The Radio Synchrotron Background: Conference Summary and Report

NASA Astrophysics Data System (ADS)

Singal, J.; Haider, J.; Ajello, M.; Ballantyne, D. R.; Bunn, E.; Condon, J.; Dowell, J.; Fixsen, D.; Fornengo, N.; Harms, B.; Holder, G.; Jones, E.; Kellermann, K.; Kogut, A.; Linden, T.; Monsalve, R.; Mertsch, P.; Murphy, E.; Orlando, E.; Regis, M.; Scott, D.; Vernstrom, T.; Xu, L.

2018-03-01

We summarize the radio synchrotron background workshop that took place 2017 July 19–21 at the University of Richmond. This first scientific meeting dedicated to the topic was convened because current measurements of the diffuse radio monopole reveal a surface brightness that is several times higher than can be straightforwardly explained by known Galactic and extragalactic sources and processes, rendering it by far the least well understood photon background at present. It was the conclusion of a majority of the participants that the radio monopole level is at or near that reported by the ARCADE 2 experiment and inferred from several absolutely calibrated zero-level lower frequency radio measurements, and unanimously agreed that the production of this level of surface brightness, if confirmed, represents a major outstanding question in astrophysics. The workshop reached a consensus on the next priorities for investigations of the radio synchrotron background.

Galaxy Selection and the Surface Brightness Distribution

NASA Astrophysics Data System (ADS)

McGaugh, Stacy S.; Bothun, Gregory D.; Schombert, James M.

1995-08-01

Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney [Nature, 263,573(1976)] suggested that the constancy of disk central surface brightness noticed by Freeman [ApJ, 160,811(1970)] was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (i.e., approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity function at L^*^. An intrinsically sharply peaked "Freeman law" distribution can be completely ruled out, and no Gaussian distribution can fit the data. Low surface brightness galaxies (those with central surface brightness fainter than 22 B mag arcsec^-2^) comprise >~ 1/2 the general galaxy population, so a representative sample of galaxies at z = 0 does not really exist at present since past surveys have been insensitive to this component of the general galaxy population.

STS-55 Earth observation of the Timor Sea

NASA Technical Reports Server (NTRS)

1993-01-01

STS-55 Earth observation taken from Columbia, Orbiter Vehicle (OV) 102, shows the Timor Sea along the south coast of Timor. The sunglint pattern shows a sharp boundary in sea surface temperature, with cooler water along the coast and warmer water offshore. The sunglint brightness reveals water surface roughness with bright indicating smooth water and dark representing rough water. Cooler water is smoother because it acts to stabilize the atmospheric boundary layer, while the warm water acts to destabilize the atmosphere. Another indication of water temperature is the cloud pattern. Advection within the atmosphere as a result of warming at the sea surface forms low-level clouds with the small, popcorn-like appearance seen in upper right corner of the photograph. The cool water, on the other hand, is relatively free of the popcorn-like clouds. The distribution of the clouds indicates that the wind is blowing toward the upper right corner of the photograph. Also note the line of low-level

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame using Ultra-Bright Cr-Doped GdAlO3 Thermographic Phosphor

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Wolfe, Douglas E.; Howard, Robert P.

2013-01-01

Luminescence-based surface temperature measurements from an ultra-bright Cr-doped GdAlO3 perovskite (GAP:Cr) coating were successfully conducted on an air-film-cooled stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing at UTSI was to demonstrate that reliable thermal barrier coating (TBC) surface temperatures based on luminescence decay of a thermographic phosphor could be obtained from the surface of an actual engine component in an aggressive afterburner flame environment and to address the challenges of a highly radiant background and high velocity gases. A high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine was coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick GAP:Cr thermographic phosphor layer was deposited by EB-PVD. The ultra-bright broadband luminescence from the GAP:Cr thermographic phosphor is shown to offer the advantage of over an order-of-magnitude greater emission intensity compared to rare-earth-doped phosphors in the engine test environment. This higher emission intensity was shown to be very desirable for overcoming the necessarily restricted probe light collection solid angle and for achieving high signal-to-background levels. Luminescence-decay-based surface temperature measurements varied from 500 to over 1000C depending on engine operating conditions and level of air film cooling.

Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies AO2, AO3 and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters AO3

NASA Technical Reports Server (NTRS)

White, Raymond E., III

1998-01-01

This final report uses ROSAT observations to analyze two different studies. These studies are: Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies; and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters.

IMPACT OF SUPERNOVA AND COSMIC-RAY DRIVING ON THE SURFACE BRIGHTNESS OF THE GALACTIC HALO IN SOFT X-RAYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, Thomas; Girichidis, Philipp; Gatto, Andrea

2015-11-10

The halo of the Milky Way contains a hot plasma with a surface brightness in soft X-rays of the order 10{sup −12} erg cm{sup −2} s{sup −1} deg{sup −2}. The origin of this gas is unclear, but so far numerical models of galactic star formation have failed to reproduce such a large surface brightness by several orders of magnitude. In this paper, we analyze simulations of the turbulent, magnetized, multi-phase interstellar medium including thermal feedback by supernova explosions as well as cosmic-ray feedback. We include a time-dependent chemical network, self-shielding by gas and dust, and self-gravity. Pure thermal feedback alonemore » is sufficient to produce the observed surface brightness, although it is very sensitive to the supernova rate. Cosmic rays suppress this sensitivity and reduce the surface brightness because they drive cooler outflows. Self-gravity has by far the largest effect because it accumulates the diffuse gas in the disk in dense clumps and filaments, so that supernovae exploding in voids can eject a large amount of hot gas into the halo. This can boost the surface brightness by several orders of magnitude. Although our simulations do not reach a steady state, all simulations produce surface brightness values of the same order of magnitude as the observations, with the exact value depending sensitively on the simulation parameters. We conclude that star formation feedback alone is sufficient to explain the origin of the hot halo gas, but measurements of the surface brightness alone do not provide useful diagnostics for the study of galactic star formation.« less

Comparative study of icy patches on comet nuclei

NASA Astrophysics Data System (ADS)

Oklay, Nilda; Pommerol, Antoine; Barucci, Maria Antonietta; Sunshine, Jessica; Sierks, Holger; Pajola, Maurizio

2016-07-01

Cometary missions Deep Impact, EPOXI and Rosetta investigated the nuclei of comets 9P/Tempel 1, 103P/Hartley 2 and 67P/Churyumov-Gerasimenko respectively. Bright patches were observed on the surfaces of each of these three comets [1-5]. Of these, the surface of 67P is mapped at the highest spatial resolution via narrow angle camera (NAC) of the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS, [6]) on board the Rosetta spacecraft. OSIRIS NAC is equipped with twelve filters covering the wavelength range of 250 nm to 1000 nm. Various filters combinations are used during surface mapping. With high spatial resolution data of comet 67P, three types of bright features were detected on the comet surface: Clustered, isolated and bright boulders [2]. In the visible spectral range, clustered bright features on comet 67P display bluer spectral slopes than the average surface [2, 4] while isolated bright features on comet 67P have flat spectra [4]. Icy patches observed on the surface of comets 9P and 103P display bluer spectral slopes than the average surface [1, 5]. Clustered and isolated bright features are blue in the RGB composites generated by using the images taken in NIR, visible and NUV wavelengths [2, 4]. This is valid for the icy patches observed on comets 9P and 103P [1, 5]. Spectroscopic observations of bright patches on comets 9P and 103P confirmed the existence of water [1, 5]. There were more than a hundred of bright features detected on the northern hemisphere of comet 67P [2]. Analysis of those features from both multispectral data and spectroscopic data is an ongoing work. Water ice is detected in eight of the bright features so far [7]. Additionally, spectroscopic observations of two clustered bright features on the surface of comet 67P revealed the existence of water ice [3]. The spectral properties of one of the icy patches were studied by [4] using OSIRIS NAC images and compared with the spectral properties of the active regions observed on comet 67P. Additionally jets rising from the same clustered bright feature were detected visually [4]. We analyzed bright patches on the surface of comets 9P, 103P and 67P using multispectral data obtained by the high-resolution instrument (HRI), medium- resolution instrument (MRI) and OSIRIS NAC using various spectral analysis techniques. Clustered bright features on comet 67P have similar visible spectra to the bright patches on comets 9P and 103P. The comparison of the bright patches includes the published results of the IR spectra. References: [1] Sunshine et al., 2006, Science, 311, 1453 [2] Pommerol et al., 2015, A&A, 583, A25 [3] Filacchione et al., 2016, Nature, 529, 368-372 [4] Oklay et al., 2016, A&A, 586, A80 [5] Sunshine et al. 2012, ACM [6] Keller et al., 2007, Space Sci. Rev., 128, 433 [7] Barucci et al., 2016, COSPAR, B04

Bright Summer Afternoon on the Mars Utopian Planitia

NASA Technical Reports Server (NTRS)

1976-01-01

A UTOPIAN BRIGHT SUMMER AFTERNOON ON MARS--Looking south from Viking 2 on September 6, the orange-red surface of the nearly level plain upon which the spacecraft sits is seen strewn with rocks as large as three feet across. Many of these rocks are porous and sponge-like, similar to some of Earth's volcanic rocks. Other rocks are coarse-grained such as the large rock at lower left. Between the rocks, the surface is blanketed with fine-grained material that, in places, is piled into small drifts and banked against some of the larger blocks. The cylindrical mast with the orange cable is the low-gain antenna used to receive commands from Earth.

Inferring Land Surface Model Parameters for the Assimilation of Satellite-Based L-Band Brightness Temperature Observations into a Soil Moisture Analysis System

NASA Technical Reports Server (NTRS)

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.

2012-01-01

The Soil Moisture and Ocean Salinity (SMOS) satellite mission provides global measurements of L-band brightness temperatures at horizontal and vertical polarization and a variety of incidence angles that are sensitive to moisture and temperature conditions in the top few centimeters of the soil. These L-band observations can therefore be assimilated into a land surface model to obtain surface and root zone soil moisture estimates. As part of the observation operator, such an assimilation system requires a radiative transfer model (RTM) that converts geophysical fields (including soil moisture and soil temperature) into modeled L-band brightness temperatures. At the global scale, the RTM parameters and the climatological soil moisture conditions are still poorly known. Using look-up tables from the literature to estimate the RTM parameters usually results in modeled L-band brightness temperatures that are strongly biased against the SMOS observations, with biases varying regionally and seasonally. Such biases must be addressed within the land data assimilation system. In this presentation, the estimation of the RTM parameters is discussed for the NASA GEOS-5 land data assimilation system, which is based on the ensemble Kalman filter (EnKF) and the Catchment land surface model. In the GEOS-5 land data assimilation system, soil moisture and brightness temperature biases are addressed in three stages. First, the global soil properties and soil hydraulic parameters that are used in the Catchment model were revised to minimize the bias in the modeled soil moisture, as verified against available in situ soil moisture measurements. Second, key parameters of the "tau-omega" RTM were calibrated prior to data assimilation using an objective function that minimizes the climatological differences between the modeled L-band brightness temperatures and the corresponding SMOS observations. Calibrated parameters include soil roughness parameters, vegetation structure parameters, and the single scattering albedo. After this climatological calibration, the modeling system can provide L-band brightness temperatures with a global mean absolute bias of less than 10K against SMOS observations, across multiple incidence angles and for horizontal and vertical polarization. Third, seasonal and regional variations in the residual biases are addressed by estimating the vegetation optical depth through state augmentation during the assimilation of the L-band brightness temperatures. This strategy, tested here with SMOS data, is part of the baseline approach for the Level 4 Surface and Root Zone Soil Moisture data product from the planned Soil Moisture Active Passive (SMAP) satellite mission.

Simultaneous Multi-band Detection of Low Surface Brightness Galaxies with Markovian Modeling

NASA Astrophysics Data System (ADS)

Vollmer, B.; Perret, B.; Petremand, M.; Lavigne, F.; Collet, Ch.; van Driel, W.; Bonnarel, F.; Louys, M.; Sabatini, S.; MacArthur, L. A.

2013-02-01

We present to the astronomical community an algorithm for the detection of low surface brightness (LSB) galaxies in images, called MARSIAA (MARkovian Software for Image Analysis in Astronomy), which is based on multi-scale Markovian modeling. MARSIAA can be applied simultaneously to different bands. It segments an image into a user-defined number of classes, according to their surface brightness and surroundings—typically, one or two classes contain the LSB structures. We have developed an algorithm, called DetectLSB, which allows the efficient identification of LSB galaxies from among the candidate sources selected by MARSIAA. The application of the method to two and three bands simultaneously was tested on simulated images. Based on our tests, we are confident that we can detect LSB galaxies down to a central surface brightness level of only 1.5 times the standard deviation from the mean pixel value in the image background. To assess the robustness of our method, the method was applied to a set of 18 B- and I-band images (covering 1.3 deg2 in total) of the Virgo Cluster to which Sabatini et al. previously applied a matched-filter dwarf LSB galaxy search algorithm. We have detected all 20 objects from the Sabatini et al. catalog which we could classify by eye as bona fide LSB galaxies. Our method has also detected four additional Virgo Cluster LSB galaxy candidates undetected by Sabatini et al. To further assess the completeness of the results of our method, both MARSIAA, SExtractor, and DetectLSB were applied to search for (1) mock Virgo LSB galaxies inserted into a set of deep Next Generation Virgo Survey (NGVS) gri-band subimages and (2) Virgo LSB galaxies identified by eye in a full set of NGVS square degree gri images. MARSIAA/DetectLSB recovered ~20% more mock LSB galaxies and ~40% more LSB galaxies identified by eye than SExtractor/DetectLSB. With a 90% fraction of false positives from an entirely unsupervised pipeline, a completeness of 90% is reached for sources with r e > 3'' at a mean surface brightness level of μg = 27.7 mag arcsec-2 and a central surface brightness of μ0 g = 26.7 mag arcsec-2. About 10% of the false positives are artifacts, the rest being background galaxies. We have found our proposed Markovian LSB galaxy detection method to be complementary to the application of matched filters and an optimized use of SExtractor, and to have the following advantages: it is scale free, can be applied simultaneously to several bands, and is well adapted for crowded regions on the sky. .

Exploring the extremely low surface brightness sky: distances to 23 newly discovered objects in Dragonfly fields

NASA Astrophysics Data System (ADS)

van Dokkum, Pieter

2016-10-01

We are obtaining deep, wide field images of nearby galaxies with the Dragonfly Telephoto Array. This telescope is optimized for low surface brightness imaging, and we are finding many low surface brightness objects in the Dragonfly fields. In Cycle 22 we obtained ACS imaging for 7 galaxies that we had discovered in a Dragonfly image of the galaxy M101. Unexpectedly, the ACS data show that only 3 of the galaxies are members of the M101 group, and the other 4 are very large Ultra Diffuse Galaxies (UDGs) at much greater distance. Building on our Cycle 22 program, here we request ACS imaging for 23 newly discovered low surface brightness objects in four Dragonfly fields centered on the galaxies NGC 1052, NGC 1084, NGC 3384, and NGC 4258. The immediate goals are to construct the satellite luminosity functions in these four fields and to constrain the number density of UDGs that are not in rich clusters. More generally, this complete sample of extremely low surface brightness objects provides the first systematic insight into galaxies whose brightness peaks at >25 mag/arcsec^2.

The Barnes-Evans color-surface brightness relation: A preliminary theoretical interpretation

NASA Technical Reports Server (NTRS)

Shipman, H. L.

1980-01-01

Model atmosphere calculations are used to assess whether an empirically derived relation between V-R and surface brightness is independent of a variety of stellar paramters, including surface gravity. This relationship is used in a variety of applications, including the determination of the distances of Cepheid variables using a method based on the Beade-Wesselink method. It is concluded that the use of a main sequence relation between V-R color and surface brightness in determining radii of giant stars is subject to systematic errors that are smaller than 10% in the determination of a radius or distance for temperature cooler than 12,000 K. The error in white dwarf radii determined from a main sequence color surface brightness relation is roughly 10%.

Using SMOS observations in the development of the SMAP level 4 surface and root-zone soil moisture project

USDA-ARS?s Scientific Manuscript database

The Soil Moisture and Ocean Salinity (SMOS; [1]) mission was launched by ESA in November 2009 and has since been observing L-band (1.4 GHz) upwelling passive microwaves. Along with these brightness temperature observations, ESA also disseminates retrievals of surface soil moisture that are derived ...

Phoenix Laser Beam in Action on Mars

NASA Image and Video Library

2008-09-30

The Surface Stereo Imager camera aboard NASA Phoenix Mars Lander acquired a series of images of the laser beam in the Martian night sky. Bright spots in the beam are reflections from ice crystals in the low level ice-fog.

THE DISCOVERY OF SEVEN EXTREMELY LOW SURFACE BRIGHTNESS GALAXIES IN THE FIELD OF THE NEARBY SPIRAL GALAXY M101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merritt, Allison; Van Dokkum, Pieter; Abraham, Roberto, E-mail: allison.merritt@yale.edu

2014-06-01

Dwarf satellite galaxies are a key probe of dark matter and of galaxy formation on small scales and of the dark matter halo masses of their central galaxies. They have very low surface brightness, which makes it difficult to identify and study them outside of the Local Group. We used a low surface brightness-optimized telescope, the Dragonfly Telephoto Array, to search for dwarf galaxies in the field of the massive spiral galaxy M101. We identify seven large, low surface brightness objects in this field, with effective radii of 10-30 arcseconds and central surface brightnesses of μ {sub g} ∼ 25.5-27.5 magmore » arcsec{sup –2}. Given their large apparent sizes and low surface brightnesses, these objects would likely be missed by standard galaxy searches in deep fields. Assuming the galaxies are dwarf satellites of M101, their absolute magnitudes are in the range –11.6 ≲ M{sub V} ≲ –9.3 and their effective radii are 350 pc-1.3 kpc. Their radial surface brightness profiles are well fit by Sersic profiles with a very low Sersic index (n ∼ 0.3-0.7). The properties of the sample are similar to those of well-studied dwarf galaxies in the Local Group, such as Sextans I and Phoenix. Distance measurements are required to determine whether these galaxies are in fact associated with M101 or are in its foreground or background.« less

GLOBAL PROPERTIES OF M31'S STELLAR HALO FROM THE SPLASH SURVEY. I. SURFACE BRIGHTNESS PROFILE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilbert, Karoline M.; Guhathakurta, Puragra; Beaton, Rachael L.

2012-11-20

We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 {+-} 0.2 and extends to amore » projected distance of at least {approx}175 kpc ({approx}2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects.« less

KECK/LRIS SPECTROSCOPIC CONFIRMATION OF COMA CLUSTER DWARF GALAXY MEMBERSHIP ASSIGNMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiboucas, Kristin; Tully, R. Brent; Marzke, Ronald O.

2010-11-01

Keck/LRIS multi-object spectroscopy has been carried out on 140 of some of the lowest and highest surface brightness faint (19 < R < 22) dwarf galaxy candidates in the core region of the Coma Cluster. These spectra are used to measure redshifts and establish membership for these faint dwarf populations. The primary goal of the low surface brightness sample is to test our ability to use morphological and surface brightness criteria to distinguish between Coma Cluster members and background galaxies using high resolution Hubble Space Telescope/Advanced Camera for Surveys images. Candidates were rated as expected members, uncertain, or expected background.more » From 93 spectra, 51 dwarf galaxy members and 20 background galaxies are identified. Our morphological membership estimation success rate is {approx}100% for objects expected to be members and better than {approx}90% for galaxies expected to be in the background. We confirm that low surface brightness is a very good indicator of cluster membership. High surface brightness galaxies are almost always background with confusion arising only from the cases of the rare compact elliptical (cE) galaxies. The more problematic cases occur at intermediate surface brightness. Many of these galaxies are given uncertain membership ratings, and these were found to be members about half of the time. Including color information will improve membership determination but will fail for some of the same objects that are already misidentified when using only surface brightness and morphology criteria. cE galaxies with B-V colors {approx}0.2 mag redward of the red sequence in particular require spectroscopic follow up. In a sample of 47 high surface brightness, ultracompact dwarf candidates, 19 objects have redshifts which place them in the Coma Cluster, while another 6 have questionable redshift measurements but may also prove to be members. Redshift measurements are presented and the use of indirect means for establishing cluster membership is discussed.« less

OH+ emission from cometary knots in planetary nebulae

NASA Astrophysics Data System (ADS)

Priestley, F. D.; Barlow, M. J.

2018-05-01

We model the molecular emission from cometary knots in planetary nebulae (PNe) using a combination of photoionization and photodissociation region (PDR) codes, for a range of central star properties and gas densities. Without the inclusion of ionizing extreme ultraviolet (EUV) radiation, our models require central star temperatures T* to be near the upper limit of the range investigated in order to match observed H2 and OH+ surface brightnesses consistent with observations - with the addition of EUV flux, our models reproduce observed OH+ surface brightnesses for T* ≥ 100 kK. For T* < 80 kK, the predicted OH+ surface brightness is much lower, consistent with the non-detection of this molecule in PNe with such central star temperatures. Our predicted level of H2 emission is somewhat weaker than commonly observed in PNe, which may be resolved by the inclusion of shock heating or fluorescence due to UV photons. Some of our models also predict ArH+ and HeH+ rotational line emission above detection thresholds, despite neither molecule having been detected in PNe, although the inclusion of photodissociation by EUV photons, which is neglected by our models, would be expected to reduce their detectability.

Topographic Ceres Map With Crater Names

NASA Image and Video Library

2015-07-28

This color-coded map from NASA Dawn mission shows the highs and lows of topography on the surface of dwarf planet Ceres. It is labeled with names of features approved by the International Astronomical Union. Occator, the mysterious crater containing Ceres' mysterious bright spots, is named after the Roman agriculture deity of harrowing, a method of leveling soil. They retain their bright appearance in this map, although they are color-coded in the same green elevation of the crater floor in which they sit. The color scale extends about 5 miles (7.5 kilometers) below the surface in indigo to 5 miles (7.5 kilometers) above the surface in white. The topographic map was constructed from analyzing images from Dawn's framing camera taken from varying sun and viewing angles. The map was combined with an image mosaic of Ceres and projected as an simple cylindrical projection. http://photojournal.jpl.nasa.gov/catalog/PIA19606

Version 3 of the SMAP Level 4 Soil Moisture Product

NASA Technical Reports Server (NTRS)

Reichle, Rolf; Liu, Qing; Ardizzone, Joe; Crow, Wade; De Lannoy, Gabrielle; Kolassa, Jana; Kimball, John; Koster, Randy

2017-01-01

The NASA Soil Moisture Active Passive (SMAP) Level 4 Soil Moisture (L4_SM) product provides 3-hourly, 9-km resolution, global estimates of surface (0-5 cm) and root zone (0-100 cm) soil moisture as well as related land surface states and fluxes from 31 March 2015 to present with a latency of 2.5 days. The ensemble-based L4_SM algorithm is a variant of the Goddard Earth Observing System version 5 (GEOS-5) land data assimilation system and ingests SMAP L-band (1.4 GHz) Level 1 brightness temperature observations into the Catchment land surface model. The soil moisture analysis is non-local (spatially distributed), performs downscaling from the 36-km resolution of the observations to that of the model, and respects the relative uncertainties of the modeled and observed brightness temperatures. Prior to assimilation, a climatological rescaling is applied to the assimilated brightness temperatures using a 6 year record of SMOS observations. A new feature in Version 3 of the L4_SM data product is the use of 2 years of SMAP observations for rescaling where SMOS observations are not available because of radio frequency interference, which expands the impact of SMAP observations on the L4_SM estimates into large regions of northern Africa and Asia. This presentation investigates the performance and data assimilation diagnostics of the Version 3 L4_SM data product. The L4_SM soil moisture estimates meet the 0.04 m3m3 (unbiased) RMSE requirement. We further demonstrate that there is little bias in the soil moisture analysis. Finally, we illustrate where the assimilation system overestimates or underestimates the actual errors in the system.

Erratum - the Lowest Surface Brightness Disc Galaxy Known

NASA Astrophysics Data System (ADS)

Davies, J. I.; Phillipps, S.; Disney, M. J.

1988-11-01

The paper "The lowest surface brightness disc galaxy known' by J.I. Davies, S. Phillipps and M.J. Disney was published in Mon. Not. R. astr. Soc. (1988), 231, 69p. The declination of the object given in section 2 of the paper is incorrect and should be changed to +19^deg^48'23". Thus the object cannot be identified with GP 1444 as in the original paper. To minimize confusion we propose to refer to the low surface brightness galaxy as GP 1444A.

MOST detects corotating bright spots on the mid-O-type giant ξ Persei

NASA Astrophysics Data System (ADS)

Ramiaramanantsoa, Tahina; Moffat, Anthony F. J.; Chené, André-Nicolas; Richardson, Noel D.; Henrichs, Huib F.; Desforges, Sébastien; Antoci, Victoria; Rowe, Jason F.; Matthews, Jaymie M.; Kuschnig, Rainer; Weiss, Werner W.; Sasselov, Dimitar; Rucinski, Slavek M.; Guenther, David B.

2014-06-01

We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei in 2011 November. This star is well known from previous work to show prominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3σ noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.

Discovery of interaction signatures in the Hickson Compact Group 88

NASA Astrophysics Data System (ADS)

Brosch, Noah

2015-08-01

I describe new observations of the Hickson Compact Group 88 (HCG88) obtained during the commissioning of a new telescope at the Wise Observatory. The observations that reach low surface brightness levels reveal a diffuse, ~20-kpc long low-surface-brightness tail emerging from the brightest component (NGC 6878) to the NW, and possibly a morphological abnormally in component B (NGC 6977). The N6878 tail could explain the asymmetry in this galaxy’s optical rotation curve. These findings show that significant interactions, including possible galactic cannibalism, have taken place in at least two galaxies of this group, contrary to previous claims that HCG88 is in a very early stage of interaction. This work emphasizes the surprisingly interesting results that can be obtained from deep imaging of interesting targets.

Titan's surface from the Cassini RADAR radiometry data during SAR mode

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Lopes, R.M.; Stofan, E.; Wall, S.D.; Lorenz, R.D.; Lunine, J.I.; Kirk, R.L.; Roth, L.; Elachi, C.

2008-01-01

We present initial results on the calibration and interpretation of the high-resolution radiometry data acquired during the Synthetic Aperture Radar (SAR) mode (SAR-radiometry) of the Cassini Radar Mapper during its first five flybys of Saturn's moon Titan. We construct maps of the brightness temperature at the 2-cm wavelength coincident with SAR swath imaging. A preliminary radiometry calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, outlining signatures that characterize various terrains and surface features. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007.

Planetary science: A 5-micron-bright spot on Titan: Evidence for surface diversity

USGS Publications Warehouse

Barnes, J.W.; Brown, R.H.; Turtle, E.P.; McEwen, A.S.; Lorenz, R.D.; Janssen, M.; Schaller, E.L.; Brown, M.E.; Buratti, B.J.; Sotin, Christophe; Griffith, C.; Clark, R.; Perry, J.; Fussner, S.; Barbara, J.; West, R.; Elachi, C.; Bouchez, A.H.; Roe, H.G.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Combes, M.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Nicholson, P.D.; Sicardy, B.

2005-01-01

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80??W and 20??S. This area is bright in reflected tight at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.

A 5-micron-bright spot on Titan: evidence for surface diversity.

PubMed

Barnes, Jason W; Brown, Robert H; Turtle, Elizabeth P; McEwen, Alfred S; Lorenz, Ralph D; Janssen, Michael; Schaller, Emily L; Brown, Michael E; Buratti, Bonnie J; Sotin, Christophe; Griffith, Caitlin; Clark, Roger; Perry, Jason; Fussner, Stephanie; Barbara, John; West, Richard; Elachi, Charles; Bouchez, Antonin H; Roe, Henry G; Baines, Kevin H; Bellucci, Giancarlo; Bibring, Jean-Pierre; Capaccioni, Fabrizio; Cerroni, Priscilla; Combes, Michel; Coradini, Angioletta; Cruikshank, Dale P; Drossart, Pierre; Formisano, Vittorio; Jaumann, Ralf; Langevin, Yves; Matson, Dennis L; McCord, Thomas B; Nicholson, Phillip D; Sicardy, Bruno

2005-10-07

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80 degrees W and 20 degrees S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.

The GALEX/S4G Surface Brightness and Color Profiles Catalog. I. Surface Photometry and Color Gradients of Galaxies

NASA Astrophysics Data System (ADS)

Bouquin, Alexandre Y. K.; Gil de Paz, Armando; Muñoz-Mateos, Juan Carlos; Boissier, Samuel; Sheth, Kartik; Zaritsky, Dennis; Peletier, Reynier F.; Knapen, Johan H.; Gallego, Jesús

2018-02-01

We present new spatially resolved surface photometry in the far-ultraviolet (FUV) and near-ultraviolet (NUV) from images obtained by the Galaxy Evolution Explorer (GALEX) and IRAC1 (3.6 μm) photometry from the Spitzer Survey of Stellar Structure in Galaxies (S4G). We analyze the radial surface brightness profiles μ FUV, μ NUV, and μ [3.6], as well as the radial profiles of (FUV ‑ NUV), (NUV ‑ [3.6]), and (FUV ‑ [3.6]) colors in 1931 nearby galaxies (z < 0.01). The analysis of the 3.6 μm surface brightness profiles also allows us to separate the bulge and disk components in a quasi-automatic way and to compare their light and color distribution with those predicted by the chemo-spectrophotometric models for the evolution of galaxy disks of Boissier & Prantzos. The exponential disk component is best isolated by setting an inner radial cutoff and an upper surface brightness limit in stellar mass surface density. The best-fitting models to the measured scale length and central surface brightness values yield distributions of spin and circular velocity within a factor of two of those obtained via direct kinematic measurements. We find that at a surface brightness fainter than μ [3.6] = 20.89 mag arcsec‑2, or below 3 × 108 M ⊙ kpc‑2 in stellar mass surface density, the average specific star formation rate (sSFR) for star-forming and quiescent galaxies remains relatively flat with radius. However, a large fraction of GALEX Green Valley galaxies show a radial decrease in sSFR. This behavior suggests that an outside-in damping mechanism, possibly related to environmental effects, could be testimony of an early evolution of galaxies from the blue sequence of star-forming galaxies toward the red sequence of quiescent galaxies.

The X-ray surface brightness distribution and spectral properties of six early-type galaxies

NASA Technical Reports Server (NTRS)

Trinchieri, G.; Fabbiano, G.; Canizares, C. R.

1986-01-01

Detailed analysis is presented of the Einstein X-ray observations of six early-type galaxies. The results show that effective cooling is probably present in these systems, at least in the innermost regions. Interaction with the surrounding medium has a major effect on the X-ray surface brightness distribution at large radii, at least for galaxies in clusters. The data do not warrant the general assumptions of isothermality and gravitational hydrostatic equilibrium at large radii. Comparison of the X-ray surface brightness profiles with model predictions indicate that 1/r-squared halos with masses of the order of 10 times the stellar masses are required to match the data. The physical model of White and Chevalier (1984) for steady cooling flows in a King law potential with no heavy halo gives a surface brightness distribution that resembles the data if supernovae heating is present.

The effect of monomolecular surface films on the microwave brightness temperature of the sea surface

NASA Technical Reports Server (NTRS)

Alpers, W.; Blume, H.-J. C.; Garrett, W. D.; Huehnerfuss, H.

1982-01-01

It is pointed out that monomolecular surface films of biological origin are often encountered on the ocean surface, especially in coastal regions. The thicknesses of the monomolecular films are of the order of 3 x 10 to the -9th m. Huehnerfuss et al. (1978, 1981) have shown that monomolecular surface films damp surface waves quite strongly in the centimeter to decimeter wavelength regime. Other effects caused by films are related to the reduction of the gas exchange at the air-sea interface and the decrease of the wind stress. The present investigation is concerned with experiments which reveal an unexpectedly large response of the microwave brightness temperature to a monomolecular oleyl alcohol slick at 1.43 GHz. Brightness temperature is a function of the complex dielectric constant of thy upper layer of the ocean. During six overflights over an ocean area covered with an artificial monomolecular alcohol film, a large decrease of the brightness temperature at the L-band was measured, while at the S-band almost no decrease was observed.

Visible Color and Photometry of Bright Materials on Vesta

NASA Technical Reports Server (NTRS)

Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

2012-01-01

The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile

NASA Astrophysics Data System (ADS)

Gilbert, Karoline M.; Guhathakurta, Puragra; Beaton, Rachael L.; Bullock, James; Geha, Marla C.; Kalirai, Jason S.; Kirby, Evan N.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J.; Tollerud, Erik J.; Tanaka, Mikito; Chiba, Masashi

2012-11-01

We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 ± 0.2 and extends to a projected distance of at least ~175 kpc (~2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Titan's surface from Cassini RADAR SAR and high resolution radiometry data of the first five flybys

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Stiles, B.; West, R.; Lorenz, R.D.; Lunine, J.I.; Wall, S.D.; Callahan, P.; Lopes, R.M.; Stofan, E.; Kirk, R.L.; Johnson, W.T.K.; Roth, L.; Elachi, C.; ,

2007-01-01

The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with spatial resolution approaching 6 km. A preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, finding differing signatures that characterize various terrains and surface features. Implications for the physical and compositional properties of these features are discussed. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007 Elsevier Inc.

Refinement in black chrome for use as a solar selective coating

NASA Technical Reports Server (NTRS)

Mcdonald, G. E.

1974-01-01

Black chrome is significant as a solar selective coating because the current extensive use of black chrome in the electroplating industry as a durable decorative finish makes black chrome widely available on a commercial scale and potentially low in cost as a solar selective coating. Black-chrome deposits were modified by underplating with dull nickel or by being plated on rough surfaces. Both of these procedures increased the visible absorptance. There was no change in the infrared reflectance for the dull-nickel - black-chrome combination from that reported for the bright-nickel - black-chrome combination. However, the bright-nickel - black-chrome coating plated on rough surfaces indicated a slight decrease in infrared reflectance. As integrated over the solar spectrum for air mass 2, the reflectance of the dull-nickel - black-chrome coating was 0.077, of the bright-nickel - black-chrome coating plated on a 0.75-micron (30-microinch) surface was 0.070, of the bright-nickel - black-chrome coating plated on a 2.5 micron (100-microinch) surface was 0.064. The corresponding values for the bright-nickel - black-chrome coating on a 0.0125-micron (0.5-microinch) surface, two samples of black nickel, and two samples of Nextrel black paint were 0.132, 0.123, 0.133, and 0.033, respectively.

SMAP Level 4 Surface and Root Zone Soil Moisture

NASA Technical Reports Server (NTRS)

Reichle, R.; De Lannoy, G.; Liu, Q.; Ardizzone, J.; Kimball, J.; Koster, R.

2017-01-01

The SMAP Level 4 soil moisture (L4_SM) product provides global estimates of surface and root zone soil moisture, along with other land surface variables and their error estimates. These estimates are obtained through assimilation of SMAP brightness temperature observations into the Goddard Earth Observing System (GEOS-5) land surface model. The L4_SM product is provided at 9 km spatial and 3-hourly temporal resolution and with about 2.5 day latency. The soil moisture and temperature estimates in the L4_SM product are validated against in situ observations. The L4_SM product meets the required target uncertainty of 0.04 m(exp. 3)m(exp. -3), measured in terms of unbiased root-mean-square-error, for both surface and root zone soil moisture.

Apparent Brightness and Topography Images of Vibidia Crater

NASA Image and Video Library

2012-03-09

The left-hand image from NASA Dawn spacecraft shows the apparent brightness of asteroid Vesta surface. The right-hand image is based on this apparent brightness image, with a color-coded height representation of the topography overlain onto it.

Thermal measurements of dark and bright surface features on Vesta as derived from Dawn/VIR

USGS Publications Warehouse

Tosi, Federico; Capria, Maria Teresa; De Sanctis, M.C.; Combe, J.-Ph.; Zambon, F.; Nathues, A.; Schröder, S.E.; Li, J.-Y.; Palomba, E.; Longobardo, A.; Blewett, D.T.; Denevi, B.W.; Palmer, E.; Capaccioni, F.; Ammannito, E.; Titus, Timothy N.; Mittlefehldt, D.W.; Sunshine, J.M.; Russell, C.T.; Raymond, C.A.; Dawn/VIR Team,

2014-01-01

Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1-10 km) is related to physical properties that can provide information about the origin of those materials. We use Dawn’s Visible and InfraRed (VIR) mapping spectrometer hyperspectral data to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 220 K. Some of the dark and bright features were observed multiple times by VIR in the various mission phases at variable spatial resolution, illumination and observation angles, local solar time, and heliocentric distance. This work presents the first temperature maps and spectral emissivities of several kilometer-scale dark and bright material units on Vesta. Results retrieved from the infrared data acquired by VIR show that bright regions generally correspond to regions with lower temperature, while dark regions correspond to areas with higher temperature. During maximum daily insolation and in the range of heliocentric distances explored by Dawn, i.e. 2.23-2.54 AU, the warmest dark unit found on Vesta rises to a temperature of 273 K, while bright units observed under comparable conditions do not exceed 266 K. Similarly, dark units appear to have higher emissivity on average compared to bright units. Dark-material units show a weak anticorrelation between temperature and albedo, whereas the relation is stronger for bright material units observed under the same conditions. Individual features may show either evanescent or distinct margins in the thermal images, as a consequence of the cohesion of the surface material. Finally, for the two categories of dark and bright materials, we were able to highlight the influence of heliocentric distance on surface temperatures, and estimate an average temperature rate change of 1% following a variation of 0.04 AU in the solar distance.

VEGAS-SSS: A VST Programme to Study the Satellite Stellar Systems around Bright Early-type Galaxies

NASA Astrophysics Data System (ADS)

Cantiello, M.; Capaccioli, M.; Napolitano, N.; Grado, A.; Limatola, L.; Paolillo, M.; Iodice, E.; Romanowsky, A. J.; Forbes, D. A.; Raimondo, G.; Spavone, M.; La Barbera, F.; Puzia, T. H.; Schipani, P.

2015-03-01

The VEGAS-SSS programme is devoted to studying the properties of small stellar systems (SSSs) in and around bright galaxies, built on the VLT Survey Telescope early-type galaxy survey (VEGAS), an ongoing guaranteed time imaging survey distributed over many semesters (Principal Investigator: Capaccioli). On completion, the VEGAS survey will have collected detailed photometric information of ~ 100 bright early-type galaxies to study the properties of diffuse light (surface brightness, colours, surface brightness fluctuations, etc.) and the distribution of clustered light (compact ''small'' stellar systems) out to previously unreached projected galactocentric radii. VEGAS-SSS will define an accurate and homogeneous dataset that will have an important legacy value for studies of the evolution and transformation processes taking place in galaxies through the fossil information provided by SSSs.

THE DOMINANCE OF METAL-RICH STREAMS IN STELLAR HALOS: A COMPARISON BETWEEN SUBSTRUCTURE IN M31 AND {lambda}CDM MODELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilbert, Karoline M.; Font, Andreea S.; Johnston, Kathryn V.

2009-08-10

Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS spectrograph on the Keck II 10 m telescope. Radial velocity criteria are used to isolate members of the kinematically cold substructures. The substructures are shown to be metal-rich relative to the rest of the dynamically hot stellar population in the fields in which they are found. We calculate the mean metallicity and average surface brightness ofmore » the various kinematical components in each field, and show that, on average, higher surface brightness features tend to be more metal-rich than lower surface brightness features. Simulations of stellar halo formation via accretion in a cosmological context are used to illustrate that the observed trend can be explained as a natural consequence of the observed dwarf galaxy mass-metallicity relation. A significant spread in metallicity at a given surface brightness is seen in the data; we show that this is due to time effects, namely, the variation in the time since accretion of the tidal streams' progenitor onto the host halo. We show that in this theoretical framework a relationship between the alpha-enhancement and surface brightness of tidal streams is expected, which arises from the varying times of accretion of the progenitor satellites onto the host halo. Thus, measurements of the alpha-enrichment, metallicity, and surface brightness of tidal debris can be used to reconstruct the luminosity and time of accretion onto the host halo of the progenitors of tidal streams.« less

Stellar populations of bulges in galaxies with a low surface-brightness disc

NASA Astrophysics Data System (ADS)

Morelli, L.; Corsini, E. M.; Pizzella, A.; Dalla Bontà, E.; Coccato, L.; Méndez-Abreu, J.

