) spectroscopy is a direct reporter of the frequency-rotational coupling. For the solute methanol in a room temperature ionic liquid, the FFCF of the hydroxyl (O-D) stretch decays due to spectral diffusion with different rates depending on the polarization of the excitation pulses. The 2D IR vibrational echo pulse sequence consists of three excitation pulses that generate the vibrational echo, a fourth pulse. A faster FFCF decay is observed when the first two excitation pulses are polarized perpendicular to the third pulse and the echo, , than in the standard all parallel configuration, , in which all four pulses have the same polarization. The 2D IR experiment with polarizations ("polarization grating" configuration) gives a FFCF that decays even more slowly than in the configuration. Polarization-selective 2D IR spectra of bulk water do not exhibit polarization-dependent FFCF decays; spectral diffusion is effectively decoupled from reorientation in the water system.

  6. Observation and theory of reorientation-induced spectral diffusion in polarization-selective 2D IR spectroscopy.

    PubMed

    Kramer, Patrick L; Nishida, Jun; Giammanco, Chiara H; Tamimi, Amr; Fayer, Michael D

    2015-05-14

    In nearly all applications of ultrafast multidimensional infrared spectroscopy, the spectral degrees of freedom (e.g., transition frequency) and the orientation of the transition dipole are assumed to be decoupled. We present experimental results which confirm that frequency fluctuations can be caused by rotational motion and observed under appropriate conditions. A theory of the frequency-frequency correlation function (FFCF) observable under various polarization conditions is introduced, and model calculations are found to reproduce the qualitative trends in FFCF rates. The FFCF determined with polarization-selective two-dimensional infrared (2D IR) spectroscopy is a direct reporter of the frequency-rotational coupling. For the solute methanol in a room temperature ionic liquid, the FFCF of the hydroxyl (O-D) stretch decays due to spectral diffusion with different rates depending on the polarization of the excitation pulses. The 2D IR vibrational echo pulse sequence consists of three excitation pulses that generate the vibrational echo, a fourth pulse. A faster FFCF decay is observed when the first two excitation pulses are polarized perpendicular to the third pulse and the echo, 〈XXY Y〉, than in the standard all parallel configuration, 〈XXXX〉, in which all four pulses have the same polarization. The 2D IR experiment with polarizations 〈XY XY〉 ("polarization grating" configuration) gives a FFCF that decays even more slowly than in the 〈XXXX〉 configuration. Polarization-selective 2D IR spectra of bulk water do not exhibit polarization-dependent FFCF decays; spectral diffusion is effectively decoupled from reorientation in the water system. PMID:25978898

  7. Multi-band optical observations of V404 Cygni and correlated spectral changes

    NASA Astrophysics Data System (ADS)

    Scarpaci, John; Maitra, Dipankar; Hynes, Rob; Markoff, Sera

    2015-06-01

    We report optical observations of V404 Cygni between 2015 June 27.10 - 27.34 UT made using Wheaton College Observatory's 0.3m telescope. During the course of the night observations were made by continuously cycling through V, R, and I band Johnson/Cousins filters.

  8. Earth observation and atmospheric sounding based on a high spectral resolution lidar

    NASA Astrophysics Data System (ADS)

    Liu, Yanyang; Luo, Haiying; Liu, Dong; Yang, Yongying

    2015-10-01

    Obtain accurate detection data on the distribution of water vapor and aerosol is the basis for researches on numerical weather prediction and dynamic meteorology. It also has great importance for finding haze formation and digestion mechanism. In this paper, the high spectral resolution lidar (HSRL) is employed to obtain the optical properties of the atmosphere such as optical depth and backscatter coefficient which are very helpful to get the accurate detection data on distribution and Interaction of water vapor and aerosol continuously. A forward simulation model is established to simulate the typical atmospheric conditions and aerosol distribution, and considered the presence of sunlight during the day and the background noise. The simulation result shows that the HSRL proposed here can perform well with satisfactory measurement accuracy for the altitudes below 8km, which is better than 10%, so that HSRL is very helpful to the improvement of the accuracy of weather forecasts and to the study on the prevention and control measures of haze and other weather disasters.

  9. Spectral Diagnostics for Early-Type Stars in Support of High-Resolution Satellite Observation

    NASA Technical Reports Server (NTRS)

    MacFarlane, Joseph J.

    2001-01-01

    High-resolution X-ray spectra have recently been obtained using the Chandra X-ray Satellite Observatory for the two hot supergiant stars zeta Pup and delta Ori. The spectra show the presence of strong K-shell line emission from O, Ne, Mg, Si, and S, as well as strong L-shell line emission from Fe. Initial examination of the spectra indicates that the lines are significantly broader than what would be expected for a stationary plasma, and appear to be consistent with Doppler-broadened emission from hot plasma forming in shock-heated regions embedded in the wind (see Figure 1). Chandra has sufficient spectral resolution to study the velocity structure of isolated X-ray line profiles. Our analysis for zeta Pup has shown blue-shifted and skewed line profiles, providing the most direct evidence that the X-ray source is embedded in the stellar wind. The sensitivity of the He-like fir (forbidden-intercombination-resonance) lines to a strong UV radiation field is used to estimate the radial distances at which lines of O VII, Ne IX, Mg XI, Si XIII, and S XV originate.

  10. X-ray timing and spectral observations of galactic black hole candidate XTE J1550-564 during outburst

    NASA Astrophysics Data System (ADS)

    Reilly, Kaice Theodore

    2003-09-01

    The timing and spectral properties of the soft X-ray transient (SXT) and microquasar XTE J1550-564 during outburst are studied, emphasizing observations made by the Unconventional Stellar Aspect (USA) Experiment. USA data show a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing flux and a fractional rms amplitude which is correlated with the USA hardness ratio. Several high- frequency quasi-periodic oscillations (HFQPOs) were detected by RXTE, during periods where the LFQPO is seen to be weakening or not detectable at all. The evolution of the USA hardness ratio with time and source flux is examined. The hardness-intensity diagram shows counterclockwise cyclical evolution and possibly indicates the presence of two independent accretion flows: a geometrically thin, optically thick accretion disk and a hot sub-Keplerian flow. A model for production of the LFQPO in XTE J1550-564 is proposed, assuming that the LFQPO is a result of acoustic oscillations in a hot sub-Keplerian transition layer (TL). Under this acoustic oscillation model (AOM), the TL is an acoustic cavity having an outer boundary at RTL, where R TL ≈ Rinner, with Rinner being the radius of the accretion disk inner edge. TL resonance is interpreted as a mechanism for the LFQPO and the eigenfrequencies are associated with the LFQPO frequencies, ν LFQPO. This LFQPO mechanism requires the presence of a TL, capable of inverse-Compton scattering, with RTL regulated by a cool Keplerian accretion disk. Support for the AOM is provided by the correlation of the LFQPO percent rms amplitude with the USA hardness ratio, and other correlations and anti-correlations found in the USA, RXTE and BATSE observations. LFQPO data show increasing rms amplitude with increasing high energy flux and increasing νLFQPO with increasing low energy flux. These observations indicate that ν LFQPO is set by the accretion disk inner edge. The spectrally inferred Rinner

  11. Modeling and Retrieval of Cometary Gas Spectral Lines for Rosetta-MIRO Observations of Comet 67P Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    von Allmen, P. A.; Lee, S.; Gulkis, S.; Hofstadter, M. D.; Kamp, L.

    2012-12-01

    The Microwave Instrument for the Rosetta Orbiter (MIRO), on board the ESA Rosetta spacecraft, will observe spectral lines of water, carbon monoxide, ammonia, and methanol at submillimeter wavelengths from the coma of Comet 67P Churyumov-Gerasimenko. For planning and interpretation of the MIRO observations, we develop forward models, which simulate observations of the cometary gas spectral lines from a given comet and coma condition, and retrieval models, which retrieve cometary parameters from the observed lines. This paper reports the forward and retrieval models developed for the Rosetta-MIRO observations and the applications of the models to observation planning and interpretation. The forward models involve multiple sequential steps starting from thermophysical modeling of the comet nucleus, to coma profile modeling, to molecular level distribution modeling, and to radiative transfer calculations. The thermophysical model provides the near surface temperature, gas temperature and velocity distribution, and outgassing rate to the coma profile modeling, which in turn provides the gas temperature, velocity, and density distribution in the coma. The molecular level distribution modeling uses the coma profile result to calculate the molecular level distribution in the coma. Finally, the radiative transfer model simulates MIRO spectral lines for a given viewing condition using the level distribution and coma profile results. The main retrieval problems for the MIRO observations are (1) to retrieve coma profiles along a single line of sight from measured spectral lines, (2) to determine a three-dimensional coma model from profiles along several lines of sights, (3) to infer nucleus surface conditions (sub-surface layer porosity and mechanical structure, jet formation, sublimation process, gas transport in the sub-surface layer) from the retrieved coma conditions. We develop two approaches for the retrieval problems. One is a fast analytical solution which makes

  12. Spectral and Imaging Observations of a White-light Solar Flare in the Mid-infrared

    NASA Astrophysics Data System (ADS)

    Penn, Matt; Krucker, Säm; Hudson, Hugh; Jhabvala, Murzy; Jennings, Don; Lunsford, Allen; Kaufmann, Pierre

    2016-03-01

    We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17:50 (C7.0), using Quantum Well Infrared Photodetector cameras at an auxiliary of the McMath-Pierce telescope. The flare emissions, the first simultaneous observations in two mid-infrared bands at 5.2 and 8.2 μ {{m}} with white-light and hard X-ray coverage, revealed impulsive time variability with increases on timescales of ˜4 s followed by exponential decay at ˜10 s in two bright regions separated by about 13\\prime\\prime . The brightest source is compact, unresolved spatially at the diffraction limit (1\\_\\_AMP\\_\\_farcs;72 at 5.2 μ {{m}}). We identify the IR sources as flare ribbons also seen in white-light emission at 6173 Å observed by SDO/HMI, with twin hard X-ray sources observed by Reuven Ramaty High Energy Solar Spectroscopic Imager, and with EUV sources (e.g., 94 Å) observed by SDO/AIA. The two infrared points have nearly the same flux density (fν, W m-2 Hz) and extrapolate to a level of about an order of magnitude below that observed in the visible band by HMI, but with a flux of more than two orders of magnitude above the free-free continuum from the hot (˜15 MK) coronal flare loop observed in the X-ray range. The observations suggest that the IR emission is optically thin; this constraint and others suggest major contributions from a density less than about 4× {10}13 cm-3. We tentatively interpret this emission mechanism as predominantly free-free emission in a highly ionized but cool and rather dense chromospheric region.

  13. Spectral observations of diffuse FUV emission from the hot phase of the interstellar medium with DUVE

    NASA Astrophysics Data System (ADS)

    Korpela, Eric John

    One of the keys to understanding the structure and distribution of interstellar matter in the galaxy is understanding the distribution of the low density hot (105 K-106 K) phase of the interstellar medium (ISM). Because of its low density and lack of easily observable tracers, this phase is much more difficult to observe than the cooler high density components of the ISM. Because gas of this temperature emits mainly in the far ultraviolet (912 A-1800 A), extreme ultraviolet (80 A-912 A), and (for gas hotter than 106 K) X-rays, observations in these bands can provide important constraints to the distribution of this gas. Because of interstellar opacity at EUV wavelengths, only FUV and X- ray observations can provide clues to the properties of hot gas outside the immediate solar neighborhood. I present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 950 A to 1080 A with 3.2 A resolution, observed a region of low neutral hydrogen column density near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line at 1026 A. I am able to place upper limits to several emission features that provide constraints to interstellar plasma parameters. I am also able to place limits to continuum emission throughout the bandpass. I compare these limits and other diffuse observations with several models of the structure of the interstellar medium and discuss the ramifications of these models.

  14. Spectral Observations of Diffuse FUV Emission from the Hot Phase of the Interstellar Medium with DUVE

    NASA Astrophysics Data System (ADS)

    Korpela, Eric John

    One of the keys to understanding the structure and distribution of interstellar matter in the galaxy is understanding the distribution of the low density hot (105 K-106 K) phase of the interstellar medium (ISM). Because of its low density and lack of easily observable tracers, this phase is much more difficult to observe than the cooler high density components of the ISM. Because gas of this temperature emits mainly in the far ultraviolet (912 A-1800 A), extreme ultraviolet (80 A-912 A), and (for gas hotter than 106 K) X-rays, observations in these bands can provide important constraints to the distribution of this gas. Because of interstellar opacity at EUV wavelengths, only FUV and X-ray observations can provide clues to the properties of hot gas outside the immediate solar neighborhood. I present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 950 A to 1080 A with 3.2 A resolution, observed a region of low neutral hydrogen column density near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line at 1026 A. I am able to place upper limits to several emission features that provide constraints to interstellar plasma parameters. I am also able to place limits to continuum emission throughout the bandpass. I compare these limits and other diffuse observations with several models of the structure of the interstellar medium and discuss the ramifications of these models.

  15. High Spectral Resolution X-ray Observation of Magnetic CVs: EX Hya

    SciTech Connect

    Luna, G; Brickhouse, N S; Mauche, C W

    2008-04-07

    In magnetic cataclysmic variables (CVs) the primary is a highly magnetized white dwarf (WD) whose field controls the accretion flow close to the WD, leading to a shock and accretion column that radiate chiefly in X-rays. We present preliminary results from a 500 ks Chandra HETG observation of the brightest magnetic CV EX Hya. From the observational dataset we are able to measure the temperature and density at different points of the cooling accretion column using sensitive line ratios. We also construct line-based light curves to search for rotational modulation of the X-ray emission.

  16. A comparison of the ultraviolet to near-infrared spectral properties of Mercury and the Moon as observed by MESSENGER

    NASA Astrophysics Data System (ADS)

    Holsclaw, Gregory M.; McClintock, William E.; Domingue, Deborah L.; Izenberg, Noam R.; Blewett, David T.; Sprague, Ann L.

    2010-09-01

    Measurements of the disk-integrated reflectance spectrum of Mercury and the Moon have been obtained by the MESSENGER spacecraft. A comparison of spectra from the two bodies, spanning the wavelength range 220-1450 nm, shows that the absolute reflectance of Mercury is lower than that of the nearside waxing Moon at the same phase angle with a spectral slope that is less steep at visible and near-infrared wavelengths. We interpret these results and the lack of an absorption feature at a wavelength near 1000 nm as evidence for a Mercury surface composition that is low in ferrous iron within silicates but is higher in the globally averaged abundance of spectrally neutral opaque minerals than the Moon. Similar conclusions have been reached by recent investigations based on observations from both MESSENGER and Mariner 10. There is weak evidence for a phase-reddening effect in Mercury that is slightly larger in magnitude than for the lunar nearside. An apparent absorption in the middle-ultraviolet wavelength range of the Mercury spectrum detected from the first MESSENGER flyby of Mercury is found to persist in subsequent observations from the second flyby. The current model of space weathering on the Moon, which also presumably applies to Mercury, does not provide an explanation for the presence of this ultraviolet absorption.

  17. Spectral Analysis of Forecast Error Investigated with an Observing System Simulation Experiment

    NASA Technical Reports Server (NTRS)

    Prive, N. C.; Errico, Ronald M.

    2015-01-01

    The spectra of analysis and forecast error are examined using the observing system simulation experiment (OSSE) framework developed at the National Aeronautics and Space Administration Global Modeling and Assimilation Office (NASAGMAO). A global numerical weather prediction model, the Global Earth Observing System version 5 (GEOS-5) with Gridpoint Statistical Interpolation (GSI) data assimilation, is cycled for two months with once-daily forecasts to 336 hours to generate a control case. Verification of forecast errors using the Nature Run as truth is compared with verification of forecast errors using self-analysis; significant underestimation of forecast errors is seen using self-analysis verification for up to 48 hours. Likewise, self analysis verification significantly overestimates the error growth rates of the early forecast, as well as mischaracterizing the spatial scales at which the strongest growth occurs. The Nature Run-verified error variances exhibit a complicated progression of growth, particularly for low wave number errors. In a second experiment, cycling of the model and data assimilation over the same period is repeated, but using synthetic observations with different explicitly added observation errors having the same error variances as the control experiment, thus creating a different realization of the control. The forecast errors of the two experiments become more correlated during the early forecast period, with correlations increasing for up to 72 hours before beginning to decrease.

  18. XMM-Newton and Swift Observations of WZ Sagittae: Spectral and Timing Analysis

    NASA Technical Reports Server (NTRS)

    Nucita, A. A.; Kuulkers, E.; De Paolis, F.; Mukai, K.; Ingrosso, G.; Maiolo, B. M. T.

    2014-01-01

    WZ Sagittae is the prototype object of a subclass of dwarf novae with rare and long (super)outbursts, in which a white dwarf primary accretes matter from a low mass companion. High-energy observations offer the possibility of a better understanding of the disk-accretion mechanism in WZ Sge-like binaries.

  19. Demonstration of random projections applied to the retrieval problem of geophysical parameters from hyper-spectral infrared observations.

    PubMed

    Serio, Carmine; Masiello, Guido; Liuzzi, Giuliano

    2016-08-20

    The random projections statistical technique has been used to reduce the dimensionality of the radiance data space generated from high spectral resolution infrared observations. The mathematical inversion of the physical radiative transfer equation for geophysical parameters has been solved in this space of reduced dimensionality. The great advantage of using random projections is that they provide an unified treatment of instrument noise and forward model error, which can be comprehensively modeled with a single variance term. The result is a novel retrieval approach, which combines computational efficiency to possibly improved accuracy of the retrieval products. The novel approach has been demonstrated through application to the Infrared Atmospheric Sounding Interferometer. We have found that state-of-the-art spectroscopy and related line-mixing treatment for the ν2CO2 absorption band, i.e., the fundamental band for temperature retrieval, show an excellent consistency with satellite observations. PMID:27556974

  20. UV-B radiation amplification factor determined based on the simultaneous observation of total ozone and global spectral irradiance

    NASA Technical Reports Server (NTRS)

    Ito, T.; Sakoda, Y.; Matsubara, K.; Kajihara, R.; Uekubo, T.; Kobayashi, M.; Shitamichi, M.; Ueno, T.; Ito, M.

    1994-01-01

    The Japan Meteorological Agency started the spectral observation of solar ultraviolet (UV) irradiance on 1 January 1990 at Tateno, Aerological Observatory in Tsukuba (35 deg N, 140 deg E). The observation has been carried out using the Brewer spectrophotometer for the wavelengths from 290 to 325 nm with a 0.5 nm interval every hour from 30 minutes before sunrise to 30 minutes after sunset throughout a year. Because of remarkable similarity within observed spectra, an observed spectrum can be expressed by a simple combination of a reference spectrum and two parameters expressing the deformation of the observed spectrum from the reference. By use of the relation between one of the deformation parameters and the total ozone simultaneously observed with the Dobson spectrophotometer, the possible increase of UV irradiance due to ozone depletion is estimated. For damaging UV, the irradiance possibly increases about 19 percent with the ozone depletion of 10 percent at noon throughout the year in the northern midlatitudes. DUV at noon on the summer solstice possibly increases about 5.6 percent with the ozone depletion of 10 m atm-cm for all latitudes in the Northern Hemisphere.

  1. On the nature of 2 gamma bursts with spectral evolutions observed by the Konus experiment

    NASA Technical Reports Server (NTRS)

    Liang, E. P.

    1982-01-01

    Several unique features of the evolving spectra of the April 2, 1979B, and November 11, 1979 gamma-ray bursts observed by the Konus experiment can be used to determine a number of critical parameters of the sources, within the context of the thermal synchrotron model, including their luminosity distance. These results shed much light on the origin of these events and possibly gamma bursts in general.

  2. Observing system simulation experiments for the laser atmospheric wind sounder using global spectral model

    NASA Technical Reports Server (NTRS)

    Rohaly, Gregg; Krishnamurti, T. N.

    1991-01-01

    Fundamental to improving the understanding of the total Earth system are increased and improved observations. In the coming decade several spaceborne instrumented platforms will be constructed and implemented. These platforms will, in large, be housing the NASA Earth Observing System (EOS) instrument suite. One of the proposed instruments is a wind profiling system which is currently referred to as the Laser Atmospheric Wind Sounder (LAWS). This instrument will use a CO2 Doppler lidar wind profiler to give wind measurements with a vertical and horizontal resolution which has yet to be seen globally. The LAWS instrument is now a candidate for launch on a NASA EOS-B platform and is fundamental to increasing our understanding of Earth system science. The LAWS data sets will form an integral component of the temporally continuous data base needed for research of the coupled climate systems. This instrument's observations will aid in giving an improved description of the atmospheric circulation, including the transports of energy, momentum, moisture, trace gases, and aerosols. Also, the wind data will be assimilated and used as the initial state for many global forecast models at various operational centers. Results of system simulation experiments are discussed, and future experiments are described.

  3. Pan-spectral observing system simulation experiments of shortwave reflectance and long-wave radiance for climate model evaluation

    NASA Astrophysics Data System (ADS)

    Feldman, D. R.; Collins, W. D.; Paige, J. L.

    2015-07-01

    Top-of-atmosphere (TOA) spectrally resolved shortwave reflectances and long-wave radiances describe the response of the Earth's surface and atmosphere to feedback processes and human-induced forcings. In order to evaluate proposed long-duration spectral measurements, we have projected 21st Century changes from the Community Climate System Model (CCSM3.0) conducted for the Intergovernmental Panel on Climate Change (IPCC) A2 Emissions Scenario onto shortwave reflectance spectra from 300 to 2500 nm and long-wave radiance spectra from 2000 to 200 cm-1 at 8 nm and 1 cm-1 resolution, respectively. The radiative transfer calculations have been rigorously validated against published standards and produce complementary signals describing the climate system forcings and feedbacks. Additional demonstration experiments were performed with the Model for Interdisciplinary Research on Climate (MIROC5) and Hadley Centre Global Environment Model version 2 Earth System (HadGEM2-ES) models for the Representative Concentration Pathway 8.5 (RCP8.5) scenario. The calculations contain readily distinguishable signatures of low clouds, snow/ice, aerosols, temperature gradients, and water vapour distributions. The goal of this effort is to understand both how climate change alters reflected solar and emitted infrared spectra of the Earth and determine whether spectral measurements enhance our detection and attribution of climate change. This effort also presents a path forward to understand the characteristics of hyperspectral observational records needed to confront models and inline instrument simulation. Such simulation will enable a diverse set of comparisons between model results from coupled model intercomparisons and existing and proposed satellite instrument measurement systems.

  4. New CRISM Along-Track Oversampled Observations and Implications for Spectral Mapping at Fine Spatial Scales

    NASA Astrophysics Data System (ADS)

    Coman, E. I.; Arvidson, R. E.; Stein, N.; Murchie, S. L.; McGovern, A.; Seelos, K. D.; Seelos, F. P.; Humm, D. C.

    2013-12-01

    The Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is a hyperspectral line scanner imaging system (0.362-3.920 micrometers at 6.55 nm/channel) that was designed to acquire targeted images at ~18 m/pixel spatial sampling. Past experiments have shown that by appropriately commanding the gimbal system, CRISM can also collect Along-Track Oversampled (ATO) observations with overlapping pixels that can be sharpened to along-track spatial resolutions as fine as 5 m/pixel. These observations were impossible to sharpen to a constant along-track spatial resolution within scenes because pixel overlap varied significantly due to irregularities in gimbal motion during imaging of targets. A new observational scheme has been implemented in which gimbaling has been adjusted to keep overlap constant, allowing consistent regularization and sharpening across the entire scene. We demonstrate two processing approaches for spatial sharpening of several scenes acquired with the new gimbaling approach. The scenes are: 1. A recent crater with dark ejecta located at 23.7N, 220.1E (areocentric) ATO00029FC9; 2. Layered rocks uplifted in crater near Solis Dorsa located at 23.14N, 281.37E ATO00029F00, and 3. Dikes in Valles Marineris Coprates Chasma located at 15.02N, 306.96 ATO00029EFD. The two methods are Tikhonov damped least squares spatial sharpening implemented in one dimensional and two dimensional schemes. The Tikhonov method for spatial sharpening replaces the overlapping pixels with smaller, regularly spaced pixels by minimizing the sums of squares of deviations between the observed data matrix and a matrix of regularized, smaller-sized pixels premultiplied by the imaging system transfer function, including ground motion smear. A side constraint is introduced to minimize the sums of squares of deviations of first derivatives for the regularized pixel matrix. This side constraint minimizes noise, and the extent of this minimization is

  5. Gamma-ray burst high time-resolution spectral observations made with the Solar Maximum Mission

    NASA Technical Reports Server (NTRS)

    Desai, U. D.; Cline, T. L.; Dennis, B. R.; Frost, K. J.; Norris, J. P.

    1983-01-01

    The gamma-ray bursts of April 19 and 21, 1980, and March 1, 1981, are characterized on the basis of observations obtained at 25-500 keV and time resolution 128 msec using the hard-X-ray-burst spectrometer of the SMM satellite. The data are presented graphically, and the parameters determined by fitting three theoretical models to the data for each phase (rising phase, decay phase, and valleys between pulses) are given in tables. Models used are thin thermal bremsstrahlung with or without absorption lines, thermal synchrotron with or without absorption lines, and power law with exponential cutoff.

  6. Unusual Galactic Cosmic Ray Intensity and Spectral Changes Observed by V1 Near The Heliopause

    NASA Astrophysics Data System (ADS)

    Webber, W. R.; Quenby, J. J.

    2015-06-01

    We discuss here two unusual increases of cosmic ray intensity that were observed by V1 in the last 1.1 AU before it crossed the heliopause in 2012 August, at 121.5 AU. These two increases are roughly similar in amplitude and result in a total increase in ˜1 GV cosmic ray nuclei of over 50% and 0.01 GV electrons of a factor ˜2. During the first increase the changes in the B field are small. After the first increase the B field changes become large and during the second increase the B field variations and cosmic ray changes are correlated to within ± one day. During these time intervals, the rigidity dependence of the increases of GCR H and He nuclei from 100-600 MeV/nuc resemble those used to describe the solar modulation near the Earth during a large transient decrease but the ratio between the intensity changes of H, He, and electrons are different. The magnitude of these increases at Voyager is ˜1/3 of the modulation that is required to produce the total modulation of protons, helium nuclei, and electrons between the local interstellar intensities and those observed at the Earth at the 2009 sunspot minima. This may imply that a significant part of the residual solar modulation at times of sunspot minima occurs near the heliopause itself.

  7. Spectral observations of FUV auroral arcs and comparison with inverted-V precipitating electrons

    NASA Astrophysics Data System (ADS)

    Lee, C. N.; Min, K. W.; Lee, J.-J.; Parks, G. K.; Fillingim, M. O.; Lummerzheim, D.; Cho, K. S.; Kim, K.-H.; Kim, Y. H.; Park, Y. D.; Han, W.; Edelstein, J.; Korpela, E.

    2010-09-01

    This paper presents first simultaneous observations of far ultraviolet (FUV) spectra of discrete and diffuse auroras, together with precipitating electrons measured on the same spacecraft, to emphasize the importance of high-resolution FUV images for accurate estimation of precipitating energy flux in the auroral region. An FUV spectrograph image with ˜2 km × 3 km resolution show small-scale features were embedded in the auroral arcs. Comparison of peak energies of inverted-V events with the corresponding FUV spectra shows that the observed long band N2 Lyman-Birge-Hopfield (LBH) emission (long LBH band (LBHL): 160.0-171.5 nm) varied more sensitively to the peak energies compared to the short band. Comparison of the inverted-V structures and their energy fluxes with the LBHL irradiance for ˜10 km × 10 km regions show they are well correlated for peak energy >2 keV. When the data are averaged over a larger area (70 km × ˜140 km), on the other hand, the LBHL irradiance becomes less bright for the corresponding electron energy flux due to the contribution from the low-intensity background diffuse aurora produced by secondary electrons. This study demonstrates a reliable relationship between precipitating electron energy flux and LBHL intensity is obtained only if the precipitating region and FUV intensity are locally matched with a scale of less than 10 km corresponding to the size of discrete auroras.

  8. High Spectral Resolution Infrared and Raman Lidar Observations for the ARM Program: Clear and Cloudy Sky Applications

    SciTech Connect

    Revercomb, Henry; Tobin, David; Knuteson, Robert; Borg, Lori; Moy, Leslie

    2009-06-17

    This grant began with the development of the Atmospheric Emitted Radiance Interferometer (AERI) for ARM. The AERI has provided highly accurate and reliable observations of downwelling spectral radiance (Knuteson et al. 2004a, 2004b) for application to radiative transfer, remote sensing of boundary layer temperature and water vapor, and cloud characterization. One of the major contributions of the ARM program has been its success in improving radiation calculation capabilities for models and remote sensing that evolved from the multi-year, clear-sky spectral radiance comparisons between AERI radiances and line-by-line calculations (Turner et al. 2004). This effort also spurred us to play a central role in improving the accuracy of water vapor measurements, again helping ARM lead the way in the community (Turner et al. 2003a, Revercomb et al. 2003). In order to add high-altitude downlooking AERI-like observations over the ARM sites, we began the development of an airborne AERI instrument that has become known as the Scanning High-resolution Interferometer Sounder (Scanning-HIS). This instrument has become an integral part of the ARM Unmanned Aerospace Vehicle (ARM-UAV) program. It provides both a cross-track mapping view of the earth and an uplooking view from the 12-15 km altitude of the Scaled Composites Proteus aircraft when flown over the ARM sites for IOPs. It has successfully participated in the first two legs of the “grand tour” of the ARM sites (SGP and NSA), resulting in a very good comparison with AIRS observations in 2002 and in an especially interesting data set from the arctic during the Mixed-Phase Cloud Experiment (M-PACE) in 2004.

  9. Full Stokes observations in the He i 1083 nm spectral region covering an M3.2 flare

    NASA Astrophysics Data System (ADS)

    Kuckein, Christoph; Collados, Manuel; Sainz, Rafael Manso; Ramos, Andrés Asensio

    2015-10-01

    We present an exceptional data set acquired with the Vacuum Tower Telescope (Tenerife, Spain) covering the pre-flare, flare, and post-flare stages of an M3.2 flare. The full Stokes spectropolarimetric observations were recorded with the Tenerife Infrared Polarimeter in the He i 1083.0 nm spectral region. The object under study was active region NOAA 11748 on 2013 May 17. During the flare the chomospheric He i 1083.0 nm intensity goes strongly into emission. However, the nearby photospheric Si i 1082.7 nm spectral line profile only gets shallower and stays in absorption. Linear polarization (Stokes Q and U) is detected in all lines of the He i triplet during the flare. Moreover, the circular polarization (Stokes V) is dominant during the flare, being the blue component of the He i triplet much stronger than the red component, and both are stronger than the Si i Stokes V profile. The Si i inversions reveal enormous changes of the photospheric magnetic field during the flare. Before the flare magnetic field concentrations of up to ~1500 G are inferred. During the flare the magnetic field strength globally decreases and in some cases it is even absent. After the flare the magnetic field recovers its strength and initial configuration.

  10. Spectral Observations of the Diffuse FUV Background with DUVE (the Diffuse UV Experiment)

    NASA Astrophysics Data System (ADS)

    Korpela, E. J.; Bowyer, S.

    1996-05-01

    We present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 970 Angstroms to 1170 Angstroms with 3.2 angstrom resolution, observed a region of low neutral hydrogen column desity near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line 1026 Angstroms. We were, however, able to place upper limits to several important interstellar emission features in this band. We compare these upper limits with predictions of FUV emission based upon several models of the structure of the hot ISM and place limits on the emission measure vs temperature distribution this gas. We also compare these emission measure limits with those obtained from measurements in other optical, UV and X-ray bands.

  11. Spectral Observations of the Diffuse FUV Background with DUVE (the Diffuse UV Experiment)

    NASA Astrophysics Data System (ADS)

    Korpela, E. J.; Bowyer, S.

    We present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 950 Angstroms to 1080 Angstroms with 3.2 Angstroms resolution, observed a region of low neutral hydrogen column density near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line at 1025 Angstroms. We were able to place upper limits to several emission features that provide constraints to interstellar plasma parameters. We were also able to place continuum limits in this band. We use these upper limits to place constraints upon the emission measure vs. temperature distribution of this gas using an isothermal Landini and Fossi model.

  12. X-Ray Spectral and Timing Observations of Cygnus X-2

    NASA Astrophysics Data System (ADS)

    Piraino, S.; Santangelo, A.; Kaaret, P.

    2002-03-01

    We report on a joint BeppoSAX/RXTE observation of the Z-type low-mass X-ray binary Cyg X-2. The source was in the so-called high overall intensity state and in less than 24 hr went through all three branches of the Z track. The continuum X-ray spectrum could be described by the absorbed sum of a soft thermal component, modeled as either a blackbody or a multicolor disk blackbody, and a Comptonized component. The timing power spectrum showed several components, including quasi-periodic oscillations in the range 28-50 Hz while the source was on the horizontal branch (horizontal branch oscillation; HBO). We found that the HBO frequency was well correlated with the parameters of the soft thermal component in the X-ray spectrum. We discuss implications of this correlation for models of the HBO.

  13. Spectral observations of 19 weathered and 23 fresh NEAs and their correlations with orbital parameters

    NASA Astrophysics Data System (ADS)

    Fevig, Ronald A.; Fink, Uwe

    2007-05-01

    Results of our visible to near-infrared spectrophotometric observations of 41 near-Earth asteroids (NEAs) are reported. These moderate-resolution spectra, along with 14 previously published spectra from our earlier survey [Hicks, M.D., Fink, U., Grundy, W.M., 1998. Icarus 133, 69-78] show a preponderance of spectra consistent with ordinary chondrites (23 NEAs with this type of spectrum, along with 19 S-types and 13 in other taxonomic groups). There exists statistically significant evidence for orbit-dependent trends in our data. While S-type NEAs from our survey reside primarily in (1) Amor orbits or (2) Aten or Apollo orbits which do not cross the asteroid main-belt, the majority of objects with spectra consistent with ordinary chondrites in our survey are in highly eccentric Apollo orbits which enter the asteroid main-belt. This trend toward fresh, relatively unweathered NEAs with ordinary chondrite type spectra in highly eccentric Apollo orbits is attributed to one or a combination of three possible causes: (1) the chaotic nature of NEA orbits can easily result in high eccentricity orbits/large aphelion distances so that they can enter the collisionally enhanced environment in the main-belt, exposing fresh surfaces, (2) they have recently been injected into such orbits after a collision in the main-belt, or (3) such objects cross the orbits of several terrestrial planets, causing tidal disruption events that expose fresh surfaces.

  14. Spectral features of lightning-induced ion cyclotron waves at low latitudes: DEMETER observations and simulation

    NASA Astrophysics Data System (ADS)

    Shklyar, D. R.; Storey, L. R. O.; Chum, J.; JiříčEk, F.; NěMec, F.; Parrot, M.; Santolik, O.; Titova, E. E.

    2012-12-01

    We use a comprehensive analysis of 6-component ELF wave data from the DEMETER satellite to study proton whistlers, placing emphasis on low-latitude events originating from lightning strokes in the hemisphere opposite to the hemisphere of observation. In this case, the formation of proton whistlers does not involve mode conversion caused by a strong mode coupling at a crossover frequency, although a polarization reversal remains an important element in formation of the phenomenon. DEMETER measurements of the six electromagnetic field components in the frequency band below 1000 Hz make it possible to determine not only the dynamic spectrum, but also the wave polarization, the wave normal angle, and the normalized parallel component of the Poynting vector. This permits us to address fine features of proton whistlers, in particular, we show that the deviation of the upper cutoff frequency from the equatorial cyclotron frequency is related to the Doppler shift. Experimental study of proton whistlers is supplemented by an investigation of ion cyclotron wave propagation in a multicomponent magnetoplasma and by numerical modeling of spectrograms, both in the frame of geometrical optics.

  15. First spectrally-resolved H2 observations towards HH 54 . Low H2O abundance in shocks

    NASA Astrophysics Data System (ADS)

    Santangelo, G.; Antoniucci, S.; Nisini, B.; Codella, C.; Bjerkeli, P.; Giannini, T.; Lorenzani, A.; Lundin, L. K.; Cabrit, S.; Calzoletti, L.; Liseau, R.; Neufeld, D.; Tafalla, M.; van Dishoeck, E. F.

    2014-09-01

    Context. Herschel observations suggest that the H2O distribution in outflows from low-mass stars resembles the H2 emission. It is still unclear which of the different excitation components that characterise the mid- and near-IR H2 distribution is associated with H2O. Aims: The aim is to spectrally resolve the different excitation components observed in the H2 emission. This will allow us to identify the H2 counterpart associated with H2O and finally derive directly an H2O abundance estimate with respect to H2. Methods: We present new high spectral resolution observations of H2 0-0 S(4), 0-0 S(9), and 1-0 S(1) towards HH 54, a bright nearby shock region in the southern sky. In addition, new Herschel/HIFI H2O (212 - 101) observations at 1670 GHz are presented. Results: Our observations show for the first time a clear separation in velocity of the different H2 lines: the 0-0 S(4) line at the lowest excitation peaks at -7 km s-1, while the more excited 0-0 S(9) and 1-0 S(1) lines peak at -15 km s-1. H2O and high-J CO appear to be associated with the H2 0-0 S(4) emission, which traces a gas component with a temperature of 700-1000 K. The H2O abundance with respect to H2 0-0 S(4) is estimated to be X(H2O) < 1.4 × 10-5 in the shocked gas over an area of 13''. Conclusions: We resolve two distinct gas components associated with the HH 54 shock region at different velocities and excitations. This allows us to constrain the temperature of the H2O emitting gas (≤1000 K) and to derive correct estimates of H2O abundance in the shocked gas, which is lower than what is expected from shock model predictions. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs: 089.C-0772, 292.C-5025.

  16. Constraining precipitation initiation in marine stratocumulus using aircraft observations and LES with high spectral resolution bin microphysics

    NASA Astrophysics Data System (ADS)

    Witte, M.; Chuang, P. Y.; Rossiter, D.; Ayala, O.; Wang, L. P.

    2015-12-01

    Turbulence has been suggested as one possible mechanism to accelerate the onset of autoconversion and widen the process "bottleneck" in the formation of warm rain. While direct observation of the collision-coalescence process remains beyond the reach of present-day instrumentation, co-located sampling of atmospheric motion and the drop size spectrum allows for comparison of in situ observations with simulation results to test representations of drop growth processes. This study evaluates whether observations of drops in the autoconversion regime can be replicated using our best theoretical understanding of collision-coalescence. A state-of-the-art turbulent collisional growth model is applied to a bin microphysics scheme within a large-eddy simulation such that the full range of cloud drop growth mechanisms are represented (i.e. CCN activation, condensation, collision-coalescence, mixing, etc.) at realistic atmospheric conditions. The spectral resolution of the microphysics scheme has been quadrupled in order to (a) more closely match the resolution of the observational instrumentation and (b) limit numerical diffusion, which leads to spurious broadening of the drop size spectrum at standard mass-doubling resolution. We compare simulated cloud drop spectra with those obtained from aircraft observations to assess the quality and limits of our theoretical knowledge. The comparison is performed for two observational cases from the Physics of Stratocumulus Top (POST) field campaign: 12 August 2008 (drizzling night flight, Rmax~2 mm/d) and 15 August 2008 (nondrizzling day flight, Rmax<0.5 mm/d). Both flights took place off the coast of Monterey, CA and the two cases differ in their radiative cooling rates, shear, cloud-top temperature and moisture jumps, and entrainment rates. Initial results from a collision box model suggest that enhancements of approximately 2 orders of magnitude over theoretical turbulent collision rates may be necessary to reproduce the

  17. Solar absorption by elemental and brown carbon determined from spectral observations

    PubMed Central

    Bahadur, Ranjit; Praveen, Puppala S.; Xu, Yangyang; Ramanathan, V.