2015-03-01

The radial profiles of the Hβ, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and α/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar α/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and α/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other phenomena, like mergers or acquisition events, need to be invoked. Such a picture is also supported by the lack of a correlation between the central value and gradient of the metallicity in bulges with very low metallicity. The stellar populations of the bulges hosted by low surface-brightness discs share many properties with those of high surface-brightness galaxies. Therefore, they are likely to have common formation scenarios and evolution histories. A strong interplay between bulges and discs is ruled out by the fact that in spite of being hosted by discs with extremely different properties, the bulges of low and high surface-brightness discs are remarkably similar.

Extracting Galaxy Cluster Gas Inhomogeneity from X-Ray Surface Brightness: A Statistical Approach and Application to Abell 3667

NASA Astrophysics Data System (ADS)

Kawahara, Hajime; Reese, Erik D.; Kitayama, Tetsu; Sasaki, Shin; Suto, Yasushi

2008-11-01

Our previous analysis indicates that small-scale fluctuations in the intracluster medium (ICM) from cosmological hydrodynamic simulations follow the lognormal probability density function. In order to test the lognormal nature of the ICM directly against X-ray observations of galaxy clusters, we develop a method of extracting statistical information about the three-dimensional properties of the fluctuations from the two-dimensional X-ray surface brightness. We first create a set of synthetic clusters with lognormal fluctuations around their mean profile given by spherical isothermal β-models, later considering polytropic temperature profiles as well. Performing mock observations of these synthetic clusters, we find that the resulting X-ray surface brightness fluctuations also follow the lognormal distribution fairly well. Systematic analysis of the synthetic clusters provides an empirical relation between the three-dimensional density fluctuations and the two-dimensional X-ray surface brightness. We analyze Chandra observations of the galaxy cluster Abell 3667, and find that its X-ray surface brightness fluctuations follow the lognormal distribution. While the lognormal model was originally motivated by cosmological hydrodynamic simulations, this is the first observational confirmation of the lognormal signature in a real cluster. Finally we check the synthetic cluster results against clusters from cosmological hydrodynamic simulations. As a result of the complex structure exhibited by simulated clusters, the empirical relation between the two- and three-dimensional fluctuation properties calibrated with synthetic clusters when applied to simulated clusters shows large scatter. Nevertheless we are able to reproduce the true value of the fluctuation amplitude of simulated clusters within a factor of 2 from their two-dimensional X-ray surface brightness alone. Our current methodology combined with existing observational data is useful in describing and inferring the statistical properties of the three-dimensional inhomogeneity in galaxy clusters.

Little Bright Spot

NASA Image and Video Library

2015-01-12

A bright spot can be seen on the left side of Rhea in this image. The spot is the crater Inktomi, named for a Lakota spider spirit. Inktomi is believed to be the youngest feature on Rhea (949 miles or 1527 kilometers across). The relative youth of the feature is evident by its brightness. Material that is newly excavated from below the moon's surface and tossed across the surface by a cratering event, appears bright. But as the newly exposed surface is subjected to the harsh space environment, it darkens. This is one technique scientists use to date features on surfaces. This view looks toward the trailing hemisphere of Rhea. North on Rhea is up and rotated 21 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 29, 2013. The view was obtained at a distance of approximately 1.0 million miles (1.6 million kilometers) fro http://photojournal.jpl.nasa.gov/catalog/PIA18300

IUE detection of bursts of H Ly-alpha emission from Saturn

NASA Technical Reports Server (NTRS)

Clarke, J. T.; Moos, H. W.; Atreya, S. K.; Lane, A. L.

1981-01-01

A new investigation is reported of the potential sources of Ly-alpha emission in a series of observations of the Saturnian system carried out between January and July 1980 using the short wavelength spectrograph of the IUE Observatory. It is noted that north-south maps of the Ly-alpha emission across the planet disk show pronounced spatial asymmetries in emission brightness. These asymmetries vary to a marked extent on a time scale of days and are interpreted as bursts of Ly-alpha emission of as much as 1 kR brightness averaged over a 6 x 10 arcsec area, above a constant planetary emission level of 700-800 R. In fact, the Ly-alpha emission peaks manifest themselves as essentially point source features in these data; it is pointed out that if the emitting region is smaller than the 6 x 10 arcsec instrumental resolution, the surface brightness must be proportionally higher.

A Search for Low Surface Brightness Galaxies in the Ultraviolet with GALEX

NASA Astrophysics Data System (ADS)

Wyder, Ted K.; GALEX Science Team

2006-12-01

Low surface brightness (LSB) galaxies have traditionally been difficult to detect at visible wavelengths due to their low contrast with the night sky and their low numbers per deg2. We describe a new search for LSB galaxies using UV images from the Galaxy Evolution Explorer (GALEX) satellite. The images are from the GALEX Medium Imaging Survey targeting mainly areas of the sky within the Sloan Digital Sky Survey (SDSS) footprint. Due to the UV sky background at high Galactic latitudes reaching levels of only approximately 28 mag arcsec-2 as well as the relatively large sky coverage from GALEX, we can potentially search for LSB galaxies that would be difficult to detect optically.After first convolving the images with a suitable kernel, we select a diameter limited set of objects which we then inspect manually in order to remove image artifacts and other spurious detections. Red galaxies that have high optical surface brightness can be identified using either the ratio of far-UV to near-UV flux or via comparison to SDSS images. We quantify our selection limits using a set of artificial galaxy tests. Our goal is to find blue, ultra-LSB galaxies that would be virtually undetectable in large optical imaging surveys. GALEX is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission.

BRITE-Constellation high-precision time-dependent photometry of the early O-type supergiant ζ Puppis unveils the photospheric drivers of its small- and large-scale wind structures

NASA Astrophysics Data System (ADS)

Ramiaramanantsoa, Tahina; Moffat, Anthony F. J.; Harmon, Robert; Ignace, Richard; St-Louis, Nicole; Vanbeveren, Dany; Shenar, Tomer; Pablo, Herbert; Richardson, Noel D.; Howarth, Ian D.; Stevens, Ian R.; Piaulet, Caroline; St-Jean, Lucas; Eversberg, Thomas; Pigulski, Andrzej; Popowicz, Adam; Kuschnig, Rainer; Zocłońska, Elżbieta; Buysschaert, Bram; Handler, Gerald; Weiss, Werner W.; Wade, Gregg A.; Rucinski, Slavek M.; Zwintz, Konstanze; Luckas, Paul; Heathcote, Bernard; Cacella, Paulo; Powles, Jonathan; Locke, Malcolm; Bohlsen, Terry; Chené, André-Nicolas; Miszalski, Brent; Waldron, Wayne L.; Kotze, Marissa M.; Kotze, Enrico J.; Böhm, Torsten

2018-02-01

From 5.5 months of dual-band optical photometric monitoring at the 1 mmag level, BRITE-Constellation has revealed two simultaneous types of variability in the O4I(n)fp star ζ Puppis: one single periodic non-sinusoidal component superimposed on a stochastic component. The monoperiodic component is the 1.78-d signal previously detected by Coriolis/Solar Mass Ejection Imager, but this time along with a prominent first harmonic. The shape of this signal changes over time, a behaviour that is incompatible with stellar oscillations but consistent with rotational modulation arising from evolving bright surface inhomogeneities. By means of a constrained non-linear light-curve inversion algorithm, we mapped the locations of the bright surface spots and traced their evolution. Our simultaneous ground-based multisite spectroscopic monitoring of the star unveiled cyclical modulation of its He II λ4686 wind emission line with the 1.78-d rotation period, showing signatures of corotating interaction regions that turn out to be driven by the bright photospheric spots observed by BRITE. Traces of wind clumps are also observed in the He II λ4686 line and are correlated with the amplitudes of the stochastic component of the light variations probed by BRITE at the photosphere, suggesting that the BRITE observations additionally unveiled the photospheric drivers of wind clumps in ζ Pup and that the clumping phenomenon starts at the very base of the wind. The origins of both the bright surface inhomogeneities and the stochastic light variations remain unknown, but a subsurface convective zone might play an important role in the generation of these two types of photospheric variability.

Giant Low Surface Brightness Galaxies

NASA Astrophysics Data System (ADS)

Mishra, Alka; Kantharia, Nimisha G.; Das, Mousumi

2018-04-01

In this paper, we present radio observations of the giant low surface brightness (LSB) galaxies made using the Giant Metrewave Radio Telescope (GMRT). LSB galaxies are generally large, dark matter dominated spirals that have low star formation efficiencies and large HI gas disks. Their properties suggest that they are less evolved compared to high surface brightness galaxies. We present GMRT emission maps of LSB galaxies with an optically-identified active nucleus. Using our radio data and archival near-infrared (2MASS) and near-ultraviolet (GALEX) data, we studied morphology and star formation efficiencies in these galaxies. All the galaxies show radio continuum emission mostly associated with the centre of the galaxy.

Jovian ultraviolet auroral activity, 1981-1991

NASA Technical Reports Server (NTRS)

Livengood, T. A.; Moos, H. W.; Ballester, G. E.; Prange, R. M.

1992-01-01

IUE observations of H2 UV emissions for the 1981-1991 period are presently used to investigate the auroral brightness distribution on the surface of Jupiter. The brightness, which is diagnostic of energy input to the atmosphere as well as of magnetospheric processes, is determined by comparing model-predicted brightnesses against empirical ones. The north and south aurorae appear to be correlated in brightness and in variations of the longitude of peak brightness. There are strong fluctuations in all the parameters of the brightness distribution on much shorter time scales than those of solar maximum-minimum.

Generalized dark-bright vector soliton solution to the mixed coupled nonlinear Schrödinger equations.

PubMed

Manikandan, N; Radhakrishnan, R; Aravinthan, K

2014-08-01

We have constructed a dark-bright N-soliton solution with 4N+3 real parameters for the physically interesting system of mixed coupled nonlinear Schrödinger equations. Using this as well as an asymptotic analysis we have investigated the interaction between dark-bright vector solitons. Each colliding dark-bright one-soliton at the asymptotic limits includes more coupling parameters not only in the polarization vector but also in the amplitude part. Our present solution generalizes the dark-bright soliton in the literature with parametric constraints. By exploiting the role of such coupling parameters we are able to control certain interaction effects, namely beating, breathing, bouncing, attraction, jumping, etc., without affecting other soliton parameters. Particularly, the results of the interactions between the bound state dark-bright vector solitons reveal oscillations in their amplitudes under certain parametric choices. A similar kind of effect was also observed experimentally in the BECs. We have also characterized the solutions with complicated structure and nonobvious wrinkle to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation. It is interesting to identify that the polarization vector of the dark-bright one-soliton evolves on a spherical surface instead of a hyperboloid surface as in the bright-bright case of the mixed coupled nonlinear Schrödinger equations.

Pinacate-gran Desierto Region, Mexico: SIR-A Data Analysis

NASA Technical Reports Server (NTRS)

Christensen, P.; Greeley, R.; Mchone, J.; Asmerom, Y.; Barnett, S.

1984-01-01

Radar images (SIR-A) from the Columbia space shuttle were used to assess the radar returns of terrain shaped by volcanic, aeolian, and fluvial processes in northwest Sonora. Field studies and photointerpretation show that sand dunes are poorly imaged by SIR-A, in contrast to SEASAT, evidently a consequence of the greater SIR-A incidence angle; star dunes are visible only as small bright spots representing merging arms at dune apices which may act as corner reflectors. Desert grasses and bushes (approx. 2 m high) have little effect on radar brightness. Only larger trees with woody trunks approx. 0.5 m across are effective radar reflectors; their presence contributes to radar bright zones along some arroyos. The radar brightness of lava flows decreases with surface roughness and presence of mantling windblown sediments and weathering products; however, old uplifted (faulted) flows are of equal brightness to fresh, unmantled aa flows. Maar craters display circular patterns of varying radar brightness which represent a combination of geometry, slope, and distribution of surface materials. Some radar bright rings in the Pinacates resemble craters on radar but are observed to be playas encircled by trees.

Availability of color calibration for consistent color display in medical images and optimization of reference brightness for clinical use

NASA Astrophysics Data System (ADS)

Iwai, Daiki; Suganami, Haruka; Hosoba, Minoru; Ohno, Kazuko; Emoto, Yutaka; Tabata, Yoshito; Matsui, Norihisa

2013-03-01

Color image consistency has not been accomplished yet except the Digital Imaging and Communication in Medicine (DICOM) Supplement 100 for implementing a color reproduction pipeline and device independent color spaces. Thus, most healthcare enterprises could not check monitor degradation routinely. To ensure color consistency in medical color imaging, monitor color calibration should be introduced. Using simple color calibration device . chromaticity of colors including typical color (Red, Green, Blue, Green and White) are measured as device independent profile connection space value called u'v' before and after calibration. In addition, clinical color images are displayed and visual differences are observed. In color calibration, monitor brightness level has to be set to quite lower value 80 cd/m2 according to sRGB standard. As Maximum brightness of most color monitors available currently for medical use have much higher brightness than 80 cd/m2, it is not seemed to be appropriate to use 80 cd/m2 level for calibration. Therefore, we propose that new brightness standard should be introduced while maintaining the color representation in clinical use. To evaluate effects of brightness to chromaticity experimentally, brightness level is changed in two monitors from 80 to 270cd/m2 and chromaticity value are compared with each brightness levels. As a result, there are no significant differences in chromaticity diagram when brightness levels are changed. In conclusion, chromaticity is close to theoretical value after color calibration. Moreover, chromaticity isn't moved when brightness is changed. The results indicate optimized reference brightness level for clinical use could be set at high brightness in current monitors .

A catalog of low surface brightness galaxies - List II

NASA Technical Reports Server (NTRS)

Schombert, James M.; Bothun, Gregory D.; Schneider, Stephen E.; Mcgaugh, Stacy S.

1992-01-01

A list of galaxies characterized by low surface brightness (LSB) is presented which facilitates the recognition of galaxies with brightnesses close to that of the sky. A total of 198 objects and 140 objects are listed in the primary and secondary catalogs respectively, and LSB galaxies are examined by means of H I redshift distributions. LSB disk galaxies are shown to have similar sizes and masses as the high-surface-brightness counterparts, and ellipticals and SOs are rarely encountered. Many LSB spirals have stellarlike nuclei, and most of the galaxies in the present catalog are late-type galaxies in the Sc, Sm, and Im classes. The LSB region of observational parameter space is shown to encompass a spectrum of types as full as that of the Hubble sequence. It is suggested that studies of LSB galaxies can provide important data regarding the formation and star-formation history of all galaxies.

Comparative testing of dark matter models with 15 HSB and 15 LSB galaxies

NASA Astrophysics Data System (ADS)

Kun, E.; Keresztes, Z.; Simkó, A.; Szűcs, G.; Gergely, L. Á.

2017-12-01

Context. We assemble a database of 15 high surface brightness (HSB) and 15 low surface brightness (LSB) galaxies, for which surface brightness density and spectroscopic rotation curve data are both available and representative for various morphologies. We use this dataset to test the Navarro-Frenk-White, the Einasto, and the pseudo-isothermal sphere dark matter models. Aims: We investigate the compatibility of the pure baryonic model and baryonic plus one of the three dark matter models with observations on the assembled galaxy database. When a dark matter component improves the fit with the spectroscopic rotational curve, we rank the models according to the goodness of fit to the datasets. Methods: We constructed the spatial luminosity density of the baryonic component based on the surface brightness profile of the galaxies. We estimated the mass-to-light (M/L) ratio of the stellar component through a previously proposed color-mass-to-light ratio relation (CMLR), which yields stellar masses independent of the photometric band. We assumed an axissymetric baryonic mass model with variable axis ratios together with one of the three dark matter models to provide the theoretical rotational velocity curves, and we compared them with the dataset. In a second attempt, we addressed the question whether the dark component could be replaced by a pure baryonic model with fitted M/L ratios, varied over ranges consistent with CMLR relations derived from the available stellar population models. We employed the Akaike information criterion to establish the performance of the best-fit models. Results: For 7 galaxies (2 HSB and 5 LSB), neither model fits the dataset within the 1σ confidence level. For the other 23 cases, one of the models with dark matter explains the rotation curve data best. According to the Akaike information criterion, the pseudo-isothermal sphere emerges as most favored in 14 cases, followed by the Navarro-Frenk-White (6 cases) and the Einasto (3 cases) dark matter models. We find that the pure baryonic model with fitted M/L ratios falls within the 1σ confidence level for 10 HSB and 2 LSB galaxies, at the price of growing the M/Ls on average by a factor of two, but the fits are inferior compared to the best-fitting dark matter model.

The Photometric Properties of a Vast Stellar Substructure in the Outskirts of M33

NASA Astrophysics Data System (ADS)

McConnachie, Alan W.; Ferguson, Annette M. N.; Irwin, Michael J.; Dubinski, John; Widrow, Lawrence M.; Dotter, Aaron; Ibata, Rodrigo; Lewis, Geraint F.

2010-11-01

We have surveyed approximately 40 deg2 surrounding M33 with Canada-France-Hawaii Telescope MegaCam/MegaPrime in the g and i filters out to a maximum projected radius from this galaxy of 50 kpc, as part of the Pan-Andromeda Archaeological Survey (PAndAS). Our observations are deep enough to resolve the top ~4 mag of the red giant branch population in this galaxy. We have previously shown that the disk of M33 is surrounded by a large, irregular, low surface brightness substructure. Here, we quantify the stellar populations and structure of this feature using the PAndAS data. We show that the stellar populations of this feature are consistent with an old population with lang[Fe/H]rang ~ -1.6 dex and an interquartile range in metallicity of ~0.5 dex. We construct a surface brightness map of M33 that traces this feature to μ V ~= 33 mag arcsec-2. At these low surface brightness levels, the structure extends to projected radii of ~40 kpc from the center of M33 in both the northwest and southeast quadrants of the galaxy. Overall, the structure has an "S-shaped" appearance that broadly aligns with the orientation of the H I disk warp. We calculate a lower limit to the integrated luminosity of the structure of -12.7 ± 0.5 mag, comparable to a bright dwarf galaxy such as Fornax or Andromeda II and slightly less than 1% of the total luminosity of M33. Further, we show that there is tentative evidence for a distortion in the distribution of young stars near the edge of the H I disk that occurs at similar azimuth to the warp in H I. The data also hint at a low-level, extended stellar component at larger radius that may be an M33 halo component. We revisit studies of M33 and its stellar populations in light of these new results and discuss possible formation scenarios for the vast stellar structure. Our favored model is that of the tidal disruption of M33 in its orbit around M31.

Classification of sea ice types with single-band (33.6 GHz) airborne passive microwave imagery

NASA Astrophysics Data System (ADS)

Eppler, Duane T.; Farmer, L. Dennis; Lohanick, Alan W.; Hoover, Mervyn

1986-09-01

During March 1983 extensive high-quality airborne passive Ka band (33.6 GHz) microwave imagery and coincident high-resolution aerial photography were obtained of ice along a 378-km flight line in the Beaufort Sea. Analysis of these data suggests that four classes of winter surfaces can be distinguished solely on the basis of 33.6-GHz brightness temperature: open water, frazil, old ice, and young/first-year ice. New ice (excluding frazil) and nilas display brightness temperatures that overlap the range of temperatures characteristic of old ice and, to a lesser extent, young/first-year ice. Scenes in which a new ice or nilas are present in appreciable amounts are subject to substantial errors in classification if static measures of Ka band radiometric brightness temperature alone are considered. Textural characteristics of nilas and new ice, however, differ significantly from textural features characteristic of other ice types and probably can be used with brightness temperature data to classify ice type in high-resolution single-band microwave images. In any case, open water is radiometrically the coldest surface observed in any scene. Lack of overlap between brightness temperatures characteristic of other surfaces indicates that estimates of the areal extent of open water based on only 33.6-GHz brightness temperatures are accurate.

Metre-size bright spots at the surface of comet 67P/Churyumov-Gerasimenko: Interpretation of OSIRIS data using laboratory experiments

NASA Astrophysics Data System (ADS)

Pommerol, Antoine; Thomas, Nicolas; Antonella Barucci, M.; Bertaux, Jean-Loup; Davidsson, Björn; Ramy El-Maarry, Mohamed; La Forgia, Fiorengela; Fornasier, Sonia; Gracia, Antonio; Groussin, Olivier; Jost, Bernhard; Keller, Horst Uwe; Kuehrt, Ekkehard; Marschall, Raphael; Massironi, Matteo; Motolla, Stefano; Naletto, Giampiero; Oklay, Nilda; Pajola, Maurizio; Poch, Olivier

2015-04-01

Since the beginning of Rosetta's orbital observations, over a hundred small bright spots have been identified in images returned by its OSIRIS NAC camera, in all types of morphological regions on the nucleus. Bright spots are found as clusters of several tens of individuals in the vicinity of cliffs, or isolated without clear structural relation to the surrounding terrain. They are however mostly observed in the areas of the nucleus currently receiving the lowest amount of insolation and some of the best examples appear completely surrounded by shadows. Their typical sizes are of the order of a few metres and they are often observed at the surfaces of boulders of larger dimension. The brightness of these spots is up to ten times the average brightness of the surrounding terrain and multi-spectral analyses show a significantly bluer spectrum over the 0.3-1µm range. Comparisons of images taken in September and November 2014 under similar illumination conditions do not show any significant change of these features. Analysis of the results of past and present laboratory experiments with H2O-ice/dust mixtures provide interesting insights about the nature and origin of the bright spots. In particular, recent sublimation experiments conducted at the University of Bern reproduce the spectro-photometric variability observed at the surface of the nucleus by sequences of formation and ejection of a mantle of refractory organic-rich dust at the surface of the icy material. The formation of hardened layers of ice by sintering/re-condensation below the uppermost dust layer can also have strong implications for both the photometric and mechanical properties of the subsurface layer. Based on the comparison between OSIRIS observations and laboratory results, our favoured interpretation of the observed features is that the bright spots are exposures of water ice, resulting from the removal of the uppermost layer of refractory dust that covers the rest of the nucleus. Some of the observations of clusters of bright spots are very indicative of a formation process, which involves the breakage and collapse of brittle layers of ice to form fields of large boulders, some of them showing bright spots on part of their surface. Some of the isolated spots observed elsewhere on the nucleus might as well have been formed by similar processes and then have been transported over large distances by multiple bounces. These surface exposures of water ice must be more recent than the last passage at perihelion, as they would rapidly sublimate at short heliocentric distance. The hypothesis formulated here will thus easily be tested as the comet approaches the Sun, by checking if and how fast the bright spots vanish and disappear.

A case study on large-scale dynamical influence on bright band using cloud radar during the Indian summer monsoon

NASA Astrophysics Data System (ADS)

Jha, Ambuj K.; Kalapureddy, M. C. R.; Devisetty, Hari Krishna; Deshpande, Sachin M.; Pandithurai, G.

2018-02-01

The present study is a first of its kind attempt in exploring the physical features (e.g., height, width, intensity, duration) of tropical Indian bright band using a Ka-band cloud radar under the influence of large-scale cyclonic circulation and attempts to explain the abrupt changes in bright band features, viz., rise in the bright band height by 430 m and deepening of the bright band by about 300 m observed at around 14:00 UTC on Sep 14, 2016, synoptically as well as locally. The study extends the utility of cloud radar to understand how the bright band features are associated with light precipitation, ranging from 0 to 1.5 mm/h. Our analysis of the precipitation event of Sep 14-15, 2016 shows that the bright band above (below) 3.7 km, thickness less (more) than 300 m can potentially lead to light drizzle of 0-0.25 mm/h (drizzle/light rain) at the surface. It is also seen that the cloud radar may be suitable for bright band study within light drizzle limits than under higher rain conditions. Further, the study illustrates that the bright band features can be determined using the polarimetric capability of the cloud radar. It is shown that an LDR value of - 22 dB can be associated with the top height of bright band in the Ka-band observations which is useful in the extraction of the bright band top height and its width. This study is useful for understanding the bright band phenomenon and could be potentially useful in establishing the bright band-surface rain relationship through the perspective of a cloud radar, which would be helpful to enhance the cloud radar-based quantitative estimates of precipitation.

Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

NASA Astrophysics Data System (ADS)

Smith, Anthony J.; Loveday, Jon; Cross, Nicholas J. G.

2009-08-01

We present luminosity and surface-brightness distributions of 40111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best-fitting Schechter function parameters for the K-band luminosity function are found to be M* - 5 logh = -23.19 +/- 0.04,α = -0.81 +/- 0.04 and φ* = (0.0166 +/- 0.0008)h3Mpc-3, although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 +/- 0.067) × 108LsolarhMpc-3. However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours, we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

Evaluations of carbon nanotube field emitters for electron microscopy

NASA Astrophysics Data System (ADS)

Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

2009-11-01

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I- V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6×109 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

Determination of cloud liquid water content using the SSM/I

NASA Technical Reports Server (NTRS)

Alishouse, John C.; Snider, Jack B.; Westwater, Ed R.; Swift, Calvin T.; Ruf, Christopher S.

1990-01-01

As part of a calibration/validation effort for the special sensor microwave/imager (SSM/I), coincident observations of SSM/I brightness temperatures and surface-based observations of cloud liquid water were obtained. These observations were used to validate initial algorithms and to derive an improved algorithm. The initial algorithms were divided into latitudinal-, seasonal-, and surface-type zones. It was found that these initial algorithms, which were of the D-matrix type, did not yield sufficiently accurate results. The surface-based measurements of channels were investigated; however, the 85V channel was excluded because of excessive noise. It was found that there is no significant correlation between the SSM/I brightness temperatures and the surface-based cloud liquid water determination when the background surface is land or snow. A high correlation was found between brightness temperatures and ground-based measurements over the ocean.

Calculations of microwave brightness temperature of rough soil surfaces: Bare field

NASA Technical Reports Server (NTRS)

Mo, T.; Schmugge, T. J.; Wang, J. R.

1985-01-01

A model for simulating the brightness temperatures of soils with rough surfaces is developed. The surface emissivity of the soil media is obtained by the integration of the bistatic scattering coefficients for rough surfaces. The roughness of a soil surface is characterized by two parameters, the surface height standard deviation sigma and its horizontal correlation length l. The model calculations are compared to the measured angular variations of the polarized brightness temperatures at both 1.4 GHz and 5 GHz frequences. A nonlinear least-squares fitting method is used to obtain the values of delta and l that best characterize the surface roughness. The effect of shadowing is incorporated by introducing a function S(theta), which represents the probability that a point on a rough surface is not shadowed by other parts of the surface. The model results for the horizontal polarization are in excellent agreement with the data. However, for the vertical polarization, some discrepancies exist between the calculations and data, particularly at the 1.4 GHz frequency. Possible causes of the discrepancy are discussed.

A reinterpretation of transparency perception in terms of gamut relativity.

PubMed

Vladusich, Tony

2013-03-01

Classical approaches to transparency perception assume that transparency constitutes a perceptual dimension corresponding to the physical dimension of transmittance. Here I present an alternative theory, termed gamut relativity, that naturally explains key aspects of transparency perception. Rather than being computed as values along a perceptual dimension corresponding to transmittance, gamut relativity postulates that transparency is built directly into the fabric of the visual system's representation of surface color. The theory, originally developed to explain properties of brightness and lightness perception, proposes how the relativity of the achromatic color gamut in a perceptual blackness-whiteness space underlies the representation of foreground and background surface layers. Whereas brightness and lightness perception were previously reanalyzed in terms of the relativity of the achromatic color gamut with respect to illumination level, transparency perception is here reinterpreted in terms of relativity with respect to physical transmittance. The relativity of the achromatic color gamut thus emerges as a fundamental computational principle underlying surface perception. A duality theorem relates the definition of transparency provided in gamut relativity with the classical definition underlying the physical blending models of computer graphics.

Simulated X-ray galaxy clusters at the virial radius: Slopes of the gas density, temperature and surface brightness profiles

NASA Astrophysics Data System (ADS)

Roncarelli, M.; Ettori, S.; Dolag, K.; Moscardini, L.; Borgani, S.; Murante, G.

2006-12-01

Using a set of hydrodynamical simulations of nine galaxy clusters with masses in the range 1.5 × 1014 < Mvir < 3.4 × 1015Msolar, we have studied the density, temperature and X-ray surface brightness profiles of the intracluster medium in the regions around the virial radius. We have analysed the profiles in the radial range well above the cluster core, the physics of which are still unclear and matter of tension between simulated and observed properties, and up to the virial radius and beyond, where present observations are unable to provide any constraints. We have modelled the radial profiles between 0.3R200 and 3R200 with power laws with one index, two indexes and a rolling index. The simulated temperature and [0.5-2] keV surface brightness profiles well reproduce the observed behaviours outside the core. The shape of all these profiles in the radial range considered depends mainly on the activity of the gravitational collapse, with no significant difference among models including extraphysics. The profiles steepen in the outskirts, with the slope of the power-law fit that changes from -2.5 to -3.4 in the gas density, from -0.5 to -1.8 in the gas temperature and from -3.5 to -5.0 in the X-ray soft surface brightness. We predict that the gas density, temperature and [0.5-2] keV surface brightness values at R200 are, on average, 0.05, 0.60, 0.008 times the measured values at 0.3R200. At 2R200, these values decrease by an order of magnitude in the gas density and surface brightness, by a factor of 2 in the temperature, putting stringent limits on the detectable properties of the intracluster-medium (ICM) in the virial regions.

Space Radar Image of Altona, Manitoba, Canada

NASA Image and Video Library

1999-05-01

This is an X-band seasonal image of the Altona test site in Manitoba, Canada, about 80 kilometers (50 miles) south of Winnipeg. The image is centered at approximately 49 degrees north latitude and 97.5 degrees west longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 11, 1994, during the first flight of the radar system, and on October 2, 1994, during the second flight of SIR-C/X-SAR. The image channels have the following color assignments: red represents data acquired on April 11, 1994; green represents data acquired on October 2, 1994; blue represents the ratio of the two data sets. The test site is located in the Red River Basin and is characterized by rich farmland where a variety of crops are grown, including wheat, barley, canola, corn, sunflowers and sugar beets. This SIR-C/X-SAR research site is applying radar remote sensing to study the characteristics of vegetation and soil moisture. The seasonal comparison between the April and October 1994 data show the dramatic differences between surface conditions on the two dates. At the time of the April acquisition, almost all agricultural fields were bare and soil moisture levels were high. In October, however, soils were drier and while most crops had been harvested, some standing vegetation was still present. The areas which are cyan in color are dark in April and bright in October. These represent fields of standing biomass (amount of vegetation in a specified area) and the differences in brightness within these cyan fields represent differences in vegetation type. The very bright fields in October represent standing broadleaf crops such as corn, which had not yet been harvested. Other standing vegetation which has less biomass, such as hay and grain fields, are less bright. The magenta indicates bare soil surfaces which were wetter (brighter) in April than in October. The variations in brightness of the magenta indicate differences in the degree of soil moisture change and differences in surface roughness. This seasonal composite demonstrates the sensitivity of radar to changes in agricultural surface conditions such as soil moisture, tillage, cropping and harvesting. http://photojournal.jpl.nasa.gov/catalog/PIA01742

Imaging the spotty surface of Betelgeuse in the H band

NASA Astrophysics Data System (ADS)

Haubois, X.; Perrin, G.; Lacour, S.; Verhoelst, T.; Meimon, S.; Mugnier, L.; Thiébaut, E.; Berger, J. P.; Ridgway, S. T.; Monnier, J. D.; Millan-Gabet, R.; Traub, W.

2009-12-01

Aims. This paper reports on H-band interferometric observations of Betelgeuse made at the three-telescope interferometer IOTA. We image Betelgeuse and its asymmetries to understand the spatial variation of the photosphere, including its diameter, limb darkening, effective temperature, surrounding brightness, and bright (or dark) star spots. Methods: We used different theoretical simulations of the photosphere and dusty environment to model the visibility data. We made images with parametric modeling and two image reconstruction algorithms: MIRA and WISARD. Results: We measure an average limb-darkened diameter of 44.28 ± 0.15 mas with linear and quadratic models and a Rosseland diameter of 45.03 ± 0.12 mas with a MARCS model. These measurements lead us to derive an updated effective temperature of 3600 ± 66 K. We detect a fully-resolved environment to which the silicate dust shell is likely to contribute. By using two imaging reconstruction algorithms, we unveiled two bright spots on the surface of Betelgeuse. One spot has a diameter of about 11 mas and accounts for about 8.5% of the total flux. The second one is unresolved (diameter < 9 mas) with 4.5% of the total flux. Conclusions: Resolved images of Betelgeuse in the H band are asymmetric at the level of a few percent. The MOLsphere is not detected in this wavelength range. The amount of measured limb-darkening is in good agreement with model predictions. The two spots imaged at the surface of the star are potential signatures of convective cells.

A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

PubMed

Nijboer, Tanja C W; Nys, Gudrun M S; van der Smagt, Maarten J; de Haan, Edward H F

2009-01-01

We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

Correlations among the properties of galaxies found in a blind HI survey, which also have SDSS optical data

NASA Astrophysics Data System (ADS)

Garcia-Appadoo, D. A.; West, A. A.; Dalcanton, J. J.; Cortese, L.; Disney, M. J.

2009-03-01

We have used the Parkes Multibeam system and the Sloan Digital Sky Survey to assemble a sample of 195 galaxies selected originally from their HI signature to avoid biases against unevolved or low surface brightness objects. For each source nine intrinsic properties are measured homogeneously, as well as inclination and an optical spectrum. The sample, which should be almost entirely free of either misidentification or confusion, includes a wide diversity of galaxies ranging from inchoate, low surface brightness dwarfs to giant spirals. Despite this diversity there are five clear correlations among their properties. They include a common dynamical mass-to-light ratio within their optical radii, a correlation between surface brightness and luminosity and a common HI surface density. Such correlation should provide strong constrains on models of galaxy formation and evolution.

Fish with red fluorescent eyes forage more efficiently under dim, blue-green light conditions.

PubMed

Harant, Ulrike Katharina; Michiels, Nicolaas Karel

2017-04-20

Natural red fluorescence is particularly conspicuous in the eyes of some small, benthic, predatory fishes. Fluorescence also increases in relative efficiency with increasing depth, which has generated speculation about its possible function as a "light organ" to detect cryptic organisms under bluish light. Here we investigate whether foraging success is improved under ambient conditions that make red fluorescence stand out more, using the triplefin Tripterygion delaisi as a model system. We repeatedly presented 10 copepods to individual fish (n = 40) kept under a narrow blue-green spectrum and compared their performance with that under a broad spectrum with the same overall brightness. The experiment was repeated for two levels of brightness, a shaded one representing 0.4% of the light present at the surface and a heavily shaded one with about 0.01% of the surface brightness. Fish were 7% more successful at catching copepods under the narrow, fluorescence-friendly spectrum than under the broad spectrum. However, this effect was significant under the heavily shaded light treatment only. This outcome corroborates previous predictions that fluorescence may be an adaptation to blue-green, heavily shaded environments, which coincides with the opportunistic biology of this species that lives in the transition zone between exposed and heavily shaded microhabitats.

The nucleus of Comet Borrelly: A study of morphology and surface brightness

USGS Publications Warehouse

Oberst, J.; Howington-Kraus, E.; Kirk, R.; Soderblom, L.; Buratti, B.; Hicks, M.; Nelson, R.; Britt, D.

2004-01-01

Stereo images obtained during the DS1 flyby were analyzed to derive a topographic model for the nucleus of Comet 19P/Borrelly for morphologic and photometric studies. The elongated nucleus has an overall concave shape, resembling a peanut, with the lower end tilted towards the camera. The bimodal character of surface-slopes and curvatures support the idea that the nucleus is a gravitational aggregate, consisting of two fragments in contact. Our photometric modeling suggests that topographic shading effects on Borrelly's surface are very minor (<10%) at the given resolution of the terrain model. Instead, albedo effects are thought to dominate Borrelly's large variations in surface brightness. With 90% of the visible surface having single scattering albedos between 0.008 and 0.024, Borrelly is confirmed to be among the darkest of the known Solar System objects. Photometrically corrected images emphasize that the nucleus has distinct, contiguous terrains covered with either bright or dark, smooth or mottled materials. Also, mapping of the changes in surface brightness with phase angle suggests that terrain roughness at subpixel scale is not uniform over the nucleus. High surface roughness is noted in particular near the transition between the upper and lower end of the nucleus, as well as near the presumed source region of Borrelly's main jets. Borrelly's surface is complex and characterized by distinct types of materials that have different compositional and/or physical properties. ?? 2003 Elsevier Inc. All rights reserved.

Thin Sea-Ice Thickness as Inferred from Passive Microwave and In Situ Observations

NASA Technical Reports Server (NTRS)

Naoki, Kazuhiro; Ukita, Jinro; Nishio, Fumihiko; Nakayama, Masashige; Comiso, Josefino C.; Gasiewski, Al

2007-01-01

Since microwave radiometric signals from sea-ice strongly reflect physical conditions of a layer near the ice surface, a relationship of brightness temperature with thickness is possible especially during the early stages of ice growth. Sea ice is most saline during formation stage and as the salinity decreases with time while at the same time the thickness of the sea ice increases, a corresponding change in the dielectric properties and hence the brightness temperature may occur. This study examines the extent to which the relationships of thickness with brightness temperature (and with emissivity) hold for thin sea-ice, approximately less than 0.2 -0.3 m, using near concurrent measurements of sea-ice thickness in the Sea of Okhotsk from a ship and passive microwave brightness temperature data from an over-flying aircraft. The results show that the brightness temperature and emissivity increase with ice thickness for the frequency range of 10-37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively support the idea that changes in the near-surface brine characteristics contribute to the observed thickness-brightness temperature/emissivity relationship. Our results suggest that for thin ice, passive microwave radiometric signals contain, ice thickness information which can be utilized in polar process studies.

Constraining the Depth of Polar Ice Deposits and Evolution of Cold Traps on Mercury with Small Craters in Permanently Shadowed Regions

NASA Technical Reports Server (NTRS)

Deutsch, Ariel N.; Head, James W.; Neumann, Gregory A.; Chabot, Nancy L.

2017-01-01

Earth-based radar observations revealed highly reflective deposits at the poles of Mercury [e.g., 1], which collocate with permanently shadowed regions (PSRs) detected from both imagery and altimetry by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft [e.g., 2]. MESSENGER also measured higher hydrogen concentrations at the north polar region, consistent with models for these deposits to be composed primarily of water ice [3]. Enigmatic to the characterization of ice deposits on Mercury is the thickness of these radar-bright features. A current minimum bound of several meters exists from the radar measurements, which show no drop in the radar cross section between 13- and 70-cm wavelength observations [4, 5]. A maximum thickness of 300 m is based on the lack of any statistically significant difference between the height of craters that host radar-bright deposits and those that do not [6]. More recently, this upper limit on the depth of a typical ice deposit has been lowered to approximately 150 m, in a study that found a mean excess thickness of 50 +/- 35 m of radar-bright deposits for 6 craters [7]. Refining such a constraint permits the derivation of a volumetric estimate of the total polar ice on Mercury, thus providing insight into possible sources of water ice on the planet. Here, we take a different approach to constrain the thickness of water-ice deposits. Permanently shadowed surfaces have been resolved in images acquired with the broadband filter on MESSENGER's wide-angle camera (WAC) using low levels of light scattered by crater walls and other topography [8]. These surfaces are not featureless and often host small craters (less than a few km in diameter). Here we utilize the presence of these small simple craters to constrain the thickness of the radar-bright ice deposits on Mercury. Specifically, we compare estimated depths made from depth-to-diameter ratios and depths from individual Mercury Laser Altimeter (MLA) tracks to constrain the fill of material of small craters that lie within the permanently shadowed, radar bright deposits of 7 north polar craters.

49 CFR 213.113 - Defective rails.

Code of Federal Regulations, 2010 CFR

2010-10-01

... smooth, bright, or dark, round or oval surface substantially at a right angle to the length of the rail... in the head of the rail as a smooth, bright, or dark surface progressing until substantially at a... head, and extending into or through it. A crack or rust streak may show under the head close to the web...

49 CFR 213.113 - Defective rails.

Code of Federal Regulations, 2011 CFR

2011-10-01

... smooth, bright, or dark, round or oval surface substantially at a right angle to the length of the rail... in the head of the rail as a smooth, bright, or dark surface progressing until substantially at a... head, and extending into or through it. A crack or rust streak may show under the head close to the web...

49 CFR 213.113 - Defective rails.

Code of Federal Regulations, 2012 CFR

2012-10-01

... smooth, bright, or dark, round or oval surface substantially at a right angle to the length of the rail... in the head of the rail as a smooth, bright, or dark surface progressing until substantially at a... head, and extending into or through it. A crack or rust streak may show under the head close to the web...