    2012-01-01

    Black carbon (BC) is functionally defined as the absorbing component of atmospheric total carbonaceous aerosols (TC) and is typically dominated by soot-like elemental carbon (EC). However, organic carbon (OC) has also been shown to absorb strongly at visible to UV wavelengths and the absorbing organics are referred to as brown carbon (BrC), which is typically not represented in climate models. We propose an observationally based analytical method for rigorously partitioning measured absorption aerosol optical depths (AAOD) and single scattering albedo (SSA) among EC and BrC, using multiwavelength measurements of total (EC, OC, and dust) absorption. EC is found to be strongly absorbing (SSA of 0.38) whereas the BrC SSA varies globally between 0.77 and 0.85. The method is applied to the California region. We find TC (EC + BrC) contributes 81% of the total absorption at 675 nm and 84% at 440 nm. The BrC absorption at 440 nm is about 40% of the EC, whereas at 675 nm it is less than 10% of EC. We find an enhanced absorption due to OC in the summer months and in southern California (related to forest fires and secondary OC). The fractions and trends are broadly consistent with aerosol chemical-transport models as well as with regional emission inventories, implying that we have obtained a representative estimate for BrC absorption. The results demonstrate that current climate models that treat OC as nonabsorbing are underestimating the total warming effect of carbonaceous aerosols by neglecting part of the atmospheric heating, particularly over biomass-burning regions that emit BrC. PMID:23045698

  18. Swift Observations of Gamma-Ray Burst Pulse Shapes: GRB Pulse Spectral Evolution Clarified

    NASA Astrophysics Data System (ADS)

    Hakkila, Jon; Lien, Amy; Sakamoto, Takanori; Morris, David; Neff, James E.; Giblin, Timothy W.

    2015-12-01

    Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by the residual fit of Hakkila & Preece: the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long, soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied to the timing of the three peaks: pulses with the largest maximum hardnesses are hardest during the precursor, those with smaller maximum hardnesses are hardest during the central peak, and all pulses can re-harden during the central peak and/or during the decay peak. Since these behaviors are essentially seen in all isolated pulses, the distinction between “hard-to-soft and “intensity-tracking” pulses really no longer applies. Additionally, the triple-peaked nature of isolated GRB pulses seems to indicate that energy is injected on three separate occasions during the pulse duration: theoretical pulse models need to account for this.

  19. Satellite observations of polar mesospheric clouds by the solar backscattered ultraviolet spectral radiometer - Evidence of a solar cycle dependence

    NASA Technical Reports Server (NTRS)

    Thomas, Gary E.; Mcpeters, Richard D.; Jensen, Eric J.

    1991-01-01

    Results are presented on eight years of satellite observations of the polar mesospheric clouds (PMCs) by the SBUV spectral radiometer, showing that PMCs occur in the summertime polar cap regions of both hemispheres and that they exhibit year-to-year variability. It was also found that the increase in the PMC occurrence frequency was inversely correlated with solar activity. Two kinds of hemispherical asymmetries could be identified: (1) PMCs in the Northern Hemisphere were significantly brighter than in the Southern Hemisphere, in accordance with previous results derived from SME data; and (2) the solar cycle response in the south is more pronounced than in the north. The paper also describes the cloud detection algorithm.

  20. STACEE observations of Markarian 421 above 100 GeV and a new method for high-energy spectral analysis

    NASA Astrophysics Data System (ADS)

    Carson, Jennifer Elaine

    Markarian 421 is a nearby (z =0.03) blazar that is actively studied to constrain both physical blazar models and models of the extragalactic background light. The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), a wavefront- sampling detector sensitive to ~ 100 GeV gamma rays, detected Mkn 421 during a multiwavelength campaign in early 2004. This thesis covers the 2004 STACEE observations of Mkn 421 and their analysis. The goal of the project was to measure the gamma-ray spectrum of Mkn 421; such a spectral result would be STACEE's first and one of the first from any detector in STACEE's energy range. Achieving this goal required the development of a new method for reconstructing gamma-ray energies from the STACEE data. The reconstruction method is described in detail, and the resulting spectrum is presented. Finally, the implications of the results for understanding high-energy emission mechanisms in AGN are discussed.

  1. TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey. I. Observations, calibration, and analysis of the line kinematics

    NASA Astrophysics Data System (ADS)

    Caux, E.; Kahane, C.; Castets, A.; Coutens, A.; Ceccarelli, C.; Bacmann, A.; Bisschop, S.; Bottinelli, S.; Comito, C.; Helmich, F. P.; Lefloch, B.; Parise, B.; Schilke, P.; Tielens, A. G. G. M.; van Dishoeck, E.; Vastel, C.; Wakelam, V.; Walters, A.

    2011-08-01

    Context. Unbiased spectral surveys are powerful tools to study the chemistry and the physics of star forming regions, because they can provide a complete census of the molecular content and the observed lines probe the physical structure of the source. Aims: While unbiased surveys at the millimeter and sub-millimeter wavelengths observable from ground-based telescopes have previously been performed towards several high mass protostars, very little exists on low mass protostars, which are believed to resemble our own Sun's progenitor. To help fill up this gap in our understanding, we carried out a complete spectral survey of the bands at 3, 2, 1, and 0.9 mm towards the solar type protostar IRAS 16293-2422. Methods: The observations covered a range of about 200 GHz and were obtained with the IRAM-30 m and JCMT-15 m telescopes during about 300 h of observations. Particular attention was devoted to the inter-calibration of the acquired spectra with previous observations. All the lines detected with more than 3σ confidence-interval certainty and free from obvious blending effects were fitted with Gaussians to estimate their basic kinematic properties. Results: More than 4000 lines were detected (with σ ≥ 3) and identified, yielding a line density of approximatively 20 lines per GHz, comparable to previous surveys in massive hot cores. The vast majority (about two-thirds) of the lines are weak and produced by complex organic molecules. The analysis of the profiles of more than 1000 lines belonging to 70 species firmly establishes the presence of two distinct velocity components associated with the two objects, A and B, forming the IRAS 16293-2422 binary system. In the source A, the line widths of several species increase with the upper level energy of the transition, a behavior compatible with gas infalling towards a ~1 M⊙ object. The source B, which does not show this effect, might have a much lower central mass of ~0.1 M⊙. The difference in the rest velocities

  2. Short-term X-ray spectral variability of the quasar PDS 456 observed in a low-flux state

    NASA Astrophysics Data System (ADS)

    Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

    2016-05-01

    We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby (z = 0.184) luminous (Lbol ˜ 1047 erg s-1) quasar PDS 456. This consisted of three observations, covering a total duration of ˜1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by a factor of >10 in the soft X-ray band when compared to previous observations. We investigated the broad-band continuum by constructing a spectral energy distribution (SED), making use of the optical/UV photometry and hard X-ray spectra from the later simultaneous XMM-Newton and NuSTAR campaign in 2014. The high-energy part of this low-flux SED cannot be accounted for by physically self-consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray continuum. At least two layers of absorbing gas are required, of column density log (NH,low/cm-2) = 22.3 ± 0.1 and log (NH,high/cm-2) = 23.2 ± 0.1, with average line-of-sight covering factors of ˜80 per cent (with typical ˜5 per cent variations) and 60 per cent (±10-15 per cent), respectively. During these observations PDS 456 displays significant short-term X-ray spectral variability, on time-scales of ˜100 ks, which can be accounted for by variable covering of the absorbing gas along the line of sight. The partial covering absorber prefers an outflow velocity of v_pc = 0.25^{+0.01}_{-0.05} c at the >99.9 per cent confidence level over the case where vpc = 0. This is consistent with the velocity of the highly ionized outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally estimates are placed upon the size-scale of the X-ray emission region from the source variability. The radial extent of the X-ray emitter is found to be of the order ˜15-20Rg

  3. VNIR spectral features observed by the Mars Exploration Rover Opportunity in hematite-bearing materials at Meridiani Planum

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Bell, J. F.; Morris, R. V.; Joliff, B. L.; Squyres, S. W.; Souza, P. A.

    2004-12-01

    The Mars Exploration Rover Opportunity was sent to Meridiani Planum based largely on MGS TES spectroscopic evidence of a large surface exposure of coarse grained gray hematite. The presence of hematite at Meridiani Planum has been confirmed through thermal infrared spectroscopy by the rover's Mini-TES instrument and by in-situ measurements by its Moessbauer (MB) spectrometer. Several types of hematite, as expressed by differences in MB spectral parameters, have been associated with various rocks and soils examined in Eagle crater and on the surrounding plains. The host materials include the small spherules (informally known as "blueberries") littering the floor of Eagle crater and the plains of Meridiani, the outcrop rock itself, specific types of soils, and two measurements on unique rocks in the Shoemaker's Patio area of Eagle crater. At the visible to near infrared (VNIR) wavelengths covered by the rover's multispectral Panoramic camera (Pancam), gray hematite is spectrally neutral. However, multispectral observations by Pancam of some of these hematite-bearing materials show discernable spectral features. Specifically, portions of the outcrop visible in the walls of Eagle crater display a strong 535 nm absorption feature. This feature resembles a similar feature in laboratory spectra of red hematite, but the characteristic 860 nm absorption of red hematite is either absent or is instead replaced by a longer wavelength absorption centered on Pancam's 900 nm channel. The blueberries display a deep and broad absorption centered on 900 nm and as well as an increase in reflectance in the 1009 nm band. The shape of the absorption feature in the blueberries is consistent with that seen in red hematite, but again the band minimum is displaced to a longer wavelength than would be expected for red hematite. The blueberries also lack the prominent absorption at the shortest wavelengths that would be expected of red hematite. The unique hematite-bearing (or coated) rocks

  4. The observation of spectral variation indicative of porphyrin biomarkers in reflectance spectra of source rock - The application of remote sensing technology to petroleum geochemistry

    NASA Technical Reports Server (NTRS)

    Holden, Peter Newhall; Gaffey, Michael J.

    1990-01-01

    The spectral signature of porphyrin compounds, considered to be biomarkers of depositional environment and thermal maturity, have been identified in reflectance spectra of oil shales. The key bands identified, in order of intensity, are the Soret (0.40 microns), alpha (0.57 microns), and beta (0.53 microns) bands. The observed bands represent the composite spectral signature of all porphyrin compounds present in the sample and, therefore, change position and intensity in accordance with changes in porphyrin chemistry.

  5. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    SciTech Connect

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  6. A wavelet spectral analysis tool for multipoint space and ground-based observations of ULF wave activity

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Balasis, G.; Georgiou, M.; Papadimitriou, C.; Zesta, E.; Anastasiadis, A.

    2012-01-01

    Magnetospheric ULF waves influence radiation belt dynamics and are therefore of particular relevance for space weather nowcasting and forecasting efforts. We have used novel algorithms based on wavelet spectral methods to analyze multipoint observations of ULF wave activity by the Cluster and THEMIS missions and by ground-based magnetometers. Wavelet analysis is becoming a common tool for analyzing localized variations of power within a time series. By decomposing a time series into time-frequency space, we are able to determine both the dominant modes of variability and how these modes vary in time. The advantage of analyzing a signal with wavelets as the analyzing kernel is that it enables us to study features of the signal locally with a detail matched to their scale. Owing to its unique time-frequency localization, wavelet analysis is especially useful for signals that are non-stationary, have short-lived transient components, have features at different scales, or have singularities. The results are rather promising for the development of automatic identification tools, which will allow the detection and classification of various categories of ULF waves from multipoint magnetospheric observations according to well-defined criteria.

  7. Space weather: recovering the variation of the stellar EUV spectral Energy distribution from the companion exoplanet FUV transit observation

    NASA Astrophysics Data System (ADS)

    Ben-Jaffel, Lotfi; Guo, Jianheng

    2016-07-01

    The stellar extreme ultraviolet (EUV) irradiation determines the atmospheric properties of exoplanets. Recently, by varying the profiles of the EUV spectral energy distribution (SED), we tested the influences of stellar EUV SEDs on the physical and chemical properties of the escaping atmosphere (Guo & Ben-Jaffel, 2015). One of our major results was that the composition and species distributions in the atmosphere could be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape rate, the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. For exoplanet HD 189733b, it was possible to explain the time variability observed during transit in the Lyman-α line by the Hubble Space Telescope (HST) between 2010 and 2011 by a change in the EUV SED of the host K star. Our proposed technique provides a straightforward and easy-to-follow proxy to connect the EUV SED of the star with the planetary companion Lyman--α transit absorption, the monitoring of which may provide a direct measure of the stellar EUV flux. Here, we extend our study using new HST FUV observations.

  8. Terrestrial Gamma-ray Flashes (TGFs) Observed with the Fermi-Gamma-ray Burst Monitor: Temporal and Spectral Properties

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Briggs, M. S.; Connaughton, W.; Wilson-Hodge, C.; Bhat, P. N.

    2010-01-01

    The Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope Observatory (Fermi) was detecting 2.1 TGFs per week. This rate has increased by a factor of 8 since new flight software was uploaded to the spacecraft in November 2009 in order to increase the sensitivity of GBM to TGFs. Further upgrades to Fermi-GBM to allow observations of weaker TGFs are in progress. The high time resolution (2 s) allows temporal features to be resolved so that some insight may be gained on the origin and transport of the gamma-ray photons through the atmosphere. The absolute time of the TGFs, known to several microseconds, also allows accurate correlations of TGFs with lightning networks and other lightning-related phenomena. The thick bismuth germanate (BGO) scintillation detectors of the GBM system have observed photon energies from TGFs at energies above 40 MeV. New results on the some temporal aspects of TGFs will be presented along with spectral characteristics and properties of several electron-positron TGF events that have been identified.

  9. The FEROS-Lick/SDSS observational data base of spectral indices of FGK stars for stellar population studies

    NASA Astrophysics Data System (ADS)

    Franchini, M.; Morossi, C.; Marcantonio, P. Di; Malagnini, M. L.; Chavez, M.

    2014-07-01

    We present FEROS-Lick/SDSS, an empirical data base of Lick/SDSS spectral indices of FGK stars to be used in population synthesis projects for discriminating different stellar populations within the integrated light of galaxies and globular clusters. From about 2500 FEROS stellar spectra obtained from the European Southern Observatory Science Archive Facility, we computed line-strength indices for 1085 non-supergiant stars with atmospheric parameter estimates from the AMBRE project. Two samples of 312 dwarfs and of 83 subgiants with solar chemical composition and no significant α-element abundance enhancement are used to compare their observational indices with the predictions of the Lick/SDSS library of synthetic indices. In general, the synthetic library reproduces very well the behaviour of observational indices as a function of temperature, but in the case of low-temperature (Teff ≲ 5000 K) dwarfs; low-temperature subgiants are not numerous enough to derive any conclusion. Several possible causes of the disagreement are discussed and promising theoretical improvements are presented.

  10. Rock spectral classes observed by the Spirit Rover's Pancam on the Gusev Crater Plains and in the Columbia Hills

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Bell, J. F.; Johnson, J. R.; Arvidson, R. E.; Crumpler, L. S.; Hurowitz, J. A.; Schröder, C.

    2008-12-01

    This paper examines the ferrous and ferric iron mineralogy of rocks inferred from 246 visible/near-infrared (430-1010 nm) multispectral observations made by the Mars Exploration Rover Spirit's Pancam on its traverse from its landing site to its second Winter Haven location. Principal component, correspondence analyses, and a sequential maximum angle convex cone technique were used to identify 14 candidate classes. Spectra from the West Spur of Husband Hill and the Watchtower area had the highest 535 and 601 nm band depths indicating that these areas were more oxidized. Differences in the depth and band center of a near infrared (NIR) absorption feature were observed using 904 nm band depth and 803:904 nm ratio and parameters gauging the 754-864 and 754-1009 nm slopes. Spectra of rocks from the southern flank of Husband Hill had negative 754-1009 nm slopes and a broad NIR absorption consistent with high olivine abundances. Rocks observed on the lower West Spur, at the Cumberland Ridge locale, at the Husband Hill summit, and at the Haskin Ridge locale had deep 904 nm band depths and steep 754-864 nm slopes consistent with greater pyroxene abundances. These observations are consistent with results on iron-bearing mineralogy from Spirit's Mössbauer spectrometer. Comparisons of these rock spectral classes with a set of terrestrial analog samples found similarities between the West Spur and Watchtower classes and red hematite-bearing impact melts. Fewer similarities were found in comparisons of the Columbia Hills classes with basaltic hydrovolcanic tephras.

  11. Observation of spectral broadening in a commercial modelocked and Q-switched Nd:YLF oscillator - Wegner`s Demon

    SciTech Connect

    Wegner, P.; Feit, M.

    1994-09-14

    We have observed spectral broadening in the pulsed output of a Quantronix model 4217 modelocked and Q-switched Nd:YLF oscillator. When Q-switched, the 76-1MHz oscillator produces a nearly gaussian train of pulses with a total energy of 3 mJ and a duration of {approximately}300 ns. Between Q-switch cycles the CW-pumped oscillator lases at a low level to enable a circulating modelocked pulse to reach steady-state transform-limited conditions. With a 1-mm intracavity etalon the steady-state modelocked pulsewidth is 150 ps and the oscillating bandwidth is 3 GHz. Measurements show that at the peak of the Q-switched train the modelocked pulse bandwidth is broadened to 11 GHz, We attribute the altered spectrum to self-phase modulation (SPM) of the circulating pulse in the 3.8-cm long acousto-optic quartz modulators. SPM has been recognized as a potential problem in this type of oscillator however we did not expect to find it in a commercial product and its occurrence in the modulators rather than the rod was a surprise. Analysis of the cavity mode has determined that the spot size is small at the ends of the cavity where the modulators are located. A large mode volume in the rod coupled with a relatively small nonlinear coefficient makes intensity-dependent: phase shifts there negligible by comparison. Since the effects of SPM in this type of oscillator are not well-documented we developed a numerical model and used it to examine the spectral evolution of the circulating modelocked pulse after Q-switching. The model incorporates a rod with gain, two passive quartz blocks with nonlinear refractive index for simulating nonlinear propagation in the modulators, a time-dependent shutter to simulate the active modelocker, an etalon, and distributed Fresnel losses. The spectra that we calculate are in good agreement with that observed, confirming the source of the broadening. The oscillator has been redesigned to increase the mode size in the modulators and eliminate the SPM.

  12. Long-term X-Ray Spectral Variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Skipper, C. J.; Emmanoulopoulos, D.

    2016-04-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In 9 of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For 6 objects, with a low accretion rate as a fraction of the Eddington rate (ṁEdd), Γ is anticorrelated with ṁEdd, i.e. `harder-when-brighter' behaviour is observed. The 3 higher-ṁEdd-rate objects show a positive correlation between Γ and ṁEdd. This transition from harder-when-brighter at low ṁEdd~to softer-when-brighter at high ṁEdd~can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonising corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that LINERs are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion-rate end of the hard state or in the hard-intermediate state.

  13. Long-term X-ray spectral variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Skipper, C. J.; Emmanoulopoulos, D.

    2016-07-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In nine of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For six objects, with a low accretion rate as a fraction of the Eddington rate (dot{m}_{Edd}), Γ is anticorrelated with dot{m}_{Edd}, i.e. `harder-when-brighter' behaviour is observed. The three higher dot{m}_{Edd}-rate objects show a positive correlation between Γ and dot{m}_{Edd}. This transition from harder-when-brighter at low dot{m}_{Edd}to softer-when-brighter at high dot{m}_{Edd} can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonizing corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that low-ionization nuclear emission-line regions are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion rate end of the hard state or in the hard-intermediate state.

  14. Solar Spectral Irradiance Variability in November/December 2012: Comparison of Observations by Instruments on the International Space Station and Models

    NASA Astrophysics Data System (ADS)

    Thuillier, G.; Schmidtke, G.; Erhardt, C.; Nikutowski, B.; Shapiro, A. I.; Bolduc, C.; Lean, J.; Krivova, N.; Charbonneau, P.; Cessateur, G.; Haberreiter, M.; Melo, S.; Delouille, V.; Mampaey, B.; Yeo, K. L.; Schmutz, W.

    2014-12-01

    Onboard the International Space Station (ISS), two instruments are observing the solar spectral irradiance (SSI) at wavelengths from 16 to 2900 nm. Although the ISS platform orientation generally precludes pointing at the Sun more than 10 - 14 days per month, in November/December 2012 a continuous period of measurements was obtained by implementing an ISS `bridging' maneuver. This enabled observations to be made of the solar spectral irradiance (SSI) during a complete solar rotation. We present these measurements, which quantify the impact of active regions on SSI, and compare them with data simultaneously gathered from other platforms, and with models of spectral irradiance variability. Our analysis demonstrates that the instruments onboard the ISS have the capability to measure SSI variations consistent with other instruments in space. A comparison among all available SSI measurements during November-December 2012 in absolute units with reconstructions using solar proxies and observed solar activity features is presented and discussed in terms of accuracy.

  15. The broadband spectral variability of MCG–6-30-15 observed by nuSTAR and XMM-Newton

    SciTech Connect

    Marinucci, A.; Matt, G.; Miniutti, G.; Guainazzi, M.; Parker, M. L.; Fabian, A. C.; Kara, E.; Brenneman, L.; Elvis, M.; Risaliti, G.; Arevalo, P.; Ballantyne, D. R.; Boggs, S. E.; Cappi, M.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Harrison, F. A.; Reynolds, C. S.; Stern, D. K.; and others

    2014-05-20

    MCG–6-30-15, at a distance of 37 Mpc (z = 0.008), is the archetypical Seyfert 1 galaxy showing very broad Fe Kα emission. We present results from a joint NuSTAR and XMM-Newton observational campaign that, for the first time, allows a sensitive, time-resolved spectral analysis from 0.35 keV up to 80 keV. The strong variability of the source is best explained in terms of intrinsic X-ray flux variations and in the context of the light-bending model: the primary, variable emission is reprocessed by the accretion disk, which produces secondary, less variable, reflected emission. The broad Fe Kα profile is, as usual for this source, well explained by relativistic effects occurring in the innermost regions of the accretion disk around a rapidly rotating black hole. We also discuss the alternative model in which the broadening of the Fe Kα is due to the complex nature of the circumnuclear absorbing structure. Even if this model cannot be ruled out, it is disfavored on statistical grounds. We also detected an occultation event likely caused by broad-line region clouds crossing the line of sight.

  16. Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations

    PubMed Central

    Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D.

    2013-01-01

    The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-57Fe-enriched [Fe4S4Cl4]= and 10%-57Fe and 90%-54Fe labeled [Fe4S4Cl4]= has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3–4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements. PMID:23955030

  17. Comparison of Gravity Wave Temperature Variances from Ray-Based Spectral Parameterization of Convective Gravity Wave Drag with AIRS Observations

    NASA Technical Reports Server (NTRS)

    Choi, Hyun-Joo; Chun, Hye-Yeong; Gong, Jie; Wu, Dong L.

    2012-01-01

    The realism of ray-based spectral parameterization of convective gravity wave drag, which considers the updated moving speed of the convective source and multiple wave propagation directions, is tested against the Atmospheric Infrared Sounder (AIRS) onboard the Aqua satellite. Offline parameterization calculations are performed using the global reanalysis data for January and July 2005, and gravity wave temperature variances (GWTVs) are calculated at z = 2.5 hPa (unfiltered GWTV). AIRS-filtered GWTV, which is directly compared with AIRS, is calculated by applying the AIRS visibility function to the unfiltered GWTV. A comparison between the parameterization calculations and AIRS observations shows that the spatial distribution of the AIRS-filtered GWTV agrees well with that of the AIRS GWTV. However, the magnitude of the AIRS-filtered GWTV is smaller than that of the AIRS GWTV. When an additional cloud top gravity wave momentum flux spectrum with longer horizontal wavelength components that were obtained from the mesoscale simulations is included in the parameterization, both the magnitude and spatial distribution of the AIRS-filtered GWTVs from the parameterization are in good agreement with those of the AIRS GWTVs. The AIRS GWTV can be reproduced reasonably well by the parameterization not only with multiple wave propagation directions but also with two wave propagation directions of 45 degrees (northeast-southwest) and 135 degrees (northwest-southeast), which are optimally chosen for computational efficiency.

  18. Multi-wavelength Airborne High Spectral Resolution Lidar Observations of Aerosol Above Clouds in California during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Hostetler, C. A.; Burton, S. P.; Ferrare, R. A.; Rogers, R. R.; Mueller, D.; Chemyakin, E.; Cook, A. L.; Harper, D. B.; Ziemba, L. D.; Beyersdorf, A. J.; Anderson, B. E.

    2013-12-01

    Accurately representing the vertical profile of aerosols is important for determining their radiative impact, which is still one of the biggest uncertainties in climate forcing. Aerosol radiative forcing can be either positive or negative depending on aerosol absorption properties and underlying albedo. Therefore, accurately characterizing the vertical distribution of aerosols, and specifically aerosols above clouds, is vital to understanding climate change. Unlike passive sensors, airborne lidar has the capability to make vertically resolved aerosol measurements of aerosols above and between clouds. Recently, NASA Langley Research Center has built and deployed the world's first airborne multi-wavelength High Spectral Resolution Lidar, HSRL-2. The HSRL-2 instrument employs the HSRL technique to measure extinction at both 355 nm and 532 nm and also measures aerosol depolarization and backscatter at 355 nm, 532 nm and 1064 nm. Additional HSRL-2 data products include aerosol type and range-resolved aerosol microphysical parameters (e.g., effective radius, number concentration, and single scattering albedo). HSRL-2 was deployed in the San Joaquin Valley, California, from January 16 to February 6, 2013, on the DISCOVER-AQ field campaign (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality). On February 6, the observation region was mostly cloudy, and HSRL-2 saw two distinct aerosol layers above the clouds. One layer was aged boundary-layer pollution located just above cloud top at approximately 1.5 km above sea level. An aged smoke layer was also observed over land and over the ocean at altitudes 4-7 km ASL. In this study, we will show HSRL-2 products for these cases, and compare them with airborne in situ measurements of the 1.5-km layer from a coincident flight of the NASA P3B. We will also compare and contrast the HSRL-2 measurements of these two aerosol layers with each other and the clear-air boundary

  19. The Self Actualized Reader.

    ERIC Educational Resources Information Center

    Marino, Michael; Moylan, Mary Elizabeth

    A study examined the commonalities that "voracious" readers share, and how their experiences can guide parents, teachers, and librarians in assisting children to become self-actualized readers. Subjects, 25 adults ranging in age from 20 to 67 years, completed a questionnaire concerning their reading histories and habits. Respondents varied in…

  20. Array observations of Love wave contribution to the ambient vibration H/V spectral ratio amplitude peak

    NASA Astrophysics Data System (ADS)

    Endrun, B.; Köhler, A.; Ohrnberger, M.

    2009-04-01

    Measurements of the H/V spectral ratio of ambient vibrations are widely used for site characterization, for example to efficiently map variations in the fundamental resonance frequency within earthquake-prone towns or to derive shear wave velocity profiles of the shallow sub-surface that are important in the estimation of local ground-motion amplification. Part of the appeal of this method is due to the possibility of fairly quickly sampling an area with short duration (appr. 15 min) measurements for which only a single three-component station is needed. However, when interpreting the measurements it is often assumed that almost all of the ambient noise energy is carried by fundamental mode Rayleigh waves and that accordingly the H/V spectral ratio curve is a first order representation of the fundamental mode Rayleigh wave ellipticity. In this case, the amplitude peak of the H/V curve corresponds to a horizontal polarization of the fundamental mode Rayleigh wave and the frequency at which it occurs depends on the shallow subsurface structure (S-wave velocities in the sedimentary layers and depth to a large velocity contrast, i.e. the bedrock interface). Theoretical studies indicate that, depending on the location of sources and the site structure, other contributions to the wavefield, e.g. Love waves, higher modes, or body waves, can be important, too. While new methods are under development to more reliably extract the pure Rayleigh wave part of the ambient vibration wavefield from the typical single-station H/V recordings, we present evidence from array field measurements which documents the sometimes predominant contribution of Love waves to the observed H/V peaks. Within the European research project NERIES JRA4 ("Developing and calibrating new techniques for geotechnical site characterization"), ambient vibration array measurements were performed at 19 selected European strong-motion sites in Greece, Italy and Turkey with varying site conditions (urban vs

  1. AMBER/VLTI observations of η Carinae with high spatial resolution and spectral resolutions of λ/Δ λ = 1500 and 12 000

    NASA Astrophysics Data System (ADS)

    Weigelt, G.; Driebe, T.; Hofmann, K.-H.; Kraus, S.; Petrov, R.; Schertl, D.

    2007-10-01

    We present the first NIR interferometric observations of the LBV η Carinae with high spectral resolution [Weigelt et al., 2007. Near-infrared interferometry of η Carinae with spectral resolutions of 1500 and 12000 using AMBER/VLTI. A&A 464, 87.]. Our observations demonstrate the potential of AMBER/VLTI to unveil new structures on the scales of milliarcseconds. The aim of this work is to study the wavelength dependence of η Car's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution. The observations were carried out with three 8.2 m VLTI Unit Telescopes. The raw data are interferograms obtained with spectral resolutions of λ/Δ λ = 1500 (MR-K mode) and 12 000 (HR-K mode). The observations were performed in the wavelength range around both the HeI 2.059 μm and the Brγ 2.166 μm emission lines. The spectrally dispersed AMBER interferograms allow us to investigate the wavelength dependence of the visibility, differential phase, and closure phase of η Car. If we fit [Hillier, D.J., Davidson, K., Ishibashi, K., Gull, T., 2001. On the Nature of the Central Source in η Carinae. ApJ 553, 837] model visibilities (Hillier et al., 2001) to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.3, 6.5, and 9.6 mas in the 2.17 μm continuum, the HeI, and the Brγ emission lines, respectively. We find good agreement between the measured visibilities and the predictions of the radiative transfer model of Hillier et al. (2001). Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.

  2. Corrigendum to "Enhancing endmember selection in multiple endmember spectral mixture analysis (MESMA) for urban impervious surface area mapping using spectral angle and spectral distance parameters" [Int. J. Appl. Earth Observ. Geoinf. 33 (2014) 290-301

    NASA Astrophysics Data System (ADS)

    Fan, Fenglei; Deng, Yingbin

    2015-04-01

    Since publication, the authors have been advised of one prior methodological article not cited in our original paper. The missed reference from the paper is "Andreou, C., Karathanassi, V., 2012. A novel multiple endmember spectral mixture analysis using spectral angle distance. Geoscience and Remote Sensing Symposium (IGARSS) 2012 IEEE International, 4110-4113." This reference "Andreou, C., Karathanassi, V., 2012 in proceeding of IGARSS" should be cited in the Part 3 and Table 1, whereby in the fist sentence of Part 3 and the last sentence of caption of Table 1. The following should be added (in Part 3: According to the traditional MESMA and referring to MESMA-SAD method which is reported by Andreou and Karathanassi; in caption of Table 1: Based on the MESMA-SAD method of Andreou and Karathanassi). We apologize to the authors and workers concerned for this oversight and are pleased to acknowledge their contributions.

  3. On the importance of spectral responsivity of Robertson-Berger-type ultraviolet radiometers for long-term observations.

    PubMed

    di Sarra, Alcide; Disterhoft, Patrick; DeLuisi, John J

    2002-07-01

    A system to determine the spectral responsivity of ultraviolet (UV) radiometers has been developed and is routinely operated at the Central Ultraviolet Calibration Facility, at the National Oceanic and Atmospheric Administration. The instrument and the measurement methodologies are described. Results of measurements from thermally controlled broadband UV radiometers of the Robertson-Berger (R-B)-type are described. Systematic differences in the spectral response curves for these instruments have been detected. The effect of these differences on the field operation of UV-B radiometers has been studied by calculating the instrumental response from modeled UV spectra. The differences of the weighted spectral UV irradiances, measured by two radiometers with different spectral response functions, caused by the daily variation in the position of the sun were estimated for fixed values of total ozone, altitude and albedo, and for cloud-free conditions. These differences increase with the solar zenith angle and are as large as 8%. Larger differences in the instrumental response may be produced by ozone variations. Thus, care must be taken when analyzing data from R-B radiometers and comparing results from different instruments. Routine cycling of UV-B radiometers in operative networks without a careful determination of the spectral responsivity, or small drifts of the spectral responsivity, may strongly affect the accuracy of UV radiation measurements and produce an erroneous trend. Because of the possible differences among radiometers, it would not be practical to derive the long-term behavior of UV radiation without routine and thorough characterization of the spectral responsivities of the instruments. PMID:12126309

  4. Label-free observation of tissues by high-speed stimulated Raman spectral microscopy and independent component analysis

    NASA Astrophysics Data System (ADS)

    Ozeki, Yasuyuki; Otsuka, Yoichi; Sato, Shuya; Hashimoto, Hiroyuki; Umemura, Wataru; Sumimura, Kazuhiko; Nishizawa, Norihiko; Fukui, Kiichi; Itoh, Kazuyoshi

    2013-02-01

    We have developed a video-rate stimulated Raman scattering (SRS) microscope with frame-by-frame wavenumber tunability. The system uses a 76-MHz picosecond Ti:sapphire laser and a subharmonically synchronized, 38-MHz Yb fiber laser. The Yb fiber laser pulses are spectrally sliced by a fast wavelength-tunable filter, which consists of a galvanometer scanner, a 4-f optical system and a reflective grating. The spectral resolution of the filter is ~ 3 cm-1. The wavenumber was scanned from 2800 to 3100 cm-1 with an arbitrary waveform synchronized to the frame trigger. For imaging, we introduced a 8-kHz resonant scanner and a galvanometer scanner. We were able to acquire SRS images of 500 x 480 pixels at a frame rate of 30.8 frames/s. Then these images were processed by principal component analysis followed by a modified algorithm of independent component analysis. This algorithm allows blind separation of constituents with overlapping Raman bands from SRS spectral images. The independent component (IC) spectra give spectroscopic information, and IC images can be used to produce pseudo-color images. We demonstrate various label-free imaging modalities such as 2D spectral imaging of the rat liver, two-color 3D imaging of a vessel in the rat liver, and spectral imaging of several sections of intestinal villi in the mouse. Various structures in the tissues such as lipid droplets, cytoplasm, fibrous texture, nucleus, and water-rich region were successfully visualized.

  5. Interpretation of Observations of Trans-Spectral Phenomena Acquired Using Hyperspectral Sensors Aboard a Remotely Operated Vehicle in Exuma Sound

    NASA Technical Reports Server (NTRS)

    Costello, D.; Carder, Kendall L.; Ivey, J.; English, D.

    2001-01-01

    Hyper-spectral (512-channel) optical data acquired during a relatively deep (102m) dive of our ROSEBUD Remotely Operated Vehicle (ROV) in the clear waters of Exuma Sound, Bahamas provided the opportunity to investigate the trans-spectral shift of photonic energy (inelastic scattering) as a function of water depth. Results show a convolution of several spectral processes (e.g. absorption, scattering) involving water molecules, dissolved material and particulates as well as trans-spectral (inelastic) processes involving fluorescence by water molecules (Raman), dissolved material and chlorophyll. The spectral signatures of these convolved causes and effects allow deconvolution with a hyperspectral approach. Intrinsic to the convolution was the ability to position the vehicle at depths where Raman fluorescence dominated at red wavelengths. Results show that the calculated Raman absorption coefficients are generally consistent with historical values (i.e. 0.9 x 10(sup)-4 at 525 nm excitation) and that an angstrom exponent of 5 is more appropriate than the often cited value of 4.

  6. The Rhythm of Fairall 9. I. Observing the Spectral Variability with XMM-Newton and NuSTAR

    NASA Astrophysics Data System (ADS)

    Lohfink, A. M.; Reynolds, C. S.; Pinto, C.; Alston, W.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; Hailey, C. J.; Harrison, F. A.; Kara, E.; Matt, G.; Parker, M. L.; Stern, D.; Walton, D.; Zhang, W. W.

    2016-04-01

    We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.5–10 keV band remain constant with time in spite of large variations in flux. This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred ionized reflection in the innermost parts of the accretion disk, and the other a continuum component such as a spatially distinct Comptonizing region. Alternatively, a more complex primary Comptonization component together with blurred ionized reflection could be responsible.

  7. Orbital and Ground-Truth Spectral Matching on the Upper Slopes of Kilimanjaro with Application to Martian Orbital Observations

    NASA Astrophysics Data System (ADS)

    Horodyskyj, U. N.

    2010-12-01

    The upper alpine desert on Kilimanjaro is significant as it is an area of low precipitation and little vegetation which provides ample opportunity to further understand the nature of weathering products in a high-altitude volcanic environment. There is also potential for extrapolating these results to orbital studies of Martian volcanic terrain. Rock alteration features were identified and matched with USGS spectra, with likely endmembers including clays, such as montmorillonite and possibly sulfates, such as jarosite. However, an exact spectral match using only one endmember, either jarosite or clay, was not possible. Chemistry data supports spectral data, given abundances of elements such as Al, Fe and S on the rock surface, which can possibly help explain a “mixed” spectrum seen in laboratory analysis. Resampling high resolution lab spectra to Landsat and ASTER resolutions allowed for identification, interpretation and mapping of the weathered unit from orbit. Hydrated mineral phases have been detected with the CRISM instrument in the Valles Marineris region of Mars. An exact spectral match of the material, using terrestrial samples such as jarosite and clay, has not been found, indicating a likely “mixed” spectrum, similar to that found on Kilimanjaro. A jarosite-clay mix on Kilimanjaro makes sense, given the low precipitation environment in the upper alpine desert and access to sulfur-rich fluids near the volcano vents. Though fumarolic activity is minimal in the present-day, it is likely to have affected rock surfaces in the past. It is also important to note the placement of these weathered rocks, down-slope from the active fumaroles, indicating a likelihood of past interaction with acidic fluids. Perhaps finding similar materials in Valles Marineris on Mars is also indicative of past interaction not only with acidic fluids to generate the sulfates, but also with water to create the clays.

  8. Direct Microlensing-Reverberation Observations of the Intrinsic Magnetic Structure of Active Galactic Nuclei in Different Spectral States: A Tale of Two Quasars

    NASA Astrophysics Data System (ADS)

    Schild, Rudolph E.; Leiter, Darryl J.; Robertson, Stanley L.