49 CFR 213.113 - Defective rails.

Code of Federal Regulations, 2013 CFR

2013-10-01

... smooth, bright, or dark, round or oval surface substantially at a right angle to the length of the rail... in the head of the rail as a smooth, bright, or dark surface progressing until substantially at a... head, and extending into or through it. A crack or rust streak may show under the head close to the web...

The spatial distribution of dwarf galaxies in the CfA slice of the universe

NASA Technical Reports Server (NTRS)

Thuan, Trinh X.; Gott, J. Richard, III; Schneider, Stephen E.

1987-01-01

A complete (with the the exception of one) redshift sample of 58 galaxies in the Nilson catalog classified as dwarf, irregular, or Magellanic irregular is used to investigate the large-scale clustering properties of these low-surface brightness galaxies in the CfA slice of the universe (alpha in the range of 8-17 h, delta in the range of 26.5-32.5 deg). It is found that the low-surface brightness dwarf galaxies also lie on the structures delineated by the high-surface brightness normal galaxies and that they do not fill in the voids. This is inconsistent with a class of biased galaxy formation theories which predict that dwarf galaxies should be present everywhere, including the voids.

Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grains

NASA Technical Reports Server (NTRS)

Witt, Adolf N.; Petersohn, Jens K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

1992-01-01

The Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.

Rutgers zodiacal light experiment on OSO-6

NASA Technical Reports Server (NTRS)

Carroll, B.

1975-01-01

A detector was placed in a slowly spinning wheel on OSO-6 whose axis was perpendicular to the line drawn to the sun, to measure the surface brightness and polarization at all elongations from the immediate neighborhood of the sun to the anti-solar point. Different wavelength settings and polarizations were calculated from the known order of magnitude brightness of the zodiacal light. The measuring sequence was arranged to give longer integration times for the regions of lower surface brightness. Three types of analysis to which the data on OSO-6 were subjected are outlined; (1) photometry, (2) colorimetry and (3) polarimetry.

Satellite-derived ice data sets no. 2: Arctic monthly average microwave brightness temperatures and sea ice concentrations, 1973-1976

NASA Technical Reports Server (NTRS)

Parkinson, C. L.; Comiso, J. C.; Zwally, H. J.

1987-01-01

A summary data set for four years (mid 70's) of Arctic sea ice conditions is available on magnetic tape. The data include monthly and yearly averaged Nimbus 5 electrically scanning microwave radiometer (ESMR) brightness temperatures, an ice concentration parameter derived from the brightness temperatures, monthly climatological surface air temperatures, and monthly climatological sea level pressures. All data matrices are applied to 293 by 293 grids that cover a polar stereographic map enclosing the 50 deg N latitude circle. The grid size varies from about 32 X 32 km at the poles to about 28 X 28 km at 50 deg N. The ice concentration parameter is calculated assuming that the field of view contains only open water and first-year ice with an ice emissivity of 0.92. To account for the presence of multiyear ice, a nomogram is provided relating the ice concentration parameter, the total ice concentration, and the fraction of the ice cover which is multiyear ice.

Surface Relief of Mapping

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Almeida, Jose B.

1989-02-01

We will describe in this communication a noncont act method of measuring surface profile, it does not require any surface preparation, and it can be used with a very large range of surfaces from highly reflecting to non reflecting ones and as complex as textile surfaces. This method is reasonably immune to dispersion and diffraction, which usually make very difficult the application of non contact profilometry methods to a wide range of materials and situations, namely on quality control systems in industrial production lines. The method is based on the horizontal shift of the bright spot on a horizontal surface when this is illuminated with an oblique beam and moved vertically. in order to make the profilometry the sample is swept by an oblique light beam and the bright spot position is compared with a reference position. The bright spot must be as small as possible, particularly in very irregular surfaces; so the light beam diameter must be as small as possible and the incidence angle must not be too small. The sensivity of a system based on this method will be given, mostly, by the reception optical system.

Surface and Atmospheric Contributions to Passive Microwave Brightness Temperatures

NASA Technical Reports Server (NTRS)

Jackson, Gail Skofronick; Johnson, Benjamin T.

2010-01-01

Physically-based passive microwave precipitation retrieval algorithms require a set of relationships between satellite observed brightness temperatures (TB) and the physical state of the underlying atmosphere and surface. These relationships are typically non-linear, such that inversions are ill-posed especially over variable land surfaces. In order to better understand these relationships, this work presents a theoretical analysis using brightness temperature weighting functions to quantify the percentage of the TB resulting from absorption/emission/reflection from the surface, absorption/emission/scattering by liquid and frozen hydrometeors in the cloud, the emission from atmospheric water vapor, and other contributors. The results are presented for frequencies from 10 to 874 GHz and for several individual precipitation profiles as well as for three cloud resolving model simulations of falling snow. As expected, low frequency channels (<89 GHz) respond to liquid hydrometeors and the surface, while the higher frequency channels become increasingly sensitive to ice hydrometeors and the water vapor sounding channels react to water vapor in the atmosphere. Low emissivity surfaces (water and snow-covered land) permit energy downwelling from clouds to be reflected at the surface thereby increasing the percentage of the TB resulting from the hydrometeors. The slant path at a 53deg viewing angle increases the hydrometeor contributions relative to nadir viewing channels and show sensitivity to surface polarization effects. The TB percentage information presented in this paper answers questions about the relative contributions to the brightness temperatures and provides a key piece of information required to develop and improve precipitation retrievals over land surfaces.

Error sources in the retrieval of aerosol information over bright surfaces from satellite measurements in the oxygen A band

NASA Astrophysics Data System (ADS)

Nanda, Swadhin; de Graaf, Martin; Sneep, Maarten; de Haan, Johan F.; Stammes, Piet; Sanders, Abram F. J.; Tuinder, Olaf; Pepijn Veefkind, J.; Levelt, Pieternel F.

2018-01-01

Retrieving aerosol optical thickness and aerosol layer height over a bright surface from measured top-of-atmosphere reflectance spectrum in the oxygen A band is known to be challenging, often resulting in large errors. In certain atmospheric conditions and viewing geometries, a loss of sensitivity to aerosol optical thickness has been reported in the literature. This loss of sensitivity has been attributed to a phenomenon known as critical surface albedo regime, which is a range of surface albedos for which the top-of-atmosphere reflectance has minimal sensitivity to aerosol optical thickness. This paper extends the concept of critical surface albedo for aerosol layer height retrievals in the oxygen A band, and discusses its implications. The underlying physics are introduced by analysing the top-of-atmosphere reflectance spectrum as a sum of atmospheric path contribution and surface contribution, obtained using a radiative transfer model. Furthermore, error analysis of an aerosol layer height retrieval algorithm is conducted over dark and bright surfaces to show the dependence on surface reflectance. The analysis shows that the derivative with respect to aerosol layer height of the atmospheric path contribution to the top-of-atmosphere reflectance is opposite in sign to that of the surface contribution - an increase in surface brightness results in a decrease in information content. In the case of aerosol optical thickness, these derivatives are anti-correlated, leading to large retrieval errors in high surface albedo regimes. The consequence of this anti-correlation is demonstrated with measured spectra in the oxygen A band from the GOME-2 instrument on board the Metop-A satellite over the 2010 Russian wildfires incident.

Discovery of Diffuse Dwarf Galaxy Candidates around M101

NASA Astrophysics Data System (ADS)

Bennet, P.; Sand, D. J.; Crnojević, D.; Spekkens, K.; Zaritsky, D.; Karunakaran, A.

2017-11-01

We have conducted a search of a 9 deg2 region of the Canada-France-Hawaii-Telescope Legacy Survey around the Milky Way analog M101 (D ˜ 7 Mpc), in order to look for previously unknown low-surface-brightness galaxies. This search has uncovered 38 new low-surface-brightness dwarf candidates, and confirmed 11 previously reported galaxies, all with central surface brightness μ(g, 0) > 23 mag arcsec-2, potentially extending the satellite luminosity function for the M101 group by ˜1.2 mag. The search was conducted using an algorithm that nearly automates the detection of diffuse dwarf galaxies. The candidates’ small sizes and low surface brightnesses mean that the faintest of these objects would likely be missed by traditional visual or computer detection techniques. The dwarf galaxy candidates span a range of -7.1 ≥ M g ≥ -10.2 and half-light radii of 118-540 pc at the distance of M101, and they are well fit by simple Sérsic surface brightness profiles. These properties are consistent with dwarfs in the Local Group, and to match the Local Group luminosity function, ˜10-20 of these candidates should be satellites of M101. Association with a massive host is supported by the lack of detected star formation and the overdensity of candidates around M101 compared to the field. The spatial distribution of the dwarf candidates is highly asymmetric, and concentrated to the northeast of M101, therefore distance measurements will be required to determine if these are genuine members of the M101 group.

Spot distribution and fast surface evolution on Vega

NASA Astrophysics Data System (ADS)

Petit, P.; Hébrard, E. M.; Böhm, T.; Folsom, C. P.; Lignières, F.

2017-11-01

Spectral signatures of surface spots were recently discovered from high cadence observations of the A star Vega. We aim at constraining the surface distribution of these photospheric inhomogeneities and investigating a possible short-term evolution of the spot pattern. Using data collected over five consecutive nights, we employ the Doppler imaging method to reconstruct three different maps of the stellar surface, from three consecutive subsets of the whole time series. The surface maps display a complex distribution of dark and bright spots, covering most of the visible fraction of the stellar surface. A number of surface features are consistently recovered in all three maps, but other features seem to evolve over the time span of observations, suggesting that fast changes can affect the surface of Vega within a few days at most. The short-term evolution is observed as emergence or disappearance of individual spots, and may also show up as zonal flows, with low- and high-latitude belts rotating faster than intermediate latitudes. It is tempting to relate the surface brightness activity to the complex magnetic field topology previously reconstructed for Vega, although strictly simultaneous brightness and magnetic maps will be necessary to assess this potential link.

Silicon and germanium nanoparticles with tailored surface chemistry as novel inorganic fiber brightening agents.

PubMed

Deb-Choudhury, Santanu; Prabakar, Sujay; Krsinic, Gail; Dyer, Jolon M; Tilley, Richard D

2013-07-31

Low-molecular-weight organic molecules, such as coumarins and stilbenes, are used commercially as fluorescent whitening agents (FWAs) to mask photoyellowing and to brighten colors in fabrics. FWAs achieve this by radiating extra blue light, thus changing the hue and also adding to the brightness. However, organic FWAs can rapidly photodegrade in the presence of ultraviolet (UV) radiation, exacerbating the yellowing process through a reaction involving singlet oxygen species. Inorganic nanoparticles, on the other hand, can provide a similar brightening effect with the added advantage of photostability. We report a targeted approach in designing new inorganic silicon- and germanium-based nanoparticles, functionalized with hydrophilic (amine) surface terminations as novel inorganic FWAs. When applied on wool, by incorporation in a sol-gel Si matrix, the inorganic FWAs improved brightness properties, demonstrated enhanced photostability toward UV radiation, especially the germanium nanoparticles, and also generated considerably lower levels of reactive oxygen species compared to a commercial stilbene-based organic FWA, Uvitex NFW.

High β effects on cosmic ray streaming in galaxy clusters

NASA Astrophysics Data System (ADS)

Wiener, Joshua; Zweibel, Ellen G.; Oh, S. Peng

2018-01-01

Diffuse, extended radio emission in galaxy clusters, commonly referred to as radio haloes, indicate the presence of high energy cosmic ray (CR) electrons and cluster-wide magnetic fields. We can predict from theory the expected surface brightness of a radio halo, given magnetic field and CR density profiles. Previous studies have shown that the nature of CR transport can radically effect the expected radio halo emission from clusters (Wiener, Oh & Guo 2013). Reasonable levels of magnetohydrodynamic (MHD) wave damping can lead to significant CR streaming speeds. But a careful treatment of MHD waves in a high β plasma, as expected in cluster environments, reveals damping rates may be enhanced by a factor of β1/2. This leads to faster CR streaming and lower surface brightnesses than without this effect. In this work, we re-examine the simplified, 1D Coma cluster simulations (with radial magnetic fields) of Wiener et al. (2013) and discuss observable consequences of this high β damping. Future work is required to study this effect in more realistic simulations.

IL15 Infusion of Cancer Patients Expands the Subpopulation of Cytotoxic CD56bright NK Cells and Increases NK-Cell Cytokine Release Capabilities.

PubMed

Dubois, Sigrid; Conlon, Kevin C; Müller, Jürgen R; Hsu-Albert, Jennifer; Beltran, Nancy; Bryant, Bonita R; Waldmann, Thomas A

2017-10-01

The cytokine IL15 is required for survival and activation of natural killer (NK) cells as well as expansion of NK-cell populations. Here, we compare the effects of continuous IL15 infusions on NK-cell subpopulations in cancer patients. Infusions affected the CD56 bright NK-cell subpopulation in that the expansion rates exceeded those of CD56 dim NK-cell populations with a 350-fold increase in their total cell numbers compared with 20-fold expansion for the CD56 dim subset. CD56 bright NK cells responded with increased cytokine release to various stimuli, as expected given their immunoregulatory functions. Moreover, CD56 bright NK cells gained the ability to kill various target cells at levels that are typical for CD56 dim NK cells. Some increased cytotoxic activities were also observed for CD56 dim NK cells. IL15 infusions induced expression changes on the surface of both NK-cell subsets, resulting in a previously undescribed and similar phenotype. These data suggest that IL15 infusions expand and arm CD56 bright NK cells that alone or in combination with tumor-targeting antibodies may be useful in the treatment of cancer. Cancer Immunol Res; 5(10); 929-38. ©2017 AACR . ©2017 American Association for Cancer Research.

Combined enzymatic and physical deinking methodology for efficient eco-friendly recycling of old newsprint.

PubMed

Virk, Antar Puneet; Puri, Minakshi; Gupta, Vijaya; Capalash, Neena; Sharma, Prince

2013-01-01

The development in the deinking process has made recycled fiber a major part of the raw material for pulp and paper industry. Enzymes have revolutionized the deinking process obtaining brightness levels surpassing conventional deinking processes. This study explores the deinking efficiencies of bacterial alkalophilic laccase (L) and xylanase (X) enzymes along with physical deinking methods of microwaving (MW) and sonication (S) for recycling of old newsprint (ONP). The operational parameters viz. enzyme dose, pH and treatment time for X and L deinking were optimized statistically using Response Surface Methodology. Laccase did not require any mediator supplementation for deinking. Deinking of ONP pulp with a combination of xylanase and laccase enzymes was investigated, and fiber surface composition and morphological changes were studied using X-ray diffraction, fourier transform infrared spectroscopy and scanning electron microscopy. Compared to the pulp deinked with xylanase (47.9%) or laccase (62.2%) individually, the percentage reduction of effective residual ink concentration (ERIC) was higher for the combined xylanase/laccase-deinked pulp (65.8%). An increase in brightness (21.6%), breaking length (16.5%), burst factor (4.2%) tear factor (6.9%), viscosity (13%) and cellulose crystallinity (10.3%) along with decrease in kappa number (22%) and chemical consumption (50%) were also observed. Surface appeared more fibrillar along with changes in surface functional groups. A combination of physical and enzymatic processes (S-MW-XL) for deinking further improved brightness (28.8%) and decreased ERIC (73.9%) substantially. This is the first report on deinking of ONP with laccase without any mediator supplementation. XL pretreatment resulted in marked improvement in paper quality and a new sequence being reported for deinking (S-MW-XL) will contribute further in decreasing chemical consumption and making the process commercially feasible.

Combined Enzymatic and Physical Deinking Methodology for Efficient Eco-Friendly Recycling of Old Newsprint

PubMed Central

Virk, Antar Puneet; Puri, Minakshi; Gupta, Vijaya; Capalash, Neena; Sharma, Prince

2013-01-01

Background The development in the deinking process has made recycled fiber a major part of the raw material for pulp and paper industry. Enzymes have revolutionized the deinking process obtaining brightness levels surpassing conventional deinking processes. This study explores the deinking efficiencies of bacterial alkalophilic laccase (L) and xylanase (X) enzymes along with physical deinking methods of microwaving (MW) and sonication (S) for recycling of old newsprint (ONP). Methods and Results The operational parameters viz. enzyme dose, pH and treatment time for X and L deinking were optimized statistically using Response Surface Methodology. Laccase did not require any mediator supplementation for deinking. Deinking of ONP pulp with a combination of xylanase and laccase enzymes was investigated, and fiber surface composition and morphological changes were studied using X-ray diffraction, fourier transform infrared spectroscopy and scanning electron microscopy. Compared to the pulp deinked with xylanase (47.9%) or laccase (62.2%) individually, the percentage reduction of effective residual ink concentration (ERIC) was higher for the combined xylanase/laccase-deinked pulp (65.8%). An increase in brightness (21.6%), breaking length (16.5%), burst factor (4.2%) tear factor (6.9%), viscosity (13%) and cellulose crystallinity (10.3%) along with decrease in kappa number (22%) and chemical consumption (50%) were also observed. Surface appeared more fibrillar along with changes in surface functional groups. A combination of physical and enzymatic processes (S-MW-XL) for deinking further improved brightness (28.8%) and decreased ERIC (73.9%) substantially. Conclusion This is the first report on deinking of ONP with laccase without any mediator supplementation. XL pretreatment resulted in marked improvement in paper quality and a new sequence being reported for deinking (S-MW-XL) will contribute further in decreasing chemical consumption and making the process commercially feasible. PMID:23977287

Evidence of Titan's climate history from evaporite distribution

NASA Astrophysics Data System (ADS)

MacKenzie, Shannon M.; Barnes, Jason W.; Sotin, Christophe; Soderblom, Jason M.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Phillip D.; McCord, Thomas B.

2014-11-01

Water-ice-poor, 5-μm-bright material on Saturn's moon Titan has previously been geomorphologically identified as evaporitic. Here we present a global distribution of the occurrences of the 5-μm-bright spectral unit, identified with Cassini's Visual Infrared Mapping Spectrometer (VIMS) and examined with RADAR when possible. We explore the possibility that each of these occurrences are evaporite deposits. The 5-μm-bright material covers 1% of Titan's surface and is not limited to the poles (the only regions with extensive, long-lived surface liquid). We find the greatest areal concentration to be in the equatorial basins Tui Regio and Hotei Regio. Our interpretations, based on the correlation between 5-μm-bright material and lakebeds, imply that there was enough liquid present at some time to create the observed 5-μm-bright material. We address the climate implications surrounding a lack of evaporitic material at the south polar basins: if the south pole basins were filled at some point in the past, then where is the evaporite?

The night sky brightness at McDonald Observatory

NASA Technical Reports Server (NTRS)

Kalinowski, J. K.; Roosen, R. G.; Brandt, J. C.

1975-01-01

Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.

Geologic Structures in Crater Walls on Vesta

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Beck, A. W.; Ammannito, E.; Carsenty, U.; DeSanctis, M. C.; LeCorre, L.; McCoy, T. J.; Reddy, V.; Schroeder, S. E.

2012-01-01

The Framing Camera (FC) on the Dawn spacecraft has imaged most of the illuminated surface of Vesta with a resolution of apporpx. 20 m/pixel through different wavelength filters that allow for identification of lithologic units. The Visible and Infrared Mapping Spectrometer (VIR) has imaged the surface at lower spatial resolution but high spectral resolution from 0.25 to 5 micron that allows for detailed mineralogical interpretation. The FC has imaged geologic structures in the walls of fresh craters and on scarps on the margin of the Rheasilvia basin that consist of cliff-forming, competent units, either as blocks or semi-continuous layers, hundreds of m to km below the rims. Different units have different albedos, FC color ratios and VIR spectral characteristics, and different units can be juxtaposed in individual craters. We will describe different examples of these competent units and present preliminary interpretations of the structures. A common occurrence is of blocks several hundred m in size of high albedo (bright) and low albedo (dark) materials protruding from crater walls. In many examples, dark material deposits lie below coherent bright material blocks. In FC Clementine color ratios, bright material is green indicating deeper 1 m pyroxene absorption band. VIR spectra show these to have deeper and wider 1 and 2 micron pyroxene absorption bands than the average vestan surface. The associated dark material has subdued pyroxene absorption features compared to the average vestan surface. Some dark material deposits are consistent with mixtures of HED materials with carbonaceous chondrites. This would indicate that some dark material deposits in crater walls are megabreccia blocks. The same would hold for bright material blocks found above them. Thus, these are not intact crustal units. Marcia crater is atypical in that the dark material forms a semi-continuous, thin layer immediately below bright material. Bright material occurs as one or more layers. In one region, there is an apparent angular unconformity between the bright material and the dark material where bright material layers appear to be truncated against the underlying dark layer. One crater within the Rheasilvia basin contains two distinct types of bright materials outcropping on its walls, one like that found elsewhere on Vesta and the other an anomalous block 200 m across. This material has the highest albedo; almost twice that of the vestan average. Unlike all other bright materials, this block has a subdued 1 micron pyroxene absorption band in FC color ratios. These data indicate that this block represents a distinct vestan lithology that is rarely exposed.

Dark Lakes on a Bright Landscape

NASA Image and Video Library

2013-10-23

Ultracold hydrocarbon lakes and seas dark shapes near the north pole of Saturn moon Titan can be seen embedded in some kind of bright surface material in this infrared mosaic from NASA Cassini mission.

A statistical examination of Nimbus 7 SMMR data and remote sensing of sea surface temperature, liquid water content in the atmosphere and surfaces wind speed

NASA Technical Reports Server (NTRS)

Prabhakara, C.; Wang, I.; Chang, A. T. C.; Gloersen, P.

1982-01-01

Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) brightness temperature measurements over the global oceans have been examined with the help of statistical and empirical techniques. Such analyses show that zonal averages of brightness temperature measured by SMMR, over the oceans, on a large scale are primarily influenced by the water vapor in the atmosphere. Liquid water in the clouds and rain, which has a much smaller spatial and temporal scale, contributes substantially to the variability of the SMMR measurements within the latitudinal zones. The surface wind not only increases the surface emissivity but through its interactions with the atmosphere produces correlations, in the SMMR brightness temperature data, that have significant meteorological implications. It is found that a simple meteorological model can explain the general characteristics of the SMMR data. With the help of this model methods to infer over the global oceans, the surface temperature, liquid water content in the atmosphere, and surface wind speed are developed. Monthly mean estimates of the sea surface temperature and surface winds are compared with the ship measurements. Estimates of liquid water content in the atmosphere are consistent with earlier satellite measurements.

Titan Surface Temperatures as Measured by Cassini CIRS

NASA Technical Reports Server (NTRS)

Jennings, Donald E.; Flasar, F.M.; Kunde, V.G.; Nixon, C.A.; Romani, P.N.; Samuelson, R.E.; Coustenis, A.; Courtin, R.

2009-01-01

Thermal radiation from the surface of Titan reaches space through a spectral window of low opacity at 19-microns wavelength. This radiance gives a measure of the brightness temperature of the surface. Composite Infrared Spectrometer' (CIRS) observations from Cassini during its first four years at Saturn have permitted latitude mapping of zonally averaged surface temperatures. The measurements are corrected for atmospheric opacity using the dependence of radiance on emission angle. With the more complete latitude coverage and much larger dataset of CIRS we have improved upon the original results from Voyager IRIS. CIRS measures the equatorial surface brightness temperature to be 93.7+/-0.6 K, the same as the temperature measured at the Huygens landing site. The surface brightness temperature decreases by 2 K toward the south pole and by 3 K toward the north pole. The drop in surface temperature between equator and north pole implies a 50% decrease in methane saturation vapor pressure and relative humidity; this may help explain the large northern lakes. The H2 mole fraction is derived as a by-product of our analysis and agrees with previous results. Evidence of seasonal variation in surface and atmospheric temperatures is emerging from CIRS measurements over the Cassini mission.

Acute effects of bright light and caffeine on nighttime melatonin and temperature levels in women taking and not taking oral contraceptives

NASA Technical Reports Server (NTRS)

Wright, K. P. Jr; Myers, B. L.; Plenzler, S. C.; Drake, C. L.; Badia, P.; Czeisler, C. A. (Principal Investigator)

2000-01-01

Caffeine and bright light effects on nighttime melatonin and temperature levels in women were tested during the luteal phase of the menstrual cycle (n=30) or the pseudo luteal phase for oral contraceptive users (n=32). Participants were randomly assigned to receive either bright (5000 lux) or dim room light (<88 lux) between 20:00 and 08:00 h under a modified constant routine protocol. Half the subjects in each lighting condition were administered either caffeine (100 mg) or placebo in a double-blind manner at 20:00, 23:00, 02:00 and 05:00 h. Results showed that the combination of bright light and caffeine enhanced nighttime temperature levels to a greater extent than did either caffeine or bright light alone. Both of the latter groups had higher temperature levels relative to the dim light placebo condition and the two groups did not differ. Temperature levels in the bright light caffeine condition were maintained at near peak circadian levels the entire night in the luteal and pseudo luteal phase. Melatonin levels were reduced throughout the duration of bright light exposure for all women. Caffeine reduced the onset of melatonin levels for women in the luteal phase, but it had little effect on melatonin levels for oral contraceptive users. The results for women in the luteal phase of the menstrual cycle are consistent with our previous findings in men. The results also suggest that oral contraceptives may alter the effects of caffeine on nighttime melatonin levels.

Discovery of a complex linearly polarized spectrum of Betelgeuse dominated by depolarization of the continuum

NASA Astrophysics Data System (ADS)

Aurière, M.; López Ariste, A.; Mathias, P.; Lèbre, A.; Josselin, E.; Montargès, M.; Petit, P.; Chiavassa, A.; Paletou, F.; Fabas, N.; Konstantinova-Antova, R.; Donati, J.-F.; Grunhut, J. H.; Wade, G. A.; Herpin, F.; Kervella, P.; Perrin, G.; Tessore, B.

2016-06-01

Context. Betelgeuse is an M supergiant that harbors spots and giant granules at its surface and presents linear polarization of its continuum. Aims: We have previously discovered linear polarization signatures associated with individual lines in the spectra of cool and evolved stars. Here, we investigate whether a similar linearly polarized spectrum exists for Betelgeuse. Methods: We used the spectropolarimeter Narval, combining multiple polarimetric sequences to obtain high signal-to-noise ratio spectra of individual lines, as well as the least-squares deconvolution (LSD) approach, to investigate the presence of an averaged linearly polarized profile for the photospheric lines. Results: We have discovered the existence of a linearly polarized spectrum for Betelgeuse, detecting a rather strong signal (at a few times 10-4 of the continuum intensity level), both in individual lines and in the LSD profiles. Studying its properties and the signal observed for the resonant Na I D lines, we conclude that we are mainly observing depolarization of the continuum by the absorption lines. The linear polarization of the Betelgeuse continuum is due to the anisotropy of the radiation field induced by brightness spots at the surface and Rayleigh scattering in the atmosphere. We have developed a geometrical model to interpret the observed polarization, from which we infer the presence of two brightness spots and their positions on the surface of Betelgeuse. We show that applying the model to each velocity bin along the Stokes Q and U profiles allows the derivation of a map of the bright spots. We use the Narval linear polarization observations of Betelgeuse obtained over a period of 1.4 yr to study the evolution of the spots and of the atmosphere. Conclusions: Our study of the linearly polarized spectrum of Betelgeuse provides a novel method for studying the evolution of brightness spots at its surface and complements quasi-simultaneous observations obtained with PIONIER at the VLTI. Based on observations obtained at the Télescope Bernard Lyot (TBL) at Observatoire du Pic du Midi, CNRS/INSU and Université de Toulouse, France.

Optical image of a cometary nucleus: 1980 flyby of Comet Encke

NASA Technical Reports Server (NTRS)

Wells, W. C.; Benson, R. S.; Anderson, A. D.; Gal, G.

1974-01-01

The feasibility was investigated of obtaining optical images of a cometary nucleus via a flyby of Comet Encke. A physical model of the dust cloud surrounding the nucleus was developed by using available physical data and theoretical knowledge of cometary physics. Using this model and a Mie scattering code, calculations were made of the absolute surface brightness of the dust in the line of sight of the on-board camera and the relative surface brightness of the dust compared to the nucleus. The brightness was calculated as a function of heliocentric distance and for different phase angles (sun-comet-spacecraft angle).

Characterization and Correction of Aquarius Long Term Calibration Drift Using On-Earth Brightness Temperature Refernces

NASA Technical Reports Server (NTRS)

Brown, Shannon; Misra, Sidharth

2013-01-01

The Aquarius/SAC-D mission was launched on June 10, 2011 from Vandenberg Air Force Base. Aquarius consists of an L-band radiometer and scatterometer intended to provide global maps of sea surface salinity. One of the main mission objectives is to provide monthly global salinity maps for climate studies of ocean circulation, surface evaporation and precipitation, air/sea interactions and other processes. Therefore, it is critical that any spatial or temporal systematic biases be characterized and corrected. One of the main mission requirements is to measure salinity with an accuracy of 0.2 psu on montly time scales which requires a brightness temperature stability of about 0.1K, which is a challenging requirement for the radiometer. A secondary use of the Aquarius data is for soil moisture applications, which requires brightness temperature stability at the warmer end of the brightness temperature dynamic range. Soon after launch, time variable drifts were observed in the Aquarius data compared to in-situ data from ARGO and models for the ocean surface salinity. These drifts could arise from a number of sources, including the various components of the retrieval algorithm, such as the correction for direct and reflected galactic emission, or from the instrument brightness temperature calibration. If arising from the brightness temperature calibration, they could have gain and offset components. It is critical that the nature of the drifts be understood before a suitable correction can be implemented. This paper describes the approach that was used to detect and characterize the components of the drift that were in the brightness temperature calibration using on-Earth reference targets that were independent of the ocean model.

Modeling the non-grey-body thermal emission from the full moon

NASA Technical Reports Server (NTRS)

Vogler, Karl J.; Johnson, Paul E.; Shorthill, Richard W.

1991-01-01

The present series of thermophysical computer models for solid-surfaced planetary bodies whose surface roughness is modeled as paraboloidal craters of specified depth/diameter ratio attempts to characterize the nongrey-body brightness temperature spectra of the moon and of the Galilean satellites. This modeling, in which nondiffuse radiation properties and surface roughness are included for rigorous analysis of scattered and reemitted radiation within a crater, explains to first order the behavior of both limb-scans and disk-integrated IR brightness temperature spectra for the full moon. Only negative surface relief can explain lunar thermal emissions' deviation from smooth Lambert-surface expectations.

THE PHOTOMETRIC PROPERTIES OF A VAST STELLAR SUBSTRUCTURE IN THE OUTSKIRTS OF M33

DOE Office of Scientific and Technical Information (OSTI.GOV)

McConnachie, Alan W.; Ferguson, Annette M. N.; Irwin, Michael J.

2010-11-10

We have surveyed approximately 40 deg{sup 2} surrounding M33 with Canada-France-Hawaii Telescope MegaCam/MegaPrime in the g and i filters out to a maximum projected radius from this galaxy of 50 kpc, as part of the Pan-Andromeda Archaeological Survey (PAndAS). Our observations are deep enough to resolve the top {approx}4 mag of the red giant branch population in this galaxy. We have previously shown that the disk of M33 is surrounded by a large, irregular, low surface brightness substructure. Here, we quantify the stellar populations and structure of this feature using the PAndAS data. We show that the stellar populations ofmore » this feature are consistent with an old population with ([Fe/H]) {approx} -1.6 dex and an interquartile range in metallicity of {approx}0.5 dex. We construct a surface brightness map of M33 that traces this feature to {mu}{sub V} {approx_equal} 33 mag arcsec{sup -2}. At these low surface brightness levels, the structure extends to projected radii of {approx}40 kpc from the center of M33 in both the northwest and southeast quadrants of the galaxy. Overall, the structure has an 'S-shaped' appearance that broadly aligns with the orientation of the H I disk warp. We calculate a lower limit to the integrated luminosity of the structure of -12.7 {+-} 0.5 mag, comparable to a bright dwarf galaxy such as Fornax or Andromeda II and slightly less than 1% of the total luminosity of M33. Further, we show that there is tentative evidence for a distortion in the distribution of young stars near the edge of the H I disk that occurs at similar azimuth to the warp in H I. The data also hint at a low-level, extended stellar component at larger radius that may be an M33 halo component. We revisit studies of M33 and its stellar populations in light of these new results and discuss possible formation scenarios for the vast stellar structure. Our favored model is that of the tidal disruption of M33 in its orbit around M31.« less

The effect of precipitation on measuring sea surface salinity from space

NASA Astrophysics Data System (ADS)

Jin, Xuchen; Pan, Delu; He, Xianqiang; Wang, Difeng; Zhu, Qiankun; Gong, Fang

2017-10-01

The sea surface salinity (SSS) can be measured from space by using L-band (1.4 GHz) microwave radiometers. The L-band has been chosen for its sensitivity of brightness temperature to the change of salinity. However, SSS remote sensing is still challenging due to the low sensitivity of brightness temperature to SSS variation: for the vertical polarization, the sensitivity is about 0.4 to 0.8 K/psu with different incident angles and sea surface temperature; for horizontal polarization, the sensitivity is about 0.2 to 0.6 K/psu. It means that we have to make radiometric measurements with accuracy better than 1K even for the best sensitivity of brightness temperature to SSS. Therefore, in order to retrieve SSS, the measured brightness temperature at the top of atmosphere (TOA) needs to be corrected for many sources of error. One main geophysical source of error comes from atmosphere. Currently, the atmospheric effect at L-band is usually corrected by absorption and emission model, which estimate the radiation absorbed and emitted by atmosphere. However, the radiation scattered by precipitation is neglected in absorption and emission models, which might be significant under heavy precipitation. In this paper, a vector radiative transfer model for coupled atmosphere and ocean systems with a rough surface is developed to simulate the brightness temperature at the TOA under different precipitations. The model is based on the adding-doubling method, which includes oceanic emission and reflection, atmospheric absorption and scattering. For the ocean system with a rough surface, an empirical emission model established by Gabarro and the isotropic Cox-Munk wave model considering shadowing effect are used to simulate the emission and reflection of sea surface. For the atmospheric attenuation, it is divided into two parts: For the rain layer, a Marshall-Palmer distribution is used and the scattering properties of the hydrometeors are calculated by Mie theory (the scattering hydrometeors are assumed to be spherical). For the other atmosphere layers, which are assumed to be clear sky, Liebe's millimeter wave propagation model (MPM93) is used to calculate the absorption coefficients of oxygen, water vapor, and cloud droplets. To simulate the change of brightness temperature caused by different rain rate (0-50 mm/h), we assume a 26-layer precipitation structure corresponding to NCEP FNL data. Our radiative transfer simulations showed that the brightness temperature at TOA can be influenced significantly by the heavy precipitation, the results indicate that the atmospheric attenuation of L-band at incidence angle of 42.5° should be a positive bias, and when rain rate rise up to 50 mm/h, the brightness temperature increases are close to 0.6 K and 0.8 K for horizontally and vertically polarized brightness temperature, respectively. Thus, in the case of heavy precipitation, the current absorption and emission model is not accurate enough to correct atmospheric effect, and a radiative transfer model which considers the effect of radiation scattering should be used.

Low-Surface-Brightness Galaxies: Hidden Galaxies Revealed

NASA Astrophysics Data System (ADS)

Bothun, G.; Impey, C.; McGaugh, S.

1997-07-01

In twenty years, low surface brightness (LSB) galaxies have evolved from being an idiosyncratic notion to being one of the major baryonic repositories in the Universe. The story of their discovery and the characterization of their properties is told here. Their recovery from the noise of the night sky background is a strong testament to the severity of surface brightness selection effects. LSB galaxies have a number of remarkable properties which distinguish them from the more familiar Hubble Sequence of spirals. The two most important are 1) they evolve at a significantly slower rate and may well experience star formation outside of the molecular cloud environment, 2) they are embedded in dark matter halos which are of lower density and more extended than the halos around high surface brightness (HSB) disk galaxies. Compared to HSB disks, LSB disks are strongly dark matter dominated at all radii and show a systematic increase in $M/L$ with decreasing central surface brightness. In addition, the recognition that large numbers of LSB galaxies actually exist has changed the form of the galaxy luminosity function and has clearly increased the space density of galaxies at z =0. Recent CCD surveys have uncovered a population of red LSB disks that may be related to the excess of faint blue galaxies detected at moderate redshifts. LSB galaxies offer us a new window into galaxy evolution and formation which is every bit as important as those processes which have produced easy to detect galaxies. Indeed, the apparent youth of some LSB galaxies suggest that galaxy formation is a greatly extended process. While the discovery of LSB galaxies have lead to new insights, it remains unwise to presume that we now have a representative sample which encompasses all galaxy types and forms. (SECTION: Invited Review Paper)

Illuminating Low Surface Brightness Galaxies with the Hyper Suprime-Cam Survey

NASA Astrophysics Data System (ADS)

Greco, Johnny P.; Greene, Jenny E.; Strauss, Michael A.; Macarthur, Lauren A.; Flowers, Xzavier; Goulding, Andy D.; Huang, Song; Kim, Ji Hoon; Komiyama, Yutaka; Leauthaud, Alexie; Leisman, Lukas; Lupton, Robert H.; Sifón, Cristóbal; Wang, Shiang-Yu

2018-04-01

We present a catalog of extended low surface brightness galaxies (LSBGs) identified in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using the first ∼200 deg2 of the survey, we have uncovered 781 LSBGs, spanning red (g ‑ i ≥ 0.64) and blue (g ‑ i < 0.64) colors and a wide range of morphologies. Since we focus on extended galaxies (r eff = 2.″5–14″), our sample is likely dominated by low-redshift objects. We define LSBGs to have mean surface brightnesses {\\bar{μ }}eff}(g)> 24.3 mag arcsec‑2, which allows nucleated galaxies into our sample. As a result, the central surface brightness distribution spans a wide range of μ 0(g) = 18–27.4 mag arcsec‑2, with 50% and 95% of galaxies fainter than 24.3 and 22 mag arcsec‑2, respectively. Furthermore, the surface brightness distribution is a strong function of color, with the red distribution being much broader and generally fainter than that of the blue LSBGs, and this trend shows a clear correlation with galaxy morphology. Red LSBGs typically have smooth light profiles that are well characterized by single-component Sérsic functions. In contrast, blue LSBGs tend to have irregular morphologies and show evidence for ongoing star formation. We cross-match our sample with existing optical, H I, and ultraviolet catalogs to gain insight into the physical nature of the LSBGs. We find that our sample is diverse, ranging from dwarf spheroidals and ultradiffuse galaxies in nearby groups to gas-rich irregulars to giant LSB spirals, demonstrating the potential of the HSC-SSP to provide a truly unprecedented view of the LSBG population.

Acute Effects of Morning Light on Plasma Glucose and Triglycerides in Healthy Men and Men with Type 2 Diabetes.

PubMed

Versteeg, Ruth I; Stenvers, Dirk J; Visintainer, Dana; Linnenbank, Andre; Tanck, Michael W; Zwanenburg, Gooitzen; Smilde, Age K; Fliers, Eric; Kalsbeek, Andries; Serlie, Mireille J; la Fleur, Susanne E; Bisschop, Peter H

2017-04-01

Ambient light intensity is signaled directly to hypothalamic areas that regulate energy metabolism. Observational studies have shown associations between ambient light intensity and plasma glucose and lipid levels, but human data on the acute metabolic effects of light are scarce. Since light is the main signal indicating the onset of the diurnal phase of physical activity and food intake in humans, we hypothesized that bright light would affect glucose and lipid metabolism. Therefore, we determined the acute effects of bright light on plasma glucose and lipid concentrations in 2 randomized crossover trials: (1) in 8 healthy lean men and (2) in 8 obese men with type 2 diabetes. From 0730 h, subjects were exposed to either bright light (4000 lux) or dim light (10 lux) for 5 h. After 1 h of light exposure, subjects consumed a 600-kcal mixed meal. Primary endpoints were fasting and postprandial plasma glucose levels. In healthy men, bright light did not affect fasting or postprandial plasma glucose levels. However, bright light increased fasting and postprandial plasma triglycerides. In men with type 2 diabetes, bright light increased fasting and postprandial glucose levels. In men with type 2 diabetes, bright light did not affect fasting triglyceride levels but increased postprandial triglyceride levels. We show that ambient light intensity acutely affects human plasma glucose and triglyceride levels. Our findings warrant further research into the consequences of the metabolic effects of light for the diagnosis and prevention of hyperglycemia and dyslipidemia.

The Stacked LYα Emission Profile from the Circum-Galactic Medium of z ˜ 2 Quasars

NASA Astrophysics Data System (ADS)

Arrigoni Battaia, Fabrizio; Hennawi, Joseph F.; Cantalupo, Sebastiano; Prochaska, J. Xavier

2016-09-01

In the context of the FLASHLIGHT survey, we obtained deep narrowband images of 15 z ˜ 2 quasars with the Gemini Multi-object Spectrograph on Gemini South in an effort to measure Lyα emission from circum- and intergalactic gas on scales of hundreds of kpc from the central quasar. We do not detect bright giant Lyα nebulae (SB ˜ 10-17 erg s-1 cm-2 arcsec-2 at distances >50 kpc) around any of our sources, although we routinely (≃47%) detect smaller-scale <50 kpc Lyα emission at this surface brightness level emerging from either the extended narrow emission line regions powered by the quasars or by star formation in their host galaxies. We stack our 15 deep images to study the average extended Lyα surface brightness profile around z ˜ 2 quasars, carefully PSF-subtracting the unresolved emission component and paying close attention to sources of systematic error. Our analysis, which achieves an unprecedented depth, reveals a surface brightness of SBLyα ˜ 10-19 erg s-1 cm-2 arcsec-2 at ˜200 kpc, with a 2.3σ detection of Lyα emission at SB {}{Lyα }=(5.5+/- 3.1)× {10}-20 erg s-1 cm-2 arcsec-2 within an annulus spanning 50 kpc < R < 500 kpc from the quasars. Assuming that this Lyα emission is powered by fluorescence from highly ionized gas illuminated by the bright central quasar, we deduce an average volume density of n H = 0.6 × 10-2 cm-3 on these large scales. Our results are in broad agreement with the densities suggested by cosmological hydrodynamical simulations of massive (M ≃ 1012.5 M ⊙) quasar hosts; however, they indicate that the typical quasars at these redshifts are surrounded by gas that is a factor of ˜100 times less dense than the (˜1 cm-3) gas responsible for the giant bright Lyα nebulae around quasars recently discovered by our group. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

High brightness InP micropillars grown on silicon with Fermi level splitting larger than 1 eV.

PubMed

Tran, Thai-Truong D; Sun, Hao; Ng, Kar Wei; Ren, Fan; Li, Kun; Lu, Fanglu; Yablonovitch, Eli; Chang-Hasnain, Constance J

2014-06-11

The growth of III-V nanowires on silicon is a promising approach for low-cost, large-scale III-V photovoltaics. However, performances of III-V nanowire solar cells have not yet been as good as their bulk counterparts, as nanostructured light absorbers are fundamentally challenged by enhanced minority carriers surface recombination rates. The resulting nonradiative losses lead to significant reductions in the external spontaneous emission quantum yield, which, in turn, manifest as penalties in the open-circuit voltage. In this work, calibrated photoluminescence measurements are utilized to construct equivalent voltage-current characteristics relating illumination intensities to Fermi level splitting ΔF inside InP microillars. Under 1 sun, we show that splitting can exceed ΔF ∼ 0.90 eV in undoped pillars. This value can be increased to values of ΔF ∼ 0.95 eV by cleaning pillar surfaces in acidic etchants. Pillars with nanotextured surfaces can yield splitting of ΔF ∼ 0.90 eV, even though they exhibit high densities of stacking faults. Finally, by introducing n-dopants, ΔF of 1.07 eV can be achieved due to a wider bandgap energy in n-doped wurzite InP, the higher brightness of doped materials, and the extraordinarily low surface recombination velocity of InP. This is the highest reported value for InP materials grown on a silicon substrate. These results provide further evidence that InP micropillars on silicon could be a promising material for low-cost, large-scale solar cells with high efficiency.

Titan's Surface Brightness Temperatures and H2 Mole Fraction from Cassini CIRS

NASA Technical Reports Server (NTRS)

Jennings, Donald E.; Flasar, F. M.; Kunde, V. G.; Samuelson, R. E.; Pearl, J. C.; Nixon, C. A.; Carlson, R. C.; Mamoutkine, A. A.; Brasunas, J. C.; Guandique, E.;

The Andromeda Optical and Infrared Disk Survey

NASA Astrophysics Data System (ADS)

Sick, J.; Courteau, S.; Cuillandre, J.-C.

2014-03-01

The Andromeda Optical and Infrared Disk Survey has mapped M31 in u* g' r' i' JKs wavelengths out to R = 40 kpc using the MegaCam and WIRCam wide-field cameras on the Canada-France-Hawaii Telescope. Our survey is uniquely designed to simultaneously resolve stars while also carefully reproducing the surface brightness of M31, allowing us to study M31's global structure in the context of both resolved stellar populations and spectral energy distributions. We use the Elixir-LSB method to calibrate the optical u* g' r' i' images by building real-time maps of the sky background with sky-target nodding. These maps are stable to μg ≲ 28.5 mag arcsec-2 and reveal warps in the outer M31 disk in surface brightness. The equivalent WIRCam mapping in the near-infrared uses a combination of sky-target nodding and image-to-image sky offset optimization to produce stable surface brightnesses. This study enables a detailed analysis of the systematics of spectral energy distribution fitting with near-infrared bands where asymptotic giant branch stars impose a significant, but ill-constrained, contribution to the near-infrared light of a galaxy. Here we present panchromatic surface brightness maps and initial results from our near-infrared resolved stellar catalog.

An Ultraviolet and Near-Infrared View of NGC 4214: A Starbursting Core Embedded in a Low Surface Brightness Disk

NASA Astrophysics Data System (ADS)

Fanelli, Michael N.; Waller, William W.; Smith, Denise A.; Freedman, Wendy L.; Madore, Barry; Neff, Susan G.; O'Connell, Robert W.; Roberts, Morton S.; Bohlin, Ralph; Smith, Andrew M.; Stecher, Theodore P.

1997-05-01

During the Astro-2 Spacelab mission in 1995 March, the Ultraviolet Imaging Telescope (UIT) obtained far-UV (λ = 1500 Å) imagery of the nearby Sm/Im galaxy NGC 4214. The UIT images have a spatial resolution of ~3" and a limiting surface brightness, μ1500 > 25 mag arcsec-2, permitting detailed investigation of the intensity and spatial distribution of the young, high-mass stellar component. These data provide the first far-UV imagery covering the full spatial extent of NGC 4214. Comparison with a corresponding I-band image reveals the presence of a starbursting core embedded in an extensive low surface brightness disk. In the far-UV (FUV), NGC 4214 is resolved into several components: a luminous, central knot; an inner region (r <~ 2.5 kpc) with ~15 resolved sources embedded in bright, diffuse emission; and a population of fainter knots extending to the edge of the optically defined disk (r ~ 5 kpc). The FUV light, which traces recent massive star formation, is observed to be more centrally concentrated than the I-band light, which traces the global stellar population. The FUV radial light profile is remarkably well represented by an R1/4 law, providing evidence that the centrally concentrated massive star formation in NGC 4214 is the result of an interaction, possibly a tidal encounter, with a dwarf companion(s). The brightest FUV source produces ~8% of the global FUV luminosity. This unresolved source, corresponding to the Wolf-Rayet knot described by Sargent & Filippenko, is located at the center of the FUV light distribution, giving NGC 4214 an active galactic nucleus-like morphology. Another strong source is present in the I band, located 19" west, 10" north of the central starburst knot, with no FUV counterpart. The I-band source may be the previously unrecognized nucleus of NGC 4214 or an evolved star cluster with an age greater than ~200 Myr. The global star formation rate derived from the total FUV flux is consistent with rates derived using data at other wavelengths and lends support to the scenario of roughly constant star formation during the last few hundred million years at a level significantly enhanced relative to the lifetime averaged star formation rate. The hybrid disk/starburst-irregular morphology evident in NGC 4214 emphasizes the danger of classifying galaxies based on their high surface brightness components at any particular wavelength.

Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Maekelae, P.; Michalek, G.; Shibasaki, K.; Hathaway, D. H.

2012-01-01

Using magnetic and microwave butterfly diagrams, we compare the behavior of solar polar regions to show that (1) the polar magnetic field and the microwave brightness temperature during solar minimum substantially diminished during the cycle 23/24 minimum compared to the 22/23 minimum. (2) The polar microwave brightness temperature (Tb) seems to be a good proxy for the underlying magnetic field strength (B). The analysis indicates a relationship, B = 0.0067Tb - 70, where B is in G and Tb in K. (3) Both the brightness temperature and the magnetic field strength show north-south asymmetry most of the time except for a short period during the maximum phase. (4) The rush-to-the-pole phenomenon observed in the prominence eruption (PE) activity seems to be complete in the northern hemisphere as of 2012 March. (5) The decline of the microwave brightness temperature in the north polar region to the quiet-Sun levels and the sustained PE activity poleward of 60degN suggest that solar maximum conditions have arrived at the northern hemisphere. The southern hemisphere continues to exhibit conditions corresponding to the rise phase of solar cycle 24. Key words: Sun: chromosphere Sun: coronal mass ejections (CMEs) Sun: filaments, prominences Sun: photosphere Sun: radio radiation Sun: surface magnetism

Skylab experiment SO73: Gegenschein/zodiacal light. [electrophotometry of surface brightness and polarization

NASA Technical Reports Server (NTRS)

Weinberg, J. L.

1976-01-01

A 10 color photoelectric polarimeter was used to measure the surface brightness and polarization associated with zodiacal light, background starlight, and spacecraft corona during each of the Skylab missions. Fixed position and sky scanning observations were obtained during Skylab missions SL-2 and SL-3 at 10 wavelenghts between 4000A and 8200A. Initial results from the fixed-position data are presented on the spacecraft corona and on the polarized brightness of the zodiacal light. Included among the fixed position regions that were observed are the north celestial pole, south ecliptic pole, two regions near the north galactic pole, and 90 deg from the sun in the ecliptic. The polarized brightness of the zodiacal light was found to have the color of the sun at each of these positions. Because previous observations found the total brightness to have the color of the sun from the near ultraviolet out to 2.4 micrometers, the degree of polarization of the zodiacal light is independent of wavelength from 4000A to 8200A.

SMOS first results over land

NASA Astrophysics Data System (ADS)

Kerr, Yann; Waldteufel, Philippe; Cabot, François; Richaume, Philippe; Jacquette, Elsa; Bitar, Ahmad Al; Mamhoodi, Ali; Delwart, Steven; Wigneron, Jean-Pierre

2010-05-01

The Soil Moisture and Ocean Salinity (SMOS) mission is ESA's (European Space Agency ) second Earth Explorer Opportunity mission, launched in November 2009. It is a joint programme between ESA CNES (Centre National d'Etudes Spatiales) and CDTI (Centro para el Desarrollo Tecnologico Industrial). SMOS carries a single payload, an L-band 2D interferometric radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the atmosphere and hence the instrument probes the Earth surface emissivity. Surface emissivity can then be related to the moisture content in the first few centimeters of soil, and, after some surface roughness and temperature corrections, to the sea surface salinity over ocean. In order to prepare the data use and dissemination, the ground segment will produce level 1 and 2 data. Level 1 consists mainly of angular brightness temperatures while level 2 consists of geophysical products. In this context, a group of institutes prepared the soil moisture and ocean salinity Algorithm Theoretical Basis documents (ATBD) to be used to produce the operational algorithm. The principle of the soil moisture retrieval algorithm is based on an iterative approach which aims at minimizing a cost function given by the sum of the squared weighted differences between measured and modelled brightness temperature (TB) data, for a variety of incidence angles. This is achieved by finding the best suited set of the parameters which drive the direct TB model, e.g. soil moisture (SM) and vegetation characteristics. Despite the simplicity of this principle, the main reason for the complexity of the algorithm is that SMOS "pixels" can correspond to rather large, inhomogeneous surface areas whose contribution to the radiometric signal is difficult to model. Moreover, the exact description of pixels, given by a weighting function which expresses the directional pattern of the SMOS interferometric radiometer, depends on the incidence angle. The goal is to retrieve soil moisture over fairly large and thus inhomogeneous areas. The retrieval is carried out at nodes of a fixed Earth surface grid. To achieve this purpose, after checking input data quality and ingesting auxiliary data, the retrieval process per se can be initiated. This cannot be done blindly as the direct model will be dependent upon surface characteristics. It is thus necessary to first assess what is the dominant land use of a node. For this, an average weighing function (MEAN_WEF) which takes into account the "antenna"pattern is run over the high resolution land use map to assess the dominant cover type. This is used to drive the decision tree which, step by step, selects the type of model to be used as per surface conditions. All this being said and done the retrieval procedure starts if all the conditions are satisfied, ideally to retrieve 3 parameters over the dominant class (the so-called rich retrieval). If the algorithm does not converge satisfactorily, a new trial is made with less floating parameters ("poorer retrieval") until either results are satisfactory or the algorithm is considered to fail. The retrieval algorithm also delivers whenever possible a dielectric constant parameter (using the-so called cardioid approach). Finally, once the retrieval converged, it is possible to compute the brightness temperature at a given fixed angle (42.5°) using the selected forward models applied to the set of parameters obtained at the end of the retrieval process. So the output product of the level 2 soil moisture algorithm should be node position, soil moisture, dielectric constants, computed brightness temperature at 42.5°, flags and quality indices. During the presentation we will describe in more details the algorithm and accompanying work in particular decision tree principle and characteristics, the auxiliary data used and the special and "exotic"cases. We will also be more explicit on the algorithm validation and verification through the data collected during the commissioning phase. The main hurdle being working in spite of spurious signals (RFI) on some areas of the globe.

Comparative Analysis of Aerosol Retrievals from MODIS, OMI and MISR Over Sahara Region

NASA Technical Reports Server (NTRS)

Lyapustin, A.; Wang, Y.; Hsu, C.; Terres, O.; Leptoukh, G.; Kalashnikova, O.; Korkin, S.

2011-01-01

MODIS is a wide field-of-view sensor providing daily global observations of the Earth. Currently, global MODIS aerosol retrievals over land are performed with the main Dark Target algorithm complimented with the Deep Blue (DB) Algorithm over bright deserts. The Dark Target algorithm relies on surface parameterization which relates reflectance in MODIS visible bands with the 2.1 micrometer region, whereas the Deep Blue algorithm uses an ancillary angular distribution model of surface reflectance developed from the time series of clear-sky MODIS observations. Recently, a new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm has been developed for MODIS. MAIAC uses a time series and an image based processing to perform simultaneous retrievals of aerosol properties and surface bidirectional reflectance. It is a generic algorithm which works over both dark vegetative surfaces and bright deserts and performs retrievals at 1 km resolution. In this work, we will provide a comparative analysis of DB, MAIAC, MISR and OMI aerosol products over bright deserts of northern Africa.

Application of Reflected Global Navigation Satellite System (GNSS-R) Signals in the Estimation of Sea Roughness Effects in Microwave Radiometry

NASA Technical Reports Server (NTRS)

Voo, Justin K.; Garrison, James L.; Yueh, Simon H.; Grant, Michael S.; Fore, Alexander G.; Haase, Jennifer S.; Clauss, Bryan

2010-01-01

In February-March 2009 NASA JPL conducted an airborne field campaign using the Passive Active L-band System (PALS) and the Ku-band Polarimetric Scatterometer (PolSCAT) collecting measurements of brightness temperature and near surface wind speeds. Flights were conducted over a region of expected high-speed winds in the Atlantic Ocean, for the purposes of algorithm development for salinity retrievals. Wind speeds encountered were in the range of 5 to 25 m/s during the two weeks deployment. The NASA-Langley GPS delay-mapping receiver (DMR) was also flown to collect GPS signals reflected from the ocean surface and generate post-correlation power vs. delay measurements. This data was used to estimate ocean surface roughness and a strong correlation with brightness temperature was found. Initial results suggest that reflected GPS signals, using small low-power instruments, will provide an additional source of data for correcting brightness temperature measurements for the purpose of sea surface salinity retrievals.

Precursor state of oxygen molecules on the Si(001) surface during the initial room-temperature adsorption

NASA Astrophysics Data System (ADS)

Hwang, Eunkyung; Chang, Yun Hee; Kim, Yong-Sung; Koo, Ja-Yong; Kim, Hanchul

2012-10-01

The initial adsorption of oxygen molecules on Si(001) is investigated at room temperature. The scanning tunneling microscopy images reveal a unique bright O2-induced feature. The very initial sticking coefficient of O2 below 0.04 Langmuir is measured to be ˜0.16. Upon thermal annealing at 250-600 °C, the bright O2-induced feature is destroyed, and the Si(001) surface is covered with dark depressions that seem to be oxidized structures with -Si-O-Si- bonds. This suggests that the observed bright O2-induced feature is an intermediate precursor state that may be either a silanone species or a molecular adsorption structure.

Low-level water vapor fields from the VAS split-window channels at 11 and 12 microns

NASA Technical Reports Server (NTRS)

Chesters, D.; Uccellini, L. W.; Robinson, W.

1983-01-01

Originally, the VAS split window channels were designed to use the differential water vapor absorption between 11 and 12 microns to estimate sea surface temperature by correcting for the radiometric losses caused by atmospheric moisture. It is shown that it is possible to reverse the procedure in order to estimate the vertically integrated low level moisture content with the background surface (skin) temperature removed, even over the bright, complex background of the land. Because the lower troposphere's water vapor content is an important factor in convective instability, the derived fields are of considerable value to mesoscale meteorology. Moisture patterns are available as quantitative fields (centimeters of precipitable water) at full VAS resolution (as fine as 7 kilometers horizontal resolution every 15 minutes), and are readily converted to image format for false color movies. The technique, demonstrated with GOES-5, uses a sequence of split window radiances taken once every 3 hours from dawn to dusk over the Eastern and Central United States. The algorithm is calibrated with the morning radiosonde sites embedded within the first VAS radiance field; then, entire moisture fields are calculated at all five observation times. Cloud contamination is removed by rejecting any pixel having a radiance less than the atmospheric brightness determined at the radiosonde sites.

Correlations between Cassini VIMS spectra and RADAR SAR images: Implications for Titan's surface composition and the character of the Huygens Probe Landing Site

USGS Publications Warehouse

Soderblom, L.A.; Kirk, R.L.; Lunine, J.I.; Anderson, J.A.; Baines, K.H.; Barnes, J.W.; Barrett, J.M.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Cruikshank, D.P.; Elachi, C.; Janssen, M.A.; Jaumann, R.; Karkoschka, E.; Le Mouélic, Stéphane; Lopes, R.M.; Lorenz, R.D.; McCord, T.B.; Nicholson, P.D.; Radebaugh, J.; Rizk, B.; Sotin, Christophe; Stofan, E.R.; Sucharski, T.L.; Tomasko, M.G.; Wall, S.D.

2007-01-01

Titan's vast equatorial fields of RADAR-dark longitudinal dunes seen in Cassini RADAR synthetic aperture images correlate with one of two dark surface units discriminated as "brown" and "blue" in Visible and Infrared Mapping Spectrometer (VIMS) color composites of short-wavelength infrared spectral cubes (RGB as 2.0, 1.6, 1.3 ??m). In such composites bluer materials exhibit higher reflectance at 1.3 ??m and lower at 1.6 and 2.0 ??m. The dark brown unit is highly correlated with the RADAR-dark dunes. The dark brown unit shows less evidence of water ice suggesting that the saltating grains of the dunes are largely composed of hydrocarbons and/or nitriles. In general, the bright units also show less evidence of absorption due to water ice and are inferred to consist of deposits of bright fine precipitating tholin aerosol dust. Some set of chemical/mechanical processes may be converting the bright fine-grained aerosol deposits into the dark saltating hydrocarbon and/or nitrile grains. Alternatively the dark dune materials may be derived from a different type of air aerosol photochemical product than are the bright materials. In our model, both the bright aerosol and dark hydrocarbon dune deposits mantle the VIMS dark blue water ice-rich substrate. We postulate that the bright mantles are effectively invisible (transparent) in RADAR synthetic aperture radar (SAR) images leading to lack of correlation in the RADAR images with optically bright mantling units. RADAR images mostly show only dark dunes and the water ice substrate that varies in roughness, fracturing, and porosity. If the rate of deposition of bright aerosol is 0.001-0.01 ??m/yr, the surface would be coated (to optical instruments) in hundreds-to-thousands of years unless cleansing processes are active. The dark dunes must be mobile on this very short timescale to prevent the accumulation of bright coatings. Huygens landed in a region of the VIMS bright and dark blue materials and about 30 km south of the nearest occurrence of dunes visible in the RADAR SAR images. Fluvial/pluvial processes, every few centuries or millennia, must be cleansing the dark floors of the incised channels and scouring the dark plains at the Huygens landing site both imaged by Descent Imager/Spectral Radiometer (DISR). ?? 2007 Elsevier Ltd. All rights reserved.

SPARC: MASS MODELS FOR 175 DISK GALAXIES WITH SPITZER PHOTOMETRY AND ACCURATE ROTATION CURVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lelli, Federico; McGaugh, Stacy S.; Schombert, James M., E-mail: federico.lelli@case.edu

2016-12-01

We introduce SPARC ( Spitzer Photometry and Accurate Rotation Curves): a sample of 175 nearby galaxies with new surface photometry at 3.6  μ m and high-quality rotation curves from previous H i/H α studies. SPARC spans a broad range of morphologies (S0 to Irr), luminosities (∼5 dex), and surface brightnesses (∼4 dex). We derive [3.6] surface photometry and study structural relations of stellar and gas disks. We find that both the stellar mass–H i mass relation and the stellar radius–H i radius relation have significant intrinsic scatter, while the H i   mass–radius relation is extremely tight. We build detailedmore » mass models and quantify the ratio of baryonic to observed velocity ( V {sub bar}/ V {sub obs}) for different characteristic radii and values of the stellar mass-to-light ratio (ϒ{sub ⋆}) at [3.6]. Assuming ϒ{sub ⋆} ≃ 0.5 M {sub ⊙}/ L {sub ⊙} (as suggested by stellar population models), we find that (i) the gas fraction linearly correlates with total luminosity; (ii) the transition from star-dominated to gas-dominated galaxies roughly corresponds to the transition from spiral galaxies to dwarf irregulars, in line with density wave theory; and (iii)  V {sub bar}/ V {sub obs} varies with luminosity and surface brightness: high-mass, high-surface-brightness galaxies are nearly maximal, while low-mass, low-surface-brightness galaxies are submaximal. These basic properties are lost for low values of ϒ{sub ⋆} ≃ 0.2 M {sub ⊙}/ L {sub ⊙} as suggested by the DiskMass survey. The mean maximum-disk limit in bright galaxies is ϒ{sub ⋆} ≃ 0.7 M {sub ⊙}/ L {sub ⊙} at [3.6]. The SPARC data are publicly available and represent an ideal test bed for models of galaxy formation.« less

SMOS L1C and L2 Validation in Australia

NASA Technical Reports Server (NTRS)

Rudiger, Christoph; Walker, Jeffrey P.; Kerr, Yann H.; Mialon, Arnaud; Merlin, Olivier; Kim, Edward J.

2012-01-01

Extensive airborne field campaigns (Australian Airborne Cal/val Experiments for SMOS - AACES) were undertaken during the 2010 summer and winter seasons of the southern hemisphere. The purpose of those campaigns was the validation of the Level 1c (brightness temperature) and Level 2 (soil moisture) products of the ESA-led Soil Moisture and Ocean Salinity (SMOS) mission. As SMOS is the first satellite to globally map L-band (1.4GHz) emissions from the Earth?s surface, and the first 2-dimensional interferometric microwave radiometer used for Earth observation, large scale and long-term validation campaigns have been conducted world-wide, of which AACES is the most extensive. AACES combined large scale medium-resolution airborne L-band and spectral observations, along with high-resolution in-situ measurements of soil moisture across a 50,000km2 area of the Murrumbidgee River catchment, located in south-eastern Australia. This paper presents a qualitative assessment of the SMOS brightness temperature and soil moisture products.

ARC-1979-A79-7020

NASA Image and Video Library

1979-02-28

Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost Galilean satellites and darkest of the four(but almost twice as bright as Earth's Moon). Mottled appearance from bright and dark patches. Bright spots seem like rayed or bright halved craters seen on our Moon. This face is always turned toward Jupiter. Photo taken through violet filter. Ganymede is slightly larger than Mercury but much less dense (twice the density of water). Its surface brightness is 4 times of Earth's Moon. Mare regions (dark features) are like the Moon's but have twice the brightness, and believed to be unlikely of rock or lava as the Moon's are. It's north pole seems covered with brighter material and may be water frost. Scattered brighter spots may be related to impact craters or source of fresh ice.

Study of the model of calibrating differences of brightness temperature from geostationary satellite generated by time zone differences

NASA Astrophysics Data System (ADS)

Li, Weidong; Shan, Xinjian; Qu, Chunyan

2010-11-01

In comparison with polar-orbiting satellites, geostationary satellites have a higher time resolution and wider field of visions, which can cover eleven time zones (an image covers about one third of the Earth's surface). For a geostationary satellite panorama graph at a point of time, the brightness temperature of different zones is unable to represent the thermal radiation information of the surface at the same point of time because of the effect of different sun solar radiation. So it is necessary to calibrate brightness temperature of different zones with respect to the same point of time. A model of calibrating the differences of the brightness temperature of geostationary satellite generated by time zone differences is suggested in this study. A total of 16 curves of four positions in four different stages are given through sample statistics of brightness temperature of every 5 days synthetic data which are from four different time zones (time zones 4, 6, 8, and 9). The above four stages span January -March (winter), April-June (spring), July-September (summer), and October-December (autumn). Three kinds of correct situations and correct formulas based on curves changes are able to better eliminate brightness temperature rising or dropping caused by time zone differences.

Acute Effects of Morning Light on Plasma Glucose and Triglycerides in Healthy Men and Men with Type 2 Diabetes

PubMed Central

Versteeg, Ruth I.; Stenvers, Dirk J.; Visintainer, Dana; Linnenbank, Andre; Tanck, Michael W.; Zwanenburg, Gooitzen; Smilde, Age K.; Fliers, Eric; Kalsbeek, Andries; Serlie, Mireille J.; la Fleur, Susanne E.; Bisschop, Peter H.

2017-01-01

Ambient light intensity is signaled directly to hypothalamic areas that regulate energy metabolism. Observational studies have shown associations between ambient light intensity and plasma glucose and lipid levels, but human data on the acute metabolic effects of light are scarce. Since light is the main signal indicating the onset of the diurnal phase of physical activity and food intake in humans, we hypothesized that bright light would affect glucose and lipid metabolism. Therefore, we determined the acute effects of bright light on plasma glucose and lipid concentrations in 2 randomized crossover trials: (1) in 8 healthy lean men and (2) in 8 obese men with type 2 diabetes. From 0730 h, subjects were exposed to either bright light (4000 lux) or dim light (10 lux) for 5 h. After 1 h of light exposure, subjects consumed a 600-kcal mixed meal. Primary endpoints were fasting and postprandial plasma glucose levels. In healthy men, bright light did not affect fasting or postprandial plasma glucose levels. However, bright light increased fasting and postprandial plasma triglycerides. In men with type 2 diabetes, bright light increased fasting and postprandial glucose levels. In men with type 2 diabetes, bright light did not affect fasting triglyceride levels but increased postprandial triglyceride levels. We show that ambient light intensity acutely affects human plasma glucose and triglyceride levels. Our findings warrant further research into the consequences of the metabolic effects of light for the diagnosis and prevention of hyperglycemia and dyslipidemia. PMID:28470119

Theoretical approaches to lightness and perception.

PubMed

Gilchrist, Alan

2015-01-01

Theories of lightness, like theories of perception in general, can be categorized as high-level, low-level, and mid-level. However, I will argue that in practice there are only two categories: one-stage mid-level theories, and two-stage low-high theories. Low-level theories usually include a high-level component and high-level theories include a low-level component, the distinction being mainly one of emphasis. Two-stage theories are the modern incarnation of the persistent sensation/perception dichotomy according to which an early experience of raw sensations, faithful to the proximal stimulus, is followed by a process of cognitive interpretation, typically based on past experience. Like phlogiston or the ether, raw sensations seem like they must exist, but there is no clear evidence for them. Proximal stimulus matches are postperceptual, not read off an early sensory stage. Visual angle matches are achieved by a cognitive process of flattening the visual world. Likewise, brightness (luminance) matches depend on a cognitive process of flattening the illumination. Brightness is not the input to lightness; brightness is slower than lightness. Evidence for an early (< 200 ms) mosaic stage is shaky. As for cognitive influences on perception, the many claims tend to fall apart upon close inspection of the evidence. Much of the evidence for the current revival of the 'new look' is probably better explained by (1) a natural desire of (some) subjects to please the experimenter, and (2) the ease of intuiting an experimental hypothesis. High-level theories of lightness are overkill. The visual system does not need to know the amount of illumination, merely which surfaces share the same illumination. This leaves mid-level theories derived from the gestalt school. Here the debate seems to revolve around layer models and framework models. Layer models fit our visual experience of a pattern of illumination projected onto a pattern of reflectance, while framework models provide a better account of illusions and failures of constancy. Evidence for and against these approaches is reviewed.

Is the zodiacal light intensity steady. [cloud surface brightness and polarization from OSO-5 data

NASA Technical Reports Server (NTRS)

Burnett, G. B.; Sparrow, J. G.; Ney, E. P.

1974-01-01

It is pointed out that conclusions reported by Sparrow and Ney (1972, 1973) could be confirmed in an investigation involving the refinement of OSO-5 data on zodiacal light. It had been found by Sparrow and Ney that the absolute value of both the surface brightness and polarization of the zodiacal cloud varied by less than 10% over the 4-yr period from January 1969 to January 1973.

Measurements of the dielectric properties of sea water at 1.43 GHz

NASA Technical Reports Server (NTRS)

Ho, W. W.; Love, A. W.; Vanmelle, M. J.

1974-01-01

Salinity and temperature of water surfaces of estuaries and bay regions are determined to accuracies of 1 ppt salinity and 0.3 kelvin surface temperature. L-band and S-band radiometers are used in combination as brightness temperature detectors. The determination of the brightness temperature versus salinity, with the water surface temperature as a parameter for 1.4 GHz, is performed with a capillary tube inserted into a resonance cavity. Detailed analysis of the results indicates that the measured values are accurate to better than 0.2 percent in the electric property epsilon' and 0.4 percent in epsilon''. The calculated brightness temperature as a function of temperature and salinity is better than 0.2 kelvin. Thus it is possible to reduce the measured data obtained with the two-frequency radiometer system with 1 ppt accuracy to values in the salinity range 5 to 40 ppt.

Low-temperature transonic cooling flows in galaxy clusters

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Burns, Jack O.; Norman, Michael L.

1989-01-01

Calculations are presented which demonstrate that cooling flow models with large sonic radii may be consistent with observed cluster gas properties. It is found that plausible cluster parameters and cooling flow mass accretion rates can produce sonic radii of 10-20 kpc for sonic point temperatures of 1-3 x 10 to the 6th K. The numerical calculations match these cooling flows to hydrostatic atmosphere solutions for the cluster gas beyond the cooling flow region. The cooling flows produce no appreciable 'holes' in the surface brightness toward the cluster center, and the model can be made to match the observed X-ray surface brightness of three clusters in which cooling flows had been believed to be absent. It is suggested that clusters with low velocity dispersion may be the natural location for such 'cool' cooling flows, and fits of these models to the X-ray surface brightness profiles for three clusters are presented.

Microwave Remote Sensing Modeling of Ocean Surface Salinity and Winds Using an Empirical Sea Surface Spectrum

NASA Technical Reports Server (NTRS)

Yueh, Simon H.

2004-01-01

Active and passive microwave remote sensing techniques have been investigated for the remote sensing of ocean surface wind and salinity. We revised an ocean surface spectrum using the CMOD-5 geophysical model function (GMF) for the European Remote Sensing (ERS) C-band scatterometer and the Ku-band GMF for the NASA SeaWinds scatterometer. The predictions of microwave brightness temperatures from this model agree well with satellite, aircraft and tower-based microwave radiometer data. This suggests that the impact of surface roughness on microwave brightness temperatures and radar scattering coefficients of sea surfaces can be consistently characterized by a roughness spectrum, providing physical basis for using combined active and passive remote sensing techniques for ocean surface wind and salinity remote sensing.

North-south asymmetry of Ca II K regions determined from OAUC spectroheliograms: 1996 - 2006

NASA Astrophysics Data System (ADS)

Dorotovič, I.; Rybák, J.; Garcia, A.; Journoud, P.

2010-12-01

The solar activity (SA) evolution levels are not identical in the northern and southern Sun's hemispheres. This fact was repeatedly confirmed in the past by the analysis of a number of long-term observations of various SA indices in individual atmospheric layers of the Sun and in different bandwidths. The north-south asymmetry (NSA) is thus a significant tool in investigation of long-term SA variations. This paper presents a software tool to determine the NSA of the area of bright chromospheric plages, as measured in the Ca II K3 spectroheliograms registered since 1926 in the Observatário Astronómico da Universidade de Coimbra, Portugal, as well as evolution of sizes of these areas in the period 1996 - 2006. The algorithm of the program is limited to determining the total area of bright features in the Ca II K3 emission line based on the definition of the threshold value for relative brightness and, therefore, it does not resolve brightness of individual chromospheric features. A comparison and cross-correlation of this NSA with the NSAs found for the sunspots and coronal green line brightness have been added. In the near future we intend to 1) determine the NSA of the area of bright chromospheric Ca II K3 regions back to the year 1926, and 2) compare the evolution of the surface area of these regions in the period 1970-2006 with the evolution of the magnetic index obtained at Mt. Wilson Observatory, which would also help in setting up a proxy reconstruction of the magnetic index back to 1926. Since 2007 new spectroheliograms have been recorded using a CCD camera and, therefore, in the future we will also address this issue for the period 2007 - present.

Archiving, processing, and disseminating ASTER products at the USGS EROS Data Center

USGS Publications Warehouse

Jones, B.; Tolk, B.; ,

2002-01-01

The U.S. Geological Survey EROS Data Center archives, processes, and disseminates Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data products. The ASTER instrument is one of five sensors onboard the Earth Observing System's Terra satellite launched December 18, 1999. ASTER collects broad spectral coverage with high spatial resolution at near infrared, shortwave infrared, and thermal infrared wavelengths with ground resolutions of 15, 30, and 90 meters, respectively. The ASTER data are used in many ways to understand local and regional earth-surface processes. Applications include land-surface climatology, volcanology, hazards monitoring, geology, agronomy, land cover change, and hydrology. The ASTER data are available for purchase from the ASTER Ground Data System in Japan and from the Land Processes Distributed Active Archive Center in the United States, which receives level 1A and level 1B data from Japan on a routine basis. These products are archived and made available to the public within 48 hours of receipt. The level 1A and level 1B data are used to generate higher level products that include routine and on-demand decorrelation stretch, brightness temperature at the sensor, emissivity, surface reflectance, surface kinetic temperature, surface radiance, polar surface and cloud classification, and digital elevation models. This paper describes the processes and procedures used to archive, process, and disseminate standard and on-demand higher level ASTER products at the Land Processes Distributed Active Archive Center.

Physical Retrievals of Over-Ocean Rain Rate from Multichannel Microwave Imagery. Part 1; Theoretical Characteristics of Normalized Polarization and Scattering Indices

NASA Technical Reports Server (NTRS)

Petty, G. W.

1994-01-01

Microwave rain rate retrieval algorithms have most often been formulated in terms of the raw brightness temperatures observed by one or more channels of a satellite radiometer. Taken individually, single-channel brightness temperatures generally represent a near-arbitrary combination of positive contributions due to liquid water emission and negative contributions due to scattering by ice and/or visibility of the radiometrically cold ocean surface. Unfortunately, for a given rain rate, emission by liquid water below the freezing level and scattering by ice particles above the freezing level are rather loosely coupled in both a physical and statistical sense. Furthermore, microwave brightness temperatures may vary significantly (approx. 30-70 K) in response to geophysical parameters other than liquid water and precipitation. Because of these complications, physical algorithms which attempt to directly invert observed brightness temperatures have typically relied on the iterative adjustment of detailed micro-physical profiles or cloud models, guided by explicit forward microwave radiative transfer calculations. In support of an effort to develop a significantly simpler and more efficient inversion-type rain rate algorithm, the physical information content of two linear transformations of single-frequency, dual-polarization brightness temperatures is studied: the normalized polarization difference P of Petty and Katsaros (1990, 1992), which is intended as a measure of footprint-averaged rain cloud transmittance for a given frequency; and a scattering index S (similar to the polarization corrected temperature of Spencer et al.,1989) which is sensitive almost exclusively to ice. A reverse Monte Carlo radiative transfer model is used to elucidate the qualitative response of these physically distinct single-frequency indices to idealized 3-dimensional rain clouds and to demonstrate their advantages over raw brightness temperatures both as stand-alone indices of precipitation activity and as primary variables in physical, multichannel rain rate retrieval schemes. As a byproduct of the present analysis, it is shown that conventional plane-parallel analyses of the well-known foot-print-filling problem for emission-based algorithms may in some cases give seriously misleading results.

The Origin of Regional Dust Deposits on Mars

NASA Technical Reports Server (NTRS)

Christensen, P. R.

1985-01-01

Recently, additional evidence was derived from the Viking Infrared Thermal Mapper observations that allows a more complete model for the formation of Low Thermal inertia-high Albedo regions to be proposed. The first observation is that dust appears to be currently accumulating in the low thermal inertia regions. Following each global dust storm a thin layer of dust is deposited globally, as evidenced by an increase in surface albedo seen from orbit and from the Viking Lander sites. During the period following the storm, the bright dust fallout is subsequently removed from low albedo regions, as indicated by the post-storm darkening of these surfaces and by an increase in the atmospheric dust content over dark regions relative to the bright, low thermal inertia regions. Thus, the fine dust storm material is removed from dark regions but not from the bright regions, resulting in a net accumulation within the bright, low thermal inertia regions. Once deposition has begun, the covering of exposed rocks and sand and the accumulation of fine material on the surface make removal of material increasingly difficult, thereby enhancing the likelihood that material will accumulate within the low thermal inertia regions.

Colors and Photometry of Bright Materials on Vesta as Seen by the Dawn Framing Camera

NASA Technical Reports Server (NTRS)

Schroeder, S. E.; Li, J.-Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.;

Mineralogical Composition of the Different Types of Bright Deposits on Vesta

NASA Technical Reports Server (NTRS)

Zambon, F.; Capaccioni, F.; DeSanctis, M. C.; Ammannito, E.; Li, J.-Y.; Longobardo, A.; Mittlefehldt, D. W.; Palomba, E.; Pieters, C. M.; Schroeder, S. E.;

Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost Galilean satellites and darkest of the four(but almost twice as bright as Earth's Moon). Mottled appearance from bright and dark patches. Bright spots seem like rayed or bright halved craters seen on our Moon. This face is always turned toward Jupiter. Photo taken through violet filter. Ganymede is slightly larger than Mercury but much less dense (twice the density of water). Its surface brightness is 4 times of Earth's Moon. Mare regions (dark features) are like the Moon's but have twice the brightness, and believed to be unlikely of rock or lava as the Moon's are. It's north pole seems covered with brighter material and may be water frost. Scattered brighter spots may be related to impact craters or source of fresh ice.

Results of soil moisture flights during April 1974

NASA Technical Reports Server (NTRS)

Schmugge, T. J.; Blanchard, B. J.; Burke, W. J.; Paris, J. F.; Swang, J. R.

1976-01-01

The results presented here are derived from measurements made during the April 5 and 6, 1974 flights of the NASA P-3A aircraft over the Phoenix, Arizona agricultural test site. The purpose of the mission was to study the use of microwave techniques for the remote sensing of soil moisture. These results include infrared (10-to 12 micrometers) 2.8-cm and 21-cm brightness temperatures for approximately 90 bare fields. These brightness temperatures are compared with surface measurements of the soil moisture made at the time of the overflights. These data indicate that the combination of the sum and difference of the vertically and the horizontally polarized brightness temperatures yield information on both the soil moisture and surface roughness conditions.