    2008-03-01

    We show how direct microlensing-reverberation analysis performed on two well-known quasars (Q2237, the Einstein Cross, and Q0957, the Twin) can be used to observe the inner structure of two quasars which are in significantly different spectral states. These observations allow us to measure the detailed internal structure of Q2237 in a radio-quiet high-soft state, and compare it to Q0957 in a radio-loud low-hard state. When taken together we find that the observed differences in the spectral states of these two quasars can be understood as being due to the location of the inner radii of their accretion disks relative to the co-rotation radii of the magnetospheric eternally collapsing objects (MECO) in the centers of these quasars. The radiating structures observed in these quasars are associated with standard accretion disks and outer outflow structures, where the latter are the major source of UV-optical continuum radiation. While the observed inner accretion disk structure of the radio-quiet quasar Q2237 is consistent with either a MECO or a black hole, the observed inner structure of the radio-loud quasar Q0957 can only be explained by the action of the intrinsic magnetic propeller of a MECO with its accretion disk. Hence a simple and unified answer to the long-standing question: "Why are some quasars radio loud?" is found if the central objects of quasars are MECO, with radio-loud and radio-quiet spectral states similar to the case of galactic black hole candidates.

  9. Fingerprints of endogenous process on Europa through linear spectral modeling of ground-based observations (ESO/VLT/SINFONI)

    NASA Astrophysics Data System (ADS)

    Ligier, Nicolas; Carter, John; Poulet, François; Langevin, Yves; Dumas, Christophe; Gourgeot, Florian

    2016-04-01

    Jupiter's moon Europa harbors a very young surface dated, based on cratering rates, to 10-50 M.y (Zahnle et al. 1998, Pappalardo et al. 1999). This young age implies rapid surface recycling and reprocessing, partially engendered by a global salty subsurface liquid ocean that could result in tectonic activity (Schmidt et al. 2011, Kattenhorn et al. 2014) and active plumes (Roth et al. 2014). The surface of Europa should contain important clues about the composition of this sub-surface briny ocean and about the potential presence of material of exobiological interest in it, thus reinforcing Europa as a major target of interest for upcoming space missions such as the ESA L-class mission JUICE. To perform the investigation of the composition of the surface of Europa, a global mapping campaign of the satellite was performed between October 2011 and January 2012 with the integral field spectrograph SINFONI on the Very Large Telescope (VLT) in Chile. The high spectral binning of this instrument (0.5 nm) is suitable to detect any narrow mineral signature in the wavelength range 1.45-2.45 μm. The spatially resolved spectra we obtained over five epochs nearly cover the entire surface of Europa with a pixel scale of 12.5 by 25 m.a.s (~35 by 70 km on Europa's surface), thus permitting a global scale study. Until recently, a large majority of studies only proposed sulfate salts along with sulfuric acid hydrate and water-ice to be present on Europa's surface. However, recent works based on Europa's surface coloration in the visible wavelength range and NIR spectral analysis support the hypothesis of the predominance of chlorine salts instead of sulfate salts (Hand & Carlson 2015, Fischer et al. 2015). Our linear spectral modeling supports this new hypothesis insofar as the use of Mg-bearing chlorines improved the fits whatever the region. As expected, the distribution of sulfuric acid hydrate is correlated to the Iogenic sulfur ion implantation flux distribution (Hendrix et al

  10. Observations of rock spectral classes by the Opportunity rover's Pancam on northern Cape York and on Matijevic Hill, Endeavour Crater, Mars

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Bell, J. F.; Johnson, J. R.; Rice, M. S.; Jolliff, B. L.; Arvidson, R. E.

    2014-11-01

    The Opportunity rover's exploration of the portion of the rim of Endeavour crater known as Cape York included examination of the sulfate-bearing Grasberg formation and the Matijevic Hill region. Multispectral visible and near-infrared (VNIR) Pancam observations were used to characterize reflectance properties of rock units. Using spectral end-member detection and classification approaches including a principal components/n-dimensional visualization, automatic sequential maximum angle convex cone method, and classification through hierarchical clustering, six main spectral classes of rock surfaces were identified: light-toned veins, Grasberg fm., the smectite-bearing Matijevic formation, the hematitic "blueberry" spherules, resistant spherules within the Matijevic fm. dubbed "newberries," and the Shoemaker formation impact breccia. Some of these could be divided into spectral subclasses. There were three types of veins: veins in the bench unit of Cape York, thinner veins in the Matijevic fm., and boxwork pattern-forming veins. The bench unit veins had higher 535 nm band depths than the other two vein subclasses and a steeper 934 to 1009 nm slope. The Grasberg fm. has VNIR spectral features that are interpreted to indicate higher fractions of red hematite than in the sulfate-bearing Burns Fm. The Matijevic fm. includes both light-toned, fine-grained matrix, and dark-toned veneers. The latter has a weak near-infrared absorption band centered near 950 nm consistent with nontronite. Observations of Rock Abrasion Tool brushed and ground newberries indicated that cuttings from the RAT grind had a longer wavelength reflectance maximum and deeper 535 nm band depth, consistent with more oxidized materials. Greater oxidation of cementing materials in the newberries is consistent with a diagenetic concretion origin.

  11. Evidence of non-LTE Effects in Mesospheric Water Vapor from Spectrally-Resolved Emissions Observed by CIRRIS-1A

    NASA Technical Reports Server (NTRS)

    Zhou, D. K.; Mlynczak, M. G.; Lopez-Puertas, M.; Zaragoza, G.

    1999-01-01

    Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality, atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010 to 000) and (020 to 010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O2 in the mesosphere. An exchange rate of 1.2 x 10(exp -12)cc/s is derived.

  12. ISO continuum observations of quasars at z=1-4. I. Spectral energy distributions of quasars from the UV to far-infrared

    NASA Astrophysics Data System (ADS)

    Oyabu, S.; Kawara, K.; Tsuzuki, Y.; Sofue, Y.; Sato, Y.; Okuda, H.; Taniguchi, Y.; Shibai, H.; Gabriel, C.; Hasegawa, T.; Nishihara, E.

    2001-01-01

    Eight luminous quasars with -30 < MB < -27 at z = 1.4-3.7 have been observed in the mid- and far-infrared using ISO. All the quasars have been detected in the mid-infrared bands of ISOCAM, while no far-infrared detections have been made with ISOPHOT. SEDs (Spectral Energy Distributions) from the UV to far-infrared have been obtained while supplementing ISO observations with photometry in the optical and near-infrared made from the ground within 17 months. The SEDs are compared with the MED (Mean spectral Energy Distributions) of low-redshift quasars with -27 < MB < -22. It is shown that our far-infrared observations were limited by confusion noise due to crowded sources. The observations reported here were made with ISO, an ESA project with instruments funded by ESA member states (especially the PI countries: France, Germany, The Netherlands, and the UK) and with the participation of ISAS and NASA, and with the facilities at the Cerro Tololo Inter-american Observatory (CTIO), NOAO, which is operated by AURA, Inc., under contract with NSF, at the Kiso Observatory, which is operated by Institute of Astronomy, the University of Tokyo, and at the Okayama Astrophysical Observatory, the National Astronomical Observatory of Japan.

  13. [Estimation of light-use efficiency of China' s mid-subtropical planted coniferous forest based on flux measurements and spectral observations].

    PubMed

    Chen, Die-cong; Wang, Shao-qiang; Huang, Kun; Zhou, Lei; Yu, Quan-zhou; Wang, Hui-min; Sun, Lei-gang

    2015-11-01

    The photochemical reflectance index (PRI) calculated from spectral reflectance has universally become a proxy for the light-use efficiency (LUE), which significantly improves the LUE-based estimation of ecosystem gross primary productivity on a large scale through upscaling. In this study, we observed the vegetation spectral reflectance of a planted subtropical coniferous forest from the top of a flux tower at Qianyanzhou Station, one of the ChinaFLUX sites, in September and December 2013, and simultaneously measured CO2 flux and meteorological variables for correlation and regression analysis. Results showed that PRI had a better correlation with LUE (R2 = 0.20, P< 0.001) than that of normalized difference vegetation index (NDVI), i.e., PRI was preferred in LUE retrieval. During the whole observation period, PRI and soil water content (SWC)-based bivariate regression model correlated well with LUE (R2 = 0.29, P < 0.001 and R2 = 0.30, P < 0.01 for daytime and midday observation, respectively), but in autumn the bivariate regression model of PRI and vapor pressure deficit (VPD) had a higher correlation with LUE (R2 = 0.448, P < 0.001) for midday observation, which showed that environmental factors, i.e., SWC and VPD, had a potential in improving the LUE retrieval from PRI, but the choice of appropriate environmental factors depended on season. PMID:26915199

  14. Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

    NASA Technical Reports Server (NTRS)

    Zodivaz, A. M.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Takakura, T.; Cliver, E. W.; Tapping, K. F.

    1986-01-01

    A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz.

  15. X-ray variability with spectral state transitions in NS-LMXBs observed with MAXI/GSC and Swift/BAT

    NASA Astrophysics Data System (ADS)

    Asai, Kazumi; Mihara, Tatehiro; Matsuoka, Masaru; Sugizaki, Mutsumi

    2015-10-01

    X-ray variabilities with spectral state transitions in bright low-mass X-ray binaries containing a neutron star are investigated by using the one-day bin light curves of MAXI/GSC (Gas Slit Camera) and Swift/BAT (Burst Alert Telescope). Four sources (4U 1636-536, 4U 1705-44, 4U 1608-52, and GS 1826-238) exhibited small-amplitude X-ray variabilities with spectral state transitions. Such "mini-outbursts" were characterized by smaller amplitudes (several times) and shorter duration (less than several tens of days) than those of "normal outbursts." A theoretical model of disk instability by Mineshige and Osaki (PASJ, 37, 1, 1985) predicts both large-amplitude outbursts and small-amplitude variabilities. We interpret the normal outbursts as the former prediction of this model, and the mini-outbursts as the latter. Here, we can also call the mini-outburst a "purr-type outburst" referring to the theoretical work. We suggest that similar variabilities lasting for several tens of days without spectral state transitions, which are often observed in the hard state, may be repeats of mini-outbursts.

  16. Spectral variation in the supergiant fast X-ray transient SAX J1818.6-1703 observed by XMM-Newton and INTEGRAL

    NASA Astrophysics Data System (ADS)

    Boon, C. M.; Bird, A. J.; Hill, A. B.; Sidoli, L.; Sguera, V.; Goossens, M. E.; Fiocchi, M.; McBride, V. A.; Drave, S. P.

    2016-03-01

    We present the results of a 30 ks XMM-Newton observation of the supergiant fast X-ray transient (SFXT) SAX J1818.6-1703 - the first in-depth soft X-ray study of this source around periastron. INTEGRAL observations shortly before and after the XMM-Newton observation show the source to be in an atypically active state. Over the course of the XMM-Newton observation, the source shows a dynamic range of ˜100 with a luminosity greater than 1 × 1035 erg s-1 for the majority of the observation. After an ˜6 ks period of low-luminosity (˜1034 erg s-1) emission, SAX J1818.6-1703 enters a phase of fast flaring activity, with flares ˜250 s long, separated by ˜2 ks. The source then enters a larger flare event of higher luminosity and ˜8 ks duration. Spectral analysis revealed evidence for a significant change in spectral shape during the observation with a photon index varying from Γ ˜ 2.5 during the initial low-luminosity emission phase, to Γ ˜ 1.9 through the fast flaring activity, and a significant change to Γ ˜ 0.3 during the main flare. The intrinsic absorbing column density throughout the observation (nH ˜ 5 × 1023 cm-2) is among the highest measured from an SFXT, and together with the XMM-Newton and INTEGRAL luminosities, consistent with the neutron star encountering an unusually dense wind environment around periastron. Although other mechanisms cannot be ruled out, we note that the onset of the brighter flares occurs at 3 × 1035erg s-1, a luminosity consistent with the threshold for the switch from a radiative-dominated to Compton cooling regime in the quasi-spherical settling accretion model.

  17. Herschel observations of extraordinary sources: Analysis of the HIFI 1.2 THz wide spectral survey toward orion KL. I. method

    SciTech Connect

    Crockett, Nathan R.; Bergin, Edwin A.; Neill, Justin L.; Favre, Cécile; Schilke, Peter; Lis, Dariusz C.; Emprechtinger, Martin; Phillips, Thomas G.; Bell, Tom A.; Cernicharo, José; Esplugues, Gisela B.; Blake, Geoffrey; Kleshcheva, Maria; Gupta, Harshal; Pearson, John; Lord, Steven; Marcelino, Nuria; McGuire, Brett A.; Plume, Rene; Van der Tak, Floris; and others

    2014-06-01

    We present a comprehensive analysis of a broadband spectral line survey of the Orion Kleinmann-Low nebula (Orion KL), one of the most chemically rich regions in the Galaxy, using the HIFI instrument on board the Herschel Space Observatory. This survey spans a frequency range from 480 to 1907 GHz at a resolution of 1.1 MHz. These observations thus encompass the largest spectral coverage ever obtained toward this high-mass star-forming region in the submillimeter with high spectral resolution and include frequencies >1 THz, where the Earth's atmosphere prevents observations from the ground. In all, we detect emission from 39 molecules (79 isotopologues). Combining this data set with ground-based millimeter spectroscopy obtained with the IRAM 30 m telescope, we model the molecular emission from the millimeter to the far-IR using the XCLASS program, which assumes local thermodynamic equilibrium (LTE). Several molecules are also modeled with the MADEX non-LTE code. Because of the wide frequency coverage, our models are constrained by transitions over an unprecedented range in excitation energy. A reduced χ{sup 2} analysis indicates that models for most species reproduce the observed emission well. In particular, most complex organics are well fit by LTE implying gas densities are high (>10{sup 6} cm{sup –3}) and excitation temperatures and column densities are well constrained. Molecular abundances are computed using H{sub 2} column densities also derived from the HIFI survey. The distribution of rotation temperatures, T {sub rot}, for molecules detected toward the hot core is significantly wider than the compact ridge, plateau, and extended ridge T {sub rot} distributions, indicating the hot core has the most complex thermal structure.

  18. Interpretation of astrophysical neutrinos observed by IceCube experiment by setting Galactic and extra-Galactic spectral components

    NASA Astrophysics Data System (ADS)

    Marinelli, Antonio; Gaggero, Daniele; Grasso, Dario; Urbano, Alfredo; Valli, Mauro

    2016-04-01

    The last IceCube catalog of High Energy Starting Events (HESE) obtained with a livetime of 1347 days comprises 54 neutrino events equally-distributed between the three families with energies between 25 TeV and few PeVs. Considering the homogeneous flavors distribution (1:1:1) and the spectral features of these neutrinos the IceCube collaboration claims the astrophysical origin of these events with more than 5σ. The spatial distribution of cited events does not show a clear correlation with known astrophysical accelerators leaving opened both the Galactic and the extra-Galactic origin interpretations. Here, we compute the neutrino diffuse emission of our Galaxy on the basis of a recently proposed phenomenological model characterized by radially-dependent cosmic-ray (CR) transport properties. We show that the astrophysical spectrum measured by IceCube experiment can be well explained adding to the diffuse Galactic neutrino flux (obtained with this new model) a extra-Galactic component derived from the astrophysical muonic neutrinos reconstructed in the Northern hemisphere. A good agreement between the expected astrophysical neutrino flux and the IceCube data is found for the full sky as well as for the Galactic plane region.

  19. Aerosol properties from multi-spectral and multi-angular aircraft 4STAR observations: expected advantages and challenges

    NASA Astrophysics Data System (ADS)

    Kassianov, Evgueni; Flynn, Connor; Redemann, Jens; Schmid, Beat; Russell, Philip B.; Sinyuk, Alexander

    2012-11-01

    The airborne Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) is developed to retrieve aerosol microphysical and optical properties from multi-angular and multi-spectral measurements of sky radiance and direct-beam sun transmittance. The necessarily compact design of the 4STAR may cause noticeable apparent enhancement of sky radiance at small scattering angles. We assess the sensitivity of expected 4STAR-based aerosol retrieval to such enhancement by applying the operational AERONET retrieval code and synthetic 4STAR-like data. Also, we assess the sensitivity of the broadband radiative fluxes and the direct aerosol radiative forcing to uncertainties in aerosol retrievals associated with the sky radiance enhancement. Our sensitivity study results suggest that the 4STARbased aerosol retrieval has limitations in obtaining detailed information on particle size distribution and scattering phase function. However, these limitations have small impact on the retrieved bulk optical parameters, such as the asymmetry factor (up to 4%, or +/-0.02) and single-scattering albedo (up to 2%, or +/-0.02), and the calculated direct aerosol radiative forcing (up to 6%, or 2 Wm-2).

  20. Aerosol Properties from Multi-spectral and Multi-angular Aircraft 4STAR Observations: Expected Advantages and Challenges

    SciTech Connect

    Kassianov, Evgueni I.; Flynn, Connor J.; Redemann, Jens; Schmid, Beat; Russell, P. B.; Sinyuk, Alexander

    2012-11-01

    The airborne Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) is developed to retrieve aerosol microphysical and optical properties from multi-angular and multi-spectral measurements of sky radiance and direct-beam sun transmittance. The necessarily compact design of the 4STAR may cause noticeable apparent enhancement of sky radiance at small scattering angles. We assess the sensitivity of expected 4STAR-based aerosol retrieval to such enhancement by applying the operational AERONET retrieval code and constructed synthetic 4STARlike data. Also, we assess the sensitivity of the broadband fluxes and the direct aerosol radiative forcing to uncertainties in aerosol retrievals associated with the sky radiance enhancement. Our sensitivity study results suggest that the 4STARbased aerosol retrieval has limitations in obtaining detailed information on particle size distribution and scattering phase function. However, these limitations have small impact on the retrieved bulk optical parameters, such as the asymmetry factor (up to 4%, or ±0.02) and single-scattering albedo (up to 2%, or ±0.02), and the calculated direct aerosol radiative forcing (up to 6%, or 2 Wm-2).

  1. Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State

    SciTech Connect

    Aharonian, F.; Akhperjanian, A.G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A.R.; Becherini, Y.; Behera, B.; Bernlohr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Brion, E.; Brucker, J.; Brun, P.; Buhler, R.; Bulik, T.; Busching, I.; Boutelier, T.; Chadwick, P.M.; Charbonnier, A.; Chaves, R.C.G.; /more authors..

    2009-05-07

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  2. SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE

    SciTech Connect

    Aharonian, F.; Bernloehr, K.; Bochow, A.; Buehler, R.; Akhperjanian, A. G.; Anton, G.; Brucker, J.; Barres de Almeida, U.; Chadwick, P. M.; Bazer-Bachi, A. R.; Borrel, V.; Behera, B.; Boisson, C.; Brion, E.; Brun, P.; Buesching, I.; Boutelier, T. E-mail: berrie@in2p3.fr E-mail: jchiang@slac.stanford.edu

    2009-05-10

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  3. Oceanic primary production: 1. Adaptation of a spectral light-photosynthesis model in view of application to satellite chlorophyll observations

    SciTech Connect

    Antoine, D.; Morel, A.

    1996-03-01

    This study was performed with two purposes: (1) to develop a method to calculate the cross section for photosynthesis per unit of chlorophyll (psi*), based on standard values for physiological parameters controlling the photosynthetic response of algae; and (2) to perform a sensitivity analysis of the impact of deviations in these parameters. A spectral light-photosynthesis model was used to generate psi* lookup tables for well-mixed or stratified upper layers with uniform or non-uniform chlorophyll vertical profiles. The tables contain values for psi*, the photosynthetically available radiation impinging at the sea surface, the column-integrated chlorphyll content, and the product of these values, the primary production (P) from the chlorophyll concentration. It was numerically verified that linear interpolations provide psi* and P values that are accurate within less than 2% compared to values computed for the specified conditions. Sensitivity analyses made in reference to the lookup tables included the effects of biomass vertical structure, possible light and temperature adaptation, and the presence of degraded pigments. The parameters were arranged in increasing order of their impact on psi* and then on P as follows: (1) the shape of the absorption spectrum of algae in correspondence with a change in dominant species has a minor effect, (2) a similar conclusion applies to inhibition, (3) ignoring or accounting for the nonuniformity of the vertical algal distribution produces serious deviations in the value of psi*, (4) the influence of the scaling irradiance is severe, and (5) the bulk maximum efficiency and the pigment activity index are crucial parameters. 55 refs., 6 figs., 1 tab.

  4. Triatomic Spectral Database

    National Institute of Standards and Technology Data Gateway

    SRD 117 Triatomic Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 55 triatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

  5. Hydrocarbon Spectral Database

    National Institute of Standards and Technology Data Gateway

    SRD 115 Hydrocarbon Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

  6. Diatomic Spectral Database

    National Institute of Standards and Technology Data Gateway

    SRD 114 Diatomic Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 121 diatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty, and reference are given for each transition reported.

  7. The Structure and Dynamics of the Coronal Part of the 06.11.1979 Flare by Ground Spectral Observation

    NASA Astrophysics Data System (ADS)

    Ograpishvili, N. B.; Maghradze, D. A.

    2014-12-01

    The analysis of observational data obtained in the Abastumani Astrophysical Observatory in the form of spectrograms and filter images of formations, related to the limb flare of November, 6th, 1979, is presented. The flare loops system, a late stage development of bright flare loops and post-flare coronal loops received in Hα and coronal lines, were studied. Physical parameters of observable structures, as well as their sizes and interposition were defined. Doppler speeds at different heights are measured. The primary direction of movement of a matter in flare loops upwards from below is revealed.

  8. RXTE Observations of the Neutron Star Low-Mass X-Ray Binary GX 17+2: Correlated X-Ray Spectral and Timing Behavior

    NASA Astrophysics Data System (ADS)

    Homan, Jeroen; van der Klis, Michiel; Jonker, Peter G.; Wijnands, Rudy; Kuulkers, Erik; Méndez, Mariano; Lewin, Walter H. G.

    2002-04-01

    We have analyzed ~600 ks of Rossi X-Ray Timing Explorer data of the neutron star low-mass X-ray binary and Z source GX 17+2. A study was performed of the properties of the noise components and quasi-periodic oscillations (QPOs) as a function of the broadband spectral properties, with the main goal to study the relation between the frequencies of the horizontal branch (HBO) and upper kHz QPOs. It was found that when the upper kHz QPO frequency is below 1030 Hz these frequencies correlate, whereas above 1030 Hz they anticorrelate. GX 17+2 is the first source in which this is observed. We also found that the frequency difference of the high-frequency QPOs was not constant and that the quality factors (Q-values) of the HBO, its second harmonic, and the kHz QPOs are similar and vary almost hand in hand by a factor of more than 3. Observations of the normal branch oscillations during two type I X-ray bursts showed that their absolute amplitude decreased as the flux from the neutron star became stronger. We discuss these and other findings in terms of models that have been proposed for these phenomena. We also compare the behavior of GX 17+2 and other Z sources with that of black hole sources and consider the possibility that the mass accretion rate might not be the driving force behind all spectral and variability changes.

  9. Shallow and Deep Latent Heating Modes Over Tropical Oceans Observed with TRMM PR Spectral Latent Heating Data

    NASA Technical Reports Server (NTRS)

    Takayabu, Yukari N.; Shige, Shoichi; Tao, Wei-Kuo; Hirota, Nagio

    2010-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. Three-dimensional distributions of latent heating estimated from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)utilizing the Spectral Latent Heating (SLH) algorithm are analyzed. Mass-weighted and vertically integrated latent heating averaged over the tropical oceans is estimated as approx.72.6 J/s (approx.2.51 mm/day), and that over tropical land is approx.73.7 J/s (approx.2.55 mm/day), for 30degN-30degS. It is shown that non-drizzle precipitation over tropical and subtropical oceans consists of two dominant modes of rainfall systems, deep systems and congestus. A rough estimate of shallow mode contribution against the total heating is about 46.7 % for the average tropical oceans, which is substantially larger than 23.7 % over tropical land. While cumulus congestus heating linearly correlates with the SST, deep mode is dynamically bounded by large-scale subsidence. It is notable that substantial amount of rain, as large as 2.38 mm day-1 in average, is brought from congestus clouds under the large-scale subsiding circulation. It is also notable that even in the region with SST warmer than 28 oC, large-scale subsidence effectively suppresses the deep convection, remaining the heating by congestus clouds. Our results support that the entrainment of mid-to-lower-tropospheric dry air, which accompanies the large

  10. Understanding the Long-Term Spectral Variability of Cygnus X-1 with Burst and Transient Source Experiment and All-Sky Monitor Observations

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Poutanen, Juri; Paciesas, William S.; Wen, Lin-Qing

    2002-01-01

    We present a comprehensive analysis of all observations of Cyg X-1 by the Compton Gamma Ray Observatory Burst and Transient Source Experiment (BATSE; 20-300 keV) and by the Rossi X-Ray Timing Explorer all-sky monitor (ASM; 1.5-12 keV) until 2002 June, including approximately 1200 days of simultaneous data. We find a number of correlations between fluxes and hardnesses in different energy bands. In the hard (low) spectral state, there is a negative correlation between the ASM 1.5-12 keV flux and the hardness at any energy. In the soft (high) spectral state, the ASM flux is positively correlated with the ASM hardness but uncorrelated with the BATSE hardness. In both spectral states, the BATSE hardness correlates with the flux above 100 keV, while it shows no correlation with the 20-100 keV flux. At the same time, there is clear correlation between the BATSE fluxes below and above 100 keV. In the hard state, most of the variability can be explained by softening the overall spectrum with a pivot at approximately 50 keV. There is also another, independent variability pattern of lower amplitude where the spectral shape does not change when the luminosity changes. In the soft state, the variability is mostly caused by a variable hard (Comptonized) spectral component of a constant shape superposed on a constant soft blackbody component. These variability patterns are in agreement with the dependencies of the rms variability on the photon energy in the two states. We also study in detail recent soft states from late 2000 until 2002. The last of them has lasted thus far for more than 200 days. Their spectra are generally harder in the 1.5-5 keV band and similar or softer in the 3-12 keV band than the spectra of the 1996 soft state, whereas the rms variability is stronger in all the ASM bands. On the other hand, the 1994 soft state transition observed by BATSE appears very similar to the 1996 one. We interpret the variability patterns in terms of theoretical Comptonization

  11. INTEGRAL observes a bright flare and spectral changes in V404 Cyg: possible hard to soft transition ahead?

    NASA Astrophysics Data System (ADS)

    Motta, S. E.; Sanchez-Fernandez, C.; Kuulkers, E.; Kajava, J.; Bozzo, E.

    We report the results of ongoing INTEGRAL TOO observations of V404 Cyg in spacecraft revolutions 1627 (from 2015-12-29 01:43 to 2015-12-31 03:04), and 1628 (from 2015-12-31 15:43 to 2016-01-02 19:41).

  12. Quasi-periodic Oscillations Associated with Spectral Branches in Rossi X-Ray Timing Explorer Observations of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert E.; Bradt, Hale V.; Levine, Alan M.; Morgan, Edward H.

    1998-10-01

    We present Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 that illustrate the variety of intensity profiles associated with the 16.55 day flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average intensity of the flaring state decreased gradually over ~12 days. Fourier power density spectra for these observations show a narrow quasi-periodic oscillation (QPO) peak that shifts in frequency between 6.8 and 32 Hz, as well as a broad QPO peak that remains roughly stationary at ~4 Hz. We identify these as Z-source horizontal and normal branch oscillations (HBOs/NBOs), respectively. Color-color and hardness-intensity diagrams (CDs/HIDs) show curvilinear tracks for each of the observations. The properties of the QPOs and very low frequency noise allow us to identify segments of these tracks with Z-source horizontal, normal, and flaring branches that shift location in the CDs and HIDs over the course of the 16.55 day cycle. These results contradict a previous prediction, based on the hypothesis that Cir X-1 is a high-Ṁ atoll source, that HBOs should never occur in this source.

  13. Spatial and spectral properties of plasma waves observed upstream of Saturn's bow shock by the Cassini spacecraft

    NASA Astrophysics Data System (ADS)

    Pisa, David; Santolik, Ondrej; Soucek, Jan; Hospodarsky, George B.; Kurth, William S.; Gurnett, Donald A.

    2016-04-01

    Plasma waves are commonly observed in the upstream regions of planetary and interplanetary shocks. Plasma waves are identified as intense narrowband emissions at a frequency very close to the local plasma frequency or weaker broadband waves below and above the plasma frequency deeper in the foreshock region. We present a statistical study of plasma waves detected upstream of Saturn's bowshock by the Cassini spacecraft. Using data from the Radio and Plasma Wave Science (RPWS) and Magnetometer (MAG) instruments we have analyzed all available waveforms obtained by the Wideband Receiver between June 2004 and December 2015. A typical wave spectrum exhibits a single intense peak. However, spectra with a superposition of two or more intense peaks are also observed. Using magnetic field observations and a model of the bow shock, plasma wave activity in the Saturn's foreshock has been analyzed. The plasma wave occurrence increases steeply behind the tangential magnetic field line and still rises with the increasing distance from the tangential line. The single peak spectra are observed across the entire foreshock while more complicated spectra are measured deeper inside the foreshock and closer to the bow shock. The most intense waves occur close to the tangent point and fade out deeper in the foreshock and along the tangential line.

  14. X-ray spectral evolution of TeV BL Lacertae objects: eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites

    NASA Astrophysics Data System (ADS)

    Massaro, F.; Tramacere, A.; Cavaliere, A.; Perri, M.; Giommi, P.

    2008-02-01

    Context: Many of the extragalactic sources detected in γ rays at TeV energies are BL Lac objects. In particular, they belong to the subclass of “high frequency peaked BL Lacs” (HBLs), as their spectral energy distributions exhibit a first peak in the X-ray band. At a closer look, their X-ray spectra appear to be generally curved into a log-parabolic shape. In a previous investigation of Mrk 421, two correlations were found between the spectral parameters. One involves the height Sp increasing with the position Ep of the first peak; this was interpreted as a signature of synchrotron emission from relativistic electrons. The other involves the curvature parameter b decreasing as Ep increases; this points toward statistical/stochastic acceleration processes for the emitting electrons. Aims: We analyse X-ray spectra of several TeV HBLs to pinpoint their behaviours in the E_p-Sp and E_p-b planes and to compare them with Mrk 421. Methods: We perfom X-ray spectral analyses of a sample of 15 BL Lacs. We report the whole set of observations obtained with the BeppoSAX, XMM-Newton and Swift satellites between 29/06/96 and 07/04/07. We focus on five sources (PKS 0548-322, 1H 1426+418, Mrk 501, 1ES 1959+650, PKS 2155-304) whose X-ray observations warrant detailed searching of correlations or trends. Results: Within our database, we find that four out of five sources, namely PKS 0548-322, 1H 1426+418, Mrk 501 and 1ES 1959+650, follow similar trends as Mrk 421 in the E_p-Sp plane, while PKS 2155-304 differs. As for the E_p-b plane, all TeV HBLs follow a similar behaviour. Conclusions: The trends exhibited by Mrk 421 appear to be shared by several TeV HBLs, such as to warrant discussing predictions from the X-ray spectral evolution to that of TeV emissions. Appendix A is only available in electronic form at http://www.aanda.org

  15. The spatio-spectral localization approach to modeling VTEC by integrating ground GPS observations and satellite altimetry data

    NASA Astrophysics Data System (ADS)

    Farzaneh, Saeed; Sharifi, Mohammad Ali

    2015-04-01

    The upper part of the Earth atmosphere is important for ground-based and satellite radio communication and navigation. It consists of free electrons and ions, mainly ionized by solar radiation. Free electrons, in the ionosphere, have a strong impact on the propagation of radio waves. When the signals pass through the ionosphere, both their group and phase velocity are disturbed. The effect is in first approximation proportional to TEC along the signal path and inversely proportional to the frequency squared. Several space geodetic techniques such as satellite altimetry, LEO satellite and Very Long Baseline Interferometry (VLBI) can be used for modeling the total electron content. In this study the combination of the data from ground GPS observation over west part of USA and from the altimetry mission Jason-2 is performed on the normal equation level in least-square producer and the least-squares variance component estimation is applied to consider the different accuracy levels of the observations. The integrated ionosphere model is expected to be more accurate and reliable than the results derived by the ground GPS observation over the oceans. Keywords: Slepian function, LS-VCE, satellite altimetry, GPS, local ionospheric modeling

  16. NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.

    2009-01-01

    Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the

  17. Ship-borne rotating shadowband radiometer observations for determination of components of spectral irradiance and aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Walther, Jonas; Deneke, Hartwig; Macke, Andreas; Bernhard, Germar

    2015-04-01

    The Maritime Aerosol Network (MAN) has been established as a sub-project of AERONET and a long-term program to collect ship-borne aerosol optical depth measurements over ocean. Its purpose is to serve as reliable reference database for the evaluation of models and satellite products. Data are currently collected by handheld Microtops II photometers, as the automated acquisition of data from sun photometers on stabilized platforms is so far too expensive for wide-spread use. A promising alternative to the sun photometer is the rotating shadowband radiometer, whose principle of operation allows the determination of the direct-beam component of solar radiation without stabilizing the instrument, if the orientation of the detector horizontal is known. OCEANET, a project to investigate the exchange fluxes of energy and matter between the atmosphere and ocean, has contributed aerosol observations to MAN on several of its cruises on RV Polarstern during the transit between the hemispheres. On the recent cruise (PS 83) from Cape Town to Bremerhaven, TROPOS has operated for the first time a 19 channel rotating shadowband radiometer (GUVis-3511) built by the company Biospherical, as a possible means to provide automated irradiance and aerosol optical depth measurements. Calibration and processing of the raw data will be described, and an initial evaluation of the instrumental performance will be given. Aerosol optical depths derived from Microtops II measurements and the rotating shadowband radiometer will be compared. We show that the standard deviation of Aerosol optical depths observed with Microtops II and the shadowband radiometer is about 0.02 for matching channels, and an aerosol type classification based on Angstrom exponent shows good agreement. Also the influence of ship smoke and ocean swell is studied. The suitability of the instrument to automate MAN observations is discussed, and an outlook to the use of the instrument to also derive cloud optical properties is

  18. Trend analysis of the Aerosol Optical Thickness and Ångström Exponent derived from the global AERONET spectral observations

    NASA Astrophysics Data System (ADS)

    Yoon, J.; von Hoyningen-Huene, W.; Kokhanovsky, A. A.; Vountas, M.; Burrows, J. P.

    2011-08-01

    Regular aerosol observations based on well-calibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding long-term trends of aerosol optical characteristics (e.g. Aerosol Optical Thickness (AOT) and Ångström Exponent (ÅE)) have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm) and ÅE (440-870 nm) using AErosol RObotic NETwork (AERONET) spectral observations. Additionally, temporal trends of Coarse- and Fine-mode dominant AOTs (CAOT and FAOT) have been estimated by applying an aerosol classification based on accurate ÅE and Ångström Exponent Difference (ÅED). In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1) monthly standard deviation and (2) Number of Observations (NO) per month. Temporal increase of FAOTs prevails over regions dominated by emerging economy or slash-burn agriculture in East Asia and South Africa. On the other hand, insignificant or negative trends for FAOTs are detected over Western Europe and North America. Over desert regions, both increase and decrease of CAOTs are observed depending on meteorological conditions.

  19. The spatio-spectral localization approach to modeling VTEC over the western part of the USA using GPS observations

    NASA Astrophysics Data System (ADS)

    Sharifi, Mohammad Ali; Farzaneh, Saeed

    2014-09-01

    The precise ionosphere modeling is crucial and remains a challenge for GPS positioning and navigation, as well as many other Earth observation systems. In this research, two approaches have been proposed to model the vertical total electron content (VTEC) of the ionosphere using spherical slepian function. For the two-dimensional case, VTEC has been modeled in a sun-fixed reference frame and the three-dimensional approach based on the system of the three-dimensional base functions has been defined as the tensor product of the spherical slepian function for the longitude and latitude in an Earth-fixed reference frame, and the polynomial B-spline function for time. Rather than the spherical harmonics, the spherical slepian functions can be employed to produce the locally and globally orthogonal bases to optimally represent the data in any arbitrary region up to a given degree. The spherical slepian functions have been applied to the real data obtained from the ground-based GPS observation across the western part of the USA.

  20. Spectral observations of the soft X-ray background with solid-state detectors - Evidence for line emissions

    NASA Technical Reports Server (NTRS)

    Rocchia, R.; Arnaud, M.; Blondel, C.; Cheron, C.; Christy, J. C.; Rothenflug, R.; Schnopper, H. W.; Delvaille, J. P.

    1984-01-01

    The soft X-ray radiation from several regions of the sky was observed with solid-state detectors Si(Li) between 0.3 and 1.2 keV during two rocket flights. The thermal nature of the diffuse emission coming from the hot bubble surrounding the solar system is confirmed by the observation of C V-C VI and O VII lines which are typical of a temperature of about 10 to the 6th K. Evidence for the existence of a weak component at a higher temperature is given. This component, well visible in the high latitude spectra, could be produced by a hot galactic halo. In the direction of the enhancement region centered on the North Polar Spur, the radiation excess spectra are well represented by a two-temperature plasma model with rather standard abundances. The two components have temperatures of 10 to the 6th and 4.7 x 10 to the 6th K.

  1. Analysis of simultaneous emission and absorption Ti spectral features observed with the MMI instrument in OMEGA implosions

    NASA Astrophysics Data System (ADS)

    Joshi, Tirtha; Johns, Heather; Mayes, Daniel; Durmaz, Tunay; Mancini, Roberto; Tommasini, Riccardo; Delettrez, Jack; Regan, Sean; Nagayama, Taisuke

    2012-10-01

    We discuss the observation and analysis of spectra from titanium-doped OMEGA direct-drive implosions. The targets were spherical plastic shells with a submicron Ti-doped tracer-layer initially located on the inner surface of the shell and filled with deuterium gas. The x-ray signal from the titanium tracer is observed at the collapse of the implosion and recorded with a streaked spectrometer (SSCA) and three identical gated,multi-monochromatic x-ray imager (MMI) instruments that view the implosion along three quasi-orthogonal lines-of-sight. Both streaked and MMI data show simultaneous emission and absorption features due to titanium K-shell line transitions but only the MMI data permits to diagnose the tracer's spatial properties in the core. To this end, MMI data were processed to obtain narrow-band images and spatially-resolved spectra.footnotetextT. Nagayama et al., J. App. Phys.109, 093303 (2011). Abel inversion of angle-averaged image intensity profiles reveal the spatial distribution of the titanium tracer in the core, while detailed analysis of the space-resolved spectra yields temperature, density and mixing distributions. Results are presented for several shell thicknesses and implosions driven with different laser pulse shapes.

  2. High-spectral resolution observations of the 3.29 micron emission feature: Comparison to QCC and PAHs

    NASA Technical Reports Server (NTRS)

    Tokunaga, Alan T.; Sellgren, Kris; Sakata, Akira; Wada, S.; Onaka, Takashi; Nakada, Y.; Nagata, T.