Keck/NIRC2 Imaging of the Warped, Asymmetric Debris Disk Around HD 32297

NASA Technical Reports Server (NTRS)

Currie, Thayne; Rodigas, Timothy J.; Debes, John; Plavchan, Peter; Kuchner, Marc; Jang-Condell, Hannah; Wilner, David; Andrews, Sean; Kraus, Adam; Dahm, Scott;

Keck/NIRC2 Imaging of the Warped, Asymmetric Debris Disk Around HD 32297

NASA Technical Reports Server (NTRS)

Currie, Thayne; Rodigas, Timothy J.; Debes, John; Plavchan, Peter; Kuchner, Marc; Jang, Condell, Hannah; Wilner, David; Andrews, Sean; Dahm, Scott; Robitaille,Thomas

2012-01-01

We present Keck/NIRC2 K(sub s) band high-contrast coronagraphic imaging of the luminous debris disk around the nearby, young A star HD 32297 resolved at a projected separation of r = 0.3 - 2.5" (approx equals 35 - 280 AU). The disk is highly warped to the north and exhibits a complex, "wavy" surface brightness profile interior to r approx equals 110 AU, where the peaks/plateaus in the profiles are shifted between the NE and SW disk lobes. The SW side of the disk is 50 - 100% brighter at r = 35 - 80 AU, and the location of its peak brightness roughly coincides with the disk's mm emission peak. Spectral energy distribution modeling suggests that HD 32297 has at least two dust populations that may originate from two separate belts likely at different locations, possibly at distances coinciding with the surface brightness peaks. A disk model fur a single dust belt including a phase function with two components and a 5 - 10 AU pericenter offset explains the disk's warped structure and reproduces some of the surface brightness profile's shape (e.g. the overall "wavy" profile, the SB peak/plateau shifts) but more poorly reproduces the disk's brightness asymmetry and the profile at wider separations (r > 110 AU). Although there may be a1ternate explanations, agreement between the SW disk brightness peak and disk's peak rom emission is consistent with an overdensity of very small, sub-blowout-sized dust and large, 0.1 - 1 mm-sized grains at approx equal 45 AU tracing the same parent population of planetesimals. New near-IR and submm observations may be able to clarify whether even more complex grain scattering properties or dynamical sculpting by an unseen planet are required to explain HD 32297's disk structure.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Implications for Spectral Line Intensity Mapping at Millimeter Wavelengths and CMB Spectral Distortions

NASA Astrophysics Data System (ADS)

Carilli, C. L.; Chluba, J.; Decarli, R.; Walter, F.; Aravena, M.; Wagg, J.; Popping, G.; Cortes, P.; Hodge, J.; Weiss, A.; Bertoldi, F.; Riechers, D.

2016-12-01

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C II] 158 μm line emission from very high redshift galaxies (z ˜ 6-7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T B = 0.94 ± 0.09 μK. In the 242 GHz band, the mean brightness is: T B = 0.55 ± 0.033 μK. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.

Interferometric Constraints on Surface Brightness Asymmetries in Long-Period Variable Stars: A Threat to Accurate Gaia Parallaxes

NASA Astrophysics Data System (ADS)

Sacuto, S.; Jorissen, A.; Cruzalèbes, P.; Pasquato, E.; Chiavassa, A.; Spang, A.; Rabbia, Y.; Chesneau, O.

2011-09-01

A monitoring of surface brightness asymmetries in evolved giants and supergiants is necessary to estimate the threat that they represent to accurate Gaia parallaxes. Closure-phase measurements obtained with AMBER/VISA in a 3-telescope configuration are fitted by a simple model to constrain the photocenter displacement. The results for the C-type star TX Psc show a large deviation of the photocenter displacement that could bias the Gaia parallax.

Evaluation and Analysis of Seasat a Scanning Multichannel Microwave Radiometer (SMMR) Antenna Pattern Correction (APC) Algorithm

NASA Technical Reports Server (NTRS)

Kitzis, S. N.; Kitzis, J. L.

1979-01-01

The accuracy of the SEASAT-A SMMR antenna pattern correction (APC) algorithm was assessed. Interim APC brightness temperature measurements for the SMMR 6.6 GHz channels are compared with surface truth derived sea surface temperatures. Plots and associated statistics are presented for SEASAT-A SMMR data acquired for the Gulf of Alaska experiment. The cross-track gradients observed in the 6.6 GHz brightness temperature data are discussed.

Simulating a slow bar in the low surface brightness galaxy UGC 628

NASA Astrophysics Data System (ADS)

Chequers, Matthew H.; Spekkens, Kristine; Widrow, Lawrence M.; Gilhuly, Colleen

2016-12-01

We present a disc-halo N-body model of the low surface brightness galaxy UGC 628, one of the few systems that harbours a `slow' bar with a ratio of corotation radius to bar length of R ≡ R_c/a_b ˜ 2. We select our initial conditions using SDSS DR10 photometry, a physically motivated radially variable mass-to-light ratio profile, and rotation curve data from the literature. A global bar instability grows in our submaximal disc model, and the disc morphology and dynamics agree broadly with the photometry and kinematics of UGC 628 at times between peak bar strength and the onset of buckling. Prior to bar formation, the disc and halo contribute roughly equally to the potential in the galaxy's inner region, giving the disc enough self-gravity for bar modes to grow. After bar formation, there is significant mass redistribution, creating a baryon-dominated inner and dark matter-dominated outer disc. This implies that, unlike most other low surface brightness galaxies, UGC 628 is not dark matter dominated everywhere. Our model nonetheless implies that UGC 628 falls on the same relationship between dark matter fraction and rotation velocity found for high surface brightness galaxies, and lends credence to the argument that the disc mass fraction measured at the location where its contribution to the potential peaks is not a reliable indicator of its dynamical importance at all radii.

The Chandra M10l Megasecond: Diffuse Emission

NASA Technical Reports Server (NTRS)

Kuntz, K. D.; Snowden, S. L.

2009-01-01

Because MIOl is nearly face-on, it provides an excellent laboratory in which to study the distribution of X-ray emitting gas in a typical late-type spiral galaxy. We obtained a Chandra observation with a cumulative exposure of roughly 1 Ms to study the diffuse X-ray emission in MlOl. The bulk of the X-ray emission is correlated with the star formation traced by the FUV emission. The global FUV/Xray correlation is non-linear (the X-ray surface brightness is roughly proportional to the square root of the FUV surface brightness) and the small-scale correlation is poor, probably due to the delay between the FUV emission and the X-ray production ill star-forming regions. The X-ray emission contains only minor contributions from unresolved stars (approximates less than 3%), unresolved X-ray point sources (approximates less than 4%), and individual supernova remnants (approximates 3%). The global spectrum of the diffuse emission can be reasonably well fitted with a three component thermal model, but the fitted temperatures are not unique; many distributions of emission measure can produce the same temperatures when observed with the current CCD energy resolution. The spectrum of the diffuse emission depends on the environment; regions with higher X-ray surface brightnesses have relatively stronger hard components, but there is no significant evidence that the temperatures of the emitting components increase with surface brightness.

The distribution of star formation and metals in the low surface brightness galaxy UGC 628

NASA Astrophysics Data System (ADS)

Young, J. E.; Kuzio de Naray, Rachel; Wang, Sharon X.

2015-09-01

We introduce the MUSCEL Programme (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies), a project aimed at determining the star-formation histories of low surface brightness galaxies. MUSCEL utilizes ground-based optical spectra and space-based UV and IR photometry to fully constrain the star-formation histories of our targets with the aim of shedding light on the processes that led low surface brightness galaxies down a different evolutionary path from that followed by high surface brightness galaxies, such as our Milky Way. Here we present the spatially resolved optical spectra of UGC 628, observed with the VIRUS-P IFU at the 2.7-m Harlen J. Smith Telescope at the McDonald Observatory, and utilize emission-line diagnostics to determine the rate and distribution of star formation as well as the gas-phase metallicity and metallicity gradient. We find highly clustered star formation throughout UGC 628, excluding the core regions, and a log(O/H) metallicity around -4.2, with more metal-rich regions near the edges of the galactic disc. Based on the emission-line diagnostics alone, the current mode of star formation, slow and concentrated in the outer disc, appears to have dominated for quite some time, although there are clear signs of a much older stellar population formed in a more standard inside-out fashion.

Daylight characterization through vision-based sensing of lighting conditions in buildings

NASA Astrophysics Data System (ADS)

di Dio, Joseph, III

A new method for describing daylight under unknown weather conditions, as captured in images of a room, is proposed. This method considers pixel brightness information to be a linear combination of diffuse and directional light components, as received by a web cam from the walls and ceiling of an occupied office. The nature of these components in each image is determined by building orientation, room geometry, neighboring structures and the position of the sun. Considering daylight in this manner also allows for an estimation of the sky conditions at a given instant to be made, and presents a means to uncover seasonal trends in the behavior of light simply by monitoring the brightness variations of points on the walls and ceiling. Significantly, this daylight characterization method also allows for an estimation of the illumination level on a target surface to be made from image data. Currently, illumination at a target surface is estimated through the use of a ceiling-mounted photosensor, as part of a lighting control system, in the hopes of achieving a suitable balance between daylight and electrical lighting in a space. Improving the ability of a sensor to estimate the illumination is of great importance to those who wish to minimize unnecessary energy consumption, as a significant percentage of all U.S. electricity is currently consumed by light fixtures. A photosensor detects light that falls on its location, which does not necessarily correspond in a fixed manner to the light level on the target areas that the photosensor is meant to monitor. Additionally, a photosensor cannot discern variations in light distribution across a room, which often occur with daylight. By considering pixel brightness information to be a linear combination of diffuse and directional light components at selected pixels in an image, information about the light reaching these pixels can be extracted from observed patterns of brightness, under different light conditions. In this manner, each pixel provides information about the light field at its corresponding point in the room, and thus each pixel can be considered to behave as if it were a remote photosensor. By using multiple pixel readings in lieu of a single photosensor reading of a given light condition, an improved assessment of the illumination level on a target surface can been achieved. It is shown that on average, the camera-based method was approximately 25% more accurate in estimating illuminance in the test room than was a simulated ceiling-mounted photosensor. It is hoped that the methodology detailed here will aid in the eventual development of a camera-based daylight characterization sensor for use in lighting control systems, so that the potential for enhanced energy savings can be realized.

Remote sensing of soil moisture content over bare fields at 1.4 GHz frequency

NASA Technical Reports Server (NTRS)

Wang, J. R.; Choudhury, B. J.

1980-01-01

A simple method of estimating moisture content (W) of a bare soil from the observed brightness temperature (T sub B) at 1.4 GHz is discussed. The method is based on a radiative transfer model calculation, which has been successfully used in the past to account for many observational results, with some modifications to take into account the effect of surface roughness. Besides the measured T sub B's, the three additional inputs required by the method are the effective soil thermodynamic temperature, the precise relation between W and the smooth field brightness temperature T sub B and a parameter specifying the surface roughness characteristics. The soil effective temperature can be readily measured and the procedures of estimating surface roughness parameter and obtaining the relation between W and smooth field brightness temperature are discussed in detail. Dual polarized radiometric measurements at an off-nadir incident angle are sufficient to estimate both surface roughness parameter and W, provided that the relation between W and smooth field brightness temperature at the same angle is known. The method of W estimate is demonstrated with two sets of experimental data, one from a controlled field experiment by a mobile tower and the other, from aircraft overflight. The results from both data sets are encouraging when the estimated W's are compared with the acquired ground truth of W's in the top 2 cm layer. An offset between the estimated and the measured W's exists in the results of the analyses, but that can be accounted for by the presently poor knowledge of the relationship between W and smooth field brightness temperature for various types of soils. An approach to quantify this relationship for different soils and thus improve the method of W estimate is suggested.

Assimilation of Smos Observations to Generate a Prototype SMAP Level 4 Surface and Root-Zone Soil Moisture Product

NASA Technical Reports Server (NTRS)

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Crow, Wade T.; Koster, Randal D.; Kimball, John

2012-01-01

The Soil Moisture Active and Passive (SMAP; [1]) mission is being implemented by NASA for launch in October 2014. The primary science objectives of SMAP are to enhance understanding of land surface controls on the water, energy and carbon cycles, and to determine their linkages. Moreover, the high-resolution soil moisture mapping provided by SMAP has practical applications in weather and seasonal climate prediction, agriculture, human health, drought and flood decision support. The Soil Moisture and Ocean Salinity (SMOS; [2]) mission was launched by ESA in November 2009 and has since been observing L-band (1.4 GHz) upwelling passive microwaves. In this paper we describe our use of SMOS brightness temperature observations to generate a prototype of the planned SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) product [5].

Assimilation of SMOS Brightness Temperatures or Soil Moisture Retrievals into a Land Surface Model

NASA Technical Reports Server (NTRS)

De Lannoy, Gabrielle J. M.; Reichle, Rolf H.

2016-01-01

Three different data products from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated separately into the Goddard Earth Observing System Model, version 5 (GEOS-5) to improve estimates of surface and root-zone soil moisture. The first product consists of multi-angle, dual-polarization brightness temperature (Tb) observations at the bottom of the atmosphere extracted from Level 1 data. The second product is a derived SMOS Tb product that mimics the data at a 40 degree incidence angle from the Soil Moisture Active Passive (SMAP) mission. The third product is the operational SMOS Level 2 surface soil moisture (SM) retrieval product. The assimilation system uses a spatially distributed ensemble Kalman filter (EnKF) with seasonally varying climatological bias mitigation for Tb assimilation, whereas a time-invariant cumulative density function matching is used for SM retrieval assimilation. All assimilation experiments improve the soil moisture estimates compared to model-only simulations in terms of unbiased root-mean-square differences and anomaly correlations during the period from 1 July 2010 to 1 May 2015 and for 187 sites across the US. Especially in areas where the satellite data are most sensitive to surface soil moisture, large skill improvements (e.g., an increase in the anomaly correlation by 0.1) are found in the surface soil moisture. The domain-average surface and root-zone skill metrics are similar among the various assimilation experiments, but large differences in skill are found locally. The observation-minus-forecast residuals and analysis increments reveal large differences in how the observations add value in the Tb and SM retrieval assimilation systems. The distinct patterns of these diagnostics in the two systems reflect observation and model errors patterns that are not well captured in the assigned EnKF error parameters. Consequently, a localized optimization of the EnKF error parameters is needed to further improve Tb or SM retrieval assimilation.

The response of the SSM/I to the marine environment. I - An analytic model for the atmospheric component of observed brightness temperatures

NASA Technical Reports Server (NTRS)

Petty, Grant W.; Katsaros, Kristina B.

1992-01-01

A detailed parameterization is developed for the contribution of the nonprecipitating atmosphere to the microwave brightness temperatures observed by the Special Sensor Microwave/Imager (SSM/I). The atmospheric variables considered include the viewing angle, the integrated water vapor amount and scale height, the effective tropospheric lapse rate and near-surface temperature, the total cloud liquid water, the effective cloud height, and the surface pressure. The dependence of the radiative variables on meteorological variables is determined for each of the SSM/I frequencies 19.35, 22.235, 37.0, and 85.5 GHz, based on the values computed from 16,893 maritime temperature and humidity profiles representing all latitude belts and all seasons. A comparison of the predicted brightness temperatures with brightness temperatures obtained by direct numerical integration of the radiative transfer equation for the radiosonde-profile dataset yielded rms differences well below 1 K for all four SSM/I frequencies.

Bright colloidal quantum dot light-emitting diodes enabled by efficient chlorination

NASA Astrophysics Data System (ADS)

Li, Xiyan; Zhao, Yong-Biao; Fan, Fengjia; Levina, Larissa; Liu, Min; Quintero-Bermudez, Rafael; Gong, Xiwen; Quan, Li Na; Fan, James; Yang, Zhenyu; Hoogland, Sjoerd; Voznyy, Oleksandr; Lu, Zheng-Hong; Sargent, Edward H.

2018-03-01

The external quantum efficiencies of state-of-the-art colloidal quantum dot light-emitting diodes (QLEDs) are now approaching the limit set by the out-coupling efficiency. However, the brightness of these devices is constrained by the use of poorly conducting emitting layers, a consequence of the present-day reliance on long-chain organic capping ligands. Here, we report how conductive and passivating halides can be implemented in Zn chalcogenide-shelled colloidal quantum dots to enable high-brightness green QLEDs. We use a surface management reagent, thionyl chloride (SOCl2), to chlorinate the carboxylic group of oleic acid and graft the surfaces of the colloidal quantum dots with passivating chloride anions. This results in devices with an improved mobility that retain high external quantum efficiencies in the high-injection-current region and also feature a reduced turn-on voltage of 2.5 V. The treated QLEDs operate with a brightness of 460,000 cd m-2, significantly exceeding that of all previously reported solution-processed LEDs.

A radar image of Venus.

NASA Technical Reports Server (NTRS)

Goldstein, R. M.; Rumsey, H. C.

1972-01-01

Radar scans of Venus have yielded a brightness map of a large portion of the surface. The bright area in the south (alpha) and the twin such areas in the north (beta and delta) were first discovered by spectral analysis of radar echos. When range-gating is also applied, their shapes are revealed, and they are seen to be roundish and about 1000 km across. Although radar brightness can be the result of either intrinsic reflectivity or surface roughness, polarization studies show these features to be rough (to the scale of the wavelength, 12.5 cm). Dark, circular areas can also be seen, many with bright central spots. The dark areas are probably smooth. The blurring of the equatorial strip is an artifact of the range-Doppler geometry; all resolution disappears at the equator. Another artifact of the method is the 'ghost', in the south, of the images of beta and delta. Such ghosts appear only at the eastern and western extremes of the map.

First direct visualization of spillover species emitted from pt nanoparticles.

PubMed

Takakusagi, Satoru; Fukui, Ken-ichi; Tero, Ryugo; Asakura, Kiyotaka; Iwasawa, Yasuhiro

2010-11-02

We studied the methanol adsorption behavior of Pt nanoparticles that were vacuum-deposited on a TiO(2)(110) surface at room temperature by using an ultrahigh vacuum (UHV) scanning tunneling microscope (STM). A large number of bright spots were observed on fivefold-coordinated Ti (Ti(5c)) rows of the TiO(2)(110) surface after exposure of the Pt/TiO(2)(110) to methanol vapor. We assigned the bright spots to methoxy species. These were mobile and were found to hop along the Ti(5c) rows. In situ time-resolved STM observations of the formation and migration of the bright spots on the Pt/TiO(2)(110) were carried out in the presence of methanol. The bright spots were produced at the periphery of the Pt nanoparticles and migrated to the substrate Ti(5c) rows. We discuss the spillover process and behavior of the methoxy species on the Pt/TiO(2)(110).

Surface-plasmon resonance-enhanced multiphoton emission of high-brightness electron beams from a nanostructured copper cathode.

PubMed

Li, R K; To, H; Andonian, G; Feng, J; Polyakov, A; Scoby, C M; Thompson, K; Wan, W; Padmore, H A; Musumeci, P

2013-02-15

We experimentally investigate surface-plasmon assisted photoemission to enhance the efficiency of metallic photocathodes for high-brightness electron sources. A nanohole array-based copper surface was designed to exhibit a plasmonic response at 800 nm, fabricated using the focused ion beam milling technique, optically characterized and tested as a photocathode in a high power radio frequency photoinjector. Because of the larger absorption and localization of the optical field intensity, the charge yield observed under ultrashort laser pulse illumination is increased by more than 100 times compared to a flat surface. We also present the first beam characterization results (intrinsic emittance and bunch length) from a nanostructured photocathode.

Extending the Deep Blue aerosol record from SeaWiFS and MODIS to NPP-VIIRS

NASA Technical Reports Server (NTRS)

Sayer, Andrew M.; Hsu, Nai-Yung Christina; Bettenhausen, Corey; Lee, Jaehwa

2015-01-01

Deep Blue expands AOD coverage to deserts and other bright surfaces. Using multiple similar satellite sensors enables us to obtain a long data record. The Deep Blue family consists of three separate aerosol optical depth (AOD) retrieval algorithms: 1. Bright Land: Surface reflectance database, BRDF correction. AOD retrieved separately at each of 412, 470/490, (650) nm. SSA retrieved for heavy dust events. 2. Dark Land: Spectral/directional surface reflectance relationship. AOD retrieved separately at 470/490 and 650 nm. 3. Water: Surface BRDF including glint, foam, underlight. Multispectral inversion (Not present in MODISdataset) All report the AOD at 550 nm, and Ångström exponent (AE).

Hunting Faint Dwarf Galaxies in the Field Using Integrated Light Surveys

NASA Astrophysics Data System (ADS)

Danieli, Shany; van Dokkum, Pieter; Conroy, Charlie

2018-03-01

We discuss the approach of searching the lowest mass dwarf galaxies, ≲ {10}6 {M}ȯ , in the general field, using integrated light surveys. By exploring the limiting surface brightness-spatial resolution (μ eff,lim‑θ) parameter space, we suggest that faint field dwarfs in the Local Volume, between 3 and 10 Mpc, are expected to be detected very effectively and in large numbers using integrated light photometric surveys, complementary to the classical star counts method. We use a sample of dwarf galaxies in the Local Group to construct relations between their photometric and structural parameters, M *–μ eff,V and M *–R eff. We use these relations, along with assumed functional forms for the halo mass function and the stellar mass–halo mass (SMHM) relation, to calculate the lowest detectable stellar masses in the Local Volume and the expected number of galaxies as a function of the limiting surface brightness and spatial resolution. The number of detected galaxies depends mostly on the limiting surface brightness for distances >3 Mpc, while spatial resolution starts to play a role for galaxies at distances >8 Mpc. Surveys with μ eff,lim ∼ 30 mag arcsec‑2 should be able to detect galaxies with stellar masses down to ∼104 M ⊙ in the Local Volume. Depending on the form of the SMHM relation, the expected number of dwarf galaxies with distances between 3 and 10 Mpc is 0.04–0.35 per square degree, assuming a limiting surface brightness of ∼29–30 mag arcsec‑2 and a spatial resolution <4″. We plan to search for a population of low-mass dwarf galaxies in the field by performing a blank wide field photometric survey with the Dragonfly Telephoto Array, an imaging system optimized for the detection of extended ultra low surface brightness structures.

The estimation of the propagation delay through the troposphere from microwave radiometer data. [very long base interferometry

NASA Technical Reports Server (NTRS)

Moran, J. M.; Rosen, B. R.

1980-01-01

The uncertainity in propagation delay estimates is due primarily to tropospheric water, the total amount and vertical distribution of which is variable. Because water vapor both delays and attenuates microwave signals, the propagation delay, or wet path length, can be estimated from the microwave brightness temperature near the 22.235 GHz transition of water vapor. The data from a total of 240 radiosonde launches taken simultaneously were analyzed. Estimates of brightness temperature at 19 and 22 GHz and wet path length were made from these data. The wet path length in the zenith direction could be estimated from the surface water vapor density to an accuracy of 5 cm for the summer data and 2 cm for winter data. Using the brightness temperatures, the wet path could be estimated to an accuracy of 0.3 cm. Two dual frequency radiometers were refurbished in order to test these techniques. These radiometers were capable of measuring the difference in the brightness temperature at 30 deg elevation angle and at the zenith to an accuracy of about 1 K. In August 1975, 45 radiosondes were launched over an 11 day period. Brightness temperature measurements were made simultaneously at 19 and 22 GHz with the radiometers. The rms error for the estimation of wet path length from surface meteorological parameters was 3.2 cm, and from the radiometer brightness temperatures, 1.5 cm.

Forward-Looking Infrared Cameras for Micrometeorological Applications within Vineyards

PubMed Central

Katurji, Marwan; Zawar-Reza, Peyman

2016-01-01

We apply the principles of atmospheric surface layer dynamics within a vineyard canopy to demonstrate the use of forward-looking infrared cameras measuring surface brightness temperature (spectrum bandwidth of 7.5 to 14 μm) at a relatively high temporal rate of 10 s. The temporal surface brightness signal over a few hours of the stable nighttime boundary layer, intermittently interrupted by periods of turbulent heat flux surges, was shown to be related to the observed meteorological measurements by an in situ eddy-covariance system, and reflected the above-canopy wind variability. The infrared raster images were collected and the resultant self-organized spatial cluster provided the meteorological context when compared to in situ data. The spatial brightness temperature pattern was explained in terms of the presence or absence of nighttime cloud cover and down-welling of long-wave radiation and the canopy turbulent heat flux. Time sequential thermography as demonstrated in this research provides positive evidence behind the application of thermal infrared cameras in the domain of micrometeorology, and to enhance our spatial understanding of turbulent eddy interactions with the surface. PMID:27649208

An enhanced VIIRS aerosol optical thickness (AOT) retrieval algorithm over land using a global surface reflectance ratio database

NASA Astrophysics Data System (ADS)

Zhang, Hai; Kondragunta, Shobha; Laszlo, Istvan; Liu, Hongqing; Remer, Lorraine A.; Huang, Jingfeng; Superczynski, Stephen; Ciren, Pubu

2016-09-01

The Visible/Infrared Imager Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite has been retrieving aerosol optical thickness (AOT), operationally and globally, over ocean and land since shortly after S-NPP launch in 2011. However, the current operational VIIRS AOT retrieval algorithm over land has two limitations in its assumptions for land surfaces: (1) it only retrieves AOT over the dark surfaces and (2) it assumes that the global surface reflectance ratios between VIIRS bands are constants. In this work, we develop a surface reflectance ratio database over land with a spatial resolution 0.1° × 0.1° using 2 years of VIIRS top of atmosphere reflectances. We enhance the current operational VIIRS AOT retrieval algorithm by applying the surface reflectance ratio database in the algorithm. The enhanced algorithm is able to retrieve AOT over both dark and bright surfaces. Over bright surfaces, the VIIRS AOT retrievals from the enhanced algorithm have a correlation of 0.79, mean bias of -0.008, and standard deviation (STD) of error of 0.139 when compared against the ground-based observations at the global AERONET (Aerosol Robotic Network) sites. Over dark surfaces, the VIIRS AOT retrievals using the surface reflectance ratio database improve the root-mean-square error from 0.150 to 0.123. The use of the surface reflectance ratio database also increases the data coverage of more than 20% over dark surfaces. The AOT retrievals over bright surfaces are comparable to MODIS Deep Blue AOT retrievals.

Near-Surface Geologic Units Exposed Along Ares Vallis and in Adjacent Areas: A Potential Source of Sediment at the Mars Pathfinder Landing Site

NASA Technical Reports Server (NTRS)

Treiman, Allan H.

1997-01-01

A sequence of layers, bright and dark, is exposed on the walls of canyons, impact craters and mesas throughout the Ares Vallis region, Chryse Planitia, and Xanthe Terra, Mars. Four layers can be seen: two pairs of alternating dark and bright albedo. The upper dark layer forms the top surface of many walls and mesas. The upper dark-bright pair was stripped as a unit from many streamlined mesas and from the walls of Ares Valles, leaving a bench at the top of the lower dark layer, approximately 250 m below the highland surface on streamlined islands and on the walls of Ares Vallis itself. Along Ares Vallis, the scarp between the highlands surface and this bench is commonly angular in plan view (not smoothly curving), suggesting that erosion of the upper dark-bright pair of layers controlled by planes of weakness, like fractures or joints. These near-surface layers in the Ares Vallis area have similar thicknesses, colors, and resistances to erosion to layers exposed near the tops of walls in Valles Marineris (Treiman et al.) and may represent the same pedogenic hardpan units. From this correlation, and from analogies with hardpans on Earth, the light-color layers may be cemented by calcite or gypsum. The dark layers are likely cemented by an iron-bearing mineral. Mars Pathfinder instruments should permit recognition and useful analyses of hardpan fragments, provided that clean uncoated surfaces are accessible. Even in hardpan-cemented materials, it should be possible to determine the broad types of lithologies in the Martian highlands. However, detailed geochemical modeling of highland rocks and soils may be compromised by the presence of hardpan cement minerals.

A Bright Lunar Impact Flash Linked to the Virginid Meteor Complex

NASA Technical Reports Server (NTRS)

Moser, D. E.; Suggs, R. M.; Suggs, R. J.

2015-01-01

On 17 March 2013 at 03:50:54 UTC, NASA detected a bright impact flash on the Moon caused by a meteoroid impacting the lunar surface. There was meteor activity in Earth's atmosphere the same night from the Virginid Meteor Complex. The impact crater associated with the impact flash was found and imaged by Lunar Reconnaissance Orbiter (LRO). Goal: Monitor the Moon for impact flashes produced by meteoroids striking the lunar surface. Determine meteoroid flux in the 10's gram to kilogram size range.

ARC-1979-AC79-7090

NASA Image and Video Library

1979-07-10

P-21762 C This color picture of Ganymede in the region 30° S 180° W shows features as small as 6 kilometers (3.7 miles) across. Shown is a bright halo impact crater that shows the fresh material thrown out of the crater. In the background is bright grooved terrain that may be the result of shearing of the surface materials along fault planes. The dark background material is the ancient heavily cratered terrain--the oldest material preserved on the Ganymede surface.

Simple Forest Canopy Thermal Exitance Model

NASA Technical Reports Server (NTRS)

Smith J. A.; Goltz, S. M.

1999-01-01

We describe a model to calculate brightness temperature and surface energy balance for a forest canopy system. The model is an extension of an earlier vegetation only model by inclusion of a simple soil layer. The root mean square error in brightness temperature for a dense forest canopy was 2.5 C. Surface energy balance predictions were also in good agreement. The corresponding root mean square errors for net radiation, latent, and sensible heat were 38.9, 30.7, and 41.4 W/sq m respectively.

Modeling Illumination Conditions on the Moon: Applications to LRO-LAMP

NASA Astrophysics Data System (ADS)

Byron, B. D.; Mazarico, E. M.; Retherford, K. D.; Mandt, K. E.; Greathouse, T.; Gladstone, R.

2017-12-01

LRO-LAMP is a UV spectrograph which uses illumination from Lyman-α sky glow along with UV light from bright stars to image the dark, permanently shadowed regions (PSRs) of the lunar surface. Accurate modeling of this UV illumination is essential to creating albedo maps of the lunar surface, which can shed light on lunar regolith processes and help to constrain the distribution of water ice in polar PSRs. In this study, the variation in reflected intensity received by the LAMP detector was modeled for South Pole crater Amundsen using the illumination program IllumNG. Amundsen was chosen for study due to the PSR in its Northern side and its highly illuminated equator-facing slopes on the Southern wall. The model works by tracing a ray from each LAMP detector pixel along its boresight until the point where it intersects the lunar surface, and calculating the percentage of the total source flux visible above the horizon. In this study, the three main illumination sources used are the Sun, Interplanetary Lyman-α sky glow, and bright UV starlight in the On Band (130-155 nm) and Off Band (155-190 nm) wavelength ranges. The model also has the capability to calculate incident flux received at the surface, as well as intensity reflected from the surface and received by the LAMP detector along each boresight. The study found a noticeable variation in received intensity between six month stretches for the year of 2010. Over the period of January through July, about 6% more IPM Lyman-α flux was reflected from the surface of Amundsen than for July through December. For stellar flux in the On Band, a 13% difference in flux was reflected between the six month periods. In comparing the monthly intensity maps created by the model with LAMP measured monthly brightness maps, similar crater features are apparent. Though the model brightness is generally higher than the LAMP brightness, after accounting for albedo ( 0.05 for the South Pole region) the values are in closer agreement. In the future, inclusion of the model results during pipeline processing could enable better calibration and analysis of LAMP data.

Flattening and surface-brightness of the fast-rotating star δ Persei with the visible VEGA/CHARA interferometer

NASA Astrophysics Data System (ADS)

Challouf, M.; Nardetto, N.; Domiciano de Souza, A.; Mourard, D.; Tallon-Bosc, I.; Aroui, H.; Farrington, C.; Ligi, R.; Meilland, A.; Mouelhi, M.

2017-08-01

Context. Rapid rotation is a common feature for massive stars, with important consequences on their physical structure, flux distribution and evolution. Fast-rotating stars are flattened and show gravity darkening (non-uniform surface intensity distribution). Another important and less studied impact of fast-rotation in early-type stars is its influence on the surface brightness colour relation (hereafter SBCR), which could be used to derive the distance of eclipsing binaries. Aims: The purpose of this paper is to determine the flattening of the fast-rotating B-type star δ Per using visible long-baseline interferometry. A second goal is to evaluate the impact of rotation and gravity darkening on the V - K colour and surface brightness of the star. Methods: The B-type star δ Per was observed with the VEGA/CHARA interferometer, which can measure spatial resolutions down to 0.3 mas and spectral resolving power of 5000 in the visible. We first used a toy model to derive the position angle of the rotation axis of the star in the plane of the sky. Then we used a code of stellar rotation, CHARRON, in order to derive the physical parameters of the star. Finally, by considering two cases, a static reference star and our best model of δ Per, we can quantify the impact of fast rotation on the surface brightness colour relation (SBCR). Results: We find a position angle of 23 ± 6 degrees. The polar axis angular diameter of δ Per is θp = 0.544 ± 0.007 mas, and the derived flatness is r = 1.121 ± 0.013. We derive an inclination angle for the star of I = 85+ 5-20 degrees and a projected rotation velocity Vsini = 175+ 8-11 km s-1 (or 57% of the critical velocity). We find also that the rotation and inclination angle of δ Per keeps the V - K colour unchanged while it decreasing its surface-brightness by about 0.05 mag. Conclusions: Correcting the impact of rotation on the SBCR of early-type stars appears feasible using visible interferometry and dedicated models.

Méthode de traitement des intérferogrammes à deux ondes pour accroître leur sensibilité.

PubMed

Roblin, G; Prévost, M

1980-08-01

Two-beam interference fringes are not always able to give sufficient information to determine the topography of very weakly deformed wave surfaces. The process described allows us to intercalate several intermediate levels, which vary linearly in terms of the phase, between the brightness extrema of a fringe. The interference pattern is submitted to an optoelectronics treatment where the photoelectric signal is compared with an adjustable electric reference signal.

Potential of fish scales as a filling material in surface coating of cellulosic paper.

PubMed

Ural, Elif; Kandirmaz, Emine A

2018-01-01

Paper is one of the important inputs for the printing industry, and the most important leading parameter in the printing process is its brightness. Brightness can be brought to paper using coatings and sizing. Desired surface properties and, most importantly, surface roughness can be achieved by changing the contents of the coating and sizing of the materials it contains. The use of biomaterials is becoming more important in the paper industry, as they represent substances with a lower carbon footprint. Fish scales are already used as a filling material, cosmetic material and fish food, as well as for determining the age of fish. Fish scales were brought to different sizes by a milling process. Paper formulations including different amounts of fish scales were prepared with fish scales, and coatings on raw paper were subjected to test printings in IGT-C1, with formulations and physical characteristics of coatings such as brightness, lightfastness, strength, adhesion etc. being determined. Regarding the value of yellowness, mixtures of 2.5%-10% can be used. The maximum value of brightness was obtained from a mixture of 10%. Aging visibly changed the colors. The coatings obtained were brighter than the initial coating compositions. The top quality formulation was the coating with 5% medium-sized fish scale particles.

Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres

NASA Astrophysics Data System (ADS)

de Sanctis, M. C.; Raponi, A.; Ammannito, E.; Ciarniello, M.; Toplis, M. J.; McSween, H. Y.; Castillo-Rogez, J. C.; Ehlmann, B. L.; Carrozzo, F. G.; Marchi, S.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; McFadden, L. A.; Pieters, C. M.; Jaumann, R.; Schenk, P.; Mugnuolo, R.; Raymond, C. A.; Russell, C. T.

2016-08-01

The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

An interpretation of photometric parameters of bright desert regions of Mars and their dependence on wave length

NASA Technical Reports Server (NTRS)

Weaver, W. R.; Meador, W. E.

1977-01-01

Photometric data from the bright desert areas of Mars were used to determine the dependence of the three photometric parameters of the photometric function on wavelength and to provide qualitative predictions about the physical properties of the surface. Knowledge of the parameters allowed the brightness of these areas of Mars to be determined for any scattering geometry in the wavelength range of 0.45 to 0.70 micron. The changes that occur in the photometric parameters due to changes in wavelength were shown to be consistent with their physical interpretations, and the predictions of surface properties were shown to be consistent with conditions expected to exist in these regions of Mars. The photometric function was shown to have potential as a diagnostic tool for the qualitative determination of surface properties, and the consistency of the behavior of the photometric parameters was considered to be support for the validity of the photometric function.

Unveiling the Low Surface Brightness Stellar Peripheries of Galaxies

NASA Astrophysics Data System (ADS)

Ferguson, Annette M. N.

2018-01-01

The low surface brightness peripheral regions of galaxies contain a gold mine of information about how minor mergers and accretions have influenced their evolution over cosmic time. Enormous stellar envelopes and copious amounts of faint tidal debris are natural outcomes of the hierarchical assembly process and the search for and study of these features, albeit highly challenging, offers the potential for unrivalled insight into the mechanisms of galaxy growth. Over the last two decades, there has been burgeoning interest in probing galaxy outskirts using resolved stellar populations. Wide-field surveys have uncovered vast tidal debris features and new populations of very remote globular clusters, while deep Hubble Space Telescope photometry has provided exquisite star formation histories back to the earliest epochs. I will highlight some recent results from studies within and beyond the Local Group and conclude by briefly discussing the great potential of future facilities, such as JWST, Euclid, LSST and WFIRST, for major breakthroughs in low surface brightness galaxy periphery science.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: On the possibility of studying the temporal evolution of a surface relief directly during exposure to high-power radiation

NASA Astrophysics Data System (ADS)

Abramov, D. V.; Arakelyan, S. M.; Galkin, A. F.; Klimovskii, Ivan I.; Kucherik, A. O.; Prokoshev, V. G.

2006-06-01

The video image of the graphite surface exposed to focused laser radiation is obtained with the help of a laser monitor. A bright ring moving over the heated surface was observed. A method for reconstructing the surface relief from the video image is proposed and realised. The method is based on the measurement of the angular distribution of the light intensity scattered by the graphite sample surface. The surface relief of the graphite sample changing in time is reconstructed. The relative change in the relief height during laser excitation is measured. The statistical characteristics of the reconstructed graphite surface shape and their variation during laser irradiation are studied. It is found that a circular convexity appears within the bright ring. The formation mechanism of this convexity requires further investigations.

An Automatic Cloud Mask Algorithm Based on Time Series of MODIS Measurements

NASA Technical Reports Server (NTRS)

Lyapustin, Alexei; Wang, Yujie; Frey, R.

2008-01-01

Quality of aerosol retrievals and atmospheric correction depends strongly on accuracy of the cloud mask (CM) algorithm. The heritage CM algorithms developed for AVHRR and MODIS use the latest sensor measurements of spectral reflectance and brightness temperature and perform processing at the pixel level. The algorithms are threshold-based and empirically tuned. They don't explicitly address the classical problem of cloud search, wherein the baseline clear-skies scene is defined for comparison. Here, we report on a new CM algorithm which explicitly builds and maintains a reference clear-skies image of the surface (refcm) using a time series of MODIS measurements. The new algorithm, developed as part of the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm for MODIS, relies on fact that clear-skies images of the same surface area have a common textural pattern, defined by the surface topography, boundaries of rivers and lakes, distribution of soils and vegetation etc. This pattern changes slowly given the daily rate of global Earth observations, whereas clouds introduce high-frequency random disturbances. Under clear skies, consecutive gridded images of the same surface area have a high covariance, whereas in presence of clouds covariance is usually low. This idea is central to initialization of refcm which is used to derive cloud mask in combination with spectral and brightness temperature tests. The refcm is continuously updated with the latest clear-skies MODIS measurements, thus adapting to seasonal and rapid surface changes. The algorithm is enhanced by an internal dynamic land-water-snow classification coupled with a surface change mask. An initial comparison shows that the new algorithm offers the potential to perform better than the MODIS MOD35 cloud mask in situations where the land surface is changing rapidly, and over Earth regions covered by snow and ice.

The Tolman Surface Brightness Test for the Reality of the Expansion. III. Hubble Space Telescope Profile and Surface Brightness Data for Early-Type Galaxies in Three High-Redshift Clusters

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Sandage, Allan

2001-09-01

Photometric data for 34 early-type galaxies in the three high-redshift clusters Cl 1324+3011 (z=0.76), Cl 1604+4304 (z=0.90), and Cl 1604+4321 (z=0.92), observed with the Hubble Space Telescope (HST) and with the Keck 10 m telescopes by Oke, Postman, & Lubin, are analyzed to obtain the photometric parameters of mean surface brightness, magnitudes for the growth curves, and angular radii at various Petrosian η radii. The angular radii at η=1.3 mag for the program galaxies are all larger than 0.24". All the galaxies are well resolved at this angular size using HST, whose point-spread function is 0.05", half-width at half-maximum. The data for each of the program galaxies are listed at η=1.0, 1.3, 1.5, 1.7, and 2.0 mag. They are corrected by color equations and K-terms for the effects of redshift to the rest-frame Cape/Cousins I for Cl 1324+3011 and Cl 1604+4304 and R for Cl 1604+4321. The K-corrections are calculated from synthetic spectral energy distributions derived from evolving stellar population models of Bruzual & Charlot, that have been fitted to the observed broadband (BVRI) AB magnitudes of each program galaxy. The listed photometric data are independent of all cosmological parameters. They are the source data for the Tolman surface brightness test made in Paper IV.