    1989-01-01

    Two of the most promising explanations for the origin of the interstellar emission features observed at 3.29, 3.4, 6.2, 7.7, 8.6, and 11.3 microns are: quenched carbonaceous composite (QCC) and polycyclic aromatic hydrocarbons (PAHs). High resolution spectra are given of the 3.29 micron emission feature which were taken with the Cooled Grating Array Spectrometer at the NASA Infrared Telescope Facility and previously published. These spectra show that the peak wavelength of the 3.29 micron feature is located at 3.295 + or - 0.005 micron and that it is coincident with the peak absorbance of QCC. The peak wavelength of the 3.29 micron feature appears to be the same in all of the sources observed thus far. However, the width of the feature in HD 44179 and Elias 1 is only 0.023 micron, which is smaller than the 0.043 micron width in NGC 7027, IRAS 21282+5050, the Orion nebula, and BD+30 deg 3639. Spectra of NGC 7027, QCC, and PAHs is shown. QCC matches the 3.29 micron interstellar emission feature very closely in the wavelength of the peak, and it produces a single feature. On the other hand, PAHs rarely match the peak of the interstellar emission feature, and characteristically produce multiple features.

  3. Direct observation of time-dependent photoluminescence spectral shift in CdS nanoparticles synthesized in polymer solutions

    NASA Astrophysics Data System (ADS)

    Mandal, Debabrata; Hosoi, Haruko; Chatterjee, Uma; Tahara, Tahei

    2009-01-01

    Direct observation of time-resolved emission spectra (TRESs) of cadmium sulfide nanoparticles in polymer solutions was carried out with picosecond resolution using a streak camera. The TRESs were found to undergo a pronounced time-dependent Stokes shift, eventually coinciding with the steady-state photoluminescence spectra within an ˜40 ns delay time. Moreover, ˜90% of the shift was complete within the first 1 ns after excitation, in contrast to the fact that overall photoluminescence involves very long time constants of 10-100 ns. The observed Stokes shift dynamics was very similar in CdS nanoparticles stabilized in two very different types of polymer solutions. Thus the solvent and/or polymeric stabilizer appeared to have a minimal effect on the shift. We propose that the relaxation proceeds through an internal mechanism involving the fast decay of high-energy traps into relatively slow-decaying low-energy traps. Time-dependent photoluminescence anisotropy experiments also revealed an ˜1 ns decay component appearing only in the higher-energy end of the photoluminescence spectrum. Because this time constant is too short to represent rotational diffusion of the nanometer-sized particles, it was associated with the rapid relaxation of the high-energy trap states.

  4. Vibrational and structural observations upon 3-((1H-benzo[d]imidazol-1-yl)methyl)naphthalen-2-ol from spectral and DFT computing approaches

    NASA Astrophysics Data System (ADS)

    Jone Pradeepa, S.; Tamilvendan, D.; Susai Boobalan, Maria; Sundaraganesan, N.

    2016-05-01

    An aggregate of experimental and computational study on synthesis, molecular structure, vibrational, electronic, nuclear magnetic resonance spectra, electronic structure, NLO activity and thermochemical characterization has been investigated for 3-((1H-benzo[d]imidazol-1-yl)methyl) naphthalen-2-ol (BDMN). The perspective on structural analysis includes the examination of equilibrium geometry, Natural Bond Orbital analysis (NBO), molecular electrostatic potential (MEP) analysis and frontier molecular orbital calculation. Similarly the following spectral analysis such as vibrational (FT-IR and FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) has been interpreted. The FT-IR, FT-Raman spectrum were recorded in the frequency range of 4000-400 cm-1 and 4000-50 cm-1 respectively. A complete potential energy distribution (PED) was achieved to interpret the normal modes by comparing the experimental and theoretical spectral data. The simulation of NMR spectrum was performed using GIAO strategy. The NLO activity of BDMN has been calibrated using hyperpolarizability. In addition, various thermodynamic entities were predicted against different temperatures. The entire computation was executed using appropriate model chemistries such as B3LYP/Sadlej pVTZ, B3LYP/6-311G(d,p) and PBEPBE (TDDFT)/6-311G(d,p) for the respective properties. The overall hand-in-hand analysis by using both theoretical and experimental calculation on BDMN provides interesting observations and inferences.

  5. HST-COS Observations of AGNs. III. Spectral Constraints in the Lyman Continuum from Composite COS/G140L Data

    NASA Astrophysics Data System (ADS)

    Tilton, Evan M.; Stevans, Matthew L.; Shull, J. Michael; Danforth, Charles W.

    2016-01-01

    The rest-frame ultraviolet (UV) spectra of active galactic nuclei (AGNs) are important diagnostics of both accretion disk physics and their contribution to the metagalactic ionizing UV background. Though the mean AGN spectrum is well characterized with composite spectra at wavelengths greater than 912 Å, the shorter-wavelength extreme-UV (EUV) remains poorly studied. In this third paper in a series on the spectra of AGNs, we combine 11 new spectra taken with the Cosmic Origins Spectrograph on the Hubble Space Telescope with archival spectra to characterize the typical EUV spectral slope of AGNs from λrest ˜ 850 Å down to λrest ˜ 425 Å. Parameterizing this slope as a power law, we obtain Fν ∝ ν-0.72±0.26, but we also discuss the limitations and systematic uncertainties of this model. We identify broad emission features in this spectral region, including emission due to ions of O, Ne, Mg, and other species, and we limit the intrinsic He i 504 Å photoelectric absorption edge opacity to τHe i < 0.047. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  6. Atomic data and spectral analysis of carbon, nitrogen, oxygen and silicon ions observed with the International Ultraviolet Explorer

    NASA Technical Reports Server (NTRS)

    Pradhan, Anil K.

    1992-01-01

    According to the plan presented in the original proposal we have now completed most of the atomic calculations involving collision strengths and rate coefficients for electron impact excitation of C II, N III, and O IV ions. These have been reported in the first two publications appended with this report. We have now moved into the applications phase of the project with the new data being used to analyze the International Ultraviolet Explorer (IUE) observations of a variety of objects, as described in the third publication recently submitted (also appended). The analysis and interpretation of archival data will continue well into the next year with several collaborators that the PI and Co-PI are involved with. In addition, the atomic calculations on Si II have been started.

  7. Spectral observation of the soft X-ray background and of the North Polar Spur with solid state spectrometers

    NASA Technical Reports Server (NTRS)

    Rocchia, R.; Arnaud, M.; Blondel, C.; Cheron, C.; Christy, J. C.; Koch, L.; Rothenflug, R.; Schnopper, H. W.; Delvaille, J. P.

    1983-01-01

    Soft X-ray diffuse background observations in the 0.3-1.5 keV interval of two sky regions, near the north galactic pole and the North Polar Spur (NPS) are reported. Data were taken with a solid-state spectrometer carried by a rocket. The near-polar region exhibited O VII ion emissions at 530 eV. A second component was not identified but was attributed to the Galactic Halo. Fe XVIII, Ne IX, and O VIII contributions were detected in the NPS, along with an enhancement at 1.35 keV from Mg XI lines. A two-temperature contour was fit to the spectra and chi-square confidence levels of 90 and 68 percent were obtained.

  8. NuSTAR OBSERVATIONS AND BROADBAND SPECTRAL ENERGY DISTRIBUTION MODELING OF THE MILLISECOND PULSAR BINARY PSR J1023+0038

    SciTech Connect

    Li, K. L.; Kong, A. K. H.; Tam, P. H. T.; Jin, Ruolan; Takata, J.; Cheng, K. S.; Hui, C. Y. E-mail: akong@phys.nthu.edu.tw

    2014-12-20

    We report the first hard X-ray (3-79 keV) observations of the millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass X-ray binary (LMXB) state and a rotation-powered MSP state. The NuSTAR observations were taken in both LMXB state and rotation-powered state. The source is clearly seen in both states up to ∼79 keV. During the LMXB state, the 3-79 keV flux is about a factor of 10 higher than in the rotation-powered state. The hard X-rays show clear orbital modulation during the X-ray faint rotation-powered state but the X-ray orbital period is not detected in the X-ray bright LMXB state. In addition, the X-ray spectrum changes from a flat power-law spectrum during the rotation-powered state to a steeper power-law spectrum in the LMXB state. We suggest that the hard X-rays are due to the intrabinary shock from the interaction between the pulsar wind and the injected material from the low-mass companion star. During the rotation-powered MSP state, the X-ray orbital modulation is due to Doppler boosting of the shocked pulsar wind. At the LMXB state, the evaporating matter of the accretion disk due to the gamma-ray irradiation from the pulsar stops almost all the pulsar wind, resulting in the disappearance of the X-ray orbital modulation.

  9. Benchmark Transiting Brown Dwarf LHS 6343 C: Spitzer Secondary Eclipse Observations Yield Brightness Temperature and Mid-T Spectral Class

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin T.; Johnson, John Asher; Fortney, Jonathan J.; Desert, Jean-Michel

    2016-05-01

    There are no field brown dwarf analogs with measured masses, radii, and luminosities, precluding our ability to connect the population of transiting brown dwarfs with measurable masses and radii and field brown dwarfs with measurable luminosities and atmospheric properties. LHS 6343 C, a weakly irradiated brown dwarf transiting one member of an M+M binary in the Kepler field, provides the first opportunity to probe the atmosphere of a non-inflated brown dwarf with a measured mass and radius. Here, we analyze four Spitzer observations of secondary eclipses of LHS 6343 C behind LHS 6343 A. Jointly fitting the eclipses with a Gaussian process noise model of the instrumental systematics, we measure eclipse depths of 1.06 ± 0.21 ppt at 3.6 μm and 2.09 ± 0.08 ppt at 4.5 μm, corresponding to brightness temperatures of 1026 ± 57 K and 1249 ± 36 K, respectively. We then apply brown dwarf evolutionary models to infer a bolometric luminosity {log}({L}\\star /{L}ȯ )=-5.16+/- 0.04. Given the known physical properties of the brown dwarf and the two M dwarfs in the LHS 6343 system, these depths are consistent with models of a 1100 K T dwarf at an age of 5 Gyr and empirical observations of field T5-6 dwarfs with temperatures of 1070 ± 130 K. We investigate the possibility that the orbit of LHS 6343 C has been altered by the Kozai–Lidov mechanism and propose additional astrometric or Rossiter–McLaughlin measurements of the system to probe the dynamical history of the system.

  10. Cassini-VIMS observations of Saturn's main rings: I. Spectral properties and temperature radial profiles variability with phase angle and elevation

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Ciarniello, M.; Capaccioni, F.; Clark, R. N.; Nicholson, P. D.; Hedman, M. M.; Cuzzi, J. N.; Cruikshank, D. P.; Dalle Ore, C. M.; Brown, R. H.; Cerroni, P.; Altobelli, N.; Spilker, L. J.

    2014-10-01

    The spectral properties and thermal behavior of Saturn's rings are determined from a dataset of ten radial mosaics acquired by Cassini-VIMS (Visual and Infrared Mapping Spectrometer) between October 29th 2004 and January 27th 2010 with phase angle ranging between 5.7° and 132.4° and elevation angles between -23.5° and 2.6°. These observations, after reduction to spectrograms, e.g. 2D arrays containing the VIS-IR (0.35-5.1 μm) spectral information versus radial distance from Saturn (from 73.500 to 141.375 km, 400 km/bin), allow us to compare the derived spectral and thermal properties of the ring particles on a common reference. Spectral properties: rings spectra are characterized by an intense reddening at visible wavelengths while they maintain a strong similarity with water ice in the infrared domain. Significant changes in VIS reddening, water ice abundance and grain sizes are observed across different radial regions resulting in correlation with optical depth and local structures. The availability of observations taken at very different phase angles allows us to examine spectrophotometric properties of the ring's particles. When observed at high phase angles, a remarkable increase of visible reddening and water ice band depths is found, probably as a consequence of the presence of a red-colored contaminant intimately mixed within water ice grains and of multiple scattering. At low phases the analysis of the 3.2-3.6 μm range shows faint spectral signatures at 3.42-3.52 μm which are compatible with the CH2 aliphatic stretch. The 3.29 μm PAH aromatic stretch absorption is not clearly detectable on this dataset. VIMS results indicate that ring particles contain about 90-95% water ice while the remaining 5-10% is consistent with different contaminants like amorphous carbon or tholins. However, we cannot exclude the presence of nanophase iron or hematite produced by iron oxidation in the rings tenuous oxygen atmosphere, intimately mixed with the ice grains

  11. A Wolf-Rayet-Like Progenitor of SN 2013cu from Spectral Observations of a Stellar Wind

    NASA Technical Reports Server (NTRS)

    Gal-Yam, Avishay; Arcavi, I.; Ofek, E. O.; Ben-Ami, S.; Cenko, S. B.; Kasliwal, M. M.; Cao, Y.; Yaron, O.; Tal, D.; Silverman, J. M.; Horesh, A.; Cia, A. De; Taddia, F.; Sollerman, J.; Perley, D.; Vreeswijk, P. M.; Kulkarni, S. R.; Nugent, P. E.; Filippenko, A. V.; Wheeler, J. C.

    2014-01-01

    The explosive fate of massive Wolf-Rayet stars (WRSs) is a key open question in stellar physics. An appealing option is that hydrogen- deficient WRSs are the progenitors of some hydrogen-poor supernova explosions of types IIb, Ib and Ic. A blue object, having luminosity and colours consistent with those of some WRSs, has recently been identified in pre-explosion images at the location of a supernova of type Ib, but has not yet been conclusively determined to have been the progenitor. Similar work has so far only resulted in non-detections. Comparison of early photometric observations of type Ic supernovae with theoretical models suggests that the progenitor stars had radii of less than 10(exp 12) centimetres, as expected for some WRSs. The signature of WRSs, their emission line spectra, cannot be probed by such studies. Here we report the detection of strong emission lines in a spectrum of type IIb supernova 2013cu (iPTF13ast) obtained approximately 15.5 hours after explosion (by 'flash spectroscopy', which captures the effects of the supernova explosion shock breakout flash on material surrounding the progenitor star).We identify Wolf-Rayet-like wind signatures, suggesting a progenitor of the WN(h) subclass (those WRSs with winds dominated by helium and nitrogen, with traces of hydrogen). The extent of this dense wind may indicate increased mass loss from the progenitor shortly before its explosion, consistent with recent theoretical predictions.

  12. HUBBLE SPACE TELESCOPE SPECTRAL OBSERVATIONS NEAR THE He II Ly{alpha} BREAK: IMPLICATIONS FOR He II REIONIZATION

    SciTech Connect

    Syphers, David; Anderson, Scott F.; Haggard, Daryl; Zheng Wei; Meiksin, Avery; Schneider, Donald P.; York, Donald G. E-mail: anderson@astro.washington.edu

    2011-01-10

    Quasars that allow the study of intergalactic medium (IGM) He II are very rare, since they must be at high redshift along sightlines free of substantial hydrogen absorption, but recent work has dramatically expanded the number of such quasars known. We analyze two dozen higher-redshift (z = 3.1-3.9) low-resolution He II quasar spectra from the Hubble Space Telescope and find that their He II Gunn-Peterson troughs suggest exclusion of very early and very late reionization models, favoring a reionization redshift of z {approx} 3. Although the data quality is not sufficient to reveal details such as the expected redshift evolution of helium opacity, we obtain the first ensemble measure of helium opacity at high redshift averaged over many sightlines: {tau} = 4.90 at z {approx} 3.3. We also find that it would be very difficult to observe the IGM red wing of absorption from the beginning of He II reionization, but depending on the redshift of reionization and the size of ionization zones, it might be possible to do so in some objects with the current generation of UV spectrographs.

  13. The Spectral Shift Function and Spectral Flow

    NASA Astrophysics Data System (ADS)

    Azamov, N. A.; Carey, A. L.; Sukochev, F. A.

    2007-11-01

    At the 1974 International Congress, I. M. Singer proposed that eta invariants and hence spectral flow should be thought of as the integral of a one form. In the intervening years this idea has lead to many interesting developments in the study of both eta invariants and spectral flow. Using ideas of [24] Singer’s proposal was brought to an advanced level in [16] where a very general formula for spectral flow as the integral of a one form was produced in the framework of noncommutative geometry. This formula can be used for computing spectral flow in a general semifinite von Neumann algebra as described and reviewed in [5]. In the present paper we take the analytic approach to spectral flow much further by giving a large family of formulae for spectral flow between a pair of unbounded self-adjoint operators D and D + V with D having compact resolvent belonging to a general semifinite von Neumann algebra {mathcal{N}} and the perturbation V in {mathcal{N}} . In noncommutative geometry terms we remove summability hypotheses. This level of generality is made possible by introducing a new idea from [3]. There it was observed that M. G. Krein’s spectral shift function (in certain restricted cases with V trace class) computes spectral flow. The present paper extends Krein’s theory to the setting of semifinite spectral triples where D has compact resolvent belonging to {mathcal{N}} and V is any bounded self-adjoint operator in {mathcal{N}} . We give a definition of the spectral shift function under these hypotheses and show that it computes spectral flow. This is made possible by the understanding discovered in the present paper of the interplay between spectral shift function theory and the analytic theory of spectral flow. It is this interplay that enables us to take Singer’s idea much further to create a large class of one forms whose integrals calculate spectral flow. These advances depend critically on a new approach to the calculus of functions of non

  14. Construction of a High Temporal-spectral Resolution Spectrometer for Detection of Fast Transients from Observations of the Sun at 1.4 GHz.

    NASA Astrophysics Data System (ADS)

    Casillas-Perez, G. A.; Jeyakumar, S.; Perez-Enriquez, R.

    2014-12-01

    Transients explosive events with time durations from nanoseconds to several hours, are observed in the Sun at high energy bands such as gamma ray and xray. In the radio band, several types of radio bursts are commonly detected from the ground. A few observations of the Sun in the past have also detected a new class of fast transients which are known to have short-live electromagnetic emissions with durations less than 100 ms. The mechanisms that produce such fast transiets remain unclear. Observations of such fast transients over a wide bandwidth is necessary to uderstand the underlying physical process that produce such fast transients. Due to their very large flux densities, fast radio transients can be observed at high time resolution using small antennas in combination with digital signal processing techniques. In this work we report the progress of an spectrometer that is currently in construction at the Observatorio de la Luz of the Universidad de Guanajuato. The instrument which will have the purpose of detecting solar fast radio transients, involves the use of digital devices such as FPGA and ADC cards, in addition with a receiver with high temporal-spectral resolution centered at 1.4 GHz and a pair of 2.3 m satellite dish.

  15. Comparative Studies of Hard X-Ray Spectral Evolution in Solar Flares with High-Energy Proton Events Observed at Earth

    NASA Astrophysics Data System (ADS)

    Kiplinger, Alan L.

    1995-11-01

    This paper presents the results of two extensive studies of hard X-ray spectral evolution in solar flares and their associations with energetic interplanetary proton events. The focus of this work is to establish the degree to which events that display progressively hardening hard X-ray spectra, at any time and over all observable timescales, are associated with high-energy interplanetary proton events. The first study examined a sample of 152 hard X-ray flares well observed with the HXRBS instrument on the Solar Maximum Mission (SMM). The study showed that 22 events revealed a progressive spectral hardening either over flux peaks (i.e., a soft-hard- harder spectral evolution) or during flux decays and that 18 of these 22 events (82%) had associated 10 MeV proton events or enhancements. Conversely, the absence of spectral hardening is associated with the absence of interplanetary protons with 124 of the 130 remaining flares (95.4%). Since the hard X-ray counting rate threshold of the first study was sufficiently high (5000 counts s-1) to exclude many flares (more than 36%) associated with the largest interplanetary proton events, a second study was conducted using 193 less intense HXRBS events (a one out of three sample) and their associations with only large proton events. This study also identifies events with progressive spectral hardening. It also employs selection criteria suggested by the results of the first study to "predict" which flares would or would not have associated large proton events. This prescription for "predicting" proton events did so correctly for four large (SESC qualified) proton events, missed none, and produced only one "false alarm" in which the criteria were met but only a small proton event was seen at earth. Thus, a correct "prediction" was made for all but one of the 193 events. The results of the first study are then combined with the weighted results of the one out of three study, using the same selection criteria, to project

  16. A Wolf-Rayet-like progenitor of SN 2013cu from spectral observations of a stellar wind.

    PubMed

    Gal-Yam, Avishay; Arcavi, I; Ofek, E O; Ben-Ami, S; Cenko, S B; Kasliwal, M M; Cao, Y; Yaron, O; Tal, D; Silverman, J M; Horesh, A; De Cia, A; Taddia, F; Sollerman, J; Perley, D; Vreeswijk, P M; Kulkarni, S R; Nugent, P E; Filippenko, A V; Wheeler, J C

    2014-05-22

    The explosive fate of massive Wolf-Rayet stars (WRSs) is a key open question in stellar physics. An appealing option is that hydrogen-deficient WRSs are the progenitors of some hydrogen-poor supernova explosions of types IIb, Ib and Ic (ref. 2). A blue object, having luminosity and colours consistent with those of some WRSs, has recently been identified in pre-explosion images at the location of a supernova of type Ib (ref. 3), but has not yet been conclusively determined to have been the progenitor. Similar work has so far only resulted in non-detections. Comparison of early photometric observations of type Ic supernovae with theoretical models suggests that the progenitor stars had radii of less than 10(12) centimetres, as expected for some WRSs. The signature of WRSs, their emission line spectra, cannot be probed by such studies. Here we report the detection of strong emission lines in a spectrum of type IIb supernova 2013cu (iPTF13ast) obtained approximately 15.5 hours after explosion (by 'flash spectroscopy', which captures the effects of the supernova explosion shock breakout flash on material surrounding the progenitor star). We identify Wolf-Rayet-like wind signatures, suggesting a progenitor of the WN(h) subclass (those WRSs with winds dominated by helium and nitrogen, with traces of hydrogen). The extent of this dense wind may indicate increased mass loss from the progenitor shortly before its explosion, consistent with recent theoretical predictions. PMID:24848059

  17. Similar Gamma-Ray Spectral Characteristics of Thermal and Non-Thermal Emission Observed in Cygnus X-1, GROJ0422+32 and GROJ1719-24

    NASA Astrophysics Data System (ADS)

    Ling, J. C.; Wheaton, Wm. A.

    2004-08-01

    BATSE-EBOP (Enhanced BATSE Occultation Package; Ling et al. 2000) gamma-ray (30 keV - 1 MeV) observations of Cygnus X-1, GROJ0422+32 and GROJ1719-24 showed that these sources displayed similar spectral characteristics when undergoing transitions between the high and low gamma-ray intensity states. The high gamma-ray state spectra (gamma-2 , for Cygnus X-1) featured two components: a Comptonized shape below 200-300 keV with a soft power-law tail (photon index > 3) that extended to ˜1 MeV or beyond. For the low gamma-ray state (gamma-0, for Cygnus X-1) spectra, however, the Comptonized spectral shape below 300 keV vanished and the entire spectrum from 30 keV to ˜1 MeV can be characterized by a single power law with a relatively harder photon index ˜2-2.7. The high and low-intensity gamma-ray spectra therefore intersect at ˜400 KeV-1 MeV range, in contrast to the spectral pivoting seen previously at lower ( ˜10 keV) energies. The presence of the power-law component in both the high- and low-intensity gamma-ray spectra strongly suggests that the non-thermal process is likely to be at work in both the high and the low-intensity situations. We have suggested a possible scenario (Ling & Wheaton, 2003,), combining the ADAF model of Esin et al. (1998) with a separate jet region that produces the non-thermal gamma-ray emission, and which explains the state transitions. Such a scenario will be discussed in the context of the observational evidence, summarized above. This work was carried out by the Jet Propulsion Laboratory, under the contract to the National Aeronautics and Space Administration. References: Esin et al., 1998, ApJ, 505, 854. Ling et al.,2000, ApJS , 127, 70. Ling & Wheaton. 2003, ApJ, 584, 399.

  18. A spectral line survey of Orion KL in the bands 486-492 and 541-577 GHz with the Odin satellite. I. The observational data

    NASA Astrophysics Data System (ADS)

    Olofsson, A. O. H.; Persson, C. M.; Koning, N.; Bergman, P.; Bernath, P. F.; Black, J. H.; Frisk, U.; Geppert, W.; Hasegawa, T. I.; Hjalmarson, Å.; Kwok, S.; Larsson, B.; Lecacheux, A.; Nummelin, A.; Olberg, M.; Sandqvist, Aa.; Wirström, E. S.

    2007-12-01

    Aims:Spectral line surveys are useful since they allow identification of new molecules and new lines in uniformly calibrated data sets. The subsequent multi-transition analysis will provide improved knowledge of molecular abundances, cloud temperatures and densities, and may also reveal previously unsuspected blends of molecular lines, which otherwise may lead to erroneous conclusions. Nonetheless, large portions of the sub-millimetre spectral regime remain unexplored due to severe absorptions by H{2}O and O{2} in the terrestrial atmosphere. The purpose of the measurements presented here is to cover wavelength regions at and around 0.55 mm - regions largely unobservable from the ground. Methods: Using the Odin astronomy/aeronomy satellite, we performed the first spectral survey of the Orion KL molecular cloud core in the bands 486-492 and 541-576 GHz with rather uniform sensitivity (22-25 mK baseline noise). Odin's 1.1 m size telescope, equipped with four cryo-cooled tuneable mixers connected to broad band spectrometers, was used in a satellite position-switching mode. Two mixers simultaneously observed different 1.1 GHz bands using frequency steps of 0.5 GHz (25 h each). An on-source integration time of 20 h was achieved for most bands. The entire campaign consumed 1100 orbits, each containing one hour of serviceable astro-observation. Results: We identified 280 spectral lines from 38 known interstellar molecules (including isotopologues) having intensities in the range 80 to 0.05 K. An additional 64 weak lines remain unidentified. Apart from the ground state rotational 1{1,0}-1{0,1} transitions of ortho-H{2}O, H{2}18O and H{2}17O, the high energy 6{2,4}-7{1,7} line of para-H{2}O (Eu=867 K) and the HDO(2{0,2}-1{1,1}) line have been observed, as well as the 1{0}-0{1} lines from NH{3} and its rare isotopologue 15NH{3}. We suggest assignments for some unidentified features, notably the new interstellar molecules ND and SH-. Severe blends have been detected in the

  19. Evidence of dispersion and refraction of a spectrally broad gravity wave packet in the mesopause region observed by the Na lidar and Mesospheric Temperature Mapper above Logan, Utah

    NASA Astrophysics Data System (ADS)

    Yuan, T.; Heale, C. J.; Snively, J. B.; Cai, X.; Pautet, P.-D.; Fish, C.; Zhao, Y.; Taylor, M. J.; Pendleton, W. R.; Wickwar, V.; Mitchell, N. J.

    2016-01-01

    Gravity wave packets excited by a source of finite duration and size possess a broad frequency and wave number spectrum and thus span a range of temporal and spatial scales. Observing at a single location relatively close to the source, the wave components with higher frequency and larger vertical wavelength dominate at earlier times and at higher altitudes, while the lower frequency components, with shorter vertical wavelength, dominate during the latter part of the propagation. Utilizing observations from the Na lidar at Utah State University and the nearby Mesospheric Temperature Mapper at Bear Lake Observatory (41.9°N, 111.4°W), we investigate a unique case of vertical dispersion for a spectrally broad gravity wave packet in the mesopause region over Logan, Utah (41.7°N, 111.8°W), that occurred on 2 September 2011, to study the waves' evolution as it propagates upward. The lidar-observed temperature perturbation was dominated by close to a 1 h modulation at 100 km during the early hours but gradually evolved into a 1.5 h modulation during the second half of the night. The vertical wavelength also decreased simultaneously, while the vertical group and phase velocities of the packet apparently slowed, as it was approaching a critical level during the second half of the night. A two-dimensional numerical model is used to simulate the observed gravity wave processes, finding that the location of the lidar relative to the source can strongly influence which portion of the spectrum can be observed at a particular location relative to a source.

  20. Spectrally selective glazings

    SciTech Connect

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  1. Radar spectral observations of snow

    NASA Technical Reports Server (NTRS)

    Stiles, W. H.; Ulaby, F. T.; Fung, A. K.; Aslam, A.

    1981-01-01

    Radar remote sensing experiments have been conducted at test sites in Kansas, Colorado, and South Dakota over the last six years to examine backscatter coefficient response to snowcovered terrain. Truck-mounted 1-35 GHz scatterometers were employed in conjunction with detailed ground-truth measurements. From these experiments and associated modeling efforts, most of the fundamental questions concerning backscatter behavior in response to important snow parameters have been, at least qualitatively, answered. The optimum angular range seems to be between 20 and 50 deg and, for these angles, the results indicate that the radar backscatter generally: (1) increases with increasing water equivalent, (2) decreases with increasing liquid water, (3) increases with increasing crystal size, (4) is insensitive to surface roughness for dry snow conditions, and (5) can be sensitive to soil state if the snowcover is dry. This paper gives a summary of these results, along with empirical and theoretical models for describing the backscatter from snow.

  2. Kirchhoff's Laws of Spectral Analysis: A Set of Computer Laboratory Exercises

    ERIC Educational Resources Information Center

    Fillmore, James A.; And Others

    1978-01-01

    A computer program which simulates an interstellar gas and dust cloud has been used to study Kirchhoff's laws of spectral analysis in introductory astronomy courses. The model parameters can be varied to stimulate various effects observed in actual clouds. Students are given exercises to use the program in a manner similar to a lab experiment.…

  3. Spectral and Spread Spectral Teleportation

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  4. Spectral Index and Quasi-Periodic Oscillation Frequency Correlation in Black Hole (BH) Sources: Observational Evidence of Two Phases and Phase Transition in BHs

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Fiorito, Ralph

    2004-01-01

    Recent studies have shown that strong correlations are observed between the low frequencies (1-10 Hz) of quasiperiodic oscillations (QPOs) and the spectral power law index of several Black Hole (BH) candidate sources, in low hard states, steep power-law (soft) states and in transition between these states. The observations indicate that the X-ray spectrum of such state (phases) show the presence of a power-law component and are sometimes related to simultaneous radio emission indicated the probable presence of a jet. Strong QPOs (less than 20% rms) are present in the power density spectrum in the spectral range where the power-law component is dominant ( i.e. 60-90% ). This evidence contradicts the dominant long standing interpretation of QPOs as a signature of the thermal accretion disk. We present the data from the literature and our own data to illustrate the dominance of power-law index-QPO frequency correlations. We provide a model, that identifies and explains the origin of the QPOs and how they are imprinted on the properties of power-law flux component. We argue the existence of a bounded compact coronal region which is a natural consequence of the adjustment of Keplerian disk flow to the innermost sub-Keplerian boundary conditions near the central object and that ultimately leads to the formation of a transition layer (TL) between the adjustment radius and the innermost boundary. The model predicts two phases or states dictated by the photon upscattering produced in the TL: (1) hard state, in which the TL is optically thin and very hot (kT approx. greater than 50 keV) producing photon upscattering via thermal Componization; the photon spectrum index Gamma appprox.1.5 for this state is dictated by gravitational energy release and Compton cooling in an optically thin shock near the adjustment radius; (2) a soft state which is optically thick and relatively cold (approx. less than 5 keV); the index for this state, Gamma approx. 2.8 is determined by soft

  5. AMBER/VLTI high spectral resolution observations of the Brγ emitting region in HD 98922. A compact disc wind launched from the inner disc region

    NASA Astrophysics Data System (ADS)

    Caratti o Garatti, A.; Tambovtseva, L. V.; Garcia Lopez, R.; Kraus, S.; Schertl, D.; Grinin, V. P.; Weigelt, G.; Hofmann, K.-H.; Massi, F.; Lagarde, S.; Vannier, M.; Malbet, F.

    2015-10-01

    Context. High angular and spectral resolution observations can provide us with fundamental clues to the complex circumstellar structure of young stellar objects (YSOs) and to the physical processes taking place close to these sources. Aims: We analyse the main physical parameters and the circumstellar environment of the young Herbig Be star HD 98922. Methods: We present AMBER/VLTI high spectral resolution (R = 12 000) interferometric observations across the Brγ line, accompanied by UVES high-resolution spectroscopy and SINFONI-AO assisted near-infrared (NIR) integral field spectroscopic data. To interpret our observations, we develop a magneto-centrifugally driven disc-wind model. Results: Our analysis of the UVES spectrum shows that HD 98922 is a young (~5 × 105 yr) Herbig Be star (SpT = B9V), located at a distance of 440± 6050 pc, with a mass accretion rate (Ṁacc) of ~(9 ± 3) × 10-7 M⊙ yr-1. SINFONI K-band AO-assisted imaging shows a spatially resolved circumstellar disc-like region (~140 AU in diameter) with asymmetric brightness distribution. Our AMBER/VLTI UT observations indicate that the Brγ emitting region (ring-fit radius ~0.31 ± 0.04 AU) is smaller than the continuum emitting region (inner dust radius ~0.7 ± 0.2 AU), showing significant non-zero V-shaped differential phases (i.e. non S-shaped, as expected for a rotating disc). The value of the continuum-corrected pure Brγ line visibility at the longest baseline (89 m) is ~0.8 ± 0.1, i.e. the Brγ emitting region is partially resolved. Our modelling suggests that the observed Brγ line-emitting region mainly originates from a disc wind with a half opening angle of 30°, and with a mass-loss rate (Ṁw) of ~2 × 10-7 M⊙ yr-1. The observed V-shaped differential phases are reliably reproduced by combining a simple asymmetric continuum disc model with our Brγ disc-wind model. Conclusions: In conclusion, the Brγ emission of HD 98922 can be modelled with a disc wind that is able to

  6. Atmospheric correction for ocean spectra retrievals from high-altitude multi-angle, multi-spectral photo-polarimetric remote sensing observations: Results for coastal ocean waters.

    NASA Astrophysics Data System (ADS)

    Chowdhary, J.; van Diedenhoven, B.; Knobelspiesse, K. D.; Cairns, B.; Wasilewski, A. P.; McCubbin, I.

    2015-12-01

    A major challenge for spaceborne observations of ocean color is to correct for atmospheric scattering, which typically contributes ≥85% to the top-of-atmosphere (TOA) radiance and varies substantially with aerosols. Ocean color missions traditionally analyze TOA radiance in the near-infrared (NIR), where the ocean is black, to constrain the TOA atmospheric scattering in the visible (VIS). However, this procedure is limited by insufficient sensitivity of NIR radiance to absorption and vertical distribution of aerosols, and by uncertainties in the extrapolation of aerosol properties from the NIR to the VIS.To improve atmospheric correction for ocean color observations, one needs to change the traditional procedure for this correction and/or increase the aerosol information. The instruments proposed to increase the aerosol information content for the Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission include ultraviolet and Oxygen A-band observations, as well as multispectral and multiangle polarimetry. However few systematic studies have been performed to quantify the improvement such measurements bring to atmospheric correction. To study the polarimetric atmospheric correction capabilities of PACE-like instruments, we conducted field experiments off the Coast of California to obtain high-altitude (65,000 ft) and ship-based observations of water-leaving radiance. The airborne data sets consist of hyperspectral radiance between 380-2500 nm by the Airborne Visible/Infrared Imaging Spectrometer, and multi-spectral multi-angle polarimetric data between 410-2250 nm by the Research Scanning Polarimeter. We discuss examples of retrieved atmosphere and ocean state vectors, and of corresponding ocean color spectra obtained by subtracting the computed atmospheric scattering contribution from the high-altitude radiance measurements. The ocean color spectra thus obtained are compared with those measured from the ship.

  7. Testing climate models with space-borne spectrally resolved observations of outgoing terrestrial long-wave radiation. Part I: optimum choice for cloud screening.

    NASA Astrophysics Data System (ADS)

    Fiorenza, C.; Coppola, E.; Cimini, D.; Marzano, F. S.; Visconti, G.

    2003-04-01

    Testing Numerical Prediction Models (NPM) is a major issue for climate studies. Different approaches are possible, based on comparison between numerical output and atmospheric and oceanic measurements, such as air temperature, humidity, sea surface temperature. More recently, another approach has been proposed [Haskins et al, 1995; 1997; 1998; Goody et al., 1998], which make use of direct observations, such as outgoing long-wave radiance, instead of retrieved products. In order to accomplish this goal, it?'s necessary to obtain an equivalent set of data from numerical models and observations. Spectrally resolved outgoing long-wave radiance from the Earth-Atmosphere system has been measured by the IRIS and IMG [Hanel et al., 1972; Kobayashi et al., 1999; Cimini et al., 2002] interferometers. On the other hand, NPM do not provide this information directly. However, by processing the thermodynamical and chemical information from the NPM about the Earth-Atmosphere system with a Radiative Tranfer Model (RTM) code, we are able to produce this quantity. Although, since NPM do not provide detailed information about the microphysics of hydrometeors, which is necessary to compute exactly the radiation extinction by clouds, we are forced to reduced our analysis to clear-sky cases [Huang et al., 2002]. Thus, from the simulation point of view, we simply don?t input clouds in the RTM, while for the observations we need to detect and remove cloud-contaminated cases from the entire dataset. Several screening techniques are available in the open literature, each one using a different approach to detect cloud contamination, which forces us to make a choice. Thus, we take in account four different techniques, and apply each one independently to the observations data set. Finally, we discuss the results, motivating our choice of the optimum? " screening technique.

  8. On the Complexity of H2 Excitation Near Hot Stars: High Spectral and Spatial Resolution Observations of Compact Planetary Nebulae with IGRINS

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Kaplan, Kyle F.; Jaffe, Daniel T.

    2015-08-01

    Near-infrared emission lines of vibrationally-excited H2 were first detected in planetary nebulae (PNe) four decades ago. In some environments, e.g. outflows from low-mass young stellar objects, such emission is generally attributed to shock heating. The situation is more complicated for PNe, which host more than one potential agent of excitation. Shocks are indeed present within PNe, due to interactions among expanding layers of different velocities. On the other hand, the UV radiation field of the central star can populate excited vibrational levels of the ground electronic state via an indirect process, initiated by transitions to excited electronic states upon absorption of non-H-ionizing UV photons (the H2 Lyman-Werner bands), followed by radiative decay. When not modified by other processes, this produces a highly distinctive “pure fluorescent” H2 spectrum (Black & van Dishoeck 1987, ApJ, 322, 412). Such emission was first identified in a PN, Hb 12, by Dinerstein et al. 1988 (ApJ, 327, L27). Later surveys (e.g. Hora et al. 1999, ApJS, 124, 195; Likkel & Dinerstein et al. 2006, AJ, 131, 1515) found that some PNe display thermal (collisionally-dominated) spectra, a few are fluorescent, and others show intermediate line ratios. It is not always easy to distinguish whether the latter is due to a superposition of radiative and shock components (Davis et al. 2003, MNRAS, 344, 262), or to thermalization of initially radiatively excited molecules due to high density, a hard radiation field, and/or advective effects (e.g. Henney et al. 2007, ApJ, 671, 137). We present new observations of H2 in PNe obtained with the high-spectral resolution (R = 40,000), broad spectral grasp IGRINS spectrometer (Park & Jaffe et al. 2014, Proc SPIE, 9147). This instrument reveals small-scale structures in position-velocity space that differ in excitation and emergent line ratios. For example, the compact PN M 1-11 contains both a fluorescent shell of H2 and higher-velocity compact

  9. First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20–650 keV Energy Range

    NASA Astrophysics Data System (ADS)

    Roques, Jean-Pierre; Jourdain, Elisabeth; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT0 ∼ 7 keV) is introduced. Above this first component, a clear excess extending up to 400–600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10‑4 ph cm‑2 s‑1 (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic, and Poland with the participation of Russia and USA.