Beyond 31 mag arcsec-2: The Frontier of Low Surface Brightness Imaging with the Largest Optical Telescopes

NASA Astrophysics Data System (ADS)

Trujillo, Ignacio; Fliri, Jüergen

2016-06-01

The detection of structures in the sky with optical surface brightnesses fainter than 30 mag arcsec-2 (3σ in 10 × 10 arcsec boxes; r-band) has remained elusive in current photometric deep surveys. Here we show how present-day telescopes of 10 m class can provide broadband imaging 1.5-2 mag deeper than most previous results within a reasonable amount of time (I.e., <10 hr on-source integration). In particular, we illustrate the ability of the 10.4 m Gran Telescopio de Canarias telescope to produce imaging with a limiting surface brightness of 31.5 mag arcsec-2 (3σ in 10 × 10 arcsec boxes; r-band) using 8.1 hr on source. We apply this power to explore the stellar halo of the galaxy UGC 00180, a galaxy analogous to M31 located at ˜150 Mpc, by obtaining a radial profile of surface brightness down to μ r ˜ 33 mag arcsec-2. This depth is similar to that obtained using the star-counts techniques for Local Group galaxies, but is achieved at a distance where this technique is unfeasible. We find that the mass of the stellar halo of this galaxy is ˜4 × 109 M ⊙, I.e., (3 ± 1)% of the total stellar mass of the whole system. This amount of mass in the stellar halo is in agreement with current theoretical expectations for galaxies of this kind.

Bright Ray Craters in Ganymede's Northern Hemisphere

NASA Technical Reports Server (NTRS)

1979-01-01

GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is of a region in the northern hemisphere near the terminator. It shows a variety of impact structures, including both razed and unrazed craters, and the odd, groove-like structures discovered by Voyager in the lighter regions. The most striking features are the bright ray craters which have a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the southern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejects patterns (such as several of the craters in the southern half of PIA01516; P21262). This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Detection of moisture and moisture related phenomena from Skylab. [correlation of brightness and antenna temperature with soil moisture for Texas and Kansas test sites

NASA Technical Reports Server (NTRS)

Eagleman, J. R.; Pogge, E. C.; Moore, R. K. (Principal Investigator); Hardy, N.; Lin, W.; League, L.

1974-01-01

The author has identified the following significant results. Skylab 2 data for June 5, 1973 (Texas site) relates favorably with previously calculated aircraft data when correlating brightness temperature to soil moisture. However, more detailed work is needed to determine the corrected surface temperature. In addition, correlations between the S194 antenna temperature and soil moisture have been obtained for five sets of Skylab data. The best correlations were obtained for the surface to one inch depth in four cases and for surface to two inches depth for the fifth case. Correlation coefficients for the surface to one inch depth were -0.98, -0.95, -0.90, -0.82, and -0.80.

Film viewing conditions in mammography.

PubMed

Hill, S J; Faulkner, K; Law, J; Starritt, H C

1997-04-01

A requirement for a minimum viewing box brightness of 3000 cd m-2 for reading mammograms has been widely advocated. Some recent work has challenged that opinion by reporting no significant variation in visibility of low contrast and fine detail objects over a wide range of brightness levels. This paper provides further experimental evidence to support the latter conclusion, at least over the range 1340-4190 cd m-2, and suggests that the currently recommended minimum viewing box brightness levels need to be revised. The importance of reducing room lighting levels is fully confirmed.

Osseointegration of zirconia implants: an SEM observation of the bone-implant interface.

PubMed

Depprich, Rita; Zipprich, Holger; Ommerborn, Michelle; Mahn, Eduardo; Lammers, Lydia; Handschel, Jörg; Naujoks, Christian; Wiesmann, Hans-Peter; Kübler, Norbert R; Meyer, Ulrich

2008-11-06

The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.

Edge Modeling by Two Blur Parameters in Varying Contrasts.

PubMed

Seo, Suyoung

2018-06-01

This paper presents a method of modeling edge profiles with two blur parameters, and estimating and predicting those edge parameters with varying brightness combinations and camera-to-object distances (COD). First, the validity of the edge model is proven mathematically. Then, it is proven experimentally with edges from a set of images captured for specifically designed target sheets and with edges from natural images. Estimation of the two blur parameters for each observed edge profile is performed with a brute-force method to find parameters that produce global minimum errors. Then, using the estimated blur parameters, actual blur parameters of edges with arbitrary brightness combinations are predicted using a surface interpolation method (i.e., kriging). The predicted surfaces show that the two blur parameters of the proposed edge model depend on both dark-side edge brightness and light-side edge brightness following a certain global trend. This is similar across varying CODs. The proposed edge model is compared with a one-blur parameter edge model using experiments of the root mean squared error for fitting the edge models to each observed edge profile. The comparison results suggest that the proposed edge model has superiority over the one-blur parameter edge model in most cases where edges have varying brightness combinations.

Brightness checkerboard lattice method for the calibration of the coaxial reverse Hartmann test

NASA Astrophysics Data System (ADS)

Li, Xinji; Hui, Mei; Li, Ning; Hu, Shinan; Liu, Ming; Kong, Lingqin; Dong, Liquan; Zhao, Yuejin

2018-01-01

The coaxial reverse Hartmann test (RHT) is widely used in the measurement of large aspheric surfaces as an auxiliary method for interference measurement, because of its large dynamic range, highly flexible test with low frequency of surface errors, and low cost. And the accuracy of the coaxial RHT depends on the calibration. However, the calibration process remains inefficient, and the signal-to-noise ratio limits the accuracy of the calibration. In this paper, brightness checkerboard lattices were used to replace the traditional dot matrix. The brightness checkerboard method can reduce the number of dot matrix projections in the calibration process, thus improving efficiency. An LCD screen displayed a brightness checkerboard lattice, in which the brighter checkerboard and the darker checkerboard alternately arranged. Based on the image on the detector, the relationship between the rays at certain angles and the photosensitive positions of the detector coordinates can be obtained. And a differential de-noising method can effectively reduce the impact of noise on the measurement results. Simulation and experimentation proved the feasibility of the method. Theoretical analysis and experimental results show that the efficiency of the brightness checkerboard lattices is about four times that of the traditional dot matrix, and the signal-to-noise ratio of the calibration is significantly improved.

Dynamics of copper-phthalocyanine molecules on Au/Ge(001).

PubMed

Sotthewes, K; Heimbuch, R; Zandvliet, H J W

2015-10-07

Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a "molecular bridge" configuration, where two benzopyrrole groups (lobes) are connected to a Au-induced nanowire, whereas the other two lobes are connected to the adjacent nanowire. Three types of lobe configurations are found: a bright lobe, a dim lobe, and a fuzzy lobe. The dim and fuzzy lobes exhibit a well-defined switching behavior between two discrete levels, while the bright lobe shows a broad oscillation band. The observed dynamic behavior is induced by electrons that are injected into the LUMO+1 orbital of the CuPc molecule. By precisely adjusting the tip-molecule distance, the switching frequency of the lobes can be tuned accurately.

Dynamics of copper-phthalocyanine molecules on Au/Ge(001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sotthewes, K.; Heimbuch, R.; Zandvliet, H. J. W.

2015-10-07

Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular bridge” configuration, where two benzopyrrole groups (lobes) are connected to a Au-induced nanowire, whereas the other two lobes are connected to the adjacent nanowire. Three types of lobe configurations are found: a bright lobe, a dim lobe, and a fuzzy lobe. The dim and fuzzy lobes exhibit a well-defined switching behavior between two discrete levels, while the bright lobe shows a broad oscillationmore » band. The observed dynamic behavior is induced by electrons that are injected into the LUMO+1 orbital of the CuPc molecule. By precisely adjusting the tip-molecule distance, the switching frequency of the lobes can be tuned accurately.« less

The use of stereoscopic satellite observation in the determination of the emissivity of cirrus

NASA Astrophysics Data System (ADS)

Szejwach, G.; Sletten, T. N.; Hasler, A. F.

The feasibility of determining cirrus ``emissivity'' from combined stereoscopic and infrared satellite observations in conjunction with radiosounding data is investigated for a particular case study. Simultaneous visible images obtained during SESAME-1979 from two geosynchronous GOES meteorological satellites were processed on the NASA/Goddard interactive system (AOIPS) and were used to determine the stereo cloud top height ZC as described by Hasler [1]. Iso-contours of radiances were outlined on the corresponding infrared image. Total brightness temperature TB and ground surface brightness temperature TS were inferred from the radiances. The special SESAME network of radiosoundings was used to determine the cloud top temperature TCLD at the level defined by ZC. The ``effective cirrus emissivity'' NE where N is the fractional cirrus cloudiness and E is the emissivity in a GOES infrared picture element of about 10 km × 10 km is then computed from TB, TS and TCLD.

Spatiotemporal analysis of brightness induction

PubMed Central

McCourt, Mark E.

2011-01-01

Brightness induction refers to a class of visual illusions in which the perceived intensity of a region of space is influenced by the luminance of surrounding regions. These illusions are significant because they provide insight into the neural organization of the visual system. A novel quadrature-phase motion cancelation technique was developed to measure the magnitude of the grating induction brightness illusion across a wide range of spatial frequencies, temporal frequencies and test field heights. Canceling contrast is greatest at low frequencies and declines with increasing frequency in both dimensions, and with increasing test field height. Canceling contrast scales as the product of inducing grating spatial frequency and test field height (the number of inducing grating cycles per test field height). When plotted using a spatial axis which indexes this product, the spatiotemporal induction surfaces for four test field heights can be described as four partially overlapping sections of a single larger surface. These properties of brightness induction are explained in the context of multiscale spatial filtering. The present study is the first to measure the magnitude of grating induction as a function of temporal frequency. Taken in conjunction with several other studies (Blakeslee & McCourt, 2008; Robinson & de Sa, 2008; Magnussen & Glad, 1975) the results of this study illustrate that at least one form of brightness induction is very much faster than that reported by DeValois et al. (1986) and Rossi and Paradiso (1996), and are inconsistent with the proposition that brightness induction results from a slow “filling in” process. PMID:21763339

Mapping Solid and Liquid Meltwater Retention on the Greenland and Antarctic Ice Sheets from Space

NASA Astrophysics Data System (ADS)

Miller, J.; Bringer, A.; Jezek, K. C.; Johnson, J. T.; Scambos, T.; Forster, R. R.; Long, D. G.

2017-12-01

We use satellite and airborne microwave radiometry to explore the potential for mapping both solid (infiltration ice) and liquid (firn aquifers) meltwater retention on ice sheets. Meltwater retention in firn is currently poorly understood, especially on an ice sheet-scale, however, critical to understanding the ultimate fate of liquid meltwater produced at the surface of ice sheets. Is it contributing to sea level? Or, is it being buffered prior to escaping into the ocean? We previously developed a simple satellite retrieval technique to map firn aquifers on the Greenland ice sheet using distinct L-band brightness temperature signatures that decrease on timescales of months following surface freeze-up, however, similar L-band brightness temperature signatures that decrease on timescales ranging from weeks to days are also present throughout the percolation facies of both the Greenland and Antarctic ice sheets. We hypothesize this characteristic family of temporal signatures represents meltwater retention within firn, where slowly decreasing signatures are characteristic of meltwater retention within perennial firn aquifers, and rapidly decreasing signatures are characteristic of meltwater retention as superimposed ice. Decreasing signatures on timescales between likely represent a continuum of firn characteristics, such as transient firn aquifers, perched firn aquifers, ice layers, ice pipes and lenses, and iced firn. To investigate these temporal signatures, we use L-band (1.4 GHz) brightness temperature observations collected over the Greenland and Antarctic ice sheets by the interferometric MIRAS instrument aboard ESA's Soil Moisture and Ocean Salinity (SMOS) satellite, and the radiometer aboard NASA's Soil Moisture Active Passive (SMAP) satellite. We will also investigate spectral signatures using multi-frequency L-band brightness temperature data (0.5-2 GHz) to be collected over several firn aquifer areas on the Greenland ice sheet by the Ohio State University developed Ultra-Wideband Software-Defined Microwave Radiometer (UWBRAD) as part of our airborne field campaign to be conducted in September 2017.

Anticorrelation of X-ray bright points with sunspot number, 1970-1978

NASA Technical Reports Server (NTRS)

Golub, L.; Davis, J. M.; Krieger, A. S.

1979-01-01

Soft X-ray observations of the solar corona over the period 1970-1978 show that the number of small short-lived bipolar magnetic features (X-ray bright points) varies inversely with the sunspot index. During the entire period from 1973 to 1978 most of the magnetic flux emerging at the solar surface appeared in the form of bright points. In 1970, near the peak of solar cycle 20, the contributions from bright points and from active regions appear to be approximately equal. These observations strongly support an earlier suggestion that the solar cycle may be characterized as an oscillator in wave-number space with relatively little variation in the average total rate of flux emergence.

Study on hexagonal super-lattice pattern with surface discharges in dielectric barrier discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ying; Dong, Lifang, E-mail: donglfhbu@163.com; Niu, Xuejiao

2015-10-15

The hexagonal super-lattice pattern with surface discharges (SDs) in dielectric barrier discharge is investigated by intensified charge-coupled device. The pattern is composed of the bright spot and the dim spot which is located at the centroid of surrounding other three bright spots. The phase diagram of the pattern as a function of the gas pressure and the argon concentration is given. The instantaneous images indicate that the bright spot emerging at the front of the current pulse is formed by the volume discharge (VD), and dim spot occurring at the tail of the current pulse is formed by the SD.more » The above result shows that the SD is induced by the VD. The simulation of the electric fields of wall charges accumulated by VDs confirms that the dim spot is formed by the confluences of the SDs of surrounding other three bright spots. By using optical emission spectrum method, both the molecule vibration temperature and electron density of the SD are larger than that of the VD.« less

The color of the Martian sky and its influence on the illumination of the Martian surface

USGS Publications Warehouse

Thomas, N.; Markiewicz, W.J.; Sablotny, R.M.; Wuttke, M.W.; Keller, H.U.; Johnson, J. R.; Reid, R.J.; Smith, R.H.

1999-01-01

The dust in the atmosphere above the Mars Pathfinder landing site produced a bright, red sky that increases in redness toward the horizon at midday. There is also evidence for an absorption band in the scattered light from the sky at 860 nm. A model of the sky brightness has been developed [Markiewicz et al., this issue] and tested against Imager for Mars Pathfinder (IMP) observations of calibration targets on the lander. The resulting model has been used to quantify the total diffuse flux onto a surface parallel to the local level for several solar elevation angles and optical depths. The model shows that the diffuse illumination in shadowed areas is strongly reddened while areas illuminated directly by the Sun (and the blue forward scattering peak) see a more solar-type spectrum, in agreement with Viking and IMP observations. Quantitative corrections for the reddening in shadowed areas are demonstrated. It is shown quantitatively that the unusual appearance of the rock Yogi (the east face of which appeared relatively blue in images taken during the morning but relatively red during the afternoon) can be explained purely by the changing illumination geometry. We conclude that any spectrophotometric analysis of surfaces on Mars must take into account the diffuse flux. Specifically, the reflectances of surfaces viewed under different illumination geometries cannot be investigated for spectral diversity unless a correction has been applied which removes the influence of the reddened diffuse flux. Copyright 1999 by the American Geophysical Union.

Modelling the phase curve and occultation of WASP-43b with SPIDERMAN

NASA Astrophysics Data System (ADS)

Louden, Tom

2017-06-01

Presenting SPIDERMAN, a fast code for calculating exoplanet phase curves and secondary eclipses with arbitrary two dimensional surface brightness distributions. SPIDERMAN uses an exact geometric algorithm to calculate the area of sub-regions of the planet that are occulted by the star, with no loss in numerical precision. The speed of this calculation makes it possible to run MCMCs to marginalise effectively over the underlying parameters controlling the brightness distribution of exoplanets. The code is fully open source and available over Github. We apply the code to the phase curve of WASP-43b using an analytical surface brightness distribution, and find an excellent fit to the data. We are able to place direct constraints on the physics of heat transport in the atmosphere, such as the ratio between advective and radiative timescales at different altitudes.

Bright Feature Appears in Titan Kraken Mare

NASA Image and Video Library

2014-11-10

Two Synthetic Aperture Radar (SAR) images from the radar experiment on NASA's Cassini spacecraft show that, between May 2013 and August 2014, a bright feature appeared in Kraken Mare, the largest hydrocarbon sea on Saturn's moon Titan. Researchers think the bright feature is likely representative of something on the hydrocarbon sea's surface, such as waves or floating debris. A similar feature appeared in Ligea Mare, another Titan sea, and was seen to evolve in appearance between 2013 and 2014 (see PIA18430). The image at left was taken on May 23, 2013 at an incidence angle of 56 degrees; the image at right was taken on August 21, 2014 at an incidence angle of 5 degrees. Incidence angle refers to the angle at which the radar beam strikes the surface. http://photojournal.jpl.nasa.gov/catalog/PIA19047

Pyrite Stability Under Venus Surface Conditions

NASA Astrophysics Data System (ADS)

Kohler, E.; Craig, P.; Port, S.; Chevrier, V.; Johnson, N.

2015-12-01

Radar mapping of the surface of Venus shows areas of high reflectivity in the Venusian highlands, increasing to 0.35 ± 0.04 to 0.43 ± 0.05 in the highlands from the planetary average of 0.14 ± 0.03. Iron sulfides, specifically pyrite (FeS2), can explain the observed high reflectivity. However, several studies suggest that pyrite is not stable under Venusian conditions and is destroyed on geologic timescales. To test the stability of pyrite on the Venusian surface, pyrite was heated in the Venus simulation chamber at NASA Goddard Space Flight Center to average Venusian surface conditions, and separately to highland conditions under an atmosphere of pure CO2 and separately under an atmosphere of 96.5% CO2, 3.5% N2 and 150 ppm SO2. After each run, the samples were weighed and analyzed using X-Ray Diffraction (XRD) to identify possible phase changes and determine the stability of pyrite under Venusian surface conditions. Under a pure CO2 atmosphere, the Fe in pyrite oxidizes to form hematite which is more stable at higher temperatures corresponding to the Venusian lowlands. Magnetite is the primary iron oxide that forms at lower temperatures corresponding to the radar-bright highlands. Our experiments also showed that the presence of atmospheric SO2 inhibits the oxidation of pyrite, increasing its stability under Venusian conditions, especially those corresponding to the highlands. This indicates that the relatively high level of SO2 in the Venusian atmosphere is key to the stability of pyrite, making it a possible candidate for the bright radar signal in the Venusian highlands.

Detection of radio emission from optically identified supernova remnants in M31

NASA Technical Reports Server (NTRS)

Dickel, J. R.; Dodorico, S.; Felli, M.; Dopita, M.

1982-01-01

The Very Large Array was used to conduct a radio search at a wavelength of 20 cm for ten optically identified supernova remnants (SNRs) in M31. Five SNRs were detected, and for the other objects, upper limits to the emission were determined. On the average, the surface brightness of an SNR in M31 appears to be fainter than that of an SNR in the Galaxy. It is suggested that the median surface brightness at a given diameter is higher in late-type spirals than in Sb systems.

Gap Junction Protein Connexin 43 Serves as a Negative Marker for a Stem Cell-Containing Population of Human Limbal Epithelial Cells

PubMed Central

Chen, Zhuo; Evans, W. Howard; Pflugfelder, Stephen C.; Li, De-Quan

2010-01-01

This study evaluated whether the gap junction protein connexin (Cx) 43 could serve as a negative cell surface marker for human corneal epithelial stem cells. Cx43 expression was evaluated in corneo-limbal tissue and primary limbal epithelial cultures. Immunofluorescent staining and laser scanning confocal microscopy showed that Cx43 was strongly expressed in the corneal and limbal suprabasal epithelial cells, but the basal cells of the limbal epithelium were negative. Cx43 antibody stained mainly large cells but not small cells in primary limbal epithelial cultures. As determined by semiquantitative reverse transcription polymerase chain reaction (PCR) and real-time PCR, Cx43 mRNA was more abundant in the corneal than limbal epithelia, and it was expressed in higher levels in mature limbal epithelial cultures. Using GAP11, a rabbit polyclonal antibody against the Cx32 extracellular loop 2 (151–187), a sequence that is highly homologous in Cx43, the Cx43dim and Cx43bright cells were selected from primary limbal epithelial cultures by fluorescence-activated cell sorting and were evaluated for stem cell properties. These Cx43dim and Cx43bright cells were confirmed by their expression levels of Cx43 protein and mRNA. The Cx43dim cells were found to contain higher percentages of slow-cycling bromodeoxyuridine (BrdU)-label retaining cells and the cells that were positive for stem cell-associated markers p63, ABCG2, and integrin β1 and negative for differentiation markers K3 and involucrin. The Cx43dim cells possessed a greater proliferative potential than Cx43bright cells and nonfractionated cells as evaluated by BrdU incorporation, colony-forming efficiency, and growth capacity. Our findings suggest that human limbal basal cells do not express connexin 43, which could serve as a negative cell surface marker for the stem cell-containing population of human limbal epithelial cells. PMID:16424398

Ganymede's Equatorial Region

NASA Technical Reports Server (NTRS)

1979-01-01

GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is south of PIA01516 (P21262) near the equator of Ganymede, and has relatively subdued colors in the visible part of the spectrum (later, scientists will analyze Voyager pictures taken in UV). The most striking features are the bright ray craters which have a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggest that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Suppression of cooling by strong magnetic fields in white dwarf stars.

PubMed

Valyavin, G; Shulyak, D; Wade, G A; Antonyuk, K; Zharikov, S V; Galazutdinov, G A; Plachinda, S; Bagnulo, S; Machado, L Fox; Alvarez, M; Clark, D M; Lopez, J M; Hiriart, D; Han, Inwoo; Jeon, Young-Beom; Zurita, C; Mujica, R; Burlakova, T; Szeifert, T; Burenkov, A

2014-11-06

Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs, which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magneto-optical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD 1953-011 taken over about eight years, and the results of an analysis of its surface temperature and magnetic field distribution. We find that the magnetic field suppresses atmospheric convection, leading to dark spots in the most magnetized areas. We also find that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarfs, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are. This explains the long-standing mystery of why magnetic fields are more common amongst cool white dwarfs, and implies that the currently accepted ages of strongly magnetic white dwarfs are systematically too young.

Low-Latitude Ethane Rain on Titan

NASA Technical Reports Server (NTRS)

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

2012-01-01

Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

SMOS/SMAP Synergy for SMAP Level 2 Soil Moisture Algorithm Evaluation

NASA Technical Reports Server (NTRS)

Bindlish, Rajat; Jackson, Thomas J.; Zhao, Tianjie; Cosh, Michael; Chan, Steven; O'Neill, Peggy; Njoku, Eni; Colliander, Andreas; Kerr, Yann

2011-01-01

Soil Moisture Active Passive (SMAP) satellite has been proposed to provide global measurements of soil moisture and land freeze/thaw state at 10 km and 3 km resolutions, respectively. SMAP would also provide a radiometer-only soil moisture product at 40-km spatial resolution. This product and the supporting brightness temperature observations are common to both SMAP and European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission. As a result, there are opportunities for synergies between the two missions. These include exploiting the data for calibration and validation and establishing longer term L-band brightness temperature and derived soil moisture products. In this investigation we will be using SMOS brightness temperature, ancillary data, and soil moisture products to develop and evaluate a candidate SMAP L2 passive soil moisture retrieval algorithm. This work will begin with evaluations based on the SMOS product grids and ancillary data sets and transition to those that will be used by SMAP. An important step in this analysis is reprocessing the multiple incidence angle observations provided by SMOS to a global brightness temperature product that simulates the constant 40 degree incidence angle observations that SMAP will provide. The reprocessed brightness temperature data provide a basis for evaluating different SMAP algorithm alternatives. Several algorithms are being considered for the SMAP radiometer-only soil moisture retrieval. In this first phase, we utilized only the Single Channel Algorithm (SCA), which is based on the radiative transfer equation and uses the channel that is most sensitive to soil moisture (H-pol). Brightness temperature is corrected sequentially for the effects of temperature, vegetation, roughness (dynamic ancillary data sets) and soil texture (static ancillary data set). European Centre for Medium-Range Weather Forecasts (ECMWF) estimates of soil temperature for the top layer (as provided as part of the SMOS ancillary data) were used to correct for surface temperature effects and to derive microwave emissivity. ECMWF data were also used for precipitation forecasts, presence of snow, and frozen ground. Vegetation options are described below. One year of soil moisture observations from a set of four watersheds in the U.S. were used to evaluate four different retrieval methodologies: (1) SMOS soil moisture estimates (version 400), (2) SeA soil moisture estimates using the SMOS/SMAP data with SMOS estimated vegetation optical depth, which is part of the SMOS level 2 product, (3) SeA soil moisture estimates using the SMOS/SMAP data and the MODIS-based vegetation climatology data, and (4) SeA soil moisture estimates using the SMOS/SMAP data and actual MODIS observations. The use of SMOS real-world global microwave observations and the analyses described here will help in the development and selection of different land surface parameters and ancillary observations needed for the SMAP soil moisture algorithms. These investigations will greatly improve the quality and reliability of this SMAP product at launch.

Daytime exposure to bright light, as compared to dim light, decreases sleepiness and improves psychomotor vigilance performance.

PubMed

Phipps-Nelson, Jo; Redman, Jennifer R; Dijk, Derk-Jan; Rajaratnam, Shantha M W

2003-09-01

This study examined the effects of bright light exposure, as compared to dim light, on daytime subjective sleepiness, incidences of slow eye movements (SEMs), and psychomotor vigilance task (PVT) performance following 2 nights of sleep restriction. The study had a mixed factorial design with 2 independent variables: light condition (bright light, 1,000 lux; dim light, < 5 lux) and time of day. The dependent variables were subjective sleepiness, PVT performance, incidences of SEMs, and salivary melatonin levels. Sleep research laboratory at Monash University. Sixteen healthy adults (10 women and 6 men) aged 18 to 35 years (mean age 25 years, 3 months). Following 2 nights of sleep restriction (5 hours each night), participants were exposed to modified constant routine conditions. Eight participants were exposed to bright light from noon until 5:00 pm. Outside the bright light exposure period (9:00 am to noon, 5:00 pm to 9:00 pm) light levels were maintained at less than 5 lux. A second group of 8 participants served as controls for the bright light exposure and were exposed to dim light throughout the entire protocol. Bright light exposure reduced subjective sleepiness, decreased SEMs, and improved PVT performance compared to dim light. Bright lights had no effect on salivary melatonin. A significant positive correlation between PVT reaction times and subjective sleepiness was observed for both groups. Changes in SEMs did not correlate significantly with either subjective sleepiness or PVT performance. Daytime bright light exposure can reduce the impact of sleep loss on sleepiness levels and performance, as compared to dim light. These effects appear to be mediated by mechanisms that are separate from melatonin suppression. The results may assist in the development of treatments for daytime sleepiness.

THE ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: IMPLICATIONS FOR SPECTRAL LINE INTENSITY MAPPING AT MILLIMETER WAVELENGTHS AND CMB SPECTRAL DISTORTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carilli, C. L.; Walter, F.; Chluba, J.

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C ii]more » 158 μ m line emission from very high redshift galaxies ( z  ∼ 6–7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T{sub B}  = 0.94 ± 0.09 μ K. In the 242 GHz band, the mean brightness is: T{sub B}  = 0.55 ± 0.033 μ K. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.« less

Global Monitoring of Martian Surface Albedo Changes from Orbital Observations

NASA Astrophysics Data System (ADS)

Geissler, P.; Enga, M.; Mukherjee, P.

2013-12-01

Martian surface changes were first observed from orbit during the Mariner 9 and Viking Orbiter missions. They were found to be caused by eolian processes, produced by deposition of dust during regional and global dust storms and subsequent darkening of the surface through erosion and transportation of dust and sand. The albedo changes accumulated in the 20 years between Viking and Mars Global Surveyor were sufficient to alter the global circulation of winds and the climate of Mars according to model calculations (Fenton et al., Nature 2007), but little was known about the timing or frequency of the changes. Since 1999, we have had the benefit of continuous monitoring by a series of orbiting spacecraft that continues today with Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Express. Daily synoptic observations enable us to determine whether the surface albedo changes are gradual or episodic in nature and to record the seasons that the changes take place. High resolution images of surface morphology and atmospheric phenomena help identify the physical mechanisms responsible for the changes. From these data, we hope to learn the combinations of atmospheric conditions and sediment properties that produce surface changes on Mars and possibly predict when they will take place in the future. Martian surface changes are particularly conspicuous in low albedo terrain, where even a thin layer of bright dust brightens the surface drastically. Equatorial dark areas are repeatedly coated and recoated by dust, which is later shed from the surface by a variety of mechanisms. An example is Syrtis Major, suddenly buried in bright dust by the global dust storm of 2001. Persistent easterly winds blew much of the dust cover away over the course of the next Martian year, but episodic changes continue today, particularly during southern summer when regional dust storms are rife. Another such region is Solis Planum, south of the Valles Marineris, where changes take place relentlessly in all seasons as bright dust and dark sand battle to dominate the landscape. Elsewhere, gradual processes steadily shift albedo boundaries between bright and dark terrain. Dark terrain near the Spirit rover landing site is gradually spreading to the north, driven by seasonal southerly winds. A bright fringe of newly deposited dust appears ahead of the moving boundary, populated by wind streaks and dust avalanches. Dark terrain at higher latitudes gradually creeps towards the equator by the dust cleaning action of dust devils, for example at Nilosytis (43°N, 85°E). Much less obvious is the deposition and erosion of dust on already bright, dust-covered terrain. Changes in the distribution of fresh dust take place frequently in the region surrounding the Tharsis Montes. Dust in this high altitude zone is constantly on the move as faint dark streaks mark the removal of recently deposited dust that is only slightly brighter than the dust already settled on the surface. Dramatic deposition of dust onto dusty terrain took place at much lower elevations in northwestern Amazonis between 2002 and 2005. Since then, the dust has been energetically eroded by towering dust devils that cluster here each summer.

Coastal retracking using along-track echograms and its dependency on coastal topography

NASA Astrophysics Data System (ADS)

Ichikawa, K.; Wang, X.

2017-12-01

Although the Brown mathematical model is the standard model for waveform retracking over open oceans, coastal waveforms usually deviate from open ocean waveform shapes due to inhomogeneous surface reflections within altimeter footprints, and thus cannot be directly interpreted by the Brown model. Generally, the two primary sources of heterogeneous surface reflections are land surfaces and bright targets such as calm surface water. The former reduces echo power, while the latter often produces particularly strong echoes. In previous studies, sub-waveform retrackers, which use waveform samples collected from around leading edges in order to avoid trailing edge noise, have been recommended for coastal waveform retracking. In the present study, the peaky-type noise caused by fixed-point bright targets is explicitly detected and masked using the parabolic signature in the sequential along-track waveforms (or, azimuth-range echograms). Moreover, the power deficit of waveform trailing edges caused by weak land reflections is compensated for by estimating the ratio of sea surface area within each annular footprint in order to produce pseudo-homogeneous reflected waveforms suitable for the Brown model. Using this method, Jason-2 altimeter waveforms are retracked in several coastal areas. Our results show that both the correlation coefficient and root mean square difference between the derived sea surface height anomalies and tide gauge records retain similar values at the open ocean (0.9 and 20 cm) level, even in areas approaching 3 km from coastlines, which is considerably improved from the 10 km correlation coefficient limit of the conventional MLE4 retracker and the 7 km sub-waveform ALES retracker limit. These values, however, depend on the coastal topography of the study areas because the approach distance limit increases (decreases) in areas with complicated (straight) coastlines

Triton - Scattering models and surface/atmosphere constraints

NASA Technical Reports Server (NTRS)

Thompson, W. Reid

1989-01-01

Modeling of Triton's spectrum indicates a bright scattering layer of optical depth tau about 3 overlying an optically deep layer of CH4 with high absorption and little scattering. UV absorption in the spectrum indicates tau about 0.3 of red-yellow haze, although some color may also arise from complex organics partially visible on the surface. An analysis of this and other (spectro)photometric evidence indicates that Triton most likely has a bright surface, which was partially visible in 1977-1980. Geometric albedo p = 0.62 + 0.18 or - 0.12 radius r = 1480 + or - 180 km, and temperature T = 48 + or - 6 K. With scattering optical depths of 0.3-3 and about 1-10 mb of N2, a Mars-like atmospheric density and surface visibility pertain.

Near-infrared scattering as a dust diagnostic

NASA Astrophysics Data System (ADS)

Saajasto, Mika; Juvela, Mika; Malinen, Johanna

2018-06-01

Context. Regarding the evolution of dust grains from diffuse regions of space to dense molecular cloud cores, many questions remain open. Scattering at near-infrared wavelengths, or "cloudshine", can provide information on cloud structure, dust properties, and the radiation field that is complementary to mid-infrared "coreshine" and observations of dust emission at longer wavelengths. Aims: We examine the possibility of using near-infrared scattering to constrain the local radiation field and the dust properties, the scattering and absorption efficiency, the size distribution of the grains, and the maximum grain size. Methods: We use radiative transfer modelling to examine the constraints provided by the J, H, and K bands in combination with mid-infrared surface brightness at 3.6 μm. We use spherical one-dimensional and elliptical three-dimensional cloud models to study the observable effects of different grain size distributions with varying absorption and scattering properties. As an example, we analyse observations of a molecular cloud in Taurus, TMC-1N. Results: The observed surface brightness ratios of the bands change when the dust properties are changed. However, even a change of ±10% in the surface brightness of one band changes the estimated power-law exponent of the size distribution γ by up to 30% and the estimated strength of the radiation field KISRF by up to 60%. The maximum grain size Amax and γ are always strongly anti-correlated. For example, overestimating the surface brightness by 10% changes the estimated radiation field strength by 20% and the exponent of the size distribution by 15%. The analysis of our synthetic observations indicates that the relative uncertainty of the parameter distributions are on average Amax, γ 25%, and the deviation between the estimated and correct values ΔQ < 15%. For the TMC-1N observations, a maximum grain size Amax > 1.5μm and a size distribution with γ > 4.0 have high probability. The mass weighted average grain size is ⟨am⟩ = 0.113μm. Conclusions: We show that scattered infrared light can be used to derive meaningful limits for the dust parameters. However, errors in the surface brightness data can result in considerable uncertainties on the derived parameters.

Venus - 3D Perspective View of Latona Corona and Dali Chasma

NASA Technical Reports Server (NTRS)

1992-01-01

This computer-generated perspective view of Latona Corona and Dali Chasma on Venus shows Magellan radar data superimposed on topography. The view is from the northeast and vertical exaggeration is 10 times. Exaggeration of relief is a common tool scientists use to detect relationships between structure (i.e. faults and fractures) and topography. Latona Corona, a circular feature approximately 1,000 kilometers (620 miles) in diameter whose eastern half is shown at the left of the image, has a relatively smooth, radar-bright raised rim. Bright lines or fractures within the corona appear to radiate away from its center toward the rim. The rest of the bright fractures in the area are associated with the relatively deep (approximately 3 kilometers or 1.9 miles) troughs of Dali Chasma. The Dali and Diana Chasma system consist of deep troughs that extend for 7,400 kilometers (4,588 miles) and are very distinct features on Venus. Those chasma connect the Ovda and Thetis highlands with the large volcanoes at Atla Regio and thus are considered to be the 'Scorpion Tail' of Aphrodite Terra. The broad, curving scarp resembles some of Earth's subduction zones where crustal plates are pushed over each other. The radar-bright surface at the highest elevation along the scarp is similar to surfaces in other elevated regions where some metallic mineral such as pyrite (fool's gold) may occur on the surface.

From 20 cm - 1 micron: Measuring the Gas and Dust in Massive Low Surface Brightness Galaxies

NASA Astrophysics Data System (ADS)

Kearsley, E.; O'Neil, K.

2005-12-01

Archival data from the IRAS, 2MASS, NVSS, and FIRST catalogs, supplemented with new measurements of HI, are used to analyze the relationship between the relative mass of the various components of galaxies (stars, atomic hydrogen, dust, and molecular gas) using a small sample of nearby (z<0.1), massive low surface brightness galaxies. The sample is compared to three sets of published data: a large collection of radio sources from the UGC having a radio continuum intensity >2.5 mJy (Condon, Cotton, & Broderick 2002 AJ 124, 675) ; a smaller sample of low surface brightness galaxies (Galaz, et al 2002 2002 AJ 124, 1360); and a collection of NIR low surface brightness galaxies (Monnier-Ragaigne, et al 2002 Ap&SS 281, 145). Overall, our sample properties are similar to the comparison samples in regard to NIR color, gas, stellar, and dynamic mass ratios, etc. Based off the galaxies' q-value (determined from the FIR/1.4 GHz ratio), it appears likely that at least two of the 28 galaxies studied harbor AGN. Notably, we also find that if we naively assume the ratio of the dust and molecular gas mass relative to the mass of HI is a constant we are unable to predict the observed ratio of stellar mass to HI mass, indicating that the HI mass ratio is a poor indicator of the total baryonic mass in the studied galaxies. HI measurements obtained during this study using the Green Bank Telescope also provide a correction to the velocity of UGC 11068.

BEYOND 31 mag arcsec{sup −2}: THE FRONTIER OF LOW SURFACE BRIGHTNESS IMAGING WITH THE LARGEST OPTICAL TELESCOPES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trujillo, Ignacio; Fliri, Jüergen, E-mail: trujillo@iac.es; Departamento de Astrofísica, Universidad de La Laguna, E-38206, La Laguna, Tenerife

2016-06-01

The detection of structures in the sky with optical surface brightnesses fainter than 30 mag arcsec{sup −2} (3 σ in 10 × 10 arcsec boxes; r -band) has remained elusive in current photometric deep surveys. Here we show how present-day telescopes of 10 m class can provide broadband imaging 1.5–2 mag deeper than most previous results within a reasonable amount of time (i.e., <10 hr on-source integration). In particular, we illustrate the ability of the 10.4 m Gran Telescopio de Canarias telescope to produce imaging with a limiting surface brightness of 31.5 mag arcsec{sup −2} (3 σ in 10 ×more » 10 arcsec boxes; r -band) using 8.1 hr on source. We apply this power to explore the stellar halo of the galaxy UGC 00180, a galaxy analogous to M31 located at ∼150 Mpc, by obtaining a radial profile of surface brightness down to μ{sub r} ∼ 33 mag arcsec{sup −2}. This depth is similar to that obtained using the star-counts techniques for Local Group galaxies, but is achieved at a distance where this technique is unfeasible. We find that the mass of the stellar halo of this galaxy is ∼4 × 10{sup 9} M {sub ⊙}, i.e., (3 ± 1)% of the total stellar mass of the whole system. This amount of mass in the stellar halo is in agreement with current theoretical expectations for galaxies of this kind.« less

49 CFR 213.337 - Defective rails.

Code of Federal Regulations, 2010 CFR

2010-10-01

... crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark... a smooth, bright, or dark surface progressing until substantially at a right angle to the length of... through it. A crack or rust streak may show under the head close to the web or pieces may be split off the...

49 CFR 213.337 - Defective rails.

Code of Federal Regulations, 2011 CFR

2011-10-01

... crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark... a smooth, bright, or dark surface progressing until substantially at a right angle to the length of... through it. A crack or rust streak may show under the head close to the web or pieces may be split off the...

49 CFR 213.337 - Defective rails.

Code of Federal Regulations, 2013 CFR

2013-10-01

... crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark... a smooth, bright, or dark surface progressing until substantially at a right angle to the length of... through it. A crack or rust streak may show under the head close to the web or pieces may be split off the...

49 CFR 213.337 - Defective rails.

Code of Federal Regulations, 2012 CFR

2012-10-01

... crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark... a smooth, bright, or dark surface progressing until substantially at a right angle to the length of... through it. A crack or rust streak may show under the head close to the web or pieces may be split off the...