  10. Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations

    NASA Astrophysics Data System (ADS)

    Yeo, K. L.; Krivova, N. A.; Solanki, S. K.; Glassmeier, K. H.

    2014-10-01

    Context. Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. Aims: We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013 based on full-disc observations from the KPVT, SoHO/MDI, and SDO/HMI. Methods: SATIRE-S ascribes variation in solar irradiance on timescales greater than a day to photospheric magnetism. The solar spectrum is reconstructed from the apparent surface coverage of bright magnetic features and sunspots in the daily data using the modelled intensity spectra of these magnetic structures. We cross-calibrated the various data sets, harmonizing the model input so as to yield a single consistent time series as the output. Results: The model replicates 92% (R2 = 0.916) of the variability in the PMOD TSI composite including the secular decline between the 1996 and 2008 solar cycle minima. The model also reproduces most of the variability in observed Lyman-α irradiance and the Mg II index. The ultraviolet solar irradiance measurements from the UARS and SORCE missions are mutually consistent up to about 180 nm before they start to exhibit discrepant rotational and cyclical variability, indicative of unresolved instrumental effects. As a result, the agreement between model and measurement, while relatively good below 180 nm, starts to deteriorate above this wavelength. As with earlier similar investigations, the reconstruction cannot reproduce the overall trends in SORCE/SIM SSI. We argue, from the lack of clear solar cycle modulation in the SIM record and the inconsistency between the total flux recorded by the instrument and TSI, that unaccounted instrumental trends are present. Conclusions: The daily solar irradiance time series is consistent with observations from multiple sources, demonstrating its validity and utility for climate models. It also provides further evidence that photospheric magnetism is the prime driver of

  11. First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20-650 keV Energy Range

    NASA Astrophysics Data System (ADS)

    Roques, Jean-Pierre; Jourdain, Elisabeth; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ˜200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT0 ˜ 7 keV) is introduced. Above this first component, a clear excess extending up to 400-600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10-4 ph cm-2 s-1 (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic, and Poland with the participation of Russia and USA.

  12. Linguistic Theory and Actual Language.

    ERIC Educational Resources Information Center

    Segerdahl, Par

    1995-01-01

    Examines Noam Chomsky's (1957) discussion of "grammaticalness" and the role of linguistics in the "correct" way of speaking and writing. It is argued that the concern of linguistics with the tools of grammar has resulted in confusion, with the tools becoming mixed up with the actual language, thereby becoming the central element in a metaphysical…

  13. Cultural and environmental effects on the spectral development patterns of corn and soybeans: Field data analysis

    NASA Technical Reports Server (NTRS)

    Crist, E. P. (Principal Investigator)

    1982-01-01

    An overall approach to crop spectral understanding is presented which serves to maintain a strong link between actual plant responses and characteristics and spectral observations from ground based and spaceborne sensors. A specific technique for evaluating field reflectance data, as a part of the overall approach, is also described. Results of the application of this technique to corn and soybeans reflectance data collected by and at Purdue/LARS indicate that a number of common cultural and environmental factors can significantly affect the temporal spectral development patterns of these crops in tasseled cap greenness (a transformed variable of LANDSAT MSS signals).

  14. Solar radius determination from SODISM/PICARD and HMI/SDO observations of the decrease of the spectral solar radiance during the 2012 June Venus transit

    SciTech Connect

    Hauchecorne, A.; Meftah, M.; Irbah, A.; Hochedez, J.-F.

    2014-03-10

    On 2012 June 5-6, the transit of Venus provided a rare opportunity to determine the radius of the Sun using solar imagers observing a well-defined object, namely, the planet and its atmosphere, partially occulting the Sun. A new method has been developed to estimate the solar radius during a planetary transit. It is based on the estimation of the spectral solar radiance decrease in a region around the contact between the planet and the Sun at the beginning of the ingress and at the end of the egress. The extrapolation to zero of the radiance decrease versus the Sun-to-Venus apparent angular distance allows estimation of the solar radius at the time of first and fourth contacts. This method presents the advantage of being almost independent on the plate scale, the distortion, the refraction by the planetary atmosphere, and on the point-spread function of the imager. It has been applied to two space solar visible imagers, SODISM/PICARD and HMI/SDO. The found results are mutually consistent, despite their different error budgets: 959.''85 ± 0.''19 (1σ) for SODISM at 607.1 nm and 959.''90 ± 0.''06 (1σ) for HMI at 617.3 nm.

  15. Planetcam UPV/EHU - A lucky imaging camera for multi-spectral observations of the Giant Planets in 0.38-1.7 microns

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Mendikoa, I.; Sánchez-Lavega, A.; Pérez-Hoyos, S.; Rojas, J. F.; García-Melendo, E.

    2015-10-01

    PlanetCam UPV/EHU [1] is an astronomical instrument designed for high-resolution observations of Solar System planets. The main scientific themes are atmospheric dynamics and the vertical cloud structure of Jupiter and Saturn. The instrument uses a dichroic mirror to separate the light in two beams with spectral ranges from 380 nm to1 micron (visible channel) and from 1 to 1.7 microns (Short Wave InfraRed, SWIR channel) and two detectors working simultaneously with fast acquisition modes. High-resolution images are built using lucky imaging techniques [2]. Several hundred short exposed images are obtained and stored in fits files. Images are automatically reduced by a pipeline called PLAYLIST (written in IDL and requiring no interaction by the user)which selects the best frames and co-registers them using image correlation over several tie-points. The result is a high signal to noise ratio image that can be processed to show the faint structures in the data. PlanetCam is a visiting instrument mainly built for the 1.2 3 and 2.2m telescopes at Calar Alto Observatory in Spain but it has also been tested in the 1.5 m Telescope Carlos Sanchez in Tenerife and the 1.05 m Telescope at the Pic du Midi observatory.

  16. Solar Radius Determination from Sodism/Picard and HMI/SDO Observations of the Decrease of the Spectral Solar Radiance during the 2012 June Venus Transit

    NASA Astrophysics Data System (ADS)

    Hauchecorne, A.; Meftah, M.; Irbah, A.; Couvidat, S.; Bush, R.; Hochedez, J.-F.

    2014-03-01

    On 2012 June 5-6, the transit of Venus provided a rare opportunity to determine the radius of the Sun using solar imagers observing a well-defined object, namely, the planet and its atmosphere, partially occulting the Sun. A new method has been developed to estimate the solar radius during a planetary transit. It is based on the estimation of the spectral solar radiance decrease in a region around the contact between the planet and the Sun at the beginning of the ingress and at the end of the egress. The extrapolation to zero of the radiance decrease versus the Sun-to-Venus apparent angular distance allows estimation of the solar radius at the time of first and fourth contacts. This method presents the advantage of being almost independent on the plate scale, the distortion, the refraction by the planetary atmosphere, and on the point-spread function of the imager. It has been applied to two space solar visible imagers, SODISM/PICARD and HMI/SDO. The found results are mutually consistent, despite their different error budgets: 959.''85 ± 0.''19 (1σ) for SODISM at 607.1 nm and 959.''90 ± 0.''06 (1σ) for HMI at 617.3 nm.

  17. Spectral Index and Quasi-Periodic Oscillation Frequency Correlation in Black Hole Sources: Observational Evidence of Two Phases and Phase Transition in Black Holes

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Fiorito, Ralph

    2004-01-01

    Recent studies have shown that strong correlations are observed between the low frequencies (1-10 Hz) of quasi-periodic oscillations (QPOs) and the spectral power law index of several black hole (BH) candidate sources, in low (hard) states, steep power law (soft) states, and transitions between these states. The observations indicate that the X-ray spectra of such state (phases) show the presence of a power-law component and are sometimes related to simultaneous radio emission, indicating the probable presence of a jet. Strong QPOs (>20% rms) are present in the power density spectrum in the spectral range where the power-law component is dominant (i.e., 60%90%). This evidence contradicts the dominant, long-standing interpretation of QPOs as a signature of the thermal accretion disk. We present the data from the literature and our own data to illustrate the dominance of power-law index-QPO frequency correlations. We provide a model that identifies and explains the origin of the QPOs and how they are imprinted on the properties of the power-law flux component. We argue for the existence of a bounded compact coronal region that is a natural consequence of the adjustment of the Keplerian disk flow to the innermost sub-Keplerian boundary conditions near the central object and that ultimately leads to the formation of a transition layer (TL) between the adjustment radius and the innermost boundary. The model predicts two phases or states dictated by the photon upscattering produced in the TL: (1) a hard state, in which the TL is optically thin and very hot (kT approximately greater than 50 keV), producing photon upscattering via thermal Comptonization (the photon spectrum index Gamma approximates 1.7 for this state is dictated by gravitational energy release and Compton cooling in an optically thin shock near the adjustment radius), and (2) a soft state that is optically thick and relatively cold (kT approximately less than 5 keV the index for this state, Gamma

  18. Covariance propagation in spectral indices

    DOE PAGESBeta

    Griffin, P. J.

    2015-01-09

    In this study, the dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This study identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, andmore » provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.« less

  19. Covariance propagation in spectral indices

    SciTech Connect

    Griffin, P. J.

    2015-01-09

    In this study, the dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This study identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, and provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.

  20. Covariance Propagation in Spectral Indices

    SciTech Connect

    Griffin, P.J.

    2015-01-15

    The dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This paper identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, and provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.

  1. Covariance Propagation in Spectral Indices

    NASA Astrophysics Data System (ADS)

    Griffin, P. J.

    2015-01-01

    The dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This paper identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, and provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.

  2. Robust Satellite Techniques for monitoring earth emitted radiation in the Japanese seismic area by using MTSAT observations in the TIR spectral range

    NASA Astrophysics Data System (ADS)

    Genzano, Nicola; Filizzola, Carolina; Hattori, Katsumi; Lisi, Mariano; Paciello, Rossana; Pergola, Nicola; Tramutoli, Valerio

    2016-04-01

    Since eighties, the fluctuations of Earth's thermally emitted radiation, measured by satellite sensors operating in the thermal infrared (TIR) spectral range, have been associated with the complex process of preparation for major earthquakes. But, like other claimed earthquake precursors (seismological, physical, chemical, biological, etc.) they have been for long-time considered with some caution by scientific community. The lack of a rigorous definition of anomalous TIR signal fluctuations and the scarce attention paid to the possibility that other causes (e.g. meteorological) different from seismic activity could be responsible for the observed TIR variations were the main causes of such skepticism. Compared with previously proposed approaches the general change detection approach, named Robust Satellite Techniques (RST), showed good ability to discriminate anomalous TIR signals possibly associated to seismic activity, from the normal variability of TIR signal due to other causes. Thanks to its full exportability on different satellite packages, since 2001 RST has been implemented on TIR images acquired by polar (e.g. NOAA-AVHRR, EOS -MODIS) and geostationary (e.g. MSG-SEVIRI, NOAA-GOES/W, GMS-5/VISSR) satellite sensors, in order to verify the presence (or absence) of TIR anomalies in presence (absence) of earthquakes (with M>4) in different seismogenic areas around the world (e.g. Italy, Greece, Turkey, India, Taiwan, etc.). In this paper, the RST data analysis approach has been implemented on TIR satellite records collected over Japan by the geostationary satellite sensor MTSAT (Multifunctional Transport SATellites) and RETIRA (Robust Estimator of TIR Anomalies) index was used to identify Significant Sequences of TIR Anomalies (SSTAs) in a possible space-time relations with seismic events. Achieved results will be discussed in the perspective of a multi-parametric approach for a time-Dependent Assessment of Seismic Hazard (t-DASH).

  3. Mass Spectral Observations of Submicron Aerosol Particles and Production of Secondary Organic Aerosol at an Anthropogenically Influenced Site during the Wet Season of GoAmazon2014

    NASA Astrophysics Data System (ADS)

    de Sá, S. S.; Palm, B. B.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Newburn, M. K.; Ferreira De Brito, J.; Artaxo, P.; Shilling, J. E.; Souza, R. A. F. D.; Manzi, A. O.; Alexander, M. L.; Jimenez, J. L.; Martin, S. T.

    2014-12-01

    As part of GoAmazon2014, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed to characterize the composition, size, and spectral markers present in submicron atmospheric aerosol particles at a site downwind of Manaus, Brazil, in the central Amazon basin. The focus was on the influence of biogenic-anthropogenic interactions on the measured aerosol particles, especially as related to the formation of secondary organic aerosol (SOA). Through a combination of meteorology, emissions, and chemistry, the research site was affected by biogenic emissions from the tropical rainforest that were periodically mixed with urban outflow from the Manaus metropolitan area. Results from the first intensive operation period, from 1 February to 31 March 2014, show that for the wet season the PM1 mass concentration had typical values on order of 1 to 2 μg/m3. The organic species were dominant, followed by sulfate. The mass-diameter distribution of the particle population had a prevailing mode between 300 and 400 nm (vacuum aerodynamic diameter, dva), and at times a smaller mode at finer size was also present. Highly oxidized organic material was frequently observed, characterized by a dominant peak at m/z 44. There was a diel trend in the elemental oxygen-to-carbon (O:C) ratio peaking in the afternoon. The analysis of the results aims at delineating the anthropogenic impact on the measurements. Multivariate statistical analysis by positive-matrix factorization (PMF) is applied to the time series of organic particle mass spectra. The factors and their loadings provide information on the relative and time-varying contributions of different sources and processes affecting the organic component of the aerosol particle phase. Relationships between AMS results and measurements from co-located instruments that provide information on anthropogenic and biogenic gas and particle tracers are investigated, toward the goal of improving the understanding of

  4. Spectral stratigraphy

    NASA Technical Reports Server (NTRS)

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  5. High temperature spectral gamma well logging

    SciTech Connect

    Normann, R.A.; Henfling, J.A.

    1997-01-01

    A high temperature spectral gamma tool has been designed and built for use in small-diameter geothermal exploration wells. Several engineering judgments are discussed regarding operating parameters, well model selection, and signal processing. An actual well log at elevated temperatures is given with spectral gamma reading showing repeatability.

  6. How People Actually Use Thermostats

    SciTech Connect

    Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel; Pritoni, Marco

    2010-08-15

    Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.

  7. Diurnal patterns of wheat spectral reflectances and their importance in the assessment of canopy parameters from remotely sensed observations. [Phoenix, Arizona

    NASA Technical Reports Server (NTRS)

    Pinter, P. J.; Jackson, R. D.; Idso, S. B.; Reginato, R. J. (Principal Investigator)

    1982-01-01

    Spectral reflectances of Produra wheat were measured at 13 different times of the day at Phoenix, Arizona, during April 1979 using a nadir-oriented hand-held 4-band radiometer which had bandpass characteristics similar to those on LANDSAT satellites. Different Sun altitude and azimuth angles caused significant diurnal changes in radiant return in both visible and near-IR regions of the spectrum and in several vegetation indices derived from them. The magnitude of these changes were related to different canopy architecture, percent cover and green leaf area conditions. Spectral measurements taken at each time period were well correlated with green leaf area index but the nature of the relationship changed significantly with time of day. Thus, a significant bias in the estimation of the green leaf area index from remotely sensed spectral data could occur if sun angles are not properly accounted for.

  8. Spectral stratigraphy

    NASA Astrophysics Data System (ADS)

    Lang, Harold R.

    1991-09-01

    Stratigraphic and structural studies of the Wind River and Bighorn basins, Wyoming, and the Guerrero-Morelos basin, Mexico, have resulted in development of ''spectral stratigraphy.'' This approach to stratigraphic analysis uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. This paper reviews selected published examples that illustrate this new stratigraphic procedure. Visible to thermal infrared laboratory, spectral measurements of sedimentary rocks are the physical basis for spectral stratigraphy. Results show that laboratory, field, and remote spectroscopy can augment conventional laboratory and field methods for petrologic analysis, stratigraphic correlation, interpretation of depositional environments, and construction of facies models. Landsat thematic mapper data are used to map strata and construct stratigraphic columns and structural cross sections at 1:24,000 scale or less. Experimental multispectral thermal infrared aircraft data facilitate lithofacies/biofacies analyses. Visible short-wavelength infrared imaging spectrometer data allow remote determination of the stratigraphic distribution of iron oxides, quartz, calcite, dolomite, gypsum, specific clay species, and other minerals diagnostic of environments of deposition. Development of a desk-top, computer-based, geologic analysis system that provides for automated application of these approaches to coregistered digital image and topographic data portends major expansion in the use of spectral stratigraphy for purely scientific (lithospheric research) or practical (resource exploration) objectives.

  9. Observation of Switchable Photoresponse of a Monolayer WSe2-MoS2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging.

    PubMed

    Son, Youngwoo; Li, Ming-Yang; Cheng, Chia-Chin; Wei, Kung-Hwa; Liu, Pingwei; Wang, Qing Hua; Li, Lain-Jong; Strano, Michael S

    2016-06-01

    In the pursuit of two-dimensional (2D) materials beyond graphene, enormous advances have been made in exploring the exciting and useful properties of transition metal dichalcogenides (TMDCs), such as a permanent band gap in the visible range and the transition from indirect to direct band gap due to 2D quantum confinement, and their potential for a wide range of device applications. In particular, recent success in the synthesis of seamless monolayer lateral heterostructures of different TMDCs via chemical vapor deposition methods has provided an effective solution to producing an in-plane p-n junction, which is a critical component in electronic and optoelectronic device applications. However, spatial variation of the electronic and optoelectonic properties of the synthesized heterojunction crystals throughout the homogeneous as well as the lateral junction region and the charge carrier transport behavior at their nanoscale junctions with metals remain unaddressed. In this work, we use photocurrent spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic diode behavior for WSe2 and MoS2, owing to the formation of a Schottky barrier of dissimilar properties. Notably, by changing the polarity and magnitude of the tip voltage applied, pixels that show the photoresponse of the heterostructure are observed to be selectively switched on and off, allowing for the realization of a hyper-resolution array of the switchable photodiode pixels. This experimental approach has significant implications toward the development of novel optoelectronic technologies for regioselective photodetection and imaging at nanoscale resolutions. Comparative 2D Fourier analysis of physical height and current images shows high spatial frequency variations in substrate/MoS2 (or WSe2) contact that

  10. Simultaneous XMM-Newton and HST-COS observation of 1H 0419-577. II. Broadband spectral modeling of a variable Seyfert galaxy

    NASA Astrophysics Data System (ADS)

    Di Gesu, L.; Costantini, E.; Piconcelli, E.; Ebrero, J.; Mehdipour, M.; Kaastra, J. S.

    2014-03-01

    In this paper, we present the longest exposed (97 ks) XMM-Newton EPIC-pn spectrum ever obtained for the Seyfert 1.5 galaxy1H 0419-577. With the aim of explaining the broadband emission of this source, we took advantage of the simultaneous coverage in the optical/UV that was provided in the present case by the XMM-Newton Optical Monitor and by a HST-COS observation. Archival FUSE flux measurements in the far-ultraviolet were also used for the present analysis. We successfully modeled the X-ray spectrum and the optical/UV fluxes data points using a Comptonization model. We found that a blackbody temperature of T ~ 56 eV accounts for the optical/UV emission originating in the accretion disk. This temperature serves as an input for the Comptonized components that model the X-ray continuum. Both a warm (Twc ~ 0.7 keV, τwc ~ 7) and a hot corona (Thc ~ 160 keV, τhc ~ 0.5) intervene to upscatter the disk photons to X-ray wavelengths. With the addition of a partially covering (Cv ~ 50%) cold absorber with a variable opacity ( NH~ [1019-1022] cm-2), this model can also explain the historical spectral variability of this source, with the present dataset presenting the lowest one ( NH~1019 cm-2). We discuss a scenario where the variable absorber becomes less opaque in the highest flux states because it gets ionized in response to the variations of the X-ray continuum. The lower limit for the absorber density derived in this scenario is typical for the broad line region clouds. We infer that1H 0419-577may be viewed from an intermediate inclination angle i ≥ 54°, and, on this basis, we speculate that the X-ray obscuration may be associated with the innermost dust-free region of the obscuring torus. Finally, we critically compare this scenario with all the different models (e.g., disk reflection) that have been used in the past to explain the variability of this source.

  11. RXTE/ASM and Swift/BAT observations of spectral transitions in bright X-ray binaries in 2005-2010

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Yu, Wen-Fei; Yan, Zhen

    2011-04-01

    We have studied X-ray spectral state transitions that can be seen in the long-term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010. We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT. In total, we identified 128 hard-to-soft transitions, of which 59 occurred after 2008. We also determined the transition fluxes and the peak fluxes of the following soft states, updated the measurements of the luminosity corresponding to the H-S transition and the peak luminosity of the following soft state in about 30 bright persistent and transient black hole and neutron star binaries following Yu & Yan, and found the luminosity correlation and the luminosity range of spectral transitions in data between 2008-2010 are about the same as those derived from data before 2008. This further strengthens the idea that the luminosity at which the H-S spectral transition occurs in the Galactic X-ray binaries is determined by non-stationary accretion parameters such as the rate-of-change of the mass accretion rate rather than the mass accretion rate itself. The correlation is also found to hold in data of individual sources 4U 1608-52 and 4U 1636-53.

  12. INFRARED SPECTRAL ENERGY DISTRIBUTIONS OF SEYFERT GALAXIES: SPITZER SPACE TELESCOPE OBSERVATIONS OF THE 12 {mu}m SAMPLE OF ACTIVE GALAXIES

    SciTech Connect

    Gallimore, J. F.; Yzaguirre, A.; Jakoboski, J.; Stevenosky, M. J.; Axon, D. J.; O'Dea, C. P.; Robinson, A.; Baum, S. A.; Buchanan, C. L.; Elitzur, M.; Elvis, M.

    2010-03-01

    The mid-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 {mu}m sample are presented. The data were collected using all three instruments, Infrared Array Camera (IRAC), Infrared Spectrograph (IRS), and Multiband Imaging Photometer for Spitzer (MIPS), aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20'' diameter circular apertures. The MIPS data were obtained in SED mode, providing very low-resolution spectroscopy (R {approx} 20) between {approx}55 and 90 {mu}m in a larger, 20'' x 30'' synthetic aperture. We further present the data from a spectral decomposition of the SEDs, including equivalent widths and fluxes of key emission lines; silicate 10 {mu}m and 18 {mu}m emission and absorption strengths; IRAC magnitudes; and mid-far-infrared spectral indices. Finally, we examine the SEDs averaged within optical classifications of activity. We find that the infrared SEDs of Seyfert 1s and Seyfert 2s with hidden broad line regions (HBLRs, as revealed by spectropolarimetry or other technique) are qualitatively similar, except that Seyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption. The infrared SEDs of other classes within the 12 {mu}m sample, including Seyfert 1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER, and H II galaxies, appear to be dominated by star formation, as evidenced by blue IRAC colors, strong polycyclic aromatic hydrocarbon emission, and strong far-infrared continuum emission, measured relative to mid-infrared continuum emission.

  13. Spectral and temporal behavior of low mass X ray binaries observed with the Einstein SSS and MPC, and the Broad Band X Ray Telescope

    NASA Astrophysics Data System (ADS)

    Christian, Damian Joseph

    An extensive survey of 50 low mass X-ray binaries was carried out using the HEAO-2 Einstein Solid State Spectrometer data (0.5-4.5 keV) with the Monitor Proportional Counter data (1.2-20.0 keV). The SSS provided 160 eV resolution below 4.5 keV with about 200 sq cm of area, 100 times that of grating instruments on Einstein and EXOSAT. Additional observations were obtained with the Broad Band X-Ray Telescope (0.5-12 keV). Although LMXRB are some of the most luminous X-ray sources and include one of the first X-ray sources discovered, the nature of their emission regions has remained uncertain. Spectra were selected on the basis of intensity and fit with a set of simple and complex spectral models. For all the subclasses, including Eddington-limited bulge sources, bursters, dippers, the soft spectrum black hole candidates, and a few transients in decline, the spectra could be fit acceptably with combinations of thermal bremsstrahlung and blackbody spectra or a Comptonized spectrum and a blackbody. The results rule out optically thick disk models for the bright Z sources and power law models for bursters. The results suggest a progression of spectra as a function of X-ray luminosity for the bursters, Atoll, and Z sources, in which there are separate emission regions, one optically thin to scattering. The optically thick component that appears for higher luminosity may be due to a boundary layer or to high optical depth to scattering in the flow. A lower temperature blackbody indicated in some cases could be an expected contribution from the accretion disk. The soft spectrum sources are dominated by blackbody spectra, but for two, low effective area of emission is a problem for the black hole interpretation. There did not appear to be any clear selection between models for the sources with high binary orbit inclinations. Column densities for absorption by cold gas were determined simultaneously with the fits. They give distance estimates for the galactic bulge sources

  14. The actual goals of geoethics

    NASA Astrophysics Data System (ADS)

    Nemec, Vaclav

    2014-05-01

    The most actual goals of geoethics have been formulated as results of the International Conference on Geoethics (October 2013) held at the geoethics birth-place Pribram (Czech Republic): In the sphere of education and public enlightenment an appropriate needed minimum know how of Earth sciences should be intensively promoted together with cultivating ethical way of thinking and acting for the sustainable well-being of the society. The actual activities of the Intergovernmental Panel of Climate Changes are not sustainable with the existing knowledge of the Earth sciences (as presented in the results of the 33rd and 34th International Geological Congresses). This knowledge should be incorporated into any further work of the IPCC. In the sphere of legislation in a large international co-operation following steps are needed: - to re-formulate the term of a "false alarm" and its legal consequences, - to demand very consequently the needed evaluation of existing risks, - to solve problems of rights of individuals and minorities in cases of the optimum use of mineral resources and of the optimum protection of the local population against emergency dangers and disasters; common good (well-being) must be considered as the priority when solving ethical dilemmas. The precaution principle should be applied in any decision making process. Earth scientists presenting their expert opinions are not exempted from civil, administrative or even criminal liabilities. Details must be established by national law and jurisprudence. The well known case of the L'Aquila earthquake (2009) should serve as a serious warning because of the proven misuse of geoethics for protecting top Italian seismologists responsible and sentenced for their inadequate superficial behaviour causing lot of human victims. Another recent scandal with the Himalayan fossil fraud will be also documented. A support is needed for any effort to analyze and to disclose the problems of the deformation of the contemporary

  15. [Analyses of spectral emissivity in radiation temperature measurement].

    PubMed

    Fu, Tai-Ran; Cheng, Xiao-Fang; Zhong, Mao-Hua; Yang, Zang-Jian

    2008-01-01

    The complexity of the spectral emissivity of actual surfaces is the key point in the research and applications of radiation temperature measurement, resulting in the difficulty in the achievement of the temperature measurement. In the present paper, based on the discussions of the Taylor expansion, the non-dimension wavelength and the exponent, the authors describe the mathematical expression of the spectral emissivity of actual surfaces, and establish the general spectral emissivity function. Through the fitting of experimental data of the spectral emissivities of different metals at different temperatures, the applicability of the spectral emissivity function is verified which especially becomes the fundamental in the research of primary spectrum pyrometry. PMID:18422106

  16. Spectral Predictors

    SciTech Connect

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  17. Spectral Dictionaries

    PubMed Central

    Kim, Sangtae; Gupta, Nitin; Bandeira, Nuno; Pevzner, Pavel A.

    2009-01-01

    Database search tools identify peptides by matching tandem mass spectra against a protein database. We study an alternative approach when all plausible de novo interpretations of a spectrum (spectral dictionary) are generated and then quickly matched against the database. We present a new MS-Dictionary algorithm for efficiently generating spectral dictionaries and demonstrate that MS-Dictionary can identify spectra that are missed in the database search. We argue that MS-Dictionary enables proteogenomics searches in six-frame translation of genomic sequences that may be prohibitively time-consuming for existing database search approaches. We show that such searches allow one to correct sequencing errors and find programmed frameshifts. PMID:18703573

  18. The actual status of Astronomy in Moldova

    NASA Astrophysics Data System (ADS)

    Gaina, A.

    The astronomical research in the Republic of Moldova after Nicolae Donitch (Donici)(1874-1956(?)) were renewed in 1957, when a satellites observations station was open in Chisinau. Fotometric observations and rotations of first Soviet artificial satellites were investigated under a program SPIN put in action by the Academy of Sciences of former Socialist Countries. The works were conducted by Assoc. prof. Dr. V. Grigorevskij, which conducted also research in variable stars. Later, at the beginning of 60-th, an astronomical Observatory at the Chisinau State University named after Lenin (actually: the State University of Moldova), placed in Lozovo-Ciuciuleni villages was open, which were coordinated by Odessa State University (Prof. V.P. Tsesevich) and the Astrosovet of the USSR. Two main groups worked in this area: first conducted by V. Grigorevskij (till 1971) and second conducted by L.I. Shakun (till 1988), both graduated from Odessa State University. Besides this research areas another astronomical observations were made: Comets observations, astroclimate and atmospheric optics in collaboration with the Institute of the Atmospheric optics of the Siberian branch of the USSR (V. Chernobai, I. Nacu, C. Usov and A.F. Poiata). Comets observations were also made since 1988 by D. I. Gorodetskij which came to Chisinau from Alma-Ata and collaborated with Ukrainean astronomers conducted by K.I. Churyumov. Another part of space research was made at the State University of Tiraspol since the beggining of 70-th by a group of teaching staff of the Tiraspol State Pedagogical University: M.D. Polanuer, V.S. Sholokhov. No a collaboration between Moldovan astronomers and Transdniestrian ones actually exist due to War in Transdniestria in 1992. An important area of research concerned the Radiophysics of the Ionosphere, which was conducted in Beltsy at the Beltsy State Pedagogical Institute by a group of teaching staff of the University since the beginning of 70-th: N. D. Filip, E

  19. Spectral and Temporal Properties of the Ultraluminous X-Ray Pulsar in M82 from 15 years of Chandra Observations and Analysis of the Pulsed Emission Using NuSTAR

    NASA Astrophysics Data System (ADS)

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felix; Hornschemeier, Ann; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko

    2016-01-01

    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 1040 erg s-1, a factor of ˜100 times the Eddington luminosity for a 1.4 M⊙ compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.5-8 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF) of the pulsar is not contaminated by nearby sources. We fit the Chandra spectra of the pulsar with a power-law model and a disk blackbody model, subjected to interstellar absorption in M82. We carefully assess for the effect of pile-up in our observations, where four observations have a pile-up fraction of >10%, which we account for during spectral modeling with a convolution model. When fitted with a power-law model, the average photon index when the source is at high luminosity (LX > 1039 erg s-1) is Γ = 1.33 ± 0.15. For the disk blackbody model, the average temperature is Tin = 3.24 ± 0.65 keV, the spectral shape being consistent with other luminous X-ray pulsars. We also investigated the inclusion of a soft excess component and spectral break, finding that the spectra are also consistent with these features common to luminous X-ray pulsars. In addition, we present spectral analysis from NuSTAR over the 3-50 keV range where we have isolated the pulsed component. We find that the pulsed emission in this band is best fit by a power-law with a high-energy cutoff, where Γ = 0.6 ± 0.3 and {E}{{C}}={14}-3+5 keV. While the pulsar has previously been identified as a transient, we find from our longer-baseline study that it has been remarkably active over the 15-year period, where for 9/19 (47%) observations that we analyzed, the pulsar appears to be emitting at a luminosity in excess of

  20. Parametric Explosion Spectral Model

    SciTech Connect

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  1. Water frost and ice - The near-infrared spectral reflectance 0.65-2.5 microns. [observed on natural satellites and other solar system objects

    NASA Technical Reports Server (NTRS)

    Clark, R. N.

    1981-01-01

    The spectral reflectance of water frost and frost on ice as a function of temperature and grain size is presented with 1-1/2% spectral resolution in the 0.65- to 2.5-micron wavelength region. The well-known 2.0-, 1.65-, and 1.5-micron solid water absorption bands are precisely defined along with the little studied 1.25-micron band and the previously unidentified (in reflectance) 1.04-, 0.90-, and 0.81-micron absorption bands. The 1.5-microns band complex is quantitatively analyzed using a nonlinear least squares algorithm to resolve the band into four Gaussian components as a function of grain size and temperature. It is found that the 1.65-micron component, which was thought to be a good temperature sensor, is highly grain-size dependent and poorly suited to temperature sensing. Another Gaussian component appears to show a dependence of width on grain size while being independent of temperature. The relative apparent band depths are different for frost layers on ice than for thick layers of frost and may explain the apparent band depths seen in many planetary reflectance spectra.

  2. Coloration Determination of Spectral Darkening Occurring on a Broadband Earth Observing Radiometer: Application to Clouds and the Earth's Radiant Energy System (CERES)

    NASA Technical Reports Server (NTRS)

    Matthews, Grant; Priestley, Kory; Loeb, Norman G.; Loukachine, Konstantin; Thomas, Susan; Walikainen, Dale; Wielicki, Bruce A.

    2006-01-01

    It is estimated that in order to best detect real changes in the Earth s climate system, space based instrumentation measuring the Earth Radiation Budget (ERB) must remain calibrated with a stability of 0.3% per decade. Such stability is beyond the specified accuracy of existing ERB programs such as the Clouds and the Earth s Radiant Energy System (CERES, using three broadband radiometric scanning channels: the shortwave 0.3 - 5microns, total 0.3. > 100microns, and window 8 - 12microns). It has been shown that when in low earth orbit, optical response to blue/UV radiance can be reduced significantly due to UV hardened contaminants deposited on the surface of the optics. Since typical onboard calibration lamps do not emit sufficient energy in the blue/UV region, this darkening is not directly measurable using standard internal calibration techniques. This paper describes a study using a model of contaminant deposition and darkening, in conjunction with in-flight vicarious calibration techniques, to derive the spectral shape of darkening to which a broadband instrument is subjected. Ultimately the model uses the reflectivity of Deep Convective Clouds as a stability metric. The results of the model when applied to the CERES instruments on board the EOS Terra satellite are shown. Given comprehensive validation of the model, these results will allow the CERES spectral responses to be updated accordingly prior to any forthcoming data release in an attempt to reach the optimum stability target that the climate community requires.

  3. Multipurpose spectral imager.

    PubMed

    Sigernes, F; Lorentzen, D A; Heia, K; Svenøe, T

    2000-06-20

    A small spectral imaging system is presented that images static or moving objects simultaneously as a function of wavelength. The main physical principle is outlined and demonstrated. The instrument is capable of resolving both spectral and spatial information from targets throughout the entire visible region. The spectral domain has a bandpass of 12 A. One can achieve the spatial domain by rotating the system's front mirror with a high-resolution stepper motor. The spatial resolution range from millimeters to several meters depends mainly on the front optics used and whether the target is fixed (static) or movable relative to the instrument. Different applications and examples are explored, including outdoor landscapes, industrial fish-related targets, and ground-level objects observed in the more traditional way from an airborne carrier (remote sensing). Through the examples, we found that the instrument correctly classifies whether a shrimp is peeled and whether it can disclose the spectral and spatial microcharacteristics of targets such as a fish nematode (parasite). In the macroregime, we were able to distinguish a marine vessel from the surrounding sea and sky. A study of the directional spectral albedo from clouds, mountains, snow cover, and vegetation has also been included. With the airborne experiment, the imager successfully classified snow cover, leads, and new and rafted ice, as seen from 10.000 ft (3.048 m). PMID:18345245

  4. Spectral Automorphisms in Quantum Logics

    NASA Astrophysics Data System (ADS)

    Ivanov, Alexandru; Caragheorgheopol, Dan

    2010-12-01

    In quantum mechanics, the Hilbert space formalism might be physically justified in terms of some axioms based on the orthomodular lattice (OML) mathematical structure (Piron in Foundations of Quantum Physics, Benjamin, Reading, 1976). We intend to investigate the extent to which some fundamental physical facts can be described in the more general framework of OMLs, without the support of Hilbert space-specific tools. We consider the study of lattice automorphisms properties as a “substitute” for Hilbert space techniques in investigating the spectral properties of observables. This is why we introduce the notion of spectral automorphism of an OML. Properties of spectral automorphisms and of their spectra are studied. We prove that the presence of nontrivial spectral automorphisms allow us to distinguish between classical and nonclassical theories. We also prove, for finite dimensional OMLs, that for every spectral automorphism there is a basis of invariant atoms. This is an analogue of the spectral theorem for unitary operators having purely point spectrum.

  5. VNIR Spectral Differences on Natural and Brushed/Wind-abraded Surfaces on Home Plate, Gusev Crater, Mars: Spirit Pancam and HiRISE Color Observations

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Johnson, J. R.; Schmidt, M. E.; Bell, J. F.

    2008-03-01

    Color differences between the eastern and western rims of Home Plate are examined using Spirit Pancam and HiRISE color observations. Differences between near-field and remote observations are considered.

  6. Herschel Observations of Extraordinary Sources: Analysi sof the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications

    NASA Astrophysics Data System (ADS)

    Crockett, N. R.; Bergin, E. A.; Neill, J. L.; Favre, C.; Blake, G. A.; Herbst, E.; Anderson, D. E.; Hassel, G. E.

    2015-06-01

    We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH3CN, C2H3CN, C2H5CN, and NH2CHO systematically trace hotter gas than the oxygen bearing organics CH3OH, C2H5OH, CH3OCH3, and CH3OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (Tkin ∼ 300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales ≳105 years, with several species being underpredicted by less than 3σ. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules that also contain oxygen (i.e., SO, SO2, and OCS) tend to probe the hottest gas toward Orion KL, indicating the formation pathways for these species are most efficient at high temperatures. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  7. Observations of plan-view sand ripple behavior and spectral wave climate on the inner shelf of San Pedro Bay, California

    USGS Publications Warehouse

    Xu, J. P.

    2005-01-01

    Concurrent video images of sand ripples and current meter measurements of directional wave spectra are analyzed to study the relations between waves and wave-generated sand ripples. The data were collected on the inner shelf off Huntington Beach, California, at 15 m water depth, where the sea floor is comprised of well-sorted very fine sands (D50=92 ??m), during the winter of 2002. The wave climate, which was controlled by southerly swells (12-18 s period) and westerly wind waves (5-10 s period), included three wave types: (A) uni-modal, swells only; (B) bi-modal, swells dominant; and (C) bi-modal, wind-wave dominant. Each wave type has distinct relations with the plan-view shapes of ripples that are classified into five types: (1) sharp-crested, two-dimensional (2-D) ripples; (2) sharp-crested, brick-pattern, 3-D ripples; (3) bifurcated, 3-D ripples; (4) round-crested, shallow, 3-D ripples; and (5) flat bed. The ripple spacing is very small and varies between 4.5 and 7.5 cm. These ripples are anorbital as ripples in many field studies. Ripple orientation is only correlated with wave directions during strong storms (wave type C). In a poly-modal, multi-directional spectral wave environment, the use of the peak parameters (frequency, direction), a common practice when spectral wave measurements are unavailable, may lead to significant errors in boundary layer and sediment transport calculations. ?? 2004 Elsevier Ltd. All rights reserved.

  8. Spectral image reconstruction through the PCA transform

    NASA Astrophysics Data System (ADS)

    Ma, Long; Qiu, Xuewei; Cong, Yangming

    2015-12-01

    Digital color image reproduction based on spectral information has become a field of much interest and practical importance in recent years. The representation of color in digital form with multi-band images is not very accurate, hence the use of spectral image is justified. Reconstructing high-dimensional spectral reflectance images from relatively low-dimensional camera signals is generally an ill-posed problem. The aim of this study is to use the Principal component analysis (PCA) transform in spectral reflectance images reconstruction. The performance is evaluated by the mean, median and standard deviation of color difference values. The values of mean, median and standard deviation of root mean square (GFC) errors between the reconstructed and the actual spectral image were also calculated. Simulation experiments conducted on a six-channel camera system and on spectral test images show the performance of the suggested method.

  9. Spectral Anisotropy of Elsässer Variables in Two-dimensional Wave-vector Space as Observed in the Fast Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Yan, Limei; He, Jiansen; Zhang, Lei; Tu, Chuanyi; Marsch, Eckart; Chen, Christopher H. K.; Wang, Xin; Wang, Linghua; Wicks, Robert T.

    2016-01-01

    Intensive studies have been conducted to understand the anisotropy of solar wind turbulence. However, the anisotropy of Elsässer variables ({{\\boldsymbol{Z}}}+/- ) in 2D wave-vector space has yet to be investigated. Here we first verify the transformation based on the projection-slice theorem between the power spectral density {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) and the spatial correlation function {{CF}}2{{D}}({r}\\parallel ,{r}\\perp ). Based on the application of the transformation to the magnetic field and the particle measurements from the WIND spacecraft, we investigate the spectral anisotropy of Elsässer variables ({{\\boldsymbol{Z}}}+/- ), and the distribution of residual energy {E}{{R}}, Alfvén ratio {R}{{A}}, and Elsässer ratio {R}{{E}} in the ({k}\\parallel ,{k}\\perp ) space. The spectra {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {\\boldsymbol{B}}, {\\boldsymbol{V}}, and {{\\boldsymbol{Z}}}{major} (the larger of {{\\boldsymbol{Z}}}+/- ) show a similar pattern that {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) is mainly distributed along a ridge inclined toward the k⊥ axis. This is probably the signature of the oblique Alfvénic fluctuations propagating outwardly. Unlike those of {\\boldsymbol{B}}, {\\boldsymbol{V}}, and {{\\boldsymbol{Z}}}{major}, the spectrum {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {{\\boldsymbol{Z}}}{minor} is distributed mainly along the k⊥ axis. Close to the k⊥ axis, | {E}{{R}}| becomes larger while {R}{{A}} becomes smaller, suggesting that the dominance of magnetic energy over kinetic energy becomes more significant at small k∥. {R}{{E}} is larger at small k∥, implying that {{PSD}}2{{D}}({k}\\parallel ,{k}\\perp ) of {{\\boldsymbol{Z}}}{minor} is more concentrated along the k⊥ direction as compared to that of {{\\boldsymbol{Z}}}{major}. The residual energy condensate at small k∥ is consistent with simulation results in which {E}{{R}} is spontaneously generated by Alfvén wave interaction.

  10. Why is the Great Red Spot Red? The Exogenic, Photolytic Origin of the UV/Blue-Absorbing Chromophores of Jupiter’s Great Red Spot as Determined by Spectral Analysis of Cassini/VIMS Observations using New Laboratory Optical Coefficients

    NASA Astrophysics Data System (ADS)

    Baines, Kevin H.; Carlson, Robert W.; Momary, Thomas W.

    2014-11-01

    For centuries, a major question for Jupiter has been: Why is the Great Red Spot red? In particular, two major theories have been proposed: (1) that the coloring is due to photolytic processes in the upper cloud layer, or (2) it is due to the upwellimg of red materials processed relatively deep within the troposphere. Utilizing indices of refraction for red choromophores generated by the photolysis of ammonia and acetylene in the laboratory, we present results of a spectral analysis of the core of Jupiter’s Great Red Spot (GRS) as observed by the visual channel of the Cassini/Visual Infrared Mapping Spectrometer (VIMS). Consistent with the physical origin of such laboratory-generated chromophores in Jupiter - i.e., by solar-driven UV photolysis within the upper levels of the GRS structure near ~ 0.3 bar - our spectral modeling yields satisfactory results for such Mie scattering chromophores only when they are confined to the upper ~ 100 mbar of the GRS. Beneath this reddish upper cloud layer, our models indicate that the remainder of the GRS cloud - assumed to extend down to at least the ammonia condensation level near 0.6 bar - must be relatively spectrally bright throughout the UV-red spectrum; that is, they must be predominantly a whitish or grey color at depth. Thus, our 0.35-1.0 micron spectral models of the GRS are inconsistent with an endogenic origin of the reddish coloring originating in the depths of Jupiter, but are consistent with a photolytic origin due to the photolysis of ammonia and acetylene in the upper troposphere.

  11. Stochastic analysis of spectral broadening by a free turbulent shear layer

    NASA Technical Reports Server (NTRS)

    Hardin, J. C.; Preisser, J. S.

    1981-01-01

    The effect of the time-varying shear layer between a harmonic acoustic source and an observer on the frequency content of the observed sound is considered. Experimental data show that the spectral content of the acoustic signal is considerably broadened upon passing through such a shear layer. Theoretical analysis is presented which shows that such spectral broadening is entirely consistent with amplitude modulation of the acoustic signal by the time-varying shear layer. Thus, no actual frequency shift need be hypothesized to explain the spectral phenomenon. Experimental tests were conducted at 2, 4, and 6 kHz and at free jet flow velocities of 10, 20, and 30 m/s. Analysis of acoustic pressure time histories obtained from these tests confirms the above conclusion, at least for the low Mach numbers considered.

  12. Multivendor Spectral-Domain Optical Coherence Tomography Dataset, Observer Annotation Performance Evaluation, and Standardized Evaluation Framework for Intraretinal Cystoid Fluid Segmentation

    PubMed Central

    Wu, Jing; Philip, Ana-Maria; Podkowinski, Dominika; Gerendas, Bianca S.; Langs, Georg; Simader, Christian

    2016-01-01

    Development of image analysis and machine learning methods for segmentation of clinically significant pathology in retinal spectral-domain optical coherence tomography (SD-OCT), used in disease detection and prediction, is limited due to the availability of expertly annotated reference data. Retinal segmentation methods use datasets that either are not publicly available, come from only one device, or use different evaluation methodologies making them difficult to compare. Thus we present and evaluate a multiple expert annotated reference dataset for the problem of intraretinal cystoid fluid (IRF) segmentation, a key indicator in exudative macular disease. In addition, a standardized framework for segmentation accuracy evaluation, applicable to other pathological structures, is presented. Integral to this work is the dataset used which must be fit for purpose for IRF segmentation algorithm training and testing. We describe here a multivendor dataset comprised of 30 scans. Each OCT scan for system training has been annotated by multiple graders using a proprietary system. Evaluation of the intergrader annotations shows a good correlation, thus making the reproducibly annotated scans suitable for the training and validation of image processing and machine learning based segmentation methods. The dataset will be made publicly available in the form of a segmentation Grand Challenge. PMID:27579177

  13. Multivendor Spectral-Domain Optical Coherence Tomography Dataset, Observer Annotation Performance Evaluation, and Standardized Evaluation Framework for Intraretinal Cystoid Fluid Segmentation.

    PubMed

    Wu, Jing; Philip, Ana-Maria; Podkowinski, Dominika; Gerendas, Bianca S; Langs, Georg; Simader, Christian; Waldstein, Sebastian M; Schmidt-Erfurth, Ursula M

    2016-01-01

    Development of image analysis and machine learning methods for segmentation of clinically significant pathology in retinal spectral-domain optical coherence tomography (SD-OCT), used in disease detection and prediction, is limited due to the availability of expertly annotated reference data. Retinal segmentation methods use datasets that either are not publicly available, come from only one device, or use different evaluation methodologies making them difficult to compare. Thus we present and evaluate a multiple expert annotated reference dataset for the problem of intraretinal cystoid fluid (IRF) segmentation, a key indicator in exudative macular disease. In addition, a standardized framework for segmentation accuracy evaluation, applicable to other pathological structures, is presented. Integral to this work is the dataset used which must be fit for purpose for IRF segmentation algorithm training and testing. We describe here a multivendor dataset comprised of 30 scans. Each OCT scan for system training has been annotated by multiple graders using a proprietary system. Evaluation of the intergrader annotations shows a good correlation, thus making the reproducibly annotated scans suitable for the training and validation of image processing and machine learning based segmentation methods. The dataset will be made publicly available in the form of a segmentation Grand Challenge. PMID:27579177

  14. Observation of spectral composition and polarization of sub-terahertz emission from dense plasma during relativistic electron beam–plasma interaction

    SciTech Connect

    Arzhannikov, A. V.; Burmasov, V. S.; Ivanov, I. A.; Kuznetsov, S. A.; Postupaev, V. V.; Sinitsky, S. L.; Vyacheslavov, L. N.; Burdakov, A. V.; Gavrilenko, D. E.; Kasatov, A. A.; Mekler, K. I.; Rovenskikh, A. F.; Polosatkin, S. V.; Sklyarov, V. F.

    2014-08-15

    The paper presents results of measurements of sub-terahertz electromagnetic emission from magnetized plasma during injection of a powerful relativistic electron beam of microsecond duration in plasma with the density of 3 × 10{sup 14 }cm{sup −3}. It was found that the spectrum of the radiation concentrated in three distinct regions with high level of spectral power density. The first region is located near f{sub 1} = 100 GHz; the second one is in the vicinity of 190 GHz, and the third region is in the frequency interval f{sub 3} = 280–340 GHz. Polarization vectors of the emission in the first and third regions (f{sub 1} and f{sub 3}) are directed mainly perpendicular to the magnetic field in the plasma. At the same time, the polarization of the radiation in the vicinity of f{sub 2} = 190 GHz is parallel to the magnetic field. The most likely mechanism of electromagnetic wave generation in the frequency regions f{sub 1} and f{sub 2} is the linear conversion of the plasma oscillations into the electromagnetic waves on strong gradients of the plasma density. The third region is situated in the vicinity of second harmonic of electron plasma frequency, and we explain this emission by the coalescence of the upper-hybrid oscillations at high level turbulence in plasma.

  15. Moral Reasoning in Hypothetical and Actual Situations.

    ERIC Educational Resources Information Center

    Sumprer, Gerard F.; Butter, Eliot J.

    1978-01-01

    Results of this investigation suggest that moral reasoning of college students, when assessed using the DIT format, is the same whether the dilemmas involve hypothetical or actual situations. Subjects, when presented with hypothetical situations, become deeply immersed in them and respond as if they were actual participants. (Author/BEF)

  16. Factors Related to Self-Actualization.

    ERIC Educational Resources Information Center

    Hogan, H. Wayne; McWilliams, Jettie M.

    1978-01-01

    Provides data to further support the notions that females score higher in self-actualization measures and that self-actualization scores correlate inversely to the degree of undesirability individuals assign to their heights and weights. Finds that, contrary to predictions, greater androgyny was related to lower, not higher, self-actualization…

  17. Spectral and Temporal Behavior of Low Mass X-ray Binaries Observed by the Einstein SSS and MPC, and the Broad Band X-ray Telescope

    NASA Astrophysics Data System (ADS)

    Christian, D. J.; Swank, J. H.

    1992-12-01

    An extensive survey of 50 low mass X-ray binaries was carried out using the HEAO-2 Einstein Solid State Spectrometer data (0.5-4.5 keV) with the Monitor Proportional Counter data (1.2-20.0 keV) and the Broad Band X-Ray Telescope (BBXRT) (0.5-12 keV). Spectra were selected on the basis of intensity and fit with a set of simple and complex spectral models. For all the subclasses, including Eddington-limited bulge sources, bursters, dippers, the soft spectrum black hole candidates, and a few transients in decline, the spectra could be fit acceptably with combinations of thermal bremsstrahlung and blackbody spectra or a Comptonized spectrum and a blackbody. The results rule out optically thick disk models for the bright Z sources and power law models for bursters. There is a progression of spectra as a function of X-ray luminosity for the bursters, Atoll and Z sources. Interpretation is discussed in terms of separate emission regions, one due to radial accretion onto a neutron star and the optically thick component that appears for higher luminosity due to a boundary layer or to high optical depth to scattering in the flow. A lower temperature blackbody required in some cases could be an expected contribution from the accretion disk. The soft spectrum sources are dominated by blackbody spectra, but for two, low effective area is a problem for the black hole interpretation. The strongest of previously reported low energy X-ray lines due to OVIII or Fe L transitions are confirmed. Similar line emission is seen for several other sources, in particular X0614+091. The photoionized gas in the inner part of an accretion disk corona can give Fe K lines from Fe XXV. BBXRT obtained upper limits for X0614+091 and M15 which are consistent with the coronal model.

  18. Constraining Distance and Inclination Angle of V4641 Sgr Using Swift and NuSTAR Observations during Low Soft Spectral State

    NASA Astrophysics Data System (ADS)

    Pahari, Mayukh; Misra, Ranjeev; Dewangan, Gulab C.; Pawar, Pramod

    2015-12-01

    We present results from NuSTAR and Swift/XRT joint spectral analysis of V4641 Sgr during a disk dominated or soft state, as well as a power law dominated or hard state. The soft state spectrum is well modeled by a relativistically blurred disk emission, a power law, a broad iron line, two narrow emission lines, and two edges. The Markov Chain Monte Carlo simulation technique and the relativistic effects seen in the disk and broad iron line allow us to self-consistently constrain the inner disk radius, disk inclination angle, and distance to the source at {2.43}-0.17+0.39Rg (GM/c2), {69.5}-4.2+12.8 degrees and {10.8}-2.5+1.6 kpc respectively. For the hard state, the spectrum is a power law with a weakly broad iron line and an edge. The distance estimate gives a measure of the Eddington fraction, {L}2.0-80.0 {keV}/{L}{Edd}, to be ˜1.3 × 10-2 and ˜1.9 × 10-3 for the soft and hard states, respectively. Unlike many other typical black hole systems, which are always in a hard state at such a low Eddington fraction, V4641 Sgr shows a soft, disk dominated state. The soft state spectrum shows narrow emission lines at ˜6.95 and ˜8.31 keV which can be identified as being due to emission from highly ionized iron and nickel in an X-ray irradiated wind respectively. If this is not due to instrumental effect or calibration error, this would be the first detection of a Ni fluorescent line in a black hole X-ray binary.

  19. Quantitative study on appearance of microvessels in spectral endoscopic imaging

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroshi; Saito, Takaaki; Shiraishi, Yasushi; Arai, Fumihito; Morimoto, Yoshinori; Yuasa, Atsuko

    2015-03-01

    Increase in abnormal microvessels in the superficial mucosa is often relevant to diagnostic findings of neoplasia in digestive endoscopy; hence, observation of superficial vasculature is crucial for cancer diagnosis. To enhance the appearance of such vessels, several spectral endoscopic imaging techniques have been developed, such as narrow-band imaging and blue laser imaging. Both techniques exploit narrow-band blue light for the enhancement. The emergence of such spectral imaging techniques has increased the importance of understanding the relation of the light wavelength to the appearance of superficial vasculature, and thus a new method is desired for quantitative analysis of vessel visibility in relation to the actual structure in the tissue. Here, we developed microvessel-simulating phantoms that allowed quantitative evaluation of the appearance of 15-μm-thick vessels. We investigated the relation between the vascular contrast and light wavelength by the phantom measurements and also verified it in experiments with swine, where the endoscopically observed vascular contrast was investigated together with its real vascular depth and diameter obtained by microscopic observation of fluorescence-labeled vessels. Our study indicates that changing the spectral property even in the wavelength range of blue light may allow selective enhancement of the vascular depth for clinical use.

  20. Spectral Observations of Diffuse Far-Ultraviolet Emission from the Hot Phase of the Interstellar Medium with the Diffuse Ultraviolet Experiment

    NASA Astrophysics Data System (ADS)

    Korpela, Eric J.; Bowyer, Stuart; Edelstein, Jerry

    1998-03-01

    One of the keys to interpreting the character and evolution of interstellar matter in the Galaxy is understanding the distribution of the low-density hot (105-106 K) phase of the interstellar medium (ISM). This phase is much more difficult to observe than the cooler high-density components of the ISM because of its low density and lack of easily observable tracers. Because gas of this temperature emits mainly in the far-ultraviolet (FUV) (912-1800 Å) and extreme-ultraviolet (EUV) (80-912 Å), and (for gas hotter than 106 K) X-rays, observations in these bands can provide important constraints to the distribution of this gas. Because of interstellar opacity at EUV wavelengths, only FUV and X-ray observations can provide clues to the properties of hot gas from distant regions. We present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in 1992 July. The DUVE spectrometer, which covers the band from 950 to 1080 Å with 3.2 Å resolution, observed a region of low neutral hydrogen column density near the south Galactic pole for a total effective integration time of 1583 s. The only emission line detected was a geocoronal hydrogen line at 1025 Å. We are able to place upper limits to several expected emission features that provide constraints on interstellar plasma parameters. We are also able to place limits on the continuum emission throughout the bandpass. We compare these limits and other diffuse observations with several models of the structure of the ISM and discuss the ramifications.

  1. Remote sensing estimates of actual evapotranspiration in an irrigation district

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate estimates of the spatial distribution of actual evapotranspiration (AET) are useful in hydrology, but can be difficult to obtain. Remote sensing provides a potential capability for routinely monitoring AET by combining remotely sensed surface temperature and vegetation cover observations w...

  2. A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Rivers, Elizabeth; Markowitz, Alex; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Furst, Felix; Suchy, Slawomir; Kreykenbohm, Ingo; Wilms, Jorn; Rothschild, Richard

    2009-01-01

    We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku observatory, The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx. 19 keV. Additionally, using the narrow CCD response of Suzaku near 6 ke V allows us to study in detail the Fe K bandpass and to quantify the Fe Kp line for this source for the first time. The source is absorbed by fully-covering material along the line of sight with a column density of N(sub H) approx. 2 x 10(exp 22)/sq cm, consistent with a wind accreting geometry, and a high Fe abundance (approx. 3 - 4 x solar). Time and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in NH along the line of sight, perhaps indicating clumpiness in the stellar wind

  3. A COMPREHENSIVE SPECTRAL ANALYSIS OF THE X-RAY PULSAR 4U 1907+09 FROM TWO OBSERVATIONS WITH THE SUZAKU X-RAY OBSERVATORY

    SciTech Connect

    Rivers, Elizabeth; Markowitz, Alex; Suchy, Slawomir; Rothschild, Richard; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Fuerst, Felix; Kreykenbohm, Ingo; Wilms, Joern

    2010-01-20

    We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku Observatory. The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx19 keV. Additionally, using the narrow CCD response of Suzaku near 6 keV allows us to study in detail the Fe K bandpass and to quantify the Fe Kbeta line for this source for the first time. The source is absorbed by fully covering material along the line of sight with a column density of N{sub H} approx 2 x 10{sup 22} cm{sup -2}, consistent with a wind-accreting geometry, and a high Fe abundance (approx3-4 times solar). Time- and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in N{sub H} along the line of sight, perhaps indicating clumpiness in the stellar wind.

  4. Airborne Multiwavelength High-Spectral-Resolution Lidar (HSRL-2) Observations During TCAP 2012: Vertical Proles of Optical and Microphysical Properties of a Smoke/Urban Haze Plume Over the Northeastern Coast of the US

    SciTech Connect

    Muller, Detlef; Hostetler, Chris A.; Ferrare, R. A.; Burton, S. P.; Chemyakin, Eduard; Kolgotin, A.; Hair, John; Cook, A. L.; Harper, David; Rogers, R. R.; Hare, Rich; Cleckner, Craig; Obland, Michael; Tomlinson, Jason M.; Berg, Larry K.; Schmid, Beat

    2014-10-10

    We present rst measurements with the rst airborne multiwavelength High-Spectral Resolution Lidar (HSRL-2), developed by NASA Langley Research Center. The instrument was operated during the Department of Energy (DOE) Two-Column Aerosol Project (TCAP) in July 2012. We observed out ow of urban haze and fresh biomass burning smoke from the East Coast of the US out over the West Atlantic Ocean. Lidar ratios at 355 and 532 nm were ... sr indicating moderately absorbing aerosols. Extinctionrelated Angstrom exponents were 1.5{2 pointing at comparably small particles. Our novel automated, unsupervised data inversion algorithm retrieves particle e*ective radii of approximately 0.2 *m, which is in agreement with the large Angstrom exponents. We nd reasonable agreement to particle size parameters obtained from situ measurements carried out with the DOE G-1 aircraft that ew during the lidar observations.

  5. Performance and Prospects of Khayyam, A Tunable Spatial Heterodyne Spectrometer (SHS) for High Spectral Resolving Power Observation of Extended Planetary Targets in Optical Wavelengths

    NASA Astrophysics Data System (ADS)

    Hosseini, S.; Harris, W.

    2014-12-01

    We present initial results, calibration and data reduction process from observations of wide-field targets using Khayyam at Mt. Hamilton, a new instrument based on a reflective spatial heterodyne spectrometer (SHS) at the focus of the Coudé Auxiliary Telescope (CAT). SHS instruments are common path two-beam Fourier transform spectrometers that produce 2-D spatial interference patterns without the requirement for moving parts. The utility of SHS comes from its combination of a wide input acceptance angle (0.5-1°), high resolving power (of order ~105), compact format, high dynamic range, and relaxed optical tolerances compared with other interferometer designs. This combination makes them extremely useful for velocity resolved for observations of wide field targets from both small and large telescopes. This report focuses on the tunable instrument at Mt Hamilton, The CAT provides a test case for on-axis use of SHS, and the impact of the resulting field non-uniformity caused by the spider pattern will be discussed. Observations of several targets will be presented that demonstrate the capabilities of SHS, including comet C/2014 E2 (Jacques), Jupiter, and both the day sky and night glow. Raw interferometric data and transformed power spectra will be shown and evaluated in terms of instrumental stability.

  6. Slow Narrow Spectral Width E Region Echoes Observed During the March 17-2015 Storm and What They Reveal About the Disturbed Ionosphere.

    NASA Astrophysics Data System (ADS)

    St-Maurice, J. P.; Chau, J. L.

    2015-12-01

    As auroral-type disturbances moved equatorward during the March 17-2015 storm, coherent E region echoes were observed simultaneously with three radar links separated by 40 km each in the east-west direction in northern Germany. One radar operated at 36.2, and the other two at 32.55 MHz. One of the latter operated in a bistatic configuration. On each radar site five separate antennas were used to locate the echoes using interferometry. The unique configuration provided an unsurpassed opportunity to study the origin and evolution of ionospheric structures in a wide field of view during a strong storm. A most noticeable feature was that over a few time intervals, several minutes in duration each, very narrow spectra were observed, with Doppler shifts roughly 1/2 the ion-acoustic speed (often called "type III" echoes in the past). The inferred location indicated that the echoes came from below 100 km altitude. Echoes moving at the nominal ion-acoustic speed came from higher up and/or different flow angles. In one particularly clear instance the "Type III" echo region came from a region 50 to 75 km in extent drifting at roughly 1.5 km/s, while moving at some small (but non-zero) flow angle with respect to the line-of-sight. In view of the observations, a reevaluation of existing theories indicates that the echoes cannot be related to ion cyclotron waves. Instead, their low altitude and flow angle dependence reveal that they are the by-product of the ion Pedersen instability, which has been investigated by a few groups in relation to a non-isothermal treatment of the Farley-Buneman instability. In our present treatment of the problem, nonlinear effects are invoked to compute the final Doppler shift of the resulting structures. We find that the stronger the electric field is, the closer the region of slow echoes has to be to the ExB direction. In our most dramatic example of Type III structures, the size of the echo region pointed to a region of high energy precipitation

  7. Simulator spectral characterization using balloon calibrated solar cells with narrow band pass filters

    NASA Technical Reports Server (NTRS)

    Goodelle, G. S.; Brooks, G. R.; Seaman, C. H.

    1981-01-01

    The development and implementation of an instrument for spectral measurement of solar simulators for testing solar cell characteristics is reported. The device was constructed for detecting changes in solar simulator behavior and for comparing simulator spectral irradiance to solar AM0 output. It consists of a standard solar cell equipped with a band pass filter narrow enough so that, when flown on a balloon to sufficient altitude along with sufficient numbers of cells, each equipped with filters of different bandpass ratings, the entire spectral response of the standard cell can be determined. Measured short circuit currents from the balloon flights thus produce cell devices which, when exposed to solar simulator light, have a current which does or does not respond as observed under actual AM0 conditions. Improvements of the filtered cells in terms of finer bandpass filter tuning and measurement of temperature coefficients are indicated.

  8. Spectral and spread-spectral teleportation

    SciTech Connect

    Humble, Travis S.

    2010-06-15

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state may be teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of the teleported wave form can be controllably and coherently dilated using a spread-spectral variant of teleportation. We calculate analytical expressions for the fidelities of spectral and spread-spectral teleportation when complex-valued Gaussian states are transferred using a proposed experimental approach. Finally, we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  9. Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star-forming core NGC 6334I

    NASA Astrophysics Data System (ADS)

    van der Wiel, M. H. D.; van der Tak, F. F. S.; Lis, D. C.; Bell, T.; Bergin, E. A.; Comito, C.; Emprechtinger, M.; Schilke, P.; Caux, E.; Ceccarelli, C.; Baudry, A.; Goldsmith, P. F.; Herbst, E.; Langer, W.; Lord, S.; Neufeld, D.; Pearson, J.; Phillips, T.; Rolffs, R.; Yorke, H.; Bacmann, A.; Benedettini, M.; Blake, G. A.; Boogert, A.; Bottinelli, S.; Cabrit, S.; Caselli, P.; Castets, A.; Cernicharo, J.; Codella, C.; Coutens, A.; Crimier, N.; Demyk, K.; Dominik, C.; Encrenaz, P.; Falgarone, E.; Fuente, A.; Gerin, M.; Helmich, F.; Hennebelle, P.; Henning, T.; Hily-Blant, P.; Jacq, T.; Kahane, C.; Kama, M.; Klotz, A.; Lefloch, B.; Lorenzani, A.; Maret, S.; Melnick, G.; Nisini, B.; Pacheco, S.; Pagani, L.; Parise, B.; Salez, M.; Saraceno, P.; Schuster, K.; Tielens, A. G. G. M.; Vastel, C.; Viti, S.; Wakelam, V.; Walters, A.; Wyrowski, F.; Edwards, K.; Zmuidzinas, J.; Morris, P.; Samoska, L. A.; Teyssier, D.

    2010-10-01

    Context. In contrast to the more extensively studied dense star-forming cores, little is known about diffuse gas surrounding star-forming regions. Aims: We study the molecular gas in the Galactic high-mass star-forming region NGC 6334I, which contains diffuse, quiescent components that are inconspicuous in widely used molecular tracers such as CO. Methods: We present Herschel/HIFI observations of methylidyne (CH) toward NGC 6334I observed as part of the “Chemical HErschel Survey of Star forming regions” (CHESS) key program. HIFI resolves each of the six hyperfine components of the lowest rotational transition (J = 3/2 - 1/2) of CH, observed in both emission and absorption. Results: The CH emission features appear close to the systemic velocity of NGC 6334I, while its measured FWHM linewidth of 3 km s-1 is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is ~7 × 10-11, two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e.g., CO and H2O toward NGC 6334I, we do not detect any outflow signatures in CH. At least two redshifted components of cold absorbing material must be present at -3.0 and +6.5 km s-1 to explain the absorption signatures. We derive a CH column density (NCH) of 7 × 1013 and 3 × 1013 cm-2 for these two absorbing clouds. We find evidence of two additional absorbing clouds at +8.0 and 0.0 km s-1, both with NCH ≈ 2 × 1013 cm-2. Turbulent linewidths for the four absorption components vary between 1.5 and 5.0 km s-1 in FWHM. We constrain the physical properties and locations of the clouds by matching our CH absorbers with the absorption signatures seen in other molecular tracers. Conclusions: In the hot core, molecules such as H2O and CO trace gas that is heated and dynamically influenced by outflow activity, whereas the CH molecule traces more quiescent material. The four CH absorbing clouds have column densities and turbulent

  10. Digital version of the CrAO archive of spectral observations of the Sun, carried out with the KG-2 coronagraph

    NASA Astrophysics Data System (ADS)

    Fursiak, Yu. A.

    2012-11-01

    With the development of computer technology a topical problem to digitize the astronomical data stored on various media, for their preservation and accessibility for further faster and more accurate processing has arisen. Creation of a digital archive of observational data obtained with the KG-2 coronagraph and stored on photographic films has been started at the Department of the Solar Physics of the Scientific Research Institute ``Crimean Astrophysical Observatory''. We obtained satisfactory results in comparing a part of the spectrum digitized with EPSON Expression 10000XL scanner and with the MF-2 type scanning microphotometer which was used before. This allows the scanner to be used in the future to create the archive. We also developed a special software, which speeds up the processing of scanned data, and tried to minimize and eliminate potential errors.

  11. Temporally and spectrally resolved observation of a crossed-flow DBD plasma jet using pure helium and argon/acetone mixed gases

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Sands, Brian L.; Ganguly, Biswa N.; Sakai, Osamu

    2012-06-01

    A crossed gas flow dielectric barrier discharge plasma jet using vertical pure helium and tilted argon/acetone mixed gases is investigated in this study, mainly by an intensified charge-coupled device (ICCD) camera. We have observed ionization-front propagation and transient glow discharge formation following the rise of the applied voltage pulse. A secondary discharge with a reverse polarity was ignited during the falling slope of the applied voltage pulse. In order to analyze excited-species distribution inside the discharge, optical interference filters were placed in front of the ICCD camera with the center wavelengths set at the excited species' transition. The imaging results revealed detailed discharge structures around the crossing point of the two gas flows including bridging emission between the two flows that changed position with time. We also discuss the ignition mechanisms of the secondary discharge considering effects of accumulated charge during the primary discharge and changes in the channel conductivity following the primary discharge.

  12. Spectral Anonymization of Data

    PubMed Central

    Lasko, Thomas A.; Vinterbo, Staal A.

    2011-01-01

    The goal of data anonymization is to allow the release of scientifically useful data in a form that protects the privacy of its subjects. This requires more than simply removing personal identifiers from the data, because an attacker can still use auxiliary information to infer sensitive individual information. Additional perturbation is necessary to prevent these inferences, and the challenge is to perturb the data in a way that preserves its analytic utility. No existing anonymization algorithm provides both perfect privacy protection and perfect analytic utility. We make the new observation that anonymization algorithms are not required to operate in the original vector-space basis of the data, and many algorithms can be improved by operating in a judiciously chosen alternate basis. A spectral basis derived from the data’s eigenvectors is one that can provide substantial improvement. We introduce the term spectral anonymization to refer to an algorithm that uses a spectral basis for anonymization, and we give two illustrative examples. We also propose new measures of privacy protection that are more general and more informative than existing measures, and a principled reference standard with which to define adequate privacy protection. PMID:21373375

  13. NIMBUS-7 SBUV (Solar Backscatter Ultraviolet) observations of solar UV spectral irradiance variations caused by solar rotation and active-region evolution for the period November 7, 1978 - November 1, 1980

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Repoff, T. P.; Donnelly, R. F.

    1984-01-01

    Observations of temporal variations of the solar UV spectral irradiance over several days to a few weeks in the 160-400 nm wavelength range are presented. Larger 28-day variations and a second episode of 13-day variations occurred during the second year of measurements. The thirteen day periodicity is not a harmonic of the 28-day periodicity. The 13-day periodicity dominates certain episodes of solar activity while others are dominated by 28-day periods accompanied by a week 14-day harmonic. Techniques for removing noise and long-term trends are described. Time series analysis results are presented for the Si II lines near 182 nm, the Al I continuum in the 190 nm to 205 nm range, the Mg I continuum in the 210 nm to 250 nm range, the MgII H & K lines at 280 nm, the Mg I line at 285 nm, and the Ca II K & H lines at 393 and 397 nm.

  14. A review of multitaper spectral analysis.

    PubMed

    Babadi, Behtash; Brown, Emery N

    2014-05-01

    Nonparametric spectral estimation is a widely used technique in many applications ranging from radar and seismic data analysis to electroencephalography (EEG) and speech processing. Among the techniques that are used to estimate the spectral representation of a system based on finite observations, multitaper spectral estimation has many important optimality properties, but is not as widely used as it possibly could be. We give a brief overview of the standard nonparametric spectral estimation theory and the multitaper spectral estimation, and give two examples from EEG analyses of anesthesia and sleep. PMID:24759284

  15. Investigating the correlation between increases in spectral gamma ray signals observed from wireline logging, geochemistry of the recovered core and reef processes in Tahiti coral reef formations (IODP Expedition 310)

    NASA Astrophysics Data System (ADS)

    Inwood, J.; Brewer, T.

    2009-04-01

    reveal small volcanic clasts within some carbonates supporting this observation. The geochemical analyses of the core also indicate increased Mg within this interval. We infer from high CaO (48 to 52 wt. %) and moderate MgO (2 to 6 wt. %) the presence of dolomite, thus implying a potential diagenetic influence. Mass balance calculations using major element oxides demonstrate that this is compatible with the geochemical data. These preliminary findings from combining spectral gamma ray observations with analyses performed on core samples provide insight into the processes operating in the Tahiti reefal carbonates.

  16. EUV SPECTRAL LINE FORMATION AND THE TEMPERATURE STRUCTURE OF ACTIVE REGION FAN LOOPS: OBSERVATIONS WITH HINODE/EIS AND SDO/AIA

    SciTech Connect

    Brooks, David H.; Young, Peter R.; Warren, Harry P.

    2011-04-01

    With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines look very similar despite the fact that ionization equilibrium calculations suggest that they have significantly different formation temperatures: log(T{sub e} /K) = 5.6 and 5.8, respectively. It is important to resolve these issues because confidence has been undermined in their use for differential emission measure (DEM) analysis, and Fe VIII is the main contributor to the AIA 131 A channel at low temperatures. Furthermore, the strong Fe VIII 185.213 A and Si VII 275.368 A lines are the best EIS lines to use for velocity studies in the transition region, and for assigning the correct temperature to velocity measurements in the fans. We find that the Fe VIII 185.213 A line is particularly sensitive to the slope of the DEM, leading to disproportionate changes in its effective formation temperature. If the DEM has a steep gradient in the log(T{sub e} /K) = 5.6-5.8 temperature range, or is strongly peaked, Fe VIII 185.213 A and Si VII 275.368 A will be formed at the same temperature. We show that this effect explains the similarity of these images in the fans. Furthermore, we show that the most recent ionization balance compilations resolve the discrepancies in absolute intensities. With these difficulties overcome, we combine EIS and AIA data to determine the temperature structure of a number of fan loops and find that they have peak temperatures of 0.8-1.2 MK. The EIS data indicate that the temperature distribution has a finite (but narrow) width < log ({sigma}{sub Te}/K) = 5.5 which, in one detailed case, is found to broaden substantially toward the loop base. AIA and EIS yield similar results on the temperature, emission

  17. EUV Spectral Line Formation and the Temperature Structure of Active Region Fan Loops: Observations with Hinode/EIS and SDO/AIA

    NASA Astrophysics Data System (ADS)

    Brooks, David H.; Warren, Harry P.; Young, Peter R.

    2011-04-01

    With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines look very similar despite the fact that ionization equilibrium calculations suggest that they have significantly different formation temperatures: log(Te /K) = 5.6 and 5.8, respectively. It is important to resolve these issues because confidence has been undermined in their use for differential emission measure (DEM) analysis, and Fe VIII is the main contributor to the AIA 131 Å channel at low temperatures. Furthermore, the strong Fe VIII 185.213 Å and Si VII 275.368 Å lines are the best EIS lines to use for velocity studies in the transition region, and for assigning the correct temperature to velocity measurements in the fans. We find that the Fe VIII 185.213 Å line is particularly sensitive to the slope of the DEM, leading to disproportionate changes in its effective formation temperature. If the DEM has a steep gradient in the log(Te /K) = 5.6-5.8 temperature range, or is strongly peaked, Fe VIII 185.213 Å and Si VII 275.368 Å will be formed at the same temperature. We show that this effect explains the similarity of these images in the fans. Furthermore, we show that the most recent ionization balance compilations resolve the discrepancies in absolute intensities. With these difficulties overcome, we combine EIS and AIA data to determine the temperature structure of a number of fan loops and find that they have peak temperatures of 0.8-1.2 MK. The EIS data indicate that the temperature distribution has a finite (but narrow) width < log (σ_{T_e}/K) = 5.5 which, in one detailed case, is found to broaden substantially toward the loop base. AIA and EIS yield similar results on the temperature, emission measure

  18. Solar Spectral Irradiance and Climate

    NASA Technical Reports Server (NTRS)

    Pilewskie, P.; Woods, T.; Cahalan, R.

    2012-01-01

    Spectrally resolved solar irradiance is recognized as being increasingly important to improving our understanding of the manner in which the Sun influences climate. There is strong empirical evidence linking total solar irradiance to surface temperature trends - even though the Sun has likely made only a small contribution to the last half-century's global temperature anomaly - but the amplitudes cannot be explained by direct solar heating alone. The wavelength and height dependence of solar radiation deposition, for example, ozone absorption in the stratosphere, absorption in the ocean mixed layer, and water vapor absorption in the lower troposphere, contribute to the "top-down" and "bottom-up" mechanisms that have been proposed as possible amplifiers of the solar signal. New observations and models of solar spectral irradiance are needed to study these processes and to quantify their impacts on climate. Some of the most recent observations of solar spectral variability from the mid-ultraviolet to the near-infrared have revealed some unexpected behavior that was not anticipated prior to their measurement, based on an understanding from model reconstructions. The atmospheric response to the observed spectral variability, as quantified in climate model simulations, have revealed similarly surprising and in some cases, conflicting results. This talk will provide an overview on the state of our understanding of the spectrally resolved solar irradiance, its variability over many time scales, potential climate impacts, and finally, a discussion on what is required for improving our understanding of Sun-climate connections, including a look forward to future observations.

  19. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  20. Are GRB blackbodies an artefact of spectral evolution?