49 CFR 213.337 - Defective rails.

Code of Federal Regulations, 2014 CFR

2014-10-01

... crystalline center or nucleus inside the head from which it spreads outward as a smooth, bright, or dark... a smooth, bright, or dark surface progressing until substantially at a right angle to the length of... through it. A crack or rust streak may show under the head close to the web or pieces may be split off the...

Correction of WindScat Scatterometric Measurements by Combining with AMSR Radiometric Data

NASA Technical Reports Server (NTRS)

Song, S.; Moore, R. K.

1996-01-01

The Seawinds scatterometer on the advanced Earth observing satellite-2 (ADEOS-2) will determine surface wind vectors by measuring the radar cross section. Multiple measurements will be made at different points in a wind-vector cell. When dense clouds and rain are present, the signal will be attenuated, thereby giving erroneous results for the wind. This report describes algorithms to use with the advanced mechanically scanned radiometer (AMSR) scanning radiometer on ADEOS-2 to correct for the attenuation. One can determine attenuation from a radiometer measurement based on the excess brightness temperature measured. This is the difference between the total measured brightness temperature and the contribution from surface emission. A major problem that the algorithm must address is determining the surface contribution. Two basic approaches were developed for this, one using the scattering coefficient measured along with the brightness temperature, and the other using the brightness temperature alone. For both methods, best results will occur if the wind from the preceding wind-vector cell can be used as an input to the algorithm. In the method based on the scattering coefficient, we need the wind direction from the preceding cell. In the method using brightness temperature alone, we need the wind speed from the preceding cell. If neither is available, the algorithm can work, but the corrections will be less accurate. Both correction methods require iterative solutions. Simulations show that the algorithms make significant improvements in the measured scattering coefficient and thus is the retrieved wind vector. For stratiform rains, the errors without correction can be quite large, so the correction makes a major improvement. For systems of separated convective cells, the initial error is smaller and the correction, although about the same percentage, has a smaller effect.

Stellar systems in the direction of the Hickson Compact Group 44. I. Low surface brightness galaxies

NASA Astrophysics Data System (ADS)

Smith Castelli, A. V.; Faifer, F. R.; Escudero, C. G.

2016-11-01

Context. In spite of the numerous studies of low-luminosity galaxies in different environments, there is still no consensus about their formation scenario. In particular, a large number of galaxies displaying extremely low-surface brightnesses have been detected in the last year, and the nature of these objects is under discussion. Aims: In this paper we report the detection of two extended low-surface brightness (LSB) objects (μeffg' ≃ 27 mag) found, in projection, next to NGC 3193 and in the zone of the Hickson Compact Group (HCG) 44, respectively. Methods: We analyzed deep, high-quality, GEMINI-GMOS images with ELLIPSE within IRAF in order to obtain their brightness profiles and structural parameters. We also searched for the presence of globular clusters (GC) in these fields. Results: We have found that, if these LSB galaxies were at the distances of NGC 3193 and HCG 44, they would show sizes and luminosities similar to those of the ultra-diffuse galaxies (UDGs) found in the Coma cluster and other associations. In that case, their sizes would be rather larger than those displayed by the Local Group dwarf spheroidal (dSph) galaxies. We have detected a few unresolved sources in the sky zone occupied by these galaxies showing colors and brightnesses typical of blue globular clusters. Conclusions: From the comparison of the properties of the galaxies presented in this work with those of similar objects reported in the literature, we have found that LSB galaxies display sizes covering a quite extended continous range (reff 0.3-4.5 kpc), in contrast to "normal" early-type galaxies, which show reff 1.0 kpc with a low dispersion. This fact might point to different formation processes for both types of galaxies.

Atmospheric transformation of solar radiation reflected from the ocean

NASA Technical Reports Server (NTRS)

Malkevich, M. S.; Istomina, L. G.; Hovis, W. A., Jr.

1977-01-01

Airborne measurements of the brightness spectrum of the Atlantic Ocean in the wavelength region from 0.4 to 0.7 micron are analyzed. These measurements were made over a tropical region of the Atlantic from an aircraft at heights of 0.3 and 10.5 km during the TROPEX-72 experiment. The results are used to estimate the contribution of the atmosphere to the overall brightness of the ocean-atmosphere system. It is concluded that: (1) the atmosphere decreases the absolute brightness of the ocean by a factor of 5 to 10 and also strongly affects the spectral behavior of solar radiation reflected from the ocean surface; (2) the atmospheric contribution to overall brightness may vary considerably under real conditions; (3) finely dispersed particles and Rayleigh scattering affect the spectral distribution of solar radiation; and (4) the spectral composition of ocean-atmosphere brightness may be completely governed by the atmosphere.

Chemical abundances in low surface brightness galaxies: Implications for their evolution

NASA Technical Reports Server (NTRS)

Mcgaugh, S. S.; Bothun, G. D.

1993-01-01

Low Surface Brightness (LSB) galaxies are an important but often neglected part of the galaxy content of the universe. Their importance stems both from the selection effects which cause them to be under-represented in galaxy catalogs, and from what they can tell us about the physical processes of galaxy evolution that has resulted in something other than the traditional Hubble sequence of spirals. An important constraint for any evolutionary model is the present day chemical abundances of LSB disks. Towards this end, spectra for a sample of 75 H 2 regions distributed in 20 LSB disks galaxies were obtained. Structurally, this sample is defined as having B(0) fainter than 23.0 mag arcsec(sup -2) and scale lengths that cluster either around 3 kpc or 10 kpc. In fact, structurally, these galaxies are very similar to the high surface brightness spirals which define the Hubble sequence. Thus, our sample galaxies are not dwarf galaxies but instead have masses comparable to or in excess of the Milky Way. The basic results from these observations are summarized.

Ceres During Opposition Surge.

NASA Image and Video Library

2017-05-16

NASA's Dawn spacecraft successfully observed Ceres at opposition on April 29, 2017, taking images from a position exactly between the sun and Ceres' surface. Mission specialists had carefully maneuvered Dawn into a special orbit so that the spacecraft could view Occator Crater, which contains the brightest area of Ceres, from this new perspective. A movie shows these opposition images, with contrast enhanced to highlight brightness differences. The bright spots of Occator stand out particularly well on an otherwise relatively bland surface. Dawn took these images from an altitude of about 12,000 miles (20,000 kilometers). Based on data from ground-based telescopes and spacecraft that have previously viewed planetary bodies at opposition, scientists predicted that Ceres would appear brighter from this opposition configuration. This increase in brightness, or "surge," relates the size of the grains of material on the surface, as well as how porous those materials are. The science motivation for performing these observations is further explained in the March 2017 issue of the Dawn Journal blog. A movie can be viewed at https://photojournal.jpl.nasa.gov/catalog/PIA21405

Constraints as a destriping tool for Hires images

NASA Technical Reports Server (NTRS)

Cao, YU; Prince, Thomas A.

1994-01-01

Images produced from the Maximum Correlation Method sometimes suffer from visible striping artifacts, especially for areas of extended sources. Possible causes are different baseline levels and calibration errors in the detectors. We incorporated these factors into the MCM algorithm, and tested the effects of different constraints on the output image. The result shows significant visual improvement over the standard MCM Method. In some areas the new images show intelligible structures that are otherwise corrupted by striping artifacts, and the removal of these artifacts could enhance performance of object classification algorithms. The constraints were also tested on low surface brightness areas, and were found to be effective in reducing the noise level.

Femtogram-level detection of Clostridium botulinum neurotoxin type A by sandwich immunoassay using nanoporous substrate and ultra-bright fluorescent suprananoparticles.

PubMed

Bok, Sangho; Korampally, Venumadhav; Darr, Charles M; Folk, William R; Polo-Parada, Luis; Gangopadhyay, Keshab; Gangopadhyay, Shubhra

2013-03-15

We report a simple, robust fluorescence biosensor for the ultra-sensitive detection of Clostridium botulinum Neurotoxin Type A (BoNT/A) in complex, real-world media. High intrinsic signal amplification was achieved through the combined use of ultra-bright, photostable dye-doped nanoparticle (DOSNP) tags and high surface area nanoporous organosilicate (NPO) thin films. DOSNP with 22 nm diameter were synthesized with more than 200 times equivalent free dye fluorescence and conjugated to antibodies with average degree of substitution of 90 dyes per antibody, representing an order of magnitude increase compared with conventional dye-labeled antibodies. The NPO films were engineered to form constructive interference at the surface where fluorophores were located. In addition, DOSNP-labeled antibodies with NPO films increased surface roughness causing diffuse scattering resulting in 24% more scattering intensity than dye-labeled antibody with NPO films. These substrates were used for immobilization of capture antibodies against BoNT/A, which was further quantified by DOSNP-labeled signal antibodies. The combination of optical effects enhanced the fluorescence and, therefore, the signal-to-noise ratio significantly. BoNT/A was detected in PBS buffer down to 21.3 fg mL(-1) in 4 h. The assay was then extended to several complex media and the four-hour detection limit was found to be 145.8 fg mL(-1) in orange juice and 164.2 fg mL(-1) in tap water, respectively, demonstrating at least two orders of magnitude improvement comparing to the reported detection limit of other enzyme-linked immunosorbent assays (ELISA). This assay, therefore, demonstrates a novel method for rapid, ultra-low level detection of not only BoNT/A, but other analytes as well. Copyright © 2012 Elsevier B.V. All rights reserved.

Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

2016-01-01

Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

Rosette globulettes and shells in the infrared

NASA Astrophysics Data System (ADS)

Mäkelä, M. M.; Haikala, L. K.; Gahm, G. F.

2014-07-01

Context. Giant galactic H ii regions surrounding central young clusters show compressed molecular shells, which have broken up into clumps, filaments, and elephant trunks interacting with UV light from central OB stars. Tiny, dense clumps of subsolar mass, called globulettes, form in this environment. Aims: We observe and explore the nature and origin of the infrared emission and extinction in these cool, dusty shell features and globulettes in one H ii region, the Rosette nebula, and search for associated newborn stars. Methods: We imaged the northwestern quadrant of the Rosette nebula in the near-infrared (NIR) through wideband JHKs filters and narrowband H2 1-0 S(1) and Pβ plus continuum filters using the Son of Isaac (SOFI) instrument at the New Technology Telescope (NTT) at European Southern Observatory (ESO). We used the NIR images to study the surface brightness of the globulettes and associated bright rims. We used the NIR JHKs photometry to create a visual extinction map and to search for objects with NIR excess emission. In addition, archival images from Spitzer Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) 24 μm and Herschel Photoconductor Array Camera and Spectrometer (PACS) observations, covering several bands in the mid-infrared and far-infrared, were used to further analyze the stellar population, to examine the structure of the trunks and other shell structures and to study this Rosette nebula photon-dominated region in more detail. Results: The globulettes and elephant trunks have bright rims in the Ks band, which are unresolved in our images, on the sides facing the central cluster. An analysis of 21 globulettes, where surface brightness in the H2 1-0 S(1) line at 2.12 μm is detected, shows that approximately a third of the surface brightness observed in the Ks filter is due to this line: the observed average of the H2/Ks surface brightness is 0.26 ± 0.02 in the globulettes' cores and 0.30 ± 0.01 in the rims. The estimated H2 1-0 S(1) surface brightness of the rims is ˜3-8 × 10-8 Wm-2 sr-1μm-1. The ratio of the surface brightnesses support fluorescence instead of shocks as the H2 excitation mechanism. The globulettes have number densities of n(H2) ˜ 10-4 cm-3 or higher. We estimated masses of individual globulettes and compared them to the results from previous optical and radio molecular line surveys. We confirm that the larger globulettes contain very dense cores, that the density is also high farther out from the core, and that their mass is subsolar. Two NIR protostellar objects were found in an elephant trunk and one was found in the most massive globulette in our study. Based on observations done at the European Southern Observatory, La Silla, Chile (ESO programmes 084.C-0299 and 088.C-0630).Appendix A is only available in electronic form at http://www.aanda.orgTables 5 and 6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A108

On the Response of the Special Sensor Microwave/Imager to the Marine Environment: Implications for Atmospheric Parameter Retrievals. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Petty, Grant W.

1990-01-01

A reasonably rigorous basis for understanding and extracting the physical information content of Special Sensor Microwave/Imager (SSM/I) satellite images of the marine environment is provided. To this end, a comprehensive algebraic parameterization is developed for the response of the SSM/I to a set of nine atmospheric and ocean surface parameters. The brightness temperature model includes a closed-form approximation to microwave radiative transfer in a non-scattering atmosphere and fitted models for surface emission and scattering based on geometric optics calculations for the roughened sea surface. The combined model is empirically tuned using suitable sets of SSM/I data and coincident surface observations. The brightness temperature model is then used to examine the sensitivity of the SSM/I to realistic variations in the scene being observed and to evaluate the theoretical maximum precision of global SSM/I retrievals of integrated water vapor, integrated cloud liquid water, and surface wind speed. A general minimum-variance method for optimally retrieving geophysical parameters from multichannel brightness temperature measurements is outlined, and several global statistical constraints of the type required by this method are computed. Finally, a unified set of efficient statistical and semi-physical algorithms is presented for obtaining fields of surface wind speed, integrated water vapor, cloud liquid water, and precipitation from SSM/I brightness temperature data. Features include: a semi-physical method for retrieving integrated cloud liquid water at 15 km resolution and with rms errors as small as approximately 0.02 kg/sq m; a 3-channel statistical algorithm for integrated water vapor which was constructed so as to have improved linear response to water vapor and reduced sensitivity to precipitation; and two complementary indices of precipitation activity (based on 37 GHz attenuation and 85 GHz scattering, respectively), each of which are relatively insensitive to variations in other environmental parameters.

A medium-bright quasar sample - New quasar surface densities in the magnitude range from 16.4 to 17.65 for B

NASA Technical Reports Server (NTRS)

Mitchell, K. J.; Warnock, A., III; Usher, P. D.

1984-01-01

A new medium-bright quasar sample (MBQS) is constructed from spectroscopic observations of 140 bright objects selected for varying degrees of blue and ultraviolet excess (B-UVX) in five Palomar 1.2 m Schmidt fields. The MBQS contains 32 quasars with B less than 17.65 mag. The new integral surface densities in the B range from 16.45 to 17.65 mag are approximately 40 percent (or more) higher than expected. The MBQS and its redshift distribution increase the area of the Hubble diagram covered by complete samples of quasars. The general spectroscopic results indicate that the three-color classification process used to catalog the spectroscopic candidates (1) has efficiently separated the intrinsically B-UVX stellar objects from the Population II subdwarfs and (2) has produced samples of B-UVX objects which are more complete than samples selected by (U - B) color alone.

Clusters in Formation - The Case of 3C61.1 and A Luminous AGN in a Merging Cluster

NASA Astrophysics Data System (ADS)

Kraft, Ralph

2017-09-01

We propose a Chandra investigation of the serendipitously detected cluster, X-CLASS 1835, that hosts the classical FRII radio source 3C61.1 as well as a radiatively efficient, X-ray bright AGN. The cluster exhibits a prominent surface brightness edge which suggests a merger and/or a major AGN outburst. The radio emission from 3C61.1 shows interaction with the hot cluster plasma. We will characterize the merger/outburst by measuring the properties of the surface brightness edge, study the interaction of the FRII radio source (its hotspots, jet, and cocoon) with the ICM, measure spectra of 3C61.1 (nucleus and hotspots) and the AGN to explore their physical properties, and measure the PV work from any detected cavities around 3C61.1 to compare to the radio power.

RESOLVE: A new algorithm for aperture synthesis imaging of extended emission in radio astronomy

NASA Astrophysics Data System (ADS)

Junklewitz, H.; Bell, M. R.; Selig, M.; Enßlin, T. A.

2016-02-01

We present resolve, a new algorithm for radio aperture synthesis imaging of extended and diffuse emission in total intensity. The algorithm is derived using Bayesian statistical inference techniques, estimating the surface brightness in the sky assuming a priori log-normal statistics. resolve estimates the measured sky brightness in total intensity, and the spatial correlation structure in the sky, which is used to guide the algorithm to an optimal reconstruction of extended and diffuse sources. During this process, the algorithm succeeds in deconvolving the effects of the radio interferometric point spread function. Additionally, resolve provides a map with an uncertainty estimate of the reconstructed surface brightness. Furthermore, with resolve we introduce a new, optimal visibility weighting scheme that can be viewed as an extension to robust weighting. In tests using simulated observations, the algorithm shows improved performance against two standard imaging approaches for extended sources, Multiscale-CLEAN and the Maximum Entropy Method.

Passive microwave sensing of soil moisture content: Soil bulk density and surface roughness

NASA Technical Reports Server (NTRS)

Wang, J. R.

1982-01-01

Microwave radiometric measurements over bare fields of different surface roughnesses were made at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz to study the frequency dependence as well as the possible time variation of surface roughness. The presence of surface roughness was found to increase the brightness temperature of soils and reduce the slope of regression between brightness temperature and soil moisture content. The frequency dependence of the surface roughness effect was relatively weak when compared with that of the vegetation effect. Radiometric time series observation over a given field indicated that field surface roughness might gradually diminish with time, especially after a rainfall or irrigation. This time variation of surface roughness served to enhance the uncertainty in remote soil moisture estimate by microwave radiometry. Three years of radiometric measurements over a test site revealed a possible inconsistency in the soil bulk density determination, which turned out to be an important factor in the interpretation of radiometric data.

Passive microwave sensing of soil moisture content - The effects of soil bulk density and surface roughness

NASA Technical Reports Server (NTRS)

Wang, J. R.

1983-01-01

Microwave radiometric measurements over bare fields of different surface roughness were made at frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz to study the frequency dependence, as well as the possible time variation, of surface roughness. An increase in surface roughness was found to increase the brightness temperature of soils and reduce the slope of regression between brightness temperature and soil moisture content. The frequency dependence of the surface roughness effect was relatively weak when compared with that of the vegetation effect. Radiometric time-series observations over a given field indicate that field surface roughness might gradually diminish with time, especially after a rainfall or irrigation. The variation of surface roughness increases the uncertainty of remote soil moisture estimates by microwave radiometry. Three years of radiometric measurements over a test site revealed a possible inconsistency in the soil bulk density determination, which is an important factor in the interpretation of radiometric data.

The nature of solar brightness variations

NASA Astrophysics Data System (ADS)

Shapiro, A. I.; Solanki, S. K.; Krivova, N. A.; Cameron, R. H.; Yeo, K. L.; Schmutz, W. K.

2017-09-01

Determining the sources of solar brightness variations1,2, often referred to as solar noise3, is important because solar noise limits the detection of solar oscillations3, is one of the drivers of the Earth's climate system4,5 and is a prototype of stellar variability6,7—an important limiting factor for the detection of extrasolar planets. Here, we model the magnetic contribution to solar brightness variability using high-cadence8,9 observations from the Solar Dynamics Observatory (SDO) and the Spectral And Total Irradiance REconstruction (SATIRE)10,11 model. The brightness variations caused by the constantly evolving cellular granulation pattern on the solar surface were computed with the Max Planck Institute for Solar System Research (MPS)/University of Chicago Radiative Magnetohydrodynamics (MURaM)12 code. We found that the surface magnetic field and granulation can together precisely explain solar noise (that is, solar variability excluding oscillations) on timescales from minutes to decades, accounting for all timescales that have so far been resolved or covered by irradiance measurements. We demonstrate that no other sources of variability are required to explain the data. Recent measurements of Sun-like stars by the COnvection ROtation and planetary Transits (CoRoT)13 and Kepler14 missions uncovered brightness variations similar to that of the Sun, but with a much wider variety of patterns15. Our finding that solar brightness variations can be replicated in detail with just two well-known sources will greatly simplify future modelling of existing CoRoT and Kepler as well as anticipated Transiting Exoplanet Survey Satellite16 and PLAnetary Transits and Oscillations of stars (PLATO)17 data.

The reports of thick discs' deaths are greatly exaggerated. Thick discs are NOT artefacts caused by diffuse scattered light

NASA Astrophysics Data System (ADS)

Comerón, S.; Salo, H.; Knapen, J. H.

2018-02-01

Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re-examine our results using a revised point spread function model that accounts for extended wings out to more than 2\\farcm5. We study the 3.6 μm images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface-brightness profiles of galaxies to model the central mass concentration - described by a Sérsic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below μ 26 mag arcsec-2. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc< 120 km s-1 - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up-bending breaks in face-on galaxies are caused by the superposition of a thin and a thick disc where the scale-length of the latter is the largest. Data of Figs. B.1 and C.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A5

Local stability of galactic discs in modified dynamics

NASA Astrophysics Data System (ADS)

Shenavar, Hossein; Ghafourian, Neda

2018-04-01

The local stability of stellar and fluid discs, under a new modified dynamical model, is surveyed by using WKB approximation. The exact form of the modified Toomre criterion is derived for both types of systems and it is shown that the new model is, in all situations, more locally stable than Newtonian model. In addition, it has been proved that the central surface density of the galaxies plays an important role in the local stability in the sense that low surface brightness (LSB) galaxies are more stable than high surface brightness (HSBs). Furthermore, the growth rate in the new model is found to be lower than the Newtonian one. We found that, according to this model, the local instability is related to the ratio of surface density of the disc to a critical surface density Σcrit. We provide observational evidence to support this result based on star formation rate in HSBs and LSBs.

Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron

NASA Astrophysics Data System (ADS)

Johnson, Michael D.; Kovalev, Yuri Y.; Gwinn, Carl R.; Gurvits, Leonid I.; Narayan, Ramesh; Macquart, Jean-Pierre; Jauncey, David L.; Voitsik, Peter A.; Anderson, James M.; Sokolovsky, Kirill V.; Lisakov, Mikhail M.

2016-03-01

Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C 273 on interferometric baselines up to 171,000 km suggest brightness temperatures exceeding expected limits from the “inverse-Compton catastrophe” by two orders of magnitude. We show that at 18 cm, these estimates most likely arise from refractive substructure introduced by scattering in the interstellar medium. We use the scattering properties to estimate an intrinsic brightness temperature of 7× {10}12 {{K}}, which is consistent with expected theoretical limits, but which is ˜15 times lower than estimates that neglect substructure. At 6.2 cm, the substructure influences the measured values appreciably but gives an estimated brightness temperature that is comparable to models that do not account for the substructure. At 1.35 {{cm}}, the substructure does not affect the extremely high inferred brightness temperatures, in excess of {10}13 {{K}}. We also demonstrate that for a source having a Gaussian surface brightness profile, a single long-baseline estimate of refractive substructure determines an absolute minimum brightness temperature, if the scattering properties along a given line of sight are known, and that this minimum accurately approximates the apparent brightness temperature over a wide range of total flux densities.

Bolivia

Atmospheric Science Data Center

2013-04-18

... in brightness between them. Varying degrees of surface moisture around the two playas are illustrated by the different display ... angular composites contain information relating to surface moisture and/or texture characteristics that are not apparent with a single ...

The formation of giant low surface brightness galaxies

NASA Technical Reports Server (NTRS)

Hoffman, Yehuda; Silk, Joseph; Wyse, Rosemary F. G.

1992-01-01

It is demonstrated that the initial structure of galaxies can be strongly affected by their large-scale environments. In particular, rare (about 3 sigma) massive galaxies in voids will have normal bulges, but unevolved, extended disks; it is proposed that the low surface brightness objects Malin I and Malin II are prototypes of this class of object. The model predicts that searches for more examples of 'crouching giants' should be fruitful, but that such galaxies do not provide a substantial fraction of mass in the universe. The identification of dwarf galaxies is relatively unaffected by their environment.

K-band observations of boxy bulges - I. Morphology and surface brightness profiles

NASA Astrophysics Data System (ADS)

Bureau, M.; Aronica, G.; Athanassoula, E.; Dettmar, R.-J.; Bosma, A.; Freeman, K. C.

2006-08-01

In this first paper of a series on the structure of boxy and peanut-shaped (B/PS) bulges, Kn-band observations of a sample of 30 edge-on spiral galaxies are described and discussed. Kn-band observations best trace the dominant luminous galactic mass and are minimally affected by dust. Images, unsharp-masked images, as well as major-axis and vertically summed surface brightness profiles are presented and discussed. Galaxies with a B/PS bulge tend to have a more complex morphology than galaxies with other bulge types, more often showing centred or off-centred X structures, secondary maxima along the major-axis and spiral-like structures. While probably not uniquely related to bars, those features are observed in three-dimensional N-body simulations of barred discs and may trace the main bar orbit families. The surface brightness profiles of galaxies with a B/PS bulge are also more complex, typically containing three or more clearly separated regions, including a shallow or flat intermediate region (Freeman Type II profiles). The breaks in the profiles offer evidence for bar-driven transfer of angular momentum and radial redistribution of material. The profiles further suggest a rapid variation of the scaleheight of the disc material, contrary to conventional wisdom but again as expected from the vertical resonances and instabilities present in barred discs. Interestingly, the steep inner region of the surface brightness profiles is often shorter than the isophotally thick part of the galaxies, itself always shorter than the flat intermediate region of the profiles. The steep inner region is also much more prominent along the major-axis than in the vertically summed profiles. Similarly to other recent work but contrary to the standard `bulge + disc' model (where the bulge is both thick and steep), we thus propose that galaxies with a B/PS bulge are composed of a thin concentrated disc (a disc-like bulge) contained within a partially thick bar (the B/PS bulge), itself contained within a thin outer disc. The inner disc likely formed secularly through bar-driven processes and is responsible for the steep inner region of the surface brightness profiles, traditionally associated with a classic bulge, while the bar is responsible for the flat intermediate region of the surface brightness profiles and the thick complex morphological structures observed. Those components are strongly coupled dynamically and are formed mostly of the same (disc) material, shaped by the weak but relentless action of the bar resonances. Any competing formation scenario for galaxies with a B/PS bulge, which represent at least 45 per cent of the local disc galaxy population, must explain equally well and self-consistently the above morphological and photometric properties, the complex gas and stellar kinematics observed, and the correlations between them.

LAMMR world data base documentation support and demonstrations

NASA Technical Reports Server (NTRS)

Chin, R.; Beaudet, P.

1980-01-01

The primary purpose of the World Surface Map is to provide the LAMMR subsystem with world surface type classifications that are used to set up LAMMR LEVEL II process control. This data base will be accessed solely by the LAMMR subsystem. The SCATT and ALT subsystems will access the data base indirectly through the T sub b (Brightness Temperature) Data Bank, where the surface types were updated from a priori to current classification, and where the surface types were organized on an orbital subtrack basis. The single most important factor in the design of the World Surface Maps is the ease of access to the information while the complexity of generating these maps is of lesser importance because their generation is a one-time, off-line process. The World Surface Map provides storage of information with a resolution of 7 km necessary to set flags concerning the earth's features with a different set of maps for each month of the year.

Implementation of an Ultra-Bright Thermographic Phosphor for Gas Turbine Engine Temperature Measurements

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Bencic, Timothy J.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.; Allison, Stephen W.; Beshears, David L.; Jenkins, Thomas P.; Heeg, Bauke; Howard, Robert P.;

Variations in Surface Texture of the North Polar Residual Cap of Mars

NASA Technical Reports Server (NTRS)

Milkovich, S. M.; Byrne, S.; Russell, P. S.

2011-01-01

The northern polar residual cap (NPRC) of Mars is a water ice deposit with a rough surface made up of pits, knobs, and linear depressions on scales of tens of meters. This roughness manifests as a series of bright mounds and dark hollows in visible images; these bright and dark patches have a characteristic wavelength and orientation. Spectral data indicate that the surface of the NPRC is composed of large-grained (and therefore old) water ice. Due to the presence of this old ice, it is thought that the NPRC is in a current state of net loss of material a result potentially at odds with impact crater statistics, which suggest ongoing deposition over the past 10-20 Kyr.

Estimation of surface temperature in remote pollution measurement experiments

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm has been developed for estimating the actual surface temperature by applying corrections to the effective brightness temperature measured by radiometers mounted on remote sensing platforms. Corrections to effective brightness temperature are computed using an accurate radiative transfer model for the 'basic atmosphere' and several modifications of this caused by deviations of the various atmospheric and surface parameters from their base model values. Model calculations are employed to establish simple analytical relations between the deviations of these parameters and the additional temperature corrections required to compensate for them. Effects of simultaneous variation of two parameters are also examined. Use of these analytical relations instead of detailed radiative transfer calculations for routine data analysis results in a severalfold reduction in computation costs.

The influence of thermal inertia on temperatures and frost stability on Triton

NASA Technical Reports Server (NTRS)

Spencer, John R.; Moore, Jeffrey M.

1992-01-01

It is presently argued, in view of (1) a thermal inertia model for the surface of Triton which (like previous ones) predicts a monotonic recession of permanent N2 deposits toward the poles and very little seasonal N2 frost in the southern hemisphere, and (2) new spectroscopic evidence for nonvolatile CO2 on Triton's bright southern hemisphere, that much of that bright southern material is not N2. Such bright southern hemisphere volatiles may allow the formation of seasonal frosts, thereby helping to explain the observed spectroscopic changes of Triton during the last decade.

Ultrahigh 6D-brightness electron beams for the light sources of the next generation

NASA Astrophysics Data System (ADS)

Habib, Fahim; Manahan, Grace G.; Scherkl, Paul; Heinemann, Thomas; Sheng, Z. M.; Bruhwiler, D. L.; Cary, J. R.; Rosenzweig, J. B.; Hidding, Bernhard

2017-10-01

The plasma photocathode mechanism (aka Trojan Horse) enables a path towards electron beams with nm-level normalized emittance and kA range peak currents, hence ultrahigh 5D-brightness. This ultrahigh 5D-brightness beams hold great prospects to realize laboratory scale free-electron-lasers. However, the GV/m-accelerating gradient in plasma accelerators leads to substantial energy chirp and spread. The large energy spread is a major show-stopper towards key application such as the free-electron-laser. Here we present a novel method for energy chirp compensation which takes advantage of tailored beam loading due to a second ``escort'' bunch released via plasma photocathode. The escort bunch reverses the accelerating field locally at the trapping position of the ultrahigh 5D-brightness beam. This induces a counter-clockwise rotation within the longitudinal phase space and allows to compensate the chirp completely. Analytical scaling predicts energy spread values below 0.01 percentage level. Ultrahigh 5D-brightness combined with minimized energy spread opens a path towards witness beams with unprecedented ultrahigh 6D-brightness.

Adaptive focusing of laser radiation onto a rough reflecting surface through the turbulent and nonlinear atmosphere

NASA Astrophysics Data System (ADS)

Vorontsov, Mikhail A.; Kolosov, Valeriy V.

2004-12-01

Target-in-the-loop (TIL) wave propagation geometry represents perhaps the most challenging case for adaptive optics applications that are related with maximization of irradiance power density on extended remotely located surfaces in the presence of dynamically changing refractive index inhomogeneities in the propagation medium. We introduce a TIL propagation model that uses a combination of the parabolic equation describing outgoing wave propagation, and the equation describing evolution of the mutual coherence function (MCF) for the backscattered (returned) wave. The resulting evolution equation for the MCF is further simplified by the use of the smooth refractive index approximation. This approximation enables derivation of the transport equation for the returned wave brightness function, analyzed here using method characteristics (brightness function trajectories). The equations for the brightness function trajectories (ray equations) can be efficiently integrated numerically. We also consider wavefront sensors that perform sensing of speckle-averaged characteristics of the wavefront phase (TIL sensors). Analysis of the wavefront phase reconstructed from Shack-Hartmann TIL sensor measurements shows that an extended target introduces a phase modulation (target-induced phase) that cannot be easily separated from the atmospheric turbulence-related phase aberrations. We also show that wavefront sensing results depend on the extended target shape, surface roughness, and the outgoing beam intensity distribution on the target surface.

MSFC Skylab contamination control systems mission evaluation

NASA Technical Reports Server (NTRS)

1974-01-01

Cluster external contamination control evaluation was made throughout the Skylab Mission. This evaluation indicated that contamination control measures instigated during the design, development, and operational phases of this program were adequate to reduce the general contamination environment external to the Cluster below the threshold senstivity levels for experiments and affected subsystems. Launch and orbit contamination control features included eliminating certain vents, rerouting vents for minimum contamination impact, establishing filters, incorporating materials with minimum outgassing characteristics and developing operational constraints and mission rules to minimize contamination effects. Prior to the launch of Skylab, contamination control math models were developed which were used to predict Cluster surface deposition and background brightness levels throughout the mission. The report summarizes the Skylab system and experiment contamination control evaluation. The Cluster systems and experiments evaluated include Induced Atmosphere, Corollary and ATM Experiments, Thermal Control Surfaces, Solar Array Systems, Windows and Star Tracker.

Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging

PubMed Central

Reisch, Andreas; Klymchenko, Andrey S.

2017-01-01

Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ~10-fold for comparable size and start reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed. PMID:26901678

The Dragonfly Nearby Galaxies Survey. IV. A Giant Stellar Disk in NGC 2841

NASA Astrophysics Data System (ADS)

Zhang, Jielai; Abraham, Roberto; van Dokkum, Pieter; Merritt, Allison; Janssens, Steven

2018-03-01

Neutral gas is commonly believed to dominate over stars in the outskirts of galaxies, and investigations of the disk-halo interface are generally considered to be in the domain of radio astronomy. This may simply be a consequence of the fact that deep H I observations typically probe to a lower-mass surface density than visible wavelength data. This paper presents low-surface-brightness, optimized visible wavelength observations of the extreme outskirts of the nearby spiral galaxy NGC 2841. We report the discovery of an enormous low-surface brightness stellar disk in this object. When azimuthally averaged, the stellar disk can be traced out to a radius of ∼70 kpc (5 R 25 or 23 inner disk scale lengths). The structure in the stellar disk traces the morphology of H I emission and extended UV emission. Contrary to expectations, the stellar mass surface density does not fall below that of the gas mass surface density at any radius. In fact, at all radii greater than ∼20 kpc, the ratio of the stellar mass to gas mass surface density is a constant 3:1. Beyond ∼30 kpc, the low-surface-brightness stellar disk begins to warp, which may be an indication of a physical connection between the outskirts of the galaxy and infall from the circumgalactic medium. A combination of stellar migration, accretion, and in situ star formation might be responsible for building up the outer stellar disk, but whatever mechanisms formed the outer disk must also explain the constant ratio between stellar and gas mass in the outskirts of this galaxy.

Extragalactic background light: a measurement at 400 nm using dark cloud shadow*†- I. Low surface brightness spectrophotometry in the area of Lynds 1642

NASA Astrophysics Data System (ADS)

Mattila, K.; Lehtinen, K.; Väisänen, P.; von Appen-Schnur, G.; Leinert, Ch.

2017-09-01

We present the method and observations for the measurement of the Extragalactic Background Light (EBL) utilizing the shadowing effect of a dark cloud. We measure the surface brightness difference between the opaque cloud core and its unobscured surroundings. In the difference the large atmospheric and Zodiacal light components are eliminated and the only remaining foreground component is the scattered starlight from the cloud itself. Although much smaller, its separation is the key problem in the method. For its separation we use spectroscopy. While the scattered starlight has the characteristic Fraunhofer lines and 400 nm discontinuity, the EBL spectrum is smooth and without these features. Medium resolution spectrophotometry at λ = 380-580 nm was performed with VLT/FORS at ESO of the surface brightness in and around the high-galactic-latitude dark cloud Lynds 1642. Besides the spectrum for the core with AV ≳ 15 mag, further spectra were obtained for intermediate-opacity cloud positions. They are used as proxy for the spectrum of the impinging starlight spectrum and to facilitate the separation of the scattered starlight (cf. Paper II; Mattila et al.). Our spectra reach a precision of ≲ 0.5 × 10-9 erg cm-2 s-1 sr-1 Å-1 as required to measure an EBL intensity in range of ˜1 to a few times 10-9 erg cm-2 s-1 sr-1 Å-1. Because all surface brightness components are measured using the same equipment, the method does not require unusually high absolute calibration accuracy, a condition that has been a problem for some previous EBL projects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagen, Lea M. Z.; Hagen, Alex; Seibert, Mark

We provide evidence that UGC 1382, long believed to be a passive elliptical galaxy, is actually a giant low surface brightness (GLSB) galaxy that rivals the archetypical GLSB Malin 1 in size. Like other GLSB galaxies, it has two components: a high surface brightness disk galaxy surrounded by an extended low surface brightness (LSB) disk. For UGC 1382, the central component is a lenticular system with an effective radius of 6 kpc. Beyond this, the LSB disk has an effective radius of ∼38 kpc and an extrapolated central surface brightness of ∼26 mag arcsec{sup 2}. Both components have a combinedmore » stellar mass of ∼8 × 10{sup 10} M {sub ⊙}, and are embedded in a massive (10{sup 10} M {sub ⊙}) low-density (<3 M {sub ⊙} pc{sup 2}) HI disk with a radius of 110 kpc, making this one of the largest isolated disk galaxies known. The system resides in a massive dark matter halo of at least 2 × 10{sup 12} M {sub ⊙}. Although possibly part of a small group, its low-density environment likely plays a role in the formation and retention of the giant LSB and HI disks. We model the spectral energy distributions and find that the LSB disk is likely older than the lenticular component. UGC 1382 has UV–optical colors typical of galaxies transitioning through the green valley. Within the LSB disk are spiral arms forming stars at extremely low efficiencies. The gas depletion timescale of ∼10{sup 11} years suggests that UGC 1382 may be a very-long-term resident of the green valley. We find that the formation and evolution of the LSB disk in UGC 1382 is best explained by the accretion of gas-rich LSB dwarf galaxies.« less

Surface brightness profiles and structural parameters for 53 rich stellar clusters in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Mackey, A. D.; Gilmore, G. F.

2003-01-01

We have compiled a pseudo-snapshot data set of two-colour observations from the Hubble Space Telescope archive for a sample of 53 rich LMC clusters with ages of 106-1010 yr. We present surface brightness profiles for the entire sample, and derive structural parameters for each cluster, including core radii, and luminosity and mass estimates. Because we expect the results presented here to form the basis for several further projects, we describe in detail the data reduction and surface brightness profile construction processes, and compare our results with those of previous ground-based studies. The surface brightness profiles show a large amount of detail, including irregularities in the profiles of young clusters (such as bumps, dips and sharp shoulders), and evidence for both double clusters and post-core-collapse (PCC) clusters. In particular, we find power-law profiles in the inner regions of several candidate PCC clusters, with slopes of approximately -0.7, but showing considerable variation. We estimate that 20 +/- 7 per cent of the old cluster population of the Large Magellanic Cloud (LMC) has entered PCC evolution, a similar fraction to that for the Galactic globular cluster system. In addition, we examine the profile of R136 in detail and show that it is probably not a PCC cluster. We also observe a trend in core radius with age that has been discovered and discussed in several previous publications by different authors. Our diagram has better resolution, however, and appears to show a bifurcation at several hundred Myr. We argue that this observed relationship reflects true physical evolution in LMC clusters, with some experiencing small-scale core expansion owing to mass loss, and others large-scale expansion owing to some unidentified characteristic or physical process.

Oxygen abundance distributions in six late-type galaxies based on SALT spectra of H II regions

NASA Astrophysics Data System (ADS)

Zinchenko, I. A.; Kniazev, A. Y.; Grebel, E. K.; Pilyugin, L. S.

2015-10-01

Spectra of 34 H ii regions in the late-type galaxies NGC 1087, NGC 2967, NGC 3023, NGC 4030, NGC 4123, and NGC 4517A were observed with the South African Large Telescope (SALT). In all 34 H ii regions, oxygen abundances were determined through the "counterpart" method (C method). Additionally, in two H ii regions in which we detected auroral lines, we measured oxygen abundances with the classic Te method. We also estimated the abundances in our H ii regions using the O3N2 and N2 calibrations and compared those with the C-based abundances. With these data, we examined the radial abundance distributions in the disks of our target galaxies. We derived surface-brightness profiles and other characteristics of the disks (the surface brightness at the disk center and the disk scale length) in three photometric bands for each galaxy using publicly available photometric imaging data. The radial distributions of the oxygen abundances predicted by the relation between abundance and disk surface brightness in the W1 band obtained for spiral galaxies in our previous study are close to the radial distributions of the oxygen abundances determined from the analysis of the emission line spectra for four galaxies where this relation is applicable. Hence, when the surface-brightness profile of a late-type galaxy is known, this parametric relation can be used to estimate the likely present-day oxygen abundance in the disk of the galaxy. Based on observations made with the Southern African Large Telescope, programs 2012-1-RSA_OTH-001, 2012-2-RSA_OTH-003 and 2013-1-RSA_OTH-005.