    NASA Astrophysics Data System (ADS)

    Burgess, J. Michael; Ryde, Felix

    2015-03-01

    The analysis of gamma-ray burst (GRB) spectra with multicomponent emission models has become an important part of the field. In particular, multicomponent analysis where one component is a blackbody representing emission from a photosphere has enabled both a more detailed understanding of the energy content of the jet as well as the ability to examine the dynamic structure of the outflow. While the existence of a blackbody-like component has been shown to be significant and not a byproduct of background fluctuations, it is very possible that it can be an artefact of spectral evolution of a single component that is being poorly resolved in time. Herein, this possibility is tested by simulating a single component evolving in time and then folding the spectra through the Fermi detector response to generate time-tagged event Gamma-ray Burst Monitor (GBM) data. We then fit both the time-integrated and -resolved generated spectral data with a multicomponent model using standard tools. It is found that in time-integrated spectra, a blackbody can be falsely identified due to the spectral curvature introduced by the spectral evolution. However, in a time-resolved analysis defined by time bins that can resolve the evolution of the spectra, the significance of the falsely identified blackbody is very low. Additionally, the evolution of the artificial blackbody parameters does not match the recurring behaviour that has been identified in the actual observations. These results reinforce the existence of the blackbody found in time-resolved analysis of GRBs and stress the point that caution should be taken when using time-integrated spectral analysis for identifying physical properties of GRBs.

  1. Spectrally-Based Assessment of Crop Seasonal Performance and Yield

    NASA Astrophysics Data System (ADS)

    Kancheva, Rumiana; Borisova, Denitsa; Georgiev, Georgy

    The rapid advances of space technologies concern almost all scientific areas from aeronautics to medicine, and a wide range of application fields from communications to crop yield predictions. Agricultural monitoring is among the priorities of remote sensing observations for getting timely information on crop development. Monitoring agricultural fields during the growing season plays an important role in crop health assessment and stress detection provided that reliable data is obtained. Successfully spreading is the implementation of hyperspectral data to precision farming associated with plant growth and phenology monitoring, physiological state assessment, and yield prediction. In this paper, we investigated various spectral-biophysical relationships derived from in-situ reflectance measurements. The performance of spectral data for the assessment of agricultural crops condition and yield prediction was examined. The approach comprisesd development of regression models between plant spectral and state-indicative variables such as biomass, vegetation cover fraction, leaf area index, etc., and development of yield forecasting models from single-date (growth stage) and multitemporal (seasonal) reflectance data. Verification of spectral predictions was performed through comparison with estimations from biophysical relationships between crop growth variables. The study was carried out for spring barley and winter wheat. Visible and near-infrared reflectance data was acquired through the whole growing season accompanied by detailed datasets on plant phenology and canopy structural and biochemical attributes. Empirical relationships were derived relating crop agronomic variables and yield to various spectral predictors. The study findings were tested using airborne remote sensing inputs. A good correspondence was found between predicted and actual (ground-truth) estimates

  2. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  3. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  4. Humanistic Education and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1984-01-01

    Stresses the need for theoretical justification for the development of humanistic education programs in today's schools. Explores Abraham Maslow's hierarchy of needs and theory of self-actualization. Argues that Maslow's theory may be the best available for educators concerned with educating the whole child. (JHZ)

  5. Children's Rights and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1982-01-01

    Educators need to seriously reflect upon the concept of children's rights. Though the idea of children's rights has been debated numerous times, the idea remains vague and shapeless; however, Maslow's theory of self-actualization can provide the children's rights idea with a needed theoretical framework. (Author)

  6. Culture Studies and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1983-01-01

    True citizenship education is impossible unless students develop the habit of intelligently evaluating cultures. Abraham Maslow's theory of self-actualization, a theory of innate human needs and of human motivation, is a nonethnocentric tool which can be used by teachers and students to help them understand other cultures. (SR)

  7. Group Counseling for Self-Actualization.

    ERIC Educational Resources Information Center

    Streich, William H.; Keeler, Douglas J.

    Self-concept, creativity, growth orientation, an integrated value system, and receptiveness to new experiences are considered to be crucial variables to the self-actualization process. A regular, year-long group counseling program was conducted with 85 randomly selected gifted secondary students in the Farmington, Connecticut Public Schools. A…

  8. Racial Discrimination in Occupations: Perceived and Actual.

    ERIC Educational Resources Information Center

    Turner, Castellano B.; Turner, Barbara F.

    The relationship between the actual representation of Blacks in certain occupations and individual perceptions of the occupational opportunity structure were examined. A scale which rated the degree of perceived discrimination against Blacks in 21 occupations was administered to 75 black male, 70 black female, 1,429 white male and 1,457 white…

  9. Developing Human Resources through Actualizing Human Potential

    ERIC Educational Resources Information Center

    Clarken, Rodney H.

    2012-01-01

    The key to human resource development is in actualizing individual and collective thinking, feeling and choosing potentials related to our minds, hearts and wills respectively. These capacities and faculties must be balanced and regulated according to the standards of truth, love and justice for individual, community and institutional development,…

  10. Spectral Information System for Australian Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    Chisholm, L. A.; Ong, C.; Hueni, A.; Suarez, L.; Restrepo-Coupe, N.

    2013-12-01

    Inherently field spectroscopy involves the study of the interrelationships between the spectral characteristics of objects and their biophysical attributes in the field environment (Bauer et al., 1986; Milton, 1987). Spectroscopy measurements taken of vegetated surfaces provide spectral characteristics indicative of the status, composition and structure of the components measured. However, additional elements are present that add undesired effects to the overall signal such as the soil background or the viewing and illumination geometry (Suarez etal 2013). Further, the leaf spectrum is affected by several factors including leaf age, phenology, a highly variable range of stressors, any of which may be the actual focus of study, and additionally influenced by a range of environmental conditions. There is a critical need to use acquired spectra to infer vegetation function, understand phenological cycles, characterise biodiversity or as part of the process to assess biogeochemical processes. However the collection of leaf spectra during field campaigns is undertaken on a project basis, where a large number of spectra tend to be collected, yet the value and ability to share and confidently re-use such collections is often restricted. Often this is because the data are stored in disparate silos with little, if any, consistency in formatting and content, and most importantly, lack metadata to aid their discovery and re-use. These datasets have significant potential for vegetation scientists but also benefit the wider earth observation remote sensing and other earth science communities. In Australia this problem has been addressed by the adoption and enhancement of the existing SPECCHIO system (Hueni et al. 2009) as a suitable standard for spectral data exchange. As a spectral database, the system provides storage of spectra and associated metadata, retrieval of spectral data using metadata space queries, information on provenance, all of which facilitate repeatability of

  11. Earthquake Induced Site Effect in the Algiers-Boumerdes Region: Relation Between Spectral Ratios Higher Peaks and Observed Damage During the May 21st M w 6.8 Boumerdes Earthquake (Algeria)

    NASA Astrophysics Data System (ADS)

    Laouami, Nasser; Slimani, Abdennasser

    2013-11-01

    The Algiers-Boumerdes regions were hit by an M w 6.8 destructive earthquake on May 21, 2003. The accelerometric and seismometric networks successfully recorded the main shock and many aftershocks at some locations where the damage was most extensive. A microtremor measurement was performed in the same locations; some of them are localized on the Mitidja basin. In this paper, we propose to analyze earthquake-induced site effect derived from horizontal to vertical spectral ratio from ambient noise (noise horizontal to vertical—NHV), or from very weak, weak, moderate and strong ( peak ground acceleration—PGA >10 % g) seismic motions (EHV), and transfer function evaluation from soil velocity profile data at four sites. H/V spectral ratios are computed by using both Fourier and response spectra. Compared to the transfer function, the obtained results show that in the case of soft soils, NHV as well as EHV give a good estimation of the soil's fundamental frequency, whereas the NHV underestimate the H/V amplitude and the EHV amplitude increase with the seismic motion intensity. In the case of firm soils, whereas the NHV gives flat curves synonymous for a rock site or a bump, the EHV is more appropriate as seen by identifying clear peaks with non negligible amplitude. In the case of soft sites as well as in the case of firm sites, strong peaks at frequencies higher than the fundamental one are found from EHV curves. Those peaks would not be found when looking at NHV ratios alone, are evidenced by the computed transfer function as well as by an analytical formulation, and are in agreement with the observed distribution of damage during the M w 6.8 2003 Boumerdes earthquake. Finally, the same analysis is performed by using response spectra rather than Fourier spectra and leads to the same conclusions. Moreover, the calculation of the response spectra is more easily compared with the smoothing operation of the Fourier spectra.

  12. Whiteheadian Actual Entitities and String Theory

    NASA Astrophysics Data System (ADS)

    Bracken, Joseph A.

    2012-06-01

    In the philosophy of Alfred North Whitehead, the ultimate units of reality are actual entities, momentary self-constituting subjects of experience which are too small to be sensibly perceived. Their combination into "societies" with a "common element of form" produces the organisms and inanimate things of ordinary sense experience. According to the proponents of string theory, tiny vibrating strings are the ultimate constituents of physical reality which in harmonious combination yield perceptible entities at the macroscopic level of physical reality. Given that the number of Whiteheadian actual entities and of individual strings within string theory are beyond reckoning at any given moment, could they be two ways to describe the same non-verifiable foundational reality? For example, if one could establish that the "superject" or objective pattern of self- constitution of an actual entity vibrates at a specific frequency, its affinity with the individual strings of string theory would be striking. Likewise, if one were to claim that the size and complexity of Whiteheadian 'societies" require different space-time parameters for the dynamic interrelationship of constituent actual entities, would that at least partially account for the assumption of 10 or even 26 instead of just 3 dimensions within string theory? The overall conclusion of this article is that, if a suitably revised understanding of Whiteheadian metaphysics were seen as compatible with the philosophical implications of string theory, their combination into a single world view would strengthen the plausibility of both schemes taken separately. Key words: actual entities, subject/superjects, vibrating strings, structured fields of activity, multi-dimensional physical reality.

  13. Easy Observation of Infrared Spectral Lines

    ERIC Educational Resources Information Center

    Cortel, Adolf

    2012-01-01

    The spectra of some chemical elements display intense infrared (IR) lines that can be used more effectively than the ones in the visible region for identification purposes. A simple setup, based on the IR sensitivity of a handycam in nightshot mode, is described to record the visible as well as the IR spectra from decorative bulbs or salts on the…

  14. Middle Atmosphere of the Southern Hemisphere (MASH) Global meteor observations system (GLOBMET) Solar Spectral Irradiance Measurements (SSIM) Global Observations and Studies of Stratospheric Aerosols (GOSSA): Progress with the MASH project

    NASA Technical Reports Server (NTRS)

    Oneill, A.

    1989-01-01

    The aim of the MASH project is to study the dynamics of the middle atmosphere in the Southern Hemisphere, emphasizing inter-hemispheric differences. Both observational data and data from simulations with numerical models are being used. It is intended that MASH will be complemented by parallel studies on the transport and photochemistry of trace species in the Southern Hemisphere. Impetus for such studies has come from the unexpected finding of a springtime ozone hole over Antarctica. A summary of recent progress with the MASH project is given. Data from polar orbiting satellites are used to discuss the large scale circulation found in the Southern Hemisphere at extratropical latitudes. Comparisons are made with that of the Northern Hemisphere. Particular attention is paid to the springtime final warming, the most spectacular large scale phenomenon in the statosphere of the Southern Hemisphere. The circulation before and after this event has to be taken into account in theories for the formation and subsequent disappearance of the ozone hole.

  15. Spectral methods to detect surface mines

    NASA Astrophysics Data System (ADS)

    Winter, Edwin M.; Schatten Silvious, Miranda

    2008-04-01

    Over the past five years, advances have been made in the spectral detection of surface mines under minefield detection programs at the U. S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD). The problem of detecting surface land mines ranges from the relatively simple, the detection of large anti-vehicle mines on bare soil, to the very difficult, the detection of anti-personnel mines in thick vegetation. While spatial and spectral approaches can be applied to the detection of surface mines, spatial-only detection requires many pixels-on-target such that the mine is actually imaged and shape-based features can be exploited. This method is unreliable in vegetated areas because only part of the mine may be exposed, while spectral detection is possible without the mine being resolved. At NVESD, hyperspectral and multi-spectral sensors throughout the reflection and thermal spectral regimes have been applied to the mine detection problem. Data has been collected on mines in forest and desert regions and algorithms have been developed both to detect the mines as anomalies and to detect the mines based on their spectral signature. In addition to the detection of individual mines, algorithms have been developed to exploit the similarities of mines in a minefield to improve their detection probability. In this paper, the types of spectral data collected over the past five years will be summarized along with the advances in algorithm development.

  16. Pulsed thermography in multiple infrared spectral bands

    NASA Astrophysics Data System (ADS)

    Netzelmann, U.; Abuhamad, M.

    2010-03-01

    Spectrally resolved active thermography by flash pulse excitation was performed in four sub-bands of a mid-wave infrared camera using spectral filtering and in the full long-wave band of a second infrared camera. On zirconia thermal barrier coatings on steel and PVC blocks, spectrally dependent decay rates of the thermal contrast were found. The observed behaviour can be explained by the infrared spectra of the specimens.

  17. The Actual Apollo 13 Prime Crew

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The actual Apollo 13 lunar landing mission prime crew from left to right are: Commander, James A. Lovell Jr., Command Module pilot, John L. Swigert Jr.and Lunar Module pilot, Fred W. Haise Jr. The original Command Module pilot for this mission was Thomas 'Ken' Mattingly Jr. but due to exposure to German measles he was replaced by his backup, Command Module pilot, John L. 'Jack' Swigert Jr.

  18. Spectral properties of ghost Neumann matrices

    SciTech Connect

    Bonora, L.; Santos, R. J. Scherer; Tolla, D. D.

    2008-05-15

    We continue the analysis of the ghost wedge states in the oscillator formalism by studying the spectral properties of the ghost matrices of Neumann coefficients. We show that the traditional spectral representation is not valid for these matrices and propose a new heuristic formula that allows one to reconstruct them from the knowledge of their eigenvalues and eigenvectors. It turns out that additional data, which we call boundary data, are needed in order to actually implement the reconstruction. In particular our result lends support to the conjecture that there exists a ghost three strings vertex with properties parallel to those of the matter three strings vertex.

  19. Evaluation of Cloud Microphysics Simulated using a Meso-Scale Model Coupled with a Spectral Bin Microphysical Scheme through Comparison with Observation Data by Ship-Borne Doppler and Space-Borne W-Band Radars

    NASA Technical Reports Server (NTRS)

    Iguchi, T.; Nakajima, T.; Khain, A. P.; Saito, K.; Takemura, T.; Okamoto, H.; Nishizawa, T.; Tao, W.-K.

    2012-01-01

    Equivalent radar reflectivity factors (Ze) measured by W-band radars are directly compared with the corresponding values calculated from a three-dimensional non-hydrostatic meso-scale model coupled with a spectral-bin-microphysical (SBM) scheme for cloud. Three case studies are the objects of this research: one targets a part of ship-borne observation using 95 GHz Doppler radar over the Pacific Ocean near Japan in May 2001; other two are aimed at two short segments of space-borne observation by the cloud profiling radar on CloudSat in November 2006. The numerical weather prediction (NWP) simulations reproduce general features of vertical structures of Ze and Doppler velocity. A main problem in the reproducibility is an overestimation of Ze in ice cloud layers. A frequency analysis shows a strong correlation between ice water contents (IWC) and Ze in the simulation; this characteristic is similar to those shown in prior on-site studies. From comparing with the empirical correlations by the prior studies, the simulated Ze is overestimated than the corresponding values in the studies at the same IWC. Whereas the comparison of Doppler velocities suggests that large-size snowflakes are necessary for producing large velocities under the freezing level and hence rules out the possibility that an overestimation of snow size causes the overestimation of Ze. Based on the results of several sensitivity tests, we conclude that the source of the overestimation is a bias in the microphysical calculation of Ze or an overestimation of IWC. To identify the source of the problems needs further validation research with other follow-up observations.

  20. Predicting Crop Yield from Biophysical and Spectral Variables

    NASA Astrophysics Data System (ADS)

    Kancheva, Rumiana; Borisova, Denitsa

    A strong stress is being put over the past years on the application and added-value of remotely sensed data. Agricultural monitoring is an important application field of remote sensing tech-nologies associated with plant growth assessment, stress detection and yield forecasting. In-terest is rapidly spreading in the use of hyperspectral data to precision farming. For precision agriculture running, regular and timely information is needed about plant growth in order to assess crop development and predict yield. Entering wider into their opperational stage, re-mote sensing technologies face higher requirements to the accuracy of the information they provide. Because of the raising need for reliability of the information products, ground-based observations are considered one of the pillars of remote sensing being used in land cover stud-ies for the development and validation of data analysis and retrieval algorithms. This paper presents the results of ground-level studies aimed at the empirical modelling of cereals yield using multispectral and multitemporal data. The objective of the study is to develop and test the performance of vegetation indices as predictors of crop production. The approach com-prises the development of yield forecasting models from single and multi-date spectral data and the verification of remote sensing predictions through comparison with estimations from yield relationships with crop agronomical parameters. Statistical relationships between crop spectral reflectance, growth variables and yield have been established. Grain yield has been related to spectral data acquired at different phenological stages of plant development and to spectral data accumulated during the entire growing season. Comparison has been made between the yield prediction results from crop biophysical, multispectral and multitemporal data in order to validate the predictive performance of the spectral models. The algorithm has been realized on winter wheat. In-situ high

  1. Development of a tunable Fabry-Perot etalon-based near-infrared interference spectrometer for measurement of the HeI 2³S-2³P spectral line shape in magnetically confined torus plasmas.

    PubMed

    Ogane, S; Shikama, T; Zushi, H; Hasuo, M

    2015-10-01

    In magnetically confined torus plasmas, the local emission intensity, temperature, and flow velocity of atoms in the inboard and outboard scrape-off layers can be separately measured by a passive emission spectroscopy assisted by observation of the Zeeman splitting in their spectral line shape. To utilize this technique, a near-infrared interference spectrometer optimized for the observation of the helium 2(3)S-2(3)P transition spectral line (wavelength 1083 nm) has been developed. The applicability of the technique to actual torus devices is elucidated by calculating the spectral line shapes expected to be observed in LHD and QUEST (Q-shu University Experiment with Steady State Spherical Tokamak). In addition, the Zeeman effect on the spectral line shape is measured using a glow-discharge tube installed in a superconducting magnet. PMID:26520955

  2. Development of a tunable Fabry-Perot etalon-based near-infrared interference spectrometer for measurement of the HeI 23S-23P spectral line shape in magnetically confined torus plasmas

    NASA Astrophysics Data System (ADS)

    Ogane, S.; Shikama, T.; Zushi, H.; Hasuo, M.

    2015-10-01

    In magnetically confined torus plasmas, the local emission intensity, temperature, and flow velocity of atoms in the inboard and outboard scrape-off layers can be separately measured by a passive emission spectroscopy assisted by observation of the Zeeman splitting in their spectral line shape. To utilize this technique, a near-infrared interference spectrometer optimized for the observation of the helium 23S-23P transition spectral line (wavelength 1083 nm) has been developed. The applicability of the technique to actual torus devices is elucidated by calculating the spectral line shapes expected to be observed in LHD and QUEST (Q-shu University Experiment with Steady State Spherical Tokamak). In addition, the Zeeman effect on the spectral line shape is measured using a glow-discharge tube installed in a superconducting magnet.

  3. Development of a tunable Fabry-Perot etalon-based near-infrared interference spectrometer for measurement of the HeI 2{sup 3}S-2{sup 3}P spectral line shape in magnetically confined torus plasmas

    SciTech Connect

    Ogane, S.; Shikama, T. Hasuo, M.; Zushi, H.

    2015-10-15

    In magnetically confined torus plasmas, the local emission intensity, temperature, and flow velocity of atoms in the inboard and outboard scrape-off layers can be separately measured by a passive emission spectroscopy assisted by observation of the Zeeman splitting in their spectral line shape. To utilize this technique, a near-infrared interference spectrometer optimized for the observation of the helium 2{sup 3}S–2{sup 3}P transition spectral line (wavelength 1083 nm) has been developed. The applicability of the technique to actual torus devices is elucidated by calculating the spectral line shapes expected to be observed in LHD and QUEST (Q-shu University Experiment with Steady State Spherical Tokamak). In addition, the Zeeman effect on the spectral line shape is measured using a glow-discharge tube installed in a superconducting magnet.

  4. Spectral procedures for estimating crop biomass

    SciTech Connect

    Wanjura, D.F.; Hatfield, J.L.

    1985-05-01

    Spectral reflectance was measured semi-weekly and used to estimate leaf area and plant dry weight accumulation in cotton, soybeans, and sunflower. Integration of spectral crop growth cycle curves explained up to 95 and 91%, respectively, of the variation in cotton lint yield and dry weight. A theoretical relationship for dry weight accumulation, in which only intercepted radiation or intercepted radiation and solar energy to biomass conversion efficiency were spectrally estimated, explained 99 and 96%, respectively, of the observed plant dry weight variation of the three crops. These results demonstrate the feasibility of predicting crop biomass from spectral measurements collected frequently during the growing season. 15 references.

  5. Submillimeter, millimeter, and microwave spectral line catalogue

    NASA Technical Reports Server (NTRS)

    Poynter, R. L.; Pickett, H. M.

    1980-01-01

    A computer accessible catalogue of submillimeter, millimeter, and microwave spectral lines in the frequency range between O and 3000 GHz (such as; wavelengths longer than 100 m) is discussed. The catalogue was used as a planning guide and as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue was constructed by using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances.

  6. Recovery of spectral data using weighted canonical correlation regression

    NASA Astrophysics Data System (ADS)

    Eslahi, Niloofar; Amirshahi, Seyed Hossein; Agahian, Farnaz

    2009-05-01

    The weighted canonical correlation regression technique is employed for reconstruction of reflectance spectra of surface colors from the related XYZ tristimulus values of samples. Flexible input data based on applying certain weights to reflectance and colorimetric values of Munsell color chips has been implemented for each particular sample which belongs to Munsell or GretagMacbeth Colorchecker DC color samples. In fact, the colorimetric and spectrophotometric data of Munsell chips are selected as fundamental bases and the color difference values between the target and samples in Munsell dataset are chosen as a criterion for determination of weighting factors. The performance of the suggested method is evaluated in spectral reflectance reconstruction. The results show considerable improvements in terms of root mean square error (RMS) and goodness-of-fit coefficient (GFC) between the actual and reconstructed reflectance curves as well as CIELAB color difference values under illuminants A and TL84 for CIE1964 standard observer.

  7. Multidimensional spectral load balancing

    SciTech Connect

    Hendrickson, B.; Leland, R.

    1993-01-01

    We describe an algorithm for the static load balancing of scientific computations that generalizes and improves upon spectral bisection. Through a novel use of multiple eigenvectors, our new spectral algorithm can divide a computation into 4 or 8 pieces at once. These multidimensional spectral partitioning algorithms generate balanced partitions that have lower communication overhead and are less expensive to compute than those produced by spectral bisection. In addition, they automatically work to minimize message contention on a hypercube or mesh architecture. These spectral partitions are further improved by a multidimensional generalization of the Kernighan-Lin graph partitioning algorithm. Results on several computational grids are given and compared with other popular methods.

  8. Air resistance measurements on actual airplane parts

    NASA Technical Reports Server (NTRS)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  9. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  10. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  11. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  12. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  13. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  14. What Galvanic Vestibular Stimulation Actually Activates

    PubMed Central

    Curthoys, Ian S.; MacDougall, Hamish Gavin

    2012-01-01

    In a recent paper in Frontiers Cohen et al. (2012) asked “What does galvanic vestibular stimulation actually activate?” and concluded that galvanic vestibular stimulation (GVS) causes predominantly otolithic behavioral responses. In this Perspective paper we show that such a conclusion does not follow from the evidence. The evidence from neurophysiology is very clear: galvanic stimulation activates primary otolithic neurons as well as primary semicircular canal neurons (Kim and Curthoys, 2004). Irregular neurons are activated at lower currents. The answer to what behavior is activated depends on what is measured and how it is measured, including not just technical details, such as the frame rate of video, but the exact experimental context in which the measurement took place (visual fixation vs total darkness). Both canal and otolith dependent responses are activated by GVS. PMID:22833733

  15. MODIS Solar Diffuser: Modelled and Actual Performance

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xiong, Xiao-Xiong; Esposito, Joe; Wang, Xin-Dong; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument's solar diffuser is used in its radiometric calibration for the reflective solar bands (VIS, NTR, and SWIR) ranging from 0.41 to 2.1 micron. The sun illuminates the solar diffuser either directly or through a attenuation screen. The attenuation screen consists of a regular array of pin holes. The attenuated illumination pattern on the solar diffuser is not uniform, but consists of a multitude of pin-hole images of the sun. This non-uniform illumination produces small, but noticeable radiometric effects. A description of the computer model used to simulate the effects of the attenuation screen is given and the predictions of the model are compared with actual, on-orbit, calibration measurements.

  16. Different optical spectral characteristics in a necrotic transmissible venereal tumor and a cystic lesion in the same canine prostate observed by triple-band trans-rectal optical tomography under trans-rectal ultrasound guidance

    NASA Astrophysics Data System (ADS)

    Jiang, Zhen; Holyoak, G. Reed; Ritchey, Jerry W.; Bartels, Kenneth E.; Rock, Kendra; Ownby, Charlotte L.; Slobodov, Gennady; Bunting, Charles F.; Piao, Daqing

    2011-03-01

    Different optical spectral characteristics were observed in a necrotic transmissible venereal tumor (TVT) and a cystic lesion in the same canine prostate by triple-wavelength trans-rectal optical tomography under trans-rectal ultrasound (TRUS) guidance. The NIR imager acquiring at 705nm, 785nm and 808nm was used to quantify both the total hemoglobin concentration (HbT) and oxygen saturation (StO2) in the prostate. The TVT tumor in the canine prostate as a model of prostate cancer was induced in a 7-year old, 27 kg dog. A 2 mL suspension of 2.5x106 cells/mL of homogenized TVT cells recovered from an in vivo subcutaneously propagated TVT tumor in an NOD/SCID mouse were injected in the cranial aspect of the right lobe of the canine prostate. The left lobe of the prostate had a cystic lesion present before TVT inoculation. After the TVT homogenate injection, the prostate was monitored weekly over a 9-week period, using trans-rectal NIR and TRUS in grey-scale and Doppler. A TVT mass within the right lobe developed a necrotic center during the later stages of this study, as the mass presented with substantially increased [HbT] in the periphery, with an area of reduced StO2 less than the area of the mass itself shown on ultrasonography. Conversely, the cystic lesion presented with slightly increased [HbT] in the periphery of the lesion shown on ultrasound with oxygen-reduction inside and in the periphery of the lesion. There was no detectable change of blood flow on Doppler US in the periphery of the cystic lesion. The slightly increased [HbT] in the periphery of the cystic lesion was correlated with intra-lesional hemorrhage upon histopathologic examination.

  17. Evaluating Spectral Signals to Identify Spectral Error.

    PubMed

    Bazar, George; Kovacs, Zoltan; Tsenkova, Roumiana

    2016-01-01

    Since the precision and accuracy level of a chemometric model is highly influenced by the quality of the raw spectral data, it is very important to evaluate the recorded spectra and describe the erroneous regions before qualitative and quantitative analyses or detailed band assignment. This paper provides a collection of basic spectral analytical procedures and demonstrates their applicability in detecting errors of near infrared data. Evaluation methods based on standard deviation, coefficient of variation, mean centering and smoothing techniques are presented. Applications of derivatives with various gap sizes, even below the bandpass of the spectrometer, are shown to evaluate the level of spectral errors and find their origin. The possibility for prudent measurement of the third overtone region of water is also highlighted by evaluation of a complex data recorded with various spectrometers. PMID:26731541

  18. Evaluating Spectral Signals to Identify Spectral Error

    PubMed Central

    Bazar, George; Kovacs, Zoltan; Tsenkova, Roumiana

    2016-01-01

    Since the precision and accuracy level of a chemometric model is highly influenced by the quality of the raw spectral data, it is very important to evaluate the recorded spectra and describe the erroneous regions before qualitative and quantitative analyses or detailed band assignment. This paper provides a collection of basic spectral analytical procedures and demonstrates their applicability in detecting errors of near infrared data. Evaluation methods based on standard deviation, coefficient of variation, mean centering and smoothing techniques are presented. Applications of derivatives with various gap sizes, even below the bandpass of the spectrometer, are shown to evaluate the level of spectral errors and find their origin. The possibility for prudent measurement of the third overtone region of water is also highlighted by evaluation of a complex data recorded with various spectrometers. PMID:26731541

  19. Spectral distortions of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Adams, Fred C.; Mcdowell, Jonathan C.; Freese, Katherine; Levin, Janna

    1989-01-01

    Recent experiments indicate that the spectrum of the cosmic microwave background deviates from a pure blackbody; here, spectral distortions produced by cosmic dust are considered. The main result is that cosmic dust in conjunction with an injected radiation field (perhaps produced by an early generation of very massive stars) can explain the observed spectral distortions without violating existing cosmological constraints. In addition, it is shown that Compton y-distortions can also explain the observed spectral shape, but the energetic requirements are more severe.

  20. Spectral methods for CFD

    NASA Technical Reports Server (NTRS)

    Zang, Thomas A.; Streett, Craig L.; Hussaini, M. Yousuff

    1989-01-01

    One of the objectives of these notes is to provide a basic introduction to spectral methods with a particular emphasis on applications to computational fluid dynamics. Another objective is to summarize some of the most important developments in spectral methods in the last two years. The fundamentals of spectral methods for simple problems will be covered in depth, and the essential elements of several fluid dynamical applications will be sketched.

  1. Planck 2013 results. IX. HFI spectral response

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Leroy, C.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; North, C.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Santos, D.; Savini, G.; Scott, D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the spectral transmission tests was to measure the relative spectral response (includingthe level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based spectral response experiments provide the definitive data set for the relative spectral calibration of the HFI. Knowledge of the relative variations in the spectral response between HFI detectors allows for a more thorough analysis of the HFI data. The spectral response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI spectral response data have also been used to provide unit conversion and colour correction analysis tools. While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight spectral response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI spectral response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band spectral signal rejection better than 108. The accuracy of the HFI relative spectral response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction

  2. Spectral response from blackbody measurements

    NASA Astrophysics Data System (ADS)

    Moore, W. J.

    1981-07-01

    Far-infrared and submillimeter detector responsivity and spectral response measurements can be performed simultaneously by sweeping the temperature of a cooled blackbody. Such measurements yield n simultaneous linear equations for n blackbody temperatures. Matrix inversion solutions are observed to fail due to a matrix ill-conditioned for inversion. However, an unconditionally convergent iterative solution can be performed. Results for a gallium-doped germanium detector are described.

  3. Caustic-Side Solvent Extraction: Prediction of Cesium Extraction for Actual Wastes and Actual Waste Simulants

    SciTech Connect

    Delmau, L.H.; Haverlock, T.J.; Sloop, F.V., Jr.; Moyer, B.A.

    2003-02-01

    This report presents the work that followed the CSSX model development completed in FY2002. The developed cesium and potassium extraction model was based on extraction data obtained from simple aqueous media. It was tested to ensure the validity of the prediction for the cesium extraction from actual waste. Compositions of the actual tank waste were obtained from the Savannah River Site personnel and were used to prepare defined simulants and to predict cesium distribution ratios using the model. It was therefore possible to compare the cesium distribution ratios obtained from the actual waste, the simulant, and the predicted values. It was determined that the predicted values agree with the measured values for the simulants. Predicted values also agreed, with three exceptions, with measured values for the tank wastes. Discrepancies were attributed in part to the uncertainty in the cation/anion balance in the actual waste composition, but likely more so to the uncertainty in the potassium concentration in the waste, given the demonstrated large competing effect of this metal on cesium extraction. It was demonstrated that the upper limit for the potassium concentration in the feed ought to not exceed 0.05 M in order to maintain suitable cesium distribution ratios.

  4. A Sight on the Variation of Spectral Parameters in GRBs

    SciTech Connect

    Hafizi, Mimoza; Boci, Sonila

    2010-01-21

    Gamma ray bursts (GRBs) are high energy photons detected during a short interval of time. They are signs of the most energetic events in the universe. Photons detected show a non thermal spectrum, very well described by the peak energy and two smoothly connected power laws with different slopes or indices. This spectrum is named Band spectrum and serves actually as the most important source of information on their physical origin. It characterizes not only the overall emission, but also the instantaneous one, found in small successive intervals of time during the event. The time-resolved spectra show an obvious evolution in energy, which is generally accepted and supported by several arguments. There is also some evidence in measuring a kind of evolution in slope parameters, which would be considered as a serious source of information for the physical mechanism. In this work we try to examine the limit in observation bands, which we suspect as a reason for the apparent variation in time of spectral indices. Our work is based on a numeric and certified code. We simulate GRBs assuming synchrotron emission in the internal shocks model. For each time-resolved spectrum we find spectral parameters based on the Band function.

  5. Piecewise spectrally band-pass for compressive coded aperture spectral imaging

    NASA Astrophysics Data System (ADS)

    Qian, Lu-Lu; Lü, Qun-Bo; Huang, Min; Xiang, Li-Bin

    2015-08-01

    Coded aperture snapshot spectral imaging (CASSI) has been discussed in recent years. It has the remarkable advantages of high optical throughput, snapshot imaging, etc. The entire spatial-spectral data-cube can be reconstructed with just a single two-dimensional (2D) compressive sensing measurement. On the other hand, for less spectrally sparse scenes, the insufficiency of sparse sampling and aliasing in spatial-spectral images reduce the accuracy of reconstructed three-dimensional (3D) spectral cube. To solve this problem, this paper extends the improved CASSI. A band-pass filter array is mounted on the coded mask, and then the first image plane is divided into some continuous spectral sub-band areas. The entire 3D spectral cube could be captured by the relative movement between the object and the instrument. The principle analysis and imaging simulation are presented. Compared with peak signal-to-noise ratio (PSNR) and the information entropy of the reconstructed images at different numbers of spectral sub-band areas, the reconstructed 3D spectral cube reveals an observable improvement in the reconstruction fidelity, with an increase in the number of the sub-bands and a simultaneous decrease in the number of spectral channels of each sub-band. Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 61225024) and the National High Technology Research and Development Program of China (Grant No. 2011AA7012022).

  6. SPECTRAL RELATIVE ABSORPTION DIFFERENCE METHOD

    SciTech Connect

    Salaymeh, S.

    2010-06-17

    When analyzing field data, the uncertainty in the background continuum emission produces the majority of error in the final gamma-source analysis. The background emission typically dominates an observed spectrum in terms of counts and is highly variable spatially and temporally. The majority of the spectral shape of the background continuum is produced by combinations of cosmic rays, {sup 40}K, {sup 235}U, and {sup 220}Rn, and the continuum is similar in shape to the 15%-20% level for most field observations. However, the goal of spectroscopy analysis is to pick up subtle peaks (<%5) upon this large background. Because the continuum is falling off as energy increases, peak detection algorithms must first define the background surrounding the peak. This definition is difficult when the range of background shapes is considered. The full spectral template matching algorithms are heavily weighted to solving for the background continuum as it produces significant counts over much of the energy range. The most appropriate background mitigation technique is to take a separate background observation without the source of interest. But, it is frequently not possible to record a background observation in the exact location before (or after) a source has been detected. Thus, one uses approximate backgrounds that rely on spatially nearby locations or similar environments. Since the error in many field observations is dominated by the background, a technique that is less sensitive to the background would be quite beneficial. We report the result of an initial investigation into a novel observation scheme for gamma-emission detection in high background environments. Employing low resolution, NaI, detectors, we examine the different between the direct emission and the 'spectral-shadow' that the gamma emission produces when passed through a thin absorber. For this detection scheme to be competitive, it is required to count and analyze individual gamma-events. We describe the

  7. Consequences of Predicted or Actual Asteroid Impacts

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.

    2003-12-01

    Earth impact by an asteroid could have enormous physical and environmental consequences. Impactors larger than 2 km diameter could be so destructive as to threaten civilization. Since such events greatly exceed any other natural or man-made catastrophe, much extrapolation is necessary just to understand environmental implications (e.g. sudden global cooling, tsunami magnitude, toxic effects). Responses of vital elements of the ecosystem (e.g. agriculture) and of human society to such an impact are conjectural. For instance, response to the Blackout of 2003 was restrained, but response to 9/11 terrorism was arguably exaggerated and dysfunctional; would society be fragile or robust in the face of global catastrophe? Even small impacts, or predictions of impacts (accurate or faulty), could generate disproportionate responses, especially if news media reports are hyped or inaccurate or if responsible entities (e.g. military organizations in regions of conflict) are inadequately aware of the phenomenology of small impacts. Asteroid impact is the one geophysical hazard of high potential consequence with which we, fortunately, have essentially no historical experience. It is thus important that decision makers familiarize themselves with the hazard and that society (perhaps using a formal procedure, like a National Academy of Sciences study) evaluate the priority of addressing the hazard by (a) further telescopic searches for dangerous but still-undiscovered asteroids and (b) development of mitigation strategies (including deflection of an oncoming asteroid and on- Earth civil defense). I exemplify these issues by discussing several representative cases that span the range of parameters. Many of the specific physical consequences of impact involve effects like those of other geophysical disasters (flood, fire, earthquake, etc.), but the psychological and sociological aspects of predicted and actual impacts are distinctive. Standard economic cost/benefit analyses may not

  8. A method of determining spectral dye densities in color films

    NASA Technical Reports Server (NTRS)

    Friederichs, G. A.; Scarpace, F. L.

    1977-01-01

    A mathematical analysis technique called characteristic vector analysis, reported by Simonds (1963), is used to determine spectral dye densities in multiemulsion film such as color or color-IR imagery. The technique involves examining a number of sets of multivariate data and determining linear transformations of these data to a smaller number of parameters which contain essentially all of the information contained in the original set of data. The steps involved in the actual procedure are outlined. It is shown that integral spectral density measurements of a large number of different color samples can be accurately reconstructed from the calculated spectral dye densities.

  9. Spectral characteristics and predictability of the NAO assessed through Singular Spectral Analysis

    NASA Astrophysics Data System (ADS)

    GáMiz-Fortis, S. R.; Pozo-VáZquez, D.; Esteban-Parra, M. J.; Castro-DíEz, Y.

    2002-12-01

    For the period 1826-2000, we analyze the spectral characteristics of the winter North Atlantic Oscillation (NAO) index and its predictability based on Singular Spectral Analysis (SSA) and Autoregressive Moving Average (ARMA) models. In the first part, SSA is applied to the winter NAO index to isolate its main spectral characteristics. Based on the SSA, a reconstruction (filtering) of the winter NAO index series was carried out. Results of the SSA indicate that the winter NAO index can be broken down into some modulated amplitude oscillations with periods around 7.7 and 4.8 years, some oscillations associated with a broadband peak of period around 2.4 years along with nonlinear trends. The sum of these components, the SSA-filtered series, explains 56% of the variance of the raw winter NAO index. The SSA-filtered series is particularly reliable, reproducing the NAO phase during extreme events (winter NAO index ≥ 1 or ≤ -1); for this subset of events, the phase of the actual and SSA-filtered series shows to be the same in 91% of the cases. The high positive values observed in the winter NAO index in the last eighties and nineties appear to be associated with the simultaneous presence of a positive trend, starting in the early eighties and of unprecedented steepness, and an oscillation with period around 7.7 years, having very high amplitude. In the second part, an ARMA model has been fitted to the filtered winter NAO index and a forecasting experiment was conducted; results are tested against the raw winter NAO index. Results show that the ARMA modeling has useful 1-year-ahead forecasting abilities. Particularly, over the period 1986-2000, not used to fit the model, the model skill is 27.8% better than climatology and 43.3% better than persistence (38.5% and 47.6%, respectively, when taking into account only extreme NAO events). Additionally, percentage of cases in which the NAO phase was accurately predicted proved to be 80% (88% for extreme NAO events). For 2001

  10. Running spectral index from inflation with modulations

    SciTech Connect

    Kobayashi, Takeshi; Takahashi, Fuminobu E-mail: fuminobu.takahashi@ipmu.jp

    2011-01-01

    We argue that a large negative running spectral index, if confirmed, might suggest that there are abundant structures in the inflaton potential, which result in a fairly large (both positive and negative) running of the spectral index at all scales. It is shown that the center value of the running spectral index suggested by the recent CMB data can be easily explained by an inflaton potential with superimposed periodic oscillations. In contrast to cases with constant running, the perturbation spectrum is enhanced at small scales, due to the repeated modulations. We mention that such features at small scales may be seen by 21 cm observations in the future.

  11. Spectral signatures of penumbral transients

    SciTech Connect

    Reardon, K.; Tritschler, A.

    2013-12-20

    In this work we investigate the properties of penumbral transients observed in the upper photospheric and chromospheric region above a sunspot penumbra using two-dimensional spectroscopic observations of the Ca II 854.21 nm line with a 5 s cadence. In our 30 minutes of observations, we identify several penumbral-micro jets (PMJs) with cotemporal observations from Dunn Solar Telescope/IBIS and Hinode/SOT. We find that the line profiles of these PMJ events show emission in the two wings of the line (±0.05 nm), but little modification of the line core. These are reminiscent of the line profiles of Ellerman bombs observed in plage and network regions. Furthermore, we find evidence that some PMJ events have a precursor phase starting 1 minute prior to the main brightening that might indicate initial heating of the plasma prior to an acoustic or bow shock event. With the IBIS data, we also find several other types of transient brightenings with timescales of less than 1 minute that are not clearly seen in the Hinode/SOT data. The spectral profiles and other characteristics of these events are significantly different from those of PMJs. The different appearances of all these transients are an indicator of the general complexity of the chromospheric magnetic field and underscore the highly dynamic behavior above sunspots. It also highlights the care that is needed in interpreting broadband filter images of chromospheric lines, which may conceal very different spectral profiles, and the underlying physical mechanisms at work.

  12. Soil spectral characterization

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F.

    1981-01-01

    The spectral characterization of soils is discussed with particular reference to the bidirectional reflectance factor as a quantitative measure of soil spectral properties, the role of soil color, soil parameters affecting soil reflectance, and field characteristics of soil reflectance. Comparisons between laboratory-measured soil spectra and Landsat MSS data have shown good agreement, especially in discriminating relative drainage conditions and organic matter levels in unvegetated soils. The capacity to measure both visible and infrared soil reflectance provides information on other soil characteristics and makes it possible to predict soil response to different management conditions. Field and laboratory soil spectral characterization helps define the extent to which intrinsic spectral information is available from soils as a consequence of their composition and field characteristics.

  13. Commission 45: Spectral Classification

    NASA Astrophysics Data System (ADS)

    Giridhar, Sunetra; Gray, Richard O.; Corbally, Christopher J.; Bailer-Jones, Coryn A. L.; Eyer, Laurent; Irwin, Michael J.; Kirkpatrick, J. Davy; Majewski, Steven; Minniti, Dante; Nordström, Birgitta

    This report gives an update of developments (since the last General Assembly at Prague) in the areas that are of relevance to the commission. In addition to numerous papers, a new monograph entitled Stellar Spectral Classification with Richard Gray and Chris Corbally as leading authors will be published by Princeton University Press as part of their Princeton Series in Astrophysics in April 2009. This book is an up-to-date and encyclopedic review of stellar spectral classification across the H-R diagram, including the traditional MK system in the blue-violet, recent extensions into the ultraviolet and infrared, the newly defined L-type and T-type spectral classes, as well as spectral classification of carbon stars, S-type stars, white dwarfs, novae, supernovae and Wolf-Rayet stars.

  14. Detection limits of about 350 prominent lines of 65 elements observed in 50 and 27 MHz inductively coupled plasmas (ICP): effects of source characteristics, noise and spectral bandwidth-"Standard" values for the 50 MHz ICP

    NASA Astrophysics Data System (ADS)

    Boumans, P. W. J. M.; Vrakking, J. J. A. M.

    This paper links up with a previous publication by the same authors [ Spectrochim. Acta41B, 1235 (1986)] dealing with the measurement of the effective line profiles of about 350 prominent lines at high spectral resolution and the determination of the physical widths of these lines. In the present work the line widths are used for a breakdown of the detection limits obtained with these lines using different ICPs and different spectrometers. This breakdown takes into account the separate effects of source characteristics, noise, and spectral bandwidth. The availability of the numerical values of the physical widths of a large number of lines permitted a more rigorous approach than in a previous work [ Spectrochim. Acta40B, 1437 (1985)]. The present approach was applied to detection limits obtained in this work with a 50 MHz ICP at high spectral resolution and to results reported by W INGEet al. [ Appl. Spectrosc.33, 206 (1979)] and WOHLERS [ ICP Information Newslett.10, 601 (1985)]for 27 MHz ICPs. The 50 MHz ICP was shown to have an advantage in source signal-to-background ratio (SBR) with respect to either of the two 27 MHz ICPs. This SBR advantage was a factor of 3-15 with respect to the "Winge ICP" and a factor of 2-6 with respect to the "Wohlers ICP". The approach was also used to convert detection limits measured in the 50 MHz ICP at high resolution into values for 15 pm spectral bandwidth and a relative standard deviation of the background signal equal to 1%. These values are recommended as standards of performance for the conventional argon ICP. The paper comprises a tabulation of the complete results for the 350 prominent lines and includes four sets of detection limits for these lines.

  15. Thermophotovoltaic Spectral Control

    SciTech Connect

    DM DePoy; PM Fourspring; PF Baldasaro; JF Beausang; EJ Brown; MW Dashiel; KD Rahner; TD Rahmlow; JE Lazo-Wasem; EJ Gratrix; B Wemsman

    2004-06-09

    Spectral control is a key technology for thermophotovoltaic (TPV) direct energy conversion systems because only a fraction (typically less than 25%) of the incident thermal radiation has energy exceeding the diode bandgap energy, E{sub g}, and can thus be converted to electricity. The goal for TPV spectral control in most applications is twofold: (1) Maximize TPV efficiency by minimizing transfer of low energy, below bandgap photons from the radiator to the TPV diode. (2) Maximize TPV surface power density by maximizing transfer of high energy, above bandgap photons from the radiator to the TPV diode. TPV spectral control options include: front surface filters (e.g. interference filters, plasma filters, interference/plasma tandem filters, and frequency selective surfaces), back surface reflectors, and wavelength selective radiators. System analysis shows that spectral performance dominates diode performance in any practical TPV system, and that low bandgap diodes enable both higher efficiency and power density when spectral control limitations are considered. Lockheed Martin has focused its efforts on front surface tandem filters which have achieved spectral efficiencies of {approx}83% for E{sub g} = 0.52 eV and {approx}76% for E{sub g} = 0.60 eV for a 950 C radiator temperature.

  16. Spectral Irradiance Calibration in the Infrared.IV. 1.2-35 micron spectra of six standard stars

    NASA Astrophysics Data System (ADS)

    Cohen, Martin; Witteborn, Fred C.; Walker, Russell G.; Bregman, Jesse D.; Wooden, Diane H.

    1995-07-01

    We present five new absolutely calibrated continuous stellar spectra from 1.2 to 35 μm, constructed as far as possible from actual observed spectral fragments taken from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars -- β Peg, α Boo, β And, β Gem, and α Hya -- augment our already created complete absolutely calibrated spectrum for α Tau. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors.

  17. Spectral Irradiance Calibration in the Infrared. Part 4; 1.2 - 35 microns Spectra of Six Standard Stars

    NASA Technical Reports Server (NTRS)

    Cohen, Martin; Witteborn, Fred C.; Walker, Russell G.; Bregman, Jesse D.; Wooden, Diane H.

    1995-01-01

    We present five new absolutely calibrated continuous stellar spectra from 1.2 to 35 microns, constructed as far as possible from actual observed spectral fragments taken from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars- beta Peg, alpha Boo, beta And, beta Gem, and alpha Hya-augment our already created complete absolutely calibrated spectrum for alpha Tau. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors.

  18. Spectral Irradiance Calibration in the Infrared. 4; 1.2-35um Spectra of Six Standard Stars

    NASA Technical Reports Server (NTRS)

    Cohen, Martin; Witteborn, Fred C.; Walker, Russell G.; Bregman, Jesse D.; Wooden, Diane H.

    1995-01-01

    We present five new absolutely calibrated continuous stellar spectra from 1.2 to 35 microns, constructed as far as possible from actual observed spectral fragments taken from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars, Beta Peg, Delta Boo, Beta And, Beta Gem, and Delta Hya, augment our already created complete absolutely calibrated spectrum for a Tau. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors.

  19. Spectral Irradiance Calibration in the Infrared. Part 4; 1.2-35 micrometer Spectra of Six Standard Stars

    NASA Technical Reports Server (NTRS)

    Cohen, Martin; Witteborn, Fred C.; Walker, Russell, G.; Bregman, Jesse D.; Wooden, Diane H.

    1995-01-01

    Five new absolutely calibrated continuous stellar spectra from 1.2 to 35 microns are presented. The spectra were constructed as far as possible from actual observed spectral fragments taken from the ground, the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars (beta Peg, alpha Boo, beta And, beta Gem, and alpha Hya) augment the author's already created complete absolutely calibrated spectrum for alpha Tau. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors.

  20. Spectral Fingerprints of Habitability

    NASA Astrophysics Data System (ADS)

    Kaltenegger, L.; Selsis, F.

    2010-01-01

    The emerging field of extrasolar planet search has shown an extraordinary ability to combine research by astrophysics, chemistry, biology and geophysics into a new and exciting interdisciplinary approach to understand our place in the universe. Are there other worlds like ours? How can we characterize those planets and assess if they are habitable? After a decade rich in giant exoplanet detections, observation techniques have now reached the ability to find planets of less than 10 M_Earth (so called Super-Earths) that may potentially be habitable. The detection and characterization of Earth-like planet is approaching rapidly with dedicated space observatories already in operation (Corot) or in development phase (Kepler, James Webb Space Telescope, Extremely Large Telescope (ELT), Darwin/TPF). Space missions like CoRoT (CNES, Rouan et al. 1998) and Kepler (NASA, Borucki et al. 1997) will give us statistics on the number, size, period and orbital distance of planets, extending to terrestrial planets on the lower mass range end as a first step, while missions like Darwin/TPF are designed to characterize their atmospheres. In this chapter we discuss how we can read a planet's spectral fingerprint and characterize if it is potentially habitable. We discuss the first steps to detect a habitable planet and set biomarker detection in context in Section 1. In Section 2 we focus on biomarkers, their signatures at different wavelengths, abiotic sources and cryptic photosynthesis - using Earth as our primary example - the only habitable planet we know of so far. Section 3 concentrates on planets around different stars, and Section 4 summarizes the chapter.

  1. Spectral statistics of nearly unidirectional quantum graphs

    NASA Astrophysics Data System (ADS)

    Akila, Maram; Gutkin, Boris

    2015-08-01

    The energy levels of a quantum graph with time reversal symmetry and unidirectional classical dynamics are doubly degenerate and obey the spectral statistics of the Gaussian unitary ensemble. These degeneracies, however, are lifted when the unidirectionality is broken in one of the graph’s vertices by a singular perturbation. Based on a random matrix model we derive an analytic expression for the nearest neighbour distribution between energy levels of such systems. As we demonstrate the result agrees excellently with the actual statistics for graphs with a uniform distribution of eigenfunctions. Yet, it exhibits quite substantial deviations for classes of graphs which show strong scarring.

  2. Spectral Data Reduction via Wavelet Decomposition

    NASA Technical Reports Server (NTRS)

    Kaewpijit, S.; LeMoigne, J.; El-Ghazawi, T.; Rood, Richard (Technical Monitor)

    2002-01-01

    The greatest advantage gained from hyperspectral imagery is that narrow spectral features can be used to give more information about materials than was previously possible with broad-band multispectral imagery. For many applications, the new larger data volumes from such hyperspectral sensors, however, present a challenge for traditional processing techniques. For example, the actual identification of each ground surface pixel by its corresponding reflecting spectral signature is still one of the most difficult challenges in the exploitation of this advanced technology, because of the immense volume of data collected. Therefore, conventional classification methods require a preprocessing step of dimension reduction to conquer the so-called "curse of dimensionality." Spectral data reduction using wavelet decomposition could be useful, as it does not only reduce the data volume, but also preserves the distinctions between spectral signatures. This characteristic is related to the intrinsic property of wavelet transforms that preserves high- and low-frequency features during the signal decomposition, therefore preserving peaks and valleys found in typical spectra. When comparing to the most widespread dimension reduction technique, the Principal Component Analysis (PCA), and looking at the same level of compression rate, we show that Wavelet Reduction yields better classification accuracy, for hyperspectral data processed with a conventional supervised classification such as a maximum likelihood method.

  3. Correlation-induced spectral changes

    NASA Astrophysics Data System (ADS)

    Wolf, Emil; James, Daniel F. V.

    1996-06-01

    This paper presents a review of research, both theoretical and experimental, concerning the influence of coherence properties of fluctuating light sources and of correlation properties of scattering media on the spectra of radiated and scattered fields. Much of this research followed a discovery made in 1986, that the spectrum of light may change on propagation, even in free space. More than 100 papers on this topic have been published to date and many of them are reviewed, or at least mentioned, in this article. After an introduction and a summary of some of the main mathematical results relating to second-order coherence theory of statistically stationary optical fields, spectral changes that may take place on superposing fields produced by two partially correlated sources are discussed. Spectral effects in fields produced by two-dimensional secondary sources and by three-dimensional primary sources are then considered. The section which follows describes spectral changes that may arise when polychromatic light is scattered on media whose physical properties vary randomly either in space and/or in time. A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another. In the final section a brief review is given of a new emerging technique sometimes called spatial-coherence spectroscopy. It is based on the discovery that it is possible, under certain circumstances, to determine field correlations from spectral measurements.

  4. Actual Versus Predicted Cardiovascular Demands in Submaximal Cycle Ergometer Testing

    PubMed Central

    HOEHN, AMANDA M.; MULLENBACH, MEGAN J.; FOUNTAINE, CHARLES J.

    2015-01-01

    The Astrand-Rhyming cycle ergometer test (ARCET) is a commonly administered submaximal test for estimating aerobic capacity. Whereas typically utilized in clinical populations, the validity of the ARCET to predict VO2max in a non-clinical population, especially female, is less clear. Therefore, the purpose of this study was to determine the accuracy of the ARCET in a sample of healthy and physically active college students. Subjects (13 females, 10 males) performed a maximal cycle ergometer test to volitional exhaustion to determine VO2max. At least 48 hours later, subjects performed the ARCET protocol. Predicted VO2max was calculated following the ARCET format using the age corrected factor. There was no significant difference (p=.045) between actual (41.0±7.97 ml/kg/min) and predicted VO2max (40.3±7.58 ml/kg/min). When split for gender there was a significant difference between actual and predicted VO2 for males, (45.1±7.74 vs. 42.7±8.26 ml/kg/min, p=0.029) but no significant difference observed for females, (37.9±6.9 vs. 38.5±6.77 ml/kg/min, p=0.675). The correlation between actual and predicted VO2 was r=0.84, p<0.001 with an SEE= 4.3 ml/kg/min. When split for gender, the correlation for males was r=0.94, p<0.001, SEE=2.72 ml/kg/min; for females, r=0.74, p=0.004, SEE=4.67 ml/kg/min. The results of this study indicate that the ARCET accurately estimated VO2max in a healthy college population of both male and female subjects. Implications of this study suggest the ARCET can be used to assess aerobic capacity in both fitness and clinical settings where measurement via open-circuit spirometry is either unavailable or impractical. PMID:27182410

  5. Submillimeter, millimeter, and microwave spectral line catalogue

    NASA Technical Reports Server (NTRS)

    Poynter, R. L.; Pickett, H. M.

    1981-01-01

    A computer accessible catalogue of submillimeter, millimeter and microwave spectral lines in the frequency range between 0 and 3000 GHZ (i.e., wavelengths longer than 100 mu m) is presented which can be used a planning guide or as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue was constructed by using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances. Future versions of this catalogue will add more atoms and molecules and update the present listings (133 species) as new data appear. The catalogue is available as a magnetic tape recorded in card images and as a set of microfiche records.

  6. Submillimeter, millimeter, and microwave spectral line catalogue

    NASA Technical Reports Server (NTRS)

    Poynter, R. L.; Pickett, H. M.

    1984-01-01

    This report describes a computer accessible catalogue of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10000 GHz (i.e., wavelengths longer than 30 micrometers). The catalogue can be used as a planning guide or as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue has been constructed using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances. Future versions of this catalogue will add more atoms and molecules and update the present listings (151 species) as new data appear. The catalogue is available from the authors as a magnetic tape recorded in card images and as a set of microfiche records.

  7. Automated spectral classification and the GAIA project

    NASA Technical Reports Server (NTRS)

    Lasala, Jerry; Kurtz, Michael J.

    1995-01-01

    Two dimensional spectral types for each of the stars observed in the global astrometric interferometer for astrophysics (GAIA) mission would provide additional information for the galactic structure and stellar evolution studies, as well as helping in the identification of unusual objects and populations. The classification of the large quantity generated spectra requires that automated techniques are implemented. Approaches for the automatic classification are reviewed, and a metric-distance method is discussed. In tests, the metric-distance method produced spectral types with mean errors comparable to those of human classifiers working at similar resolution. Data and equipment requirements for an automated classification survey, are discussed. A program of auxiliary observations is proposed to yield spectral types and radial velocities for the GAIA-observed stars.

  8. Photovoltaic spectral responsivity measurements

    SciTech Connect

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T.

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  9. Spectral library searching in proteomics.

    PubMed

    Griss, Johannes

    2016-03-01

    Spectral library searching has become a mature method to identify tandem mass spectra in proteomics data analysis. This review provides a comprehensive overview of available spectral library search engines and highlights their distinct features. Additionally, resources providing spectral libraries are summarized and tools presented that extend experimental spectral libraries by simulating spectra. Finally, spectrum clustering algorithms are discussed that utilize the same spectrum-to-spectrum matching algorithms as spectral library search engines and allow novel methods to analyse proteomics data. PMID:26616598

  10. Reference data set for camera spectral sensitivity estimation.

    PubMed

    Darrodi, Maryam Mohammadzadeh; Finlayson, Graham; Goodman, Teresa; Mackiewicz, Michal

    2015-03-01

    In this article, we describe a spectral sensitivity measurement procedure at the National Physical Laboratory, London, with the aim of obtaining ground truth spectral sensitivity functions for Nikon D5100 and Sigma SD1 Merill cameras. The novelty of our data is that the potential measurement errors are estimated at each wavelength. We determine how well the measured spectral sensitivity functions represent the actual camera sensitivity functions (as a function of wavelength). The second contribution of this paper is to test the performance of various leading sensor estimation techniques implemented from the literature using measured and synthetic data and also evaluate them based on ground truth data for the two cameras. We conclude that the estimation techniques tested are not sufficiently accurate when compared with our measured ground truth data and that there remains significant scope to improve estimation algorithms for spectral estimation. To help in this endeavor, we will make all our data available online for the community. PMID:26366649

  11. Microwave spectral line listing

    NASA Technical Reports Server (NTRS)

    White, W. F., Jr.

    1975-01-01

    The frequency, intensity, and identification of 9615 spectral lines belonging to 75 molecules are tabulated in order of increasing frequency. Measurements for all 75 molecules were made in the frequency range from 26500 to 40000 MHz by a computer controlled spectrometer. Measurements were also made in the 18000 to 26500 MHz range for some of the molecules.

  12. Large Spectral Library Problem

    SciTech Connect

    Chilton, Lawrence K.; Walsh, Stephen J.

    2008-10-03

    Hyperspectral imaging produces a spectrum or vector at each image pixel. These spectra can be used to identify materials present in the image. In some cases, spectral libraries representing atmospheric chemicals or ground materials are available. The challenge is to determine if any of the library chemicals or materials exist in the hyperspectral image. The number of spectra in these libraries can be very large, far exceeding the number of spectral channels collected in the ¯eld. Suppose an image pixel contains a mixture of p spectra from the library. Is it possible to uniquely identify these p spectra? We address this question in this paper and refer to it as the Large Spectral Library (LSL) problem. We show how to determine if unique identi¯cation is possible for any given library. We also show that if p is small compared to the number of spectral channels, it is very likely that unique identi¯cation is possible. We show that unique identi¯cation becomes less likely as p increases.

  13. LCLS Spectral Flux Viewer

    2005-10-25

    This application (FluxViewer) is a tool for displaying spectral flux data for the Linac Coherent Light Source (LCLS). This tool allows the user to view sliced spatial and energy distributions of the photons selected for specific energies and positions transverse to the beam axis.

  14. Symmetries of Spectral Problems

    NASA Astrophysics Data System (ADS)

    Shabat, A.

    Deriving abelian KdV and NLS hierarchies, we describe non-abelian symmetries and "pre-Lax" elementary approach to Lax pairs. Discrete symmetries of spectral problems are considered in Sect. 4.2. Here we prove Darboux classical theorem and discuss a modern theory of dressing chains.

  15. Spectral Redundancy in Tissue Characterization

    NASA Astrophysics Data System (ADS)

    Varghese, Tomy

    1995-01-01

    response and the presence of diffuse scattering (speckle). The SAC function is also shown to be relatively insensitive to the presence of the diffuse component which adds directly to the power spectrum. Mean scatterer spacing estimates are compared for techniques that use the cepstrum and the SAC function. Simulations are used to demonstrate a relationship between the average number of scatterers per resolution cell and the average spectral correlation value. The spectral correlation measure can be used to determine the effect of diffuse scattering on the SAC function. Resolution cells with 1 and 2 scatterers can be consistently discriminated from cells with 3 or more scatterers for gamma distributed scatterer positions. The simulation results are validated using in vivo scans of the breast and liver tissue. Significant spectral correlation peaks due to the underlying periodicity is observed in liver tissue. Parametric images obtained using the mean scatterer spacing and the average correlation parameter are used to observe the disruptions caused by metastases and other diffuse diseases in the liver and breast tissue. The cepstral technique is unable to differentiate between normal and metastatic regions of the liver tissue. The average correlation feature inversely related to the scatterer density is used to characterize breast tissue. Significant variations are observed in the average correlation estimates between benign and malignant breast tumors.

  16. Rotational Variability in Ultraviolet Solar Spectral Irradiance

    NASA Astrophysics Data System (ADS)

    Snow, M. A.; Richard, E. C.; Harder, J. W.; Thuillier, G. O.

    2011-12-01

    There are currently many observations and models of the Solar Spectral Irradiance (SSI) in the ultraviolet (UV). The models and the observations are often in agreement, but sometimes have significant differences. Using the decline of solar cycle 23 and the rise of solar cycle 24 as a test case, we will investigate the systematic differences between the short term SSI variation observed by satellite instruments and the predictions of proxy models.

  17. Spectral imaging using forward-viewing spectrally encoded endoscopy

    PubMed Central

    Zeidan, Adel; Yelin, Dvir

    2016-01-01

    Spectrally encoded endoscopy (SEE) enables miniature, small-diameter endoscopic probes for minimally invasive imaging; however, using the broadband spectrum to encode space makes color and spectral imaging nontrivial and challenging. By careful registration and analysis of image data acquired by a prototype of a forward-viewing dual channel spectrally encoded rigid probe, we demonstrate spectral and color imaging within a narrow cylindrical lumen. Spectral imaging of calibration cylindrical test targets and an ex-vivo blood vessel demonstrates high-resolution spatial-spectral imaging with short (10 μs/line) exposure times. PMID:26977348

  18. Spectral imaging using forward-viewing spectrally encoded endoscopy.

    PubMed

    Zeidan, Adel; Yelin, Dvir

    2016-02-01

    Spectrally encoded endoscopy (SEE) enables miniature, small-diameter endoscopic probes for minimally invasive imaging; however, using the broadband spectrum to encode space makes color and spectral imaging nontrivial and challenging. By careful registration and analysis of image data acquired by a prototype of a forward-viewing dual channel spectrally encoded rigid probe, we demonstrate spectral and color imaging within a narrow cylindrical lumen. Spectral imaging of calibration cylindrical test targets and an ex-vivo blood vessel demonstrates high-resolution spatial-spectral imaging with short (10 μs/line) exposure times. PMID:26977348

  19. 26 CFR 1.953-2 - Actual United States risks.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., and water damage risks incurred when property is actually located in the United States and marine... 26 Internal Revenue 10 2014-04-01 2013-04-01 true Actual United States risks. 1.953-2 Section 1... coverage as “.825% plus .3% fire, etc. risks plus .12% water risks = 1.245%”, a reasonable basis exists...

  20. Self-actualization: Its Use and Misuse in Teacher Education.

    ERIC Educational Resources Information Center

    Ivie, Stanley D.

    1982-01-01

    The writings of Abraham Maslow are analyzed to determine the meaning of the psychological term "self-actualization." After pointing out that self-actualization is a rare quality and that it has little to do with formal education, the author concludes that the concept has little practical relevance for teacher education. (PP)

  1. The Self-Actualization of Polk Community College Students.

    ERIC Educational Resources Information Center

    Pearsall, Howard E.; Thompson, Paul V., Jr.

    This article investigates the concept of self-actualization introduced by Abraham Maslow (1954). A summary of Maslow's Needs Hierarchy, along with a description of the characteristics of the self-actualized person, is presented. An analysis of humanistic education reveals it has much to offer as a means of promoting the principles of…

  2. From Self-Awareness to Self-Actualization

    ERIC Educational Resources Information Center

    Cangemi, Joseph P.; Englander, Meryl R.

    1974-01-01

    Highest priority of education is to help students utilize as much of their talent as is possible. Third Force psychologists would interpret this as becoming self-actualized. Self-awareness is required for psychological growth. Without self-awareness there can be no growth, no mental hygiene, and no self-actualization. (Author)

  3. 12 CFR 1806.203 - Selection Process, actual award amounts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Selection Process, actual award amounts. 1806... OF THE TREASURY BANK ENTERPRISE AWARD PROGRAM Awards § 1806.203 Selection Process, actual award... round: (1) To select Applicants not previously selected, using the calculation and selection...

  4. Self-Actualization and the Effective Social Studies Teacher.

    ERIC Educational Resources Information Center

    Farmer, Rodney B.

    1980-01-01

    Discusses a study undertaken to investigate the relationship between social studies teachers' degrees of self-actualization and their teacher effectiveness. Investigates validity of using Maslow's theory of self-actualization as a way of identifying the effective social studies teacher personality. (Author/DB)

  5. Facebook as a Library Tool: Perceived vs. Actual Use

    ERIC Educational Resources Information Center

    Jacobson, Terra B.

    2011-01-01

    As Facebook has come to dominate the social networking site arena, more libraries have created their own library pages on Facebook to create library awareness and to function as a marketing tool. This paper examines reported versus actual use of Facebook in libraries to identify discrepancies between intended goals and actual use. The results of a…

  6. Perceived and Actual Student Support Needs in Distance Education.

    ERIC Educational Resources Information Center

    Visser, Lya; Visser, Yusra Laila

    2000-01-01

    This study sought to determine the academic, affective, and administrative support expectations of distance education students, and to compare actual expectations of distance education students with the instructor's perceptions of such expectations. Results demonstrated divergence between perceived and actual expectations of student support in…

  7. Gebrauchstexte im Fremdsprachenunterricht ("Actual" Texts in Foreign Language Teaching)

    ERIC Educational Resources Information Center

    Ziegesar, Detlef von

    1976-01-01

    Presents for analysis actual texts and texts specially written for teaching, arriving at a basis for a typology of actual texts. Defines teaching aims using such texts, and develops, from a TV program, a teaching unit used in a Karlsruhe school. (Text is in German.) (IFS/WGA)

  8. Self-Actualizing Men and Women: A Comparison Study.

    ERIC Educational Resources Information Center

    Hall, Eleanor G.; Hansen, Jan B.

    1997-01-01

    The self-actualization of 167 women who lived in the Martha Cook (MC) dormitory of the University of Michigan (1950-1970) was compared to that of a group of Ivy League men researched in another study. In addition, two groups of MC women were compared to each other to identify differences which might explain why some self-actualized while other did…

  9. SELF-ACTUALIZATION AND THE UTILIZATION OF TALENT.

    ERIC Educational Resources Information Center

    FRENCH, JOHN R.P.; MILLER, DANIEL R.

    THIS STUDY ATTEMPTED (1) TO DEVELOP A THEORY OF THE CAUSES AND CONSEQUENCES OF SELF-ACTUALIZATION AS RELATED TO THE UTILIZATION OF TALENT, (2) TO FIT THE THEORY TO EXISTING DATA, AND (3) TO PLAN ONE OR MORE RESEARCH PROJECTS TO TEST THE THEORY. TWO ARTICLES ON IDENTITY AND MOTIVATION AND SELF-ACTUALIZATION AND SELF-IDENTITY THEORY REPORTED THE…

  10. Self-Actualization Effects Of A Marathon Growth Group

    ERIC Educational Resources Information Center

    Jones, Dorothy S.; Medvene, Arnold M.

    1975-01-01

    This study examined the effects of a marathon group experience on university student's level of self-actualization two days and six weeks after the experience. Gains in self-actualization as a result of marathon group participation depended upon an individual's level of ego strength upon entering the group. (Author)

  11. 26 CFR 1.962-3 - Treatment of actual distributions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 10 2013-04-01 2013-04-01 false Treatment of actual distributions. 1.962-3... TAX (CONTINUED) INCOME TAXES (CONTINUED) Controlled Foreign Corporations § 1.962-3 Treatment of actual... a foreign corporation. (ii) Treatment of section 962 earnings and profits under § 1.959-3....

  12. School Guidance Counselors' Perceptions of Actual and Preferred Job Duties

    ERIC Educational Resources Information Center

    Edwards, John Dexter

    2010-01-01

    The purpose of this study was to provide process data for school counselors, administrators, and the public, regarding school counselors' actual roles within the guidance counselor preferred job duties and actual job duties. In addition, factors including National Certification or no National Certification, years of counseling experience, and…

  13. Spectral Maps of Titan’s Surface

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin Ann; Penteado, Paulo; Turner, Jake D.; Khamsi, Tymon; Montiel, Nicholas J.

    2015-11-01

    Titan’s surface can be observed most clearly at 7 spectral regions that lie in between the strong methane bands in Titan’s spectrum. Within these ”windows”, between 0.8 to 5 microns, the surface is nonetheless obscured by methane and haze, the latter of which is optically thick at lower wavelengths. Studies of Titan’s surface must eliminate the effects of atmospheric extinction, which particularly at high latitudes, are not well constrained. A more general challenge in the study of planetary surfaces is the extraction of subtle spectral features from a large quantity of low-resolution data, which have dominant spectral trends, upon which lesser trends reside. This characteristic (a dominant spectral trend) is seen in Titan’s data: images at all 7 wavelengths appear essentially the same, with the bright terrain relatively bright at all wavelengths and vise versa. The question arises as to how to discern and map the smaller and orthogonal spectral trends of Titan’s surface in order to investigate the composition. Towards this goal we have constructed spectral maps of Titan’s surface by minimizing the covariance matrix of the I/F values (and separately the surface albedo) at the 7 window wavelengths. This application of the Principal Components Analyses (PCA) yields the orthogonal spectral trends based on the variance of the I/F values, and, separately, the surface albedos derived from radiative transfer models. Here we will present some of the interesting spectral trends detected through the application of this method to small sections of Titan’s surface.

  14. Selective perceptual phase entrainment to speech rhythm in the absence of spectral energy fluctuations.

    PubMed

    Zoefel, Benedikt; VanRullen, Rufin

    2015-02-01

    Perceptual phase entrainment improves speech intelligibility by phase-locking the brain's high-excitability and low-excitability phases to relevant or irrelevant events in the speech input. However, it remains unclear whether phase entrainment to speech can be explained by a passive "following" of rhythmic changes in sound amplitude and spectral content or whether entrainment entails an active tracking of higher-level cues: in everyday speech, rhythmic fluctuations in low-level and high-level features always covary. Here, we resolve this issue by constructing novel speech/noise stimuli with intelligible speech but without systematic changes in sound amplitude and spectral content. The probability of detecting a tone pip, presented to human listeners at random moments during our speech/noise stimuli, was significantly modulated by the rhythmic changes in high-level information. Thus, perception can entrain to the speech rhythm even without concurrent fluctuations in sound amplitude or spectral content. Strikingly, the actual entrainment phase depended on the tone-pip frequency, with tone pips within and beyond the principal frequency range of the speech sound modulated in opposite fashion. This result suggests that only those neural populations processing the actually presented frequencies are set to their high-excitability phase, whereas other populations are entrained to the opposite, low-excitability phase. Furthermore, we show that the perceptual entrainment is strongly reduced when speech intelligibility is abolished by presenting speech/noise stimuli in reverse, indicating that linguistic information plays an important role for the observed perceptual entrainment. PMID:25653354

  15. Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes.

    PubMed

    Prasad, Dilip K; Agarwal, Krishna

    2016-01-01

    We propose a method for classifying radiometric oceanic color data measured by hyperspectral satellite sensors into known spectral classes, irrespective of the downwelling irradiance of the particular day, i.e., the illumination conditions. The focus is not on retrieving the inherent optical properties but to classify the pixels according to the known spectral classes of the reflectances from the ocean. The method compensates for the unknown downwelling irradiance by white balancing the radiometric data at the ocean pixels using the radiometric data of bright pixels (typically from clouds). The white-balanced data is compared with the entries in a pre-calibrated lookup table in which each entry represents the spectral properties of one class. The proposed approach is tested on two datasets of in situ measurements and 26 different daylight illumination spectra for medium resolution imaging spectrometer (MERIS), moderate-resolution imaging spectroradiometer (MODIS), sea-viewing wide field-of-view sensor (SeaWiFS), coastal zone color scanner (CZCS), ocean and land colour instrument (OLCI), and visible infrared imaging radiometer suite (VIIRS) sensors. Results are also shown for CIMEL's SeaPRISM sun photometer sensor used on-board field trips. Accuracy of more than 92% is observed on the validation dataset and more than 86% is observed on the other dataset for all satellite sensors. The potential of applying the algorithms to non-satellite and non-multi-spectral sensors mountable on airborne systems is demonstrated by showing classification results for two consumer cameras. Classification on actual MERIS data is also shown. Additional results comparing the spectra of remote sensing reflectance with level 2 MERIS data and chlorophyll concentration estimates of the data are included. PMID:27011185

  16. Classification of Hyperspectral or Trichromatic Measurements of Ocean Color Data into Spectral Classes

    PubMed Central

    Prasad, Dilip K.; Agarwal, Krishna

    2016-01-01

    We propose a method for classifying radiometric oceanic color data measured by hyperspectral satellite sensors into known spectral classes, irrespective of the downwelling irradiance of the particular day, i.e., the illumination conditions. The focus is not on retrieving the inherent optical properties but to classify the pixels according to the known spectral classes of the reflectances from the ocean. The method compensates for the unknown downwelling irradiance by white balancing the radiometric data at the ocean pixels using the radiometric data of bright pixels (typically from clouds). The white-balanced data is compared with the entries in a pre-calibrated lookup table in which each entry represents the spectral properties of one class. The proposed approach is tested on two datasets of in situ measurements and 26 different daylight illumination spectra for medium resolution imaging spectrometer (MERIS), moderate-resolution imaging spectroradiometer (MODIS), sea-viewing wide field-of-view sensor (SeaWiFS), coastal zone color scanner (CZCS), ocean and land colour instrument (OLCI), and visible infrared imaging radiometer suite (VIIRS) sensors. Results are also shown for CIMEL’s SeaPRISM sun photometer sensor used on-board field trips. Accuracy of more than 92% is observed on the validation dataset and more than 86% is observed on the other dataset for all satellite sensors. The potential of applying the algorithms to non-satellite and non-multi-spectral sensors mountable on airborne systems is demonstrated by showing classification results for two consumer cameras. Classification on actual MERIS data is also shown. Additional results comparing the spectra of remote sensing reflectance with level 2 MERIS data and chlorophyll concentration estimates of the data are included. PMID:27011185

  17. [Plant Spectral Discrimination Based on Phenological Features].

    PubMed

    Zhang, Lei; Zhao, Jian-long; Jia, Kun; Li, Xiao-song

    2015-10-01

    Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation

  18. Reconciling actual and perceived rates of predation by domestic cats

    PubMed Central

    McDonald, Jennifer L; Maclean, Mairead; Evans, Matthew R; Hodgson, Dave J

    2015-01-01

    The predation of wildlife by domestic cats (Felis catus) is a complex problem: Cats are popular companion animals in modern society but are also acknowledged predators of birds, herpetofauna, invertebrates, and small mammals. A comprehensive understanding of this conservation issue demands an understanding of both the ecological consequence of owning a domestic cat and the attitudes of cat owners. Here, we determine whether cat owners are aware of the predatory behavior of their cats, using data collected from 86 cats in two UK villages. We examine whether the amount of prey their cat returns influences the attitudes of 45 cat owners toward the broader issue of domestic cat predation. We also contribute to the wider understanding of physiological, spatial, and behavioral drivers of prey returns among cats. We find an association between actual prey returns and owner predictions at the coarse scale of predatory/nonpredatory behavior, but no correlation between the observed and predicted prey-return rates among predatory cats. Cat owners generally disagreed with the statement that cats are harmful to wildlife, and disfavored all mitigation options apart from neutering. These attitudes were uncorrelated with the predatory behavior of their cats. Cat owners failed to perceive the magnitude of their cats’ impacts on wildlife and were not influenced by ecological information. Management options for the mitigation of cat predation appear unlikely to work if they focus on “predation awareness” campaigns or restrictions of cat freedom. PMID:26306163