Galaxy And Mass Assembly (GAMA): detection of low-surface-brightness galaxies from SDSS data

NASA Astrophysics Data System (ADS)

Williams, Richard P.; Baldry, I. K.; Kelvin, L. S.; James, P. A.; Driver, S. P.; Prescott, M.; Brough, S.; Brown, M. J. I.; Davies, L. J. M.; Holwerda, B. W.; Liske, J.; Norberg, P.; Moffett, A. J.; Wright, A. H.

2016-12-01

We report on a search for new low-surface-brightness galaxies (LSBGs) using Sloan Digital Sky Survey (SDSS) data within the Galaxy And Mass Assembly (GAMA) equatorial fields. The search method consisted of masking objects detected with SDSS PHOTO, combining gri images weighted to maximize the expected signal-to-noise ratio, and smoothing the images. The processed images were then run through a detection algorithm that finds all pixels above a set threshold and groups them based on their proximity to one another. The list of detections was cleaned of contaminants such as diffraction spikes and the faint wings of masked objects. From these, selecting potentially the brightest in terms of total flux, a list of 343 LSBGs was produced having been confirmed using VISTA Kilo-degree Infrared Galaxy Survey (VIKING) imaging. The photometry of this sample was refined using the deeper VIKING Z band as the aperture-defining band. Measuring their g - I and J - K colours shows that most are consistent with being at redshifts less than 0.2. The photometry is carried out using an AUTO aperture for each detection giving surface brightnesses of μr ≳ 25 mag arcsec-2 and magnitudes of r > 19.8 mag. None of these galaxies are bright enough to be within the GAMA main survey limit but could be part of future deeper surveys to measure the low-mass end of the galaxy stellar mass function.

Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

NASA Astrophysics Data System (ADS)

Higgs, C. R.; McConnachie, A. W.; Irwin, M.; Bate, N. F.; Lewis, G. F.; Walker, M. G.; Côté, P.; Venn, K.; Battaglia, G.

2016-05-01

We introduce the Solitary Local dwarfs survey (Solo), a wide-field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multiband imaging from Canada-France-Hawaii Telescope/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than MV ≃ -18 situated beyond the nominal virial radius of the Milky Way and M31 (≳300 kpc) are included in this volume-limited sample, for a total of 42 targets. In addition to reviewing the survey goals and strategy, we present results for the Sagittarius dwarf irregular galaxy (Sag DIG), one of the most isolated, low-mass galaxies, located at the edge of the Local Group. We analyse its resolved stellar populations and their spatial distributions. We provide updated estimates of its central surface brightness and integrated luminosity, and trace its surface brightness profile to a level fainter than 30 mag arcsec-2. Sag DIG is well described by a highly elliptical (disc-like) system following a single component Sérsic model. However, a low-level distortion is present at the outer edges of the galaxy that, were Sag DIG not so isolated, would likely be attributed to some kind of previous tidal interaction. Further, we find evidence of an extremely low level, extended distribution of stars beyond ˜5 arcmin (>1.5 kpc) that suggests Sag DIG may be embedded in a very low-density stellar halo. We compare the stellar and H I structures of Sag DIG, and discuss results for this galaxy in relation to other isolated, dwarf irregular galaxies in the Local Group.

Soil Moisture Active/Passive (SMAP) Radiometer Subband Calibration and Calibration Drift

NASA Technical Reports Server (NTRS)

Peng, Jinzheng; Piepmeier, Jeffrey R.; De Amici, Giovanni; Mohammed, Priscilla

2016-01-01

The SMAP is one of four first-tier missions recommended by the US National Research Council's Committee on Earth Science and Applications from Space (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007)]. The observatory was launched on Jan 31, 2015. The goal of the SMAP is to measure the global soil moisture and freeze/thaw from space. The L-band radiometer is the passive portion of the spaceborne instrument. It measures all four Stokes antenna temperatures and outputs counts. The Level 1B Brightness Temperature (L1B_TB) science algorithm converts radiometer counts to the Earths surface brightness temperature. The results are reported in the radiometer level 1B data product together with the calibrated antenna temperature (TA) and all of the corrections to the unwanted sources contribution. The calibrated L1B data product are required to satisfy the overall radiometer error budget of 1.3 K needed to meet the soil moisture requirement of 0.04 volumetric fraction uncertainty and the calibration drift requirement of no larger than 0.4 K per month.

Soil Moisture Active Passive (SMAP) Radiometer Subband Calibration and Calibration Drift

NASA Technical Reports Server (NTRS)

Peng, Jinzheng; Piepmeier, Jeffrey R.; De Amici, Giovanni; Mohammed, Priscilla N.

2016-01-01

The SMAP is one of four first-tier missions recommended by the US National Research Council's Committee on Earth Science and Applications from Space (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007). The observatory was launched on Jan 31, 2015. The goal of the SMAP is to measure the global soil moisture and freeze/thaw from space. The L-band radiometer is the passive portion of the spaceborne instrument. It measures all four Stokes antenna temperatures and outputs counts. The Level 1B Brightness Temperature (L1B_TB) science algorithm converts radiometer counts to the Earths surface brightness temperature. The results are reported in the radiometer level 1B data product together with the calibrated antenna temperature (TA) and all of the corrections to the unwanted sources contribution. The calibrated L1B data product are required to satisfy the overall radiometer error budget of 1.3 K needed to meet the soil moisture requirement of 0.04 volumetric fraction uncertainty and the calibration drift requirement of no larger than 0.4 K per month.

Hurricane Georges' Landfall in the Dominican Republic: Detailed Airborne Doppler Radar Imagery

NASA Technical Reports Server (NTRS)

Geerts, B.; Heymsfield, G. M.; Tian, L.; Halverson, J. B.; Guillory, A.; Mejia, M. I.

1999-01-01

Current understanding of landfalling tropical cyclones is limited, especially with regard to convective scale processes. On 22 September 1998 Hurricane Georges made landfall on the island of Hispaniola, leaving behind a trail of death and devastation, largely the result of excessive rainfall, not sea level surge or wind. Detailed airborne measurements were taken as part of the Third Convection and Moisture Experiment (CAMEX-3). Of Particular interest are the ER-2 nadir X-band Doppler radar (EDOP) data, which provide a first-time high-resolution view of the precipitation and airflow changes as a hurricane interacts with mountainous terrain. The circulation of hurricane Georges underwent an obvious transition during landfall, evident in the rapid increase in minimum sea-level pressure, the subsidence of the eyewall anvil, and a decrease in average ice concentrations in the eyewall. The eye, as seen in satellite imagery, disappeared, but contrary to current understanding, this was not due to eyewall contraction but rather to convective eruption within the eye. The main convective event within the eye, with upper-level updraft magnitudes near 20 m/s and 89 GHz brightness temperatures below 100 K, occurred when the eye moved over the Cordillera Central, the island's main mountain chain. The location, intensity and evolution of this convection indicate that it was coupled to the surface orography. It is likely that surface rain rates increased during landfall, because of effective droplet collection, both in the convection and in the more widespread stratiform rainfall areas over the island. Evidence for this is the increase in radar reflectivity below the bright band of 1-2 dB/km down to ground-level. Such increase was absent offshore. Such low-level rain enhancement, which cannot be detected in satellite images of upwelling infrared or microwave radiation, must be due to the ascent of boundary-layer air over the topography.

Spatial and Temporal Patterns of SMAP Brightness Temperatures for Use in Level 1 TB Characterization

NASA Astrophysics Data System (ADS)

Kim, E. J.

2015-12-01

1. IntroductionThe recent launch of NASA's Soil Moisture Active Passive (SMAP) mission [Entekhabi, et al] has opened the door to improved brightness temperature (TB) calibration of satellite L-band microwave radiometers, through the use of SMAP's lower noise performance and better immunity to man-made interference (vs. ESA's Soil Moisture Ocean Salinity (SMOS) mission [Kerr, et al]), better spatial resolution (vs. NASA's Aquarius sea surface salinity mission [Le Vine, et al]), and cleaner antenna pattern (vs. SMOS). All three radiometers use/used large homogeneous places on Earth's surface as calibration targets—parts of the ocean, Antarctica, and tropical forests. Despite the recent loss of Aquarius data, there is still hope for creating a longer-term L-band data set that spans the timeframe of all 3 missions. 2. Description of Analyses and Expected Results In this paper, we analyze SMAP brightness temperature data to quantify the spatial and temporal characteristics of external target areas in the oceans, Antarctica, forests, and other areas. Existing analyses have examined these targets in terms of averages, standard deviations, and other basic statistics (for Aquarius & SMOS as well). This paper will approach the problem from a signal processing perspective. Coupled with the use of SMAP's novel RFI-mitigated TBs, and the aforementioned lower noise and cleaner antenna pattern, it is expected that of the 3 L-band missions, SMAP should do the best job of characterizing such external targets. The resulting conclusions should be useful to extract the best possible TB calibration from all 3 missions, helping to inter-compare the TB from the 3 missions, and to eventually inter-calibrate the TBs into a single long-term dataset.

Low baseline levels of NK cells may predict a positive response to ipilimumab in melanoma therapy.

PubMed

Tietze, Julia K; Angelova, Daniela; Heppt, Markus V; Ruzicka, Thomas; Berking, Carola

2017-07-01

The introduction of immune checkpoint blockade (ICB) has been a breakthrough in the therapy of metastatic melanoma. The influence of ICB on T-cell populations has been studied extensively, but little is known about the effect on NK cells. In this study, we analysed the relative and absolute amounts of NK cells and of the subpopulations of CD56 dim and CD56 bright NK cells among the peripheral blood mononuclear cells (PBMCs) of 32 patients with metastatic melanoma before and under treatment with ipilimumab or pembrolizumab by flow cytometry. In 15 (47%) patients, an abnormal low amount of NK cells was found at baseline. Analysis of the subpopulations showed also low or normal baseline levels for CD56 dim NK cells, whereas the baseline levels of CD56 bright NK cells were either normal or abnormally high. The relative and absolute amounts of NK cells and of CD56 dim and CD56 bright NK cell subpopulations in patients with a normal baseline did not change under treatment. However, patients with a low baseline of NK cells and CD56 dim NK cells showed a significant increase in these immune cell subsets, but the amounts remained to be lower than the normal baseline. The amount of CD56 bright NK cells was unaffected by treatment. The baseline levels of NK cells were correlated with the number of metastatic organs. Their proportion increased, whereas the expression of NKG2D decreased significantly when more than one organ was affected by metastases. Low baseline levels of NK cells and CD56 dim NK cells as well as normal baseline levels of CD56 bright NK cells correlated significantly with a positive response to ipilimumab but not to pembrolizumab. Survival curves of patients with low amounts of CD56 dim NK cells treated with ipilimumab showed a trend to longer survival. Normal baseline levels of CD56 bright NK cells were significantly correlated with longer survival as compared to patients with high baseline levels. In conclusion, analysis of the amounts of total NK cells and of CD56 dim and CD56 bright NK cells subpopulations at baseline may help to predict the outcome of treatment with ipilimumab. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

In-depth Analysis of Land Surface Emissivity using Microwave Polarization Difference Index to Improve Satellite QPE

NASA Astrophysics Data System (ADS)

Zheng, Y.; Kirstetter, P. E.; Hong, Y.; Wen, Y.; Turk, J.; Gourley, J. J.

2015-12-01

One of primary uncertainties in satellite overland quantitative precipitation estimates (QPE) from passive sensors such as radiometers is the impact on the brightness temperatures by the surface land emissivity. The complexity of surface land emissivity is linked to its temporal variations (diurnal and seasonal) and spatial variations (subsurface vertical profiles of soil moisture, vegetation structure and surface temperature) translating into sub-pixel heterogeneity within the satellite field of view (FOV). To better extract the useful signal from hydrometeors, surface land emissivity needs to be determined and filtered from the satellite-measured brightness temperatures. Based on the dielectric properties of surface land cover constitutes, Microwave Polarization Differential index (MPDI) is expected to carry the composite effect of surface land properties on land surface emissivity, with a higher MPDI indicating a lower emissivity. This study analyses the dependence of MPDI to soil moisture, vegetation and surface skin temperature over 9 different land surface types. Such analysis is performed using the normalized difference vegetation index (NDVI) from MODIS, the near surface air temperature from the RAP model and ante-precedent precipitation accumulation from the Multi-Radar Multi-Sensor as surrogates for the vegetation, surface skin temperature and shallow layer soil moisture, respectively. This paper provides 1) evaluations of brightness temperature-based MPDI from the TRMM and GPM Microwave Imagers in both raining and non-raining conditions to test the dependence of MPDI to precipitation; 2) comparisons of MPDI categorized into instantly before, during and immediately after selected precipitation events to examine the impact of modest-to-heavy precipitation on the spatial pattern of MPDI; 3) inspections of relationship between MPDI versus rain fraction and rain rate within the satellite sensors FOV to investigate the behaviors of MPDI in varying precipitation conditions; 4) analysis of discrepancies of MPDI over 10.65, 19.35, 37 and 85.8 GHz to identify the sensitivity of MPDS to microwave wavelengths.

Infrared Image of Low Clouds on Venus

NASA Technical Reports Server (NTRS)

1993-01-01

This false-color image is a near-infrared map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet's night side on February 10, 1990. Bright slivers of sunlit high clouds are visible above and below the dark, glowing hemisphere. The spacecraft is about 100,000 kilometers (60,000 miles) above the planet. An infrared wavelength of 2.3 microns (about three times the longest wavelength visible to the human eye) was used. The map shows the turbulent, cloudy middle atmosphere some 50-55 kilometers (30- 33 miles) above the surface, 10-16 kilometers or 6-10 miles below the visible cloudtops. The red color represents the radiant heat from the lower atmosphere (about 400 degrees Fahrenheit) shining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. This cloud layer is at about -30 degrees Fahrenheit, at a pressure about 1/2 Earth's surface atmospheric pressure. Near the equator, the clouds appear fluffy and blocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick clouds at this altitude.

FIRST RESULTS FROM THE DRAGONFLY TELEPHOTO ARRAY: THE APPARENT LACK OF A STELLAR HALO IN THE MASSIVE SPIRAL GALAXY M101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Dokkum, Pieter G.; Merritt, Allison; Abraham, Roberto

2014-02-20

We use a new telescope concept, the Dragonfly Telephoto Array, to study the low surface brightness outskirts of the spiral galaxy M101. The radial surface brightness profile is measured down to μ {sub g} ∼ 32 mag arcsec{sup –2}, a depth that approaches the sensitivity of star count studies in the Local Group. We convert surface brightness to surface mass density using the radial g – r color profile. The mass density profile shows no significant upturn at large radius and is well-approximated by a simple bulge + disk model out to R = 70 kpc, corresponding to 18 diskmore » scale lengths. Fitting a bulge + disk + halo model we find that the best-fitting halo mass M{sub halo}=1.7{sub −1.7}{sup +3.4}×10{sup 8} M {sub ☉}. The total stellar mass of M101 is M{sub tot,∗}=5.3{sub −1.3}{sup +1.7}×10{sup 10} M {sub ☉}, and we infer that the halo mass fraction f{sub halo}=M{sub halo}/M{sub tot,∗}=0.003{sub −0.003}{sup +0.006}. This mass fraction is lower than that of the Milky Way (f {sub halo} ∼ 0.02) and M31 (f {sub halo} ∼ 0.04). All three galaxies fall below the f {sub halo}-M {sub tot,} {sub *} relation predicted by recent cosmological simulations that trace the light of disrupted satellites, with M101's halo mass a factor of ∼10 below the median expectation. However, the predicted scatter in this relation is large, and more galaxies are needed to better quantify this possible tension with galaxy formation models. Dragonfly is well suited for this project: as integrated-light surface brightness is independent of distance, large numbers of galaxies can be studied in a uniform way.« less

Comparison of measured brightness temperatures from SMOS with modelled ones from ORCHIDEE and H-TESSEL over the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Barella-Ortiz, Anaïs; Polcher, Jan; de Rosnay, Patricia; Piles, Maria; Gelati, Emiliano

2017-01-01

L-band radiometry is considered to be one of the most suitable techniques to estimate surface soil moisture (SSM) by means of remote sensing. Brightness temperatures are key in this process, as they are the main input in the retrieval algorithm which yields SSM estimates. The work exposed compares brightness temperatures measured by the SMOS mission to two different sets of modelled ones, over the Iberian Peninsula from 2010 to 2012. The two modelled sets were estimated using a radiative transfer model and state variables from two land-surface models: (i) ORCHIDEE and (ii) H-TESSEL. The radiative transfer model used is the CMEM. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations at the moment. Further hypotheses are proposed and will be explored in a forthcoming paper. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies.

Analysis of the Convective Storm using Meteosat Second Generation and SPOL Radar over a Megacity, on May 18, 2014

NASA Astrophysics Data System (ADS)

da Silva Júnior, Ivon Wilson; José Pereira Filho, Augusto; Alves Barbosa, Humberto

2017-04-01

The rapid populational growth in urban areas of Southeast and South Brazil has increased anthropic effects on severe weather caused by thunderstorms whose impacts require mitigation on a small space-time scale more susceptible to natural disasters such as flooding. The 18 May 2015 thunderstorms in The Metropolitan Area of São Paulo (MASP) caused many losses due to heavy rain, gusty winds and falling hail. The local press reported 310 tons of ice removed from the surface. Meteosat Second Generation (MSG) images, polarimetric weather radar measurements, radiosondes and surface weather variables data sets were used to analyze the event. The environmental thermodynamic analysis showed a dry layer at mid levels with wind shear at upper levels. Diabatic heating increased throughout the day and made the atmosphere very unstable at the end of the afternoon with greater potential energy induced by the local sea breeze. The 0 °C isotherm was at 3781 m. Initially, the rapid horizontal expansion of the storm caused by environmental wind shear was observed at 10.8 mm IR MSG channel brightness temperature (BT) was of -57 ° C. The brightness temperature differences (BTD) between WV and IR MSG channels evidenced vertical moisture transport from near the surface to the upper levels during convection. In the mature stage, radar reflectivity showed widespread multi cellular storm structures. Vertical cross-section indicated reflectivities between 45 dBZ to 55 dBZ with cloud tops with reflectivity greater than 30 dBZ at 14 km altitude when updrafts were more intense. Vertical profiles of differential reflectivity (ZDR) showed a deep column from to +2 to +4 dB between 6 km to 12 km altitude where intense vertical transport of large drops and a mixture of water and ice well above the 0 ° C isotherm level. This environment increased efficiency of the Wegener-Bergeron-Findeisen type microphysics with rapid ice crystal growth to hail with later precipitation at the surface that lasted from 1855 UTC to 1935 UTC. The thunderstorms main cores crossed MASP also due local circulations induced by the heat island. These results can contribute to the development of nowcasting tools and short-term warning systems by integrating satellite and weather radar data sets so to increase the resilience of megacities to such severe convective events.

A new, bright and hard aluminum surface produced by anodization

NASA Astrophysics Data System (ADS)

Hou, Fengyan; Hu, Bo; Tay, See Leng; Wang, Yuxin; Xiong, Chao; Gao, Wei

2017-07-01

Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance.

A semiempirical model for interpreting microwave emission from semiarid land surfaces as seen from space

NASA Technical Reports Server (NTRS)

Kerr, Yann H.; Njoku, Eni G.

1990-01-01

A radiative-transfer model for simulating microwave brightness temperatures over land surfaces is described. The model takes into account sensor viewing conditions (spacecraft altitude, viewing angle, frequency, and polarization) and atmospheric parameters over a soil surface characterized by its moisture, roughness, and temperature and covered with a layer of vegetation characterized by its temperature, water content, single scattering albedo, structure, and percent coverage. In order to reduce the influence of atmospheric and surface temperature effects, the brightness temperatures are expressed as polarization ratios that depend primarily on the soil moisture and roughness, canopy water content, and percentage of cover. The sensitivity of the polarization ratio to these parameters is investigated. Simulation of the temporal evolution of the microwave signal over semiarid areas in the African Sahel is presented and compared to actual satellite data from the SMMR instrument on Nimbus-7.

Surface brightness profiles of 10 comets

NASA Astrophysics Data System (ADS)

Jewitt, D. C.; Meech, K. J.

1987-06-01

CCD photometric observations of the comae of 10 comets, obtained at the 4-m and 2.1-m telescopes at KPNO during 1985-1986 using filters centered at 700.5, 650.0, or 546.0 nm, are reported. The data are presented in extensive tables and graphs and characterized in detail. The radial surface brightness profiles are shown to be steeper than predicted by an idealized spherically symmetric steady-state comet model, the steepness increasing with the projected distance from the nucleus. These profiles are attributed, on the basis of Monte Carlo simulations, to imperfect coupling between the sublimated gas and the optically dominant grains of the coma.

Rayleigh beacon for measuring the surface profile of a radio telescope.

PubMed

Padin, S

2014-12-01

Millimeter-wavelength Rayleigh scattering from water droplets in a cloud is proposed as a means of generating a bright beacon for measuring the surface profile of a radio telescope. A λ=3  mm transmitter, with an output power of a few watts, illuminating a stratiform cloud, can generate a beacon with the same flux as Mars in 10 GHz bandwidth, but the beacon has a narrow line width, so it is extremely bright. The key advantage of the beacon is that it can be used at any time, and positioned anywhere in the sky, as long as there are clouds.

Planetary camera observations of the double nucleus of M31

NASA Technical Reports Server (NTRS)

Lauer, Tod R.; Faber, S. M.; Groth, Edward J.; Shaya, Edward J.; Campbell, Bel; Code, Arthur; Currie, Douglas G.; Baum, William A.; Ewald, S. P.; Hester, J. J.

1993-01-01

HST Planetary Camera images obtained in the V and I band for M31 show its inner nucleus to consist of two components that are separated by 0.49 arcsec. The nuclear component with lower surface brightness closely coincides with the bulge photocenter and is argued to be at the kinematic center of the galaxy. It is surmised that, if dust absorption generates the asymmetric nuclear morphology observed, the dust grain size must either be exceptionally large, or the dust optical depth must be extremely high; the higher surface-brightness and off-center nuclear component may alternatively be a separate stellar system.

Compact Groups analysis using weak gravitational lensing II: CFHT Stripe 82 data

NASA Astrophysics Data System (ADS)

Chalela, Martín; Gonzalez, Elizabeth Johana; Makler, Martín; Lambas, Diego García; Pereira, Maria E. S.; O'mill, Ana; Shan, HuanYuan

2018-06-01

In this work we present a lensing study of Compact Groups (CGs) using data obtained from the high quality Canada-France-Hawaii Telescope Stripe 82 Survey. Using stacking techniques we obtain the average density contrast profile. We analyse the lensing signal dependence on the groups surface brightness and morphological content, for CGs in the redshift range z = 0.2 - 0.4. We obtain a larger lensing signal for CGs with higher surface brightness, probably due to their lower contamination by interlopers. Also, we find a strong dependence of the lensing signal on the group concentration parameter, with the most concentrated quintile showing a significant lensing signal, consistent with an isothermal sphere with σV = 336 ± 28 km/s and a NFW profile with R200 = 0.60 ± 0.05 h_{70}^{-1}Mpc. We also compare lensing results with dynamical estimates finding a good agreement with lensing determinations for CGs with higher surface brightness and higher concentration indexes. On the other hand, CGs that are more contaminated by interlopers show larger dynamical dispersions, since interlopers bias dynamical estimates to larger values, although the lensing signal is weakened.

Exponential Stellar Disks in Low Surface Brightness Galaxies: A Critical Test of Viscous Evolution

NASA Astrophysics Data System (ADS)

Bell, Eric F.

2002-12-01

Viscous redistribution of mass in Milky Way-type galactic disks is an appealing way of generating an exponential stellar profile over many scale lengths, almost independent of initial conditions, requiring only that the viscous timescale and star formation timescale are approximately equal. However, galaxies with solid-body rotation curves cannot undergo viscous evolution. Low surface brightness (LSB) galaxies have exponential surface brightness profiles, yet have slowly rising, nearly solid-body rotation curves. Because of this, viscous evolution may be inefficient in LSB galaxies: the exponential profiles, instead, would give important insight into initial conditions for galaxy disk formation. Using star formation laws from the literature and tuning the efficiency of viscous processes to reproduce an exponential stellar profile in Milky Way-type galaxies, I test the role of viscous evolution in LSB galaxies. Under the conservative and not unreasonable condition that LSB galaxies are gravitationally unstable for at least a part of their lives, I find that it is impossible to rule out a significant role for viscous evolution. This type of model still offers an attractive way of producing exponential disks, even in LSB galaxies with slowly rising rotation curves.

Tracers of Stellar Mass-loss. II. Mid-IR Colors and Surface Brightness Fluctuations

NASA Astrophysics Data System (ADS)

González-Lópezlira, Rosa A.

2018-04-01

I present integrated colors and surface brightness fluctuation magnitudes in the mid-infrared (IR), derived from stellar population synthesis models that include the effects of the dusty envelopes around thermally pulsing asymptotic giant branch (TP-AGB) stars. The models are based on the Bruzual & Charlot CB* isochrones; they are single-burst, range in age from a few Myr to 14 Gyr, and comprise metallicities between Z = 0.0001 and Z = 0.04. I compare these models to mid-IR data of AGB stars and star clusters in the Magellanic Clouds, and study the effects of varying self-consistently the mass-loss rate, the stellar parameters, and the output spectra of the stars plus their dusty envelopes. I find that models with a higher than fiducial mass-loss rate are needed to fit the mid-IR colors of “extreme” single AGB stars in the Large Magellanic Cloud. Surface brightness fluctuation magnitudes are quite sensitive to metallicity for 4.5 μm and longer wavelengths at all stellar population ages, and powerful diagnostics of mass-loss rate in the TP-AGB for intermediate-age populations, between 100 Myr and 2–3 Gyr.

Automated detection of very Low Surface Brightness galaxies in the Virgo Cluster

NASA Astrophysics Data System (ADS)

Prole, D. J.; Davies, J. I.; Keenan, O. C.; Davies, L. J. M.

2018-04-01

We report the automatic detection of a new sample of very low surface brightness (LSB) galaxies, likely members of the Virgo cluster. We introduce our new software, DeepScan, that has been designed specifically to detect extended LSB features automatically using the DBSCAN algorithm. We demonstrate the technique by applying it over a 5 degree2 portion of the Next-Generation Virgo Survey (NGVS) data to reveal 53 low surface brightness galaxies that are candidate cluster members based on their sizes and colours. 30 of these sources are new detections despite the region being searched specifically for LSB galaxies previously. Our final sample contains galaxies with 26.0 ≤ ⟨μe⟩ ≤ 28.5 and 19 ≤ mg ≤ 21, making them some of the faintest known in Virgo. The majority of them have colours consistent with the red sequence, and have a mean stellar mass of 106.3 ± 0.5M⊙ assuming cluster membership. After using ProFit to fit Sérsic profiles to our detections, none of the new sources have effective radii larger than 1.5 Kpc and do not meet the criteria for ultra-diffuse galaxy (UDG) classification, so we classify them as ultra-faint dwarfs.

Giant Lyman-alpha Nebulae in the Illustris Simulation

NASA Astrophysics Data System (ADS)

Gronke, Max; Bird, Simeon

2017-02-01

Several “giant” Lyα nebulae with an extent ≳300 kpc and observed Lyα luminosity of ≳1044 erg s-1 cm-2 arcsec-2 have recently been detected, and it has been speculated that their presence hints at a substantial cold gas reservoir in small cool clumps not resolved in modern hydrodynamical simulations. We use the Illustris simulation to predict the Lyα emission emerging from large halos (M > 1011.5 M⊙) at z ˜ 2 and thus test this model. We consider both active galactic nucleus (AGN) and star driven ionization, and compare the simulated surface brightness maps, profiles, and Lyα spectra to a model where most gas is clumped below the simulation resolution scale. We find that with Illustris, no additional clumping is necessary to explain the extents, luminosities, and surface brightness profiles of the “giant Lyα nebulae” observed. Furthermore, the maximal extents of the objects show a wide spread for a given luminosity and do not correlate significantly with any halo properties. We also show how the detected size depends strongly on the employed surface brightness cutoff, and predict that further examples of such objects will be found in the near future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrmann, Kimberly A.; Hunter, Deidre A.; Elmegreen, Bruce G., E-mail: kah259@psu.edu, E-mail: dah@lowell.edu, E-mail: bge@us.ibm.com

In this second paper of a series, we explore the B  −  V , U  −  B , and FUV−NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that the colors of (1) Type I dwarfs generally become redder with increasing radius, unlike spirals which have a blueing trend that flattens beyond ∼1.5 disk scale lengths, (2) Type II dwarfs come in six different “flavors,” one of whichmore » mimics the “U” shape of spirals, and (3) Type III dwarfs have a stretched “S” shape where the central colors are flattish, become steeply redder toward the surface brightness break, then remain roughly constant beyond, which is similar to spiral Type III color profiles, but without the central outward bluing. Faint (−9 >  M{sub B}  > −14) Type II dwarfs tend to have continuously red or “U” shaped colors and steeper color slopes than bright (−14 >  M{sub B}  > −19) Type II dwarfs, which additionally have colors that become bluer or remain constant with increasing radius. Sm dwarfs and BCDs tend to have at least some blue and red radial color trend, respectively. Additionally, we determine stellar surface mass density (Σ) profiles and use them to show that the break in Σ generally remains in Type II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs (unlike Type III spirals). Moreover, the break in Σ is strong, intermediate, and weak in faint dwarfs, bright dwarfs, and spirals, respectively, indicating that Σ may straighten with increasing galaxy mass. Finally, the average stellar surface mass density at the surface brightness break is roughly 1−2  M {sub ⊙} pc{sup −2} for Type II dwarfs but higher at 5.9  M {sub ⊙} pc{sup −2} or 27  M {sub ⊙} pc{sup −2} for Type III BCDs and dIms, respectively.« less

Teradiode's high brightness semiconductor lasers

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

2016-03-01

TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, <0.08 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. Our TeraBlade industrial platform achieves world-record brightness levels for direct diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

Surface temperatures and retention of H2O frost on Ganymede and Callisto

NASA Technical Reports Server (NTRS)

Squyres, S. W.

1980-01-01

Surface temperatures and ice evaporation rates are calculated for Ganymede and Callisto as functions of latitude, time of day, and albedo, according to a model that uses surface thermal properties determined by eclipse radiometry and albedos determined from photometrically decalibrated Voyager images. The difference in temperature between Ganymede and Callisto is not great enough to account for the lack of bright polar caps on Callisto, which seems instead to reflect a real deficiency in the amount of available water frost relative to Ganymede. The temperature difference between Ganymede's grooved and cratered terrains also cannot account for the high concentration of bright ray craters in the former, suggesting that an internal geologic process has enriched the grooved terrain in ice content relative to the cratered terrain.

Sea Surface Salinity and Wind Retrieval Algorithm Using Combined Passive-Active L-Band Microwave Data

NASA Technical Reports Server (NTRS)

Yueh, Simon H.; Chaubell, Mario J.

2011-01-01

Aquarius is a combined passive/active L-band microwave instrument developed to map the salinity field at the surface of the ocean from space. The data will support studies of the coupling between ocean circulation, the global water cycle, and climate. The primary science objective of this mission is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean with a spatial resolution of 150 kilometers and a retrieval accuracy of 0.2 practical salinity units globally on a monthly basis. The measurement principle is based on the response of the L-band (1.413 gigahertz) sea surface brightness temperatures (T (sub B)) to sea surface salinity. To achieve the required 0.2 practical salinity units accuracy, the impact of sea surface roughness (e.g. wind-generated ripples and waves) along with several factors on the observed brightness temperature has to be corrected to better than a few tenths of a degree Kelvin. To the end, Aquarius includes a scatterometer to help correct for this surface roughness effect.

Microwave Brightness Temperatures of Tilted Convective Systems

NASA Technical Reports Server (NTRS)

Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

1998-01-01

Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

VEGAS-SSS: A VST Early-Type GAlaxy Survey: Analysis of Small Stellar System

NASA Astrophysics Data System (ADS)

Cantiello, M.

VEGAS-SSS is a program devoted to study the properties of small stellar systems (SSSs) around bright galaxies, built on the VEGAS survey. At completion, the survey will have collected detailed photometric information of ˜ 100 bright early-type galaxies to study the properties of diffuse light (surface brightness, colours, SBF, etc.) and the clustered light (compact stellar systems) out to previously unreached projected galactocentric radii. VEGAS-SSS will define an accurate and homogeneous dataset that will have an important legacy value for studies of the evolution and transformation processes taking place in galaxies through the fossil information provided by SSSs.

Photometric study of fine structure of a sunspot penumbra (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, R.

1973-10-01

The microphotometric analysis of the fime structure of a sunspot penumbra, photographed in white hight with the 38 cm refractor of the Pic du Midi Observatory with a resolution very close to 0.3'', allows to give from it, at lambda 5280, the following picture: the penumbra appears to consist of bright grains, lined up in the form of filaments, with am average brightness I/sub beta //I = 0.95 of average width 0.36''(270 km) and which cover 43% of its surface, show-ing up a dark background of brightness I/sub beta //I = 0.6 nearly uniform. (auth)

IRAS surface brightness maps of reflection nebulae in the Pleiades

NASA Technical Reports Server (NTRS)

Castelaz, Michael W.; Werner, M. W.; Sellgren, K.

1987-01-01

Surface brightness maps at 12, 25, 60, and 100 microns were made of a 2.5 deg x 2.5 deg area of the reflection nebulae in the Pleiades by coadding IRAS scans of this region. Emission is seen surrounding 17 Tau, 20 Tau, 23 Tau, and 25 Tau in all four bands, coextensive with the visible reflection nebulosity, and extending as far as 30 arcminutes from the illuminating stars. The infrared energy distributions of the nebulae peak in the 100 micron band, but up to 40 percent of the total infrared power lies in the 12 and 25 micron bands. The brightness of the 12 and 25 micron emission and the absence of temperature gradients at these wavelengths are inconsistent with the predictions of equilibrium thermal emission models. The emission at these wavelengths appears to be the result of micron nonequilibrium emission from very small grains, or from molecules consisting of 10-100 carbon atoms, which have been excited by ultraviolet radiation from the illuminating stars.

Application of photometric models to asteroids

NASA Technical Reports Server (NTRS)

Bowell, Edward; Hapke, Bruce; Domingue, Deborah; Lumme, Kari; Peltoniemi, Jouni; Harris, Alan W.

1989-01-01

The way an asteroid or other atmosphereless solar system body varies in brightness in response to changing illumination and viewing geometry depends in a very complicated way on the physical and optical properties of its surface and on its overall shape. This paper summarizes the formulation and application of recent photometric models by Hapke (1981, 1984, 1986) and by Lumme and Bowell (1981). In both models, the brightness of a rough and porous surface is parameterized in terms of the optical properties of individual particles, by shadowing between particles, and by the way in which light is scattered among collections of particles. Both models succeed in their goal of fitting the observed photometric behavior of a wide variety of bodies, but neither has led to a very complete understanding of the properties of asteroid regoliths, primarily because, in most cases, the parameters in the present models cannot be adequately constrained by observations of integral brightness alone over a restricted range of phase angles.

A Methodology for Surface Soil Moisture and Vegetation Optical Depth Retrieval Using the Microwave Polarization Difference Index

NASA Technical Reports Server (NTRS)

Owe, Manfred; deJeu, Richard; Walker, Jeffrey; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

A methodology for retrieving surface soil moisture and vegetation optical depth from satellite microwave radiometer data is presented. The procedure is tested with historical 6.6 GHz brightness temperature observations from the Scanning Multichannel Microwave Radiometer over several test sites in Illinois. Results using only nighttime data are presented at this time, due to the greater stability of nighttime surface temperature estimation. The methodology uses a radiative transfer model to solve for surface soil moisture and vegetation optical depth simultaneously using a non-linear iterative optimization procedure. It assumes known constant values for the scattering albedo and roughness. Surface temperature is derived by a procedure using high frequency vertically polarized brightness temperatures. The methodology does not require any field observations of soil moisture or canopy biophysical properties for calibration purposes and is totally independent of wavelength. Results compare well with field observations of soil moisture and satellite-derived vegetation index data from optical sensors.

ARC-1969-AC79-0164-2

NASA Image and Video Library

1979-02-05

Photo by Voyager 1 (JPL) Jupiter, its Great Red Spot and three of its four largest satellites are visible in this photo taken Feb 5, 1979 by Voyager 1. The spacecraft was 28.4 million kilomters (17.5 million miles) from the planet at the time. The inner-most large satellite, Io, can be seen against Jupiter's disk. Io is distinguished by its bright, brown-yellow surface. To the right of Jupiter is the satellite Europa, also very bright but with fainter surface markings. The darkest satellite, Callisto (still nearly twice as bright as Earth's Moon), is barely visible at the bottom left of the picture. Callisto shows a bright patch in its northern hemisphere. All tThree orbit Jupiter in the equatorial plane, and appear in their present position because Voyageris above the plane. All three satellites show the same face to Jupiter always -- just as Earth's Moon always shows us the same face. In this photo we see the sides of the satellites that always face away from the planet. Jupiter's colorfully banded atmosphere displays complex patterns highlighted by the Great Red Spot, a large, circulating atmospheric disturbance. This photo was assembled from three black and white negatives by the Image Processing Lab at Jet Propulsion Laboratory. JPL manages and controls the Voyage Project for NASA's Office of Space Science. (ref: P-21083)

VizieR Online Data Catalog: Reference Catalogue of Bright Galaxies (RC1; de Vaucouleurs+ 1964)

NASA Astrophysics Data System (ADS)

de Vaucouleurs, G.; de Vaucouleurs, A.

1995-11-01

The Reference Catalogue of Bright Galaxies lists for each entry the following information: NGC number, IC number, or A number; A, B, or C designation; B1950.0 positions, position at 100 year precession; galactic and supergalactic positions; revised morphological type and source; type and color class in Yerkes list 1 and 2; Hubble-Sandage type; revised Hubble type according to Holmberg; logarithm of mean major diameter (log D) and ratio of major to minor diameter (log R) and their weights; logarithm of major diameter; sources of the diameters; David Dunlap Observatory type and luminosity class; Harvard photographic apparent magnitude; weight of V, B-V(0), U-B(0); integrated magnitude B(0) and its weight in the B system; mean surface brightness in magnitude per square minute of arc and sources for the B magnitude; mean B surface brightness derived from corrected Harvard magnitude; the integrated color index in the standard B-V system; "intrinsic" color index; sources of B-V and/or U-B; integrated color in the standard U-B system; observed radial velocity in km/sec; radial velocity corrected for solar motion in km/sec; sources of radial velocities; solar motion correction; and direct photographic source. The catalog was created by concatenating four files side by side. (1 data file).

Evidence of Titan's Climate History from Evaporite Distribution

NASA Astrophysics Data System (ADS)

MacKenzie, Shannon; Barnes, J. W.; Brown, R.; Sotin, C.; Buratti, B. J.; Clark, R.; Baines, K. H.; Nicholson, P. D.; Le Mouelic, S.; Rodriguez, S.

2013-10-01

5-μm bright material on the surface of Titan has been positively correlated with the shores of RADAR-dark (liquid-filled) and the bottoms of RADAR-bright (empty) lakebeds in the region just south of Ligea Mare by Barnes et al. (2011). This water ice-poor spectral unit was thus proposed to be evaporite, the formerly-dissolved solute deposits left behind when the solvent (here presumably a methane/ethane mixture) evaporates. Because evaporite forms under specific conditions—solute and solvent at or near saturation, no outlets or other means of affecting the solution balance, etc.—the presence of evaporite can shed light on Titan's climate history. Adding to the previously identified cases, we use the breadth of available Cassini VIMS data to comprehensively map new instances of evaporite. In particular, we found new instances of evaporite in the north polar region and the midlatitudes. Our map of the global distribution of Titan's 5-μm-bright deposits can be used to constrain the historical evolution of Titan's surface volatile inventory and may bear on the question of the time variation of the methane concentration in Titan's atmosphere. Furthermore, we explore the implications of the idea that the 5-$\\mu$m-bright areas are indeed mostly evaporitic in nature with respect to the relationship between the regional and global volatile cycles.

Colour analysis of the equine endometrium: comparison of spectrophotometry and computer-assisted analysis of photographs within the L*a*b* colour space system.

PubMed

Neuhauser, S; Handler, J

2013-09-01

The aims of this study were to compare two different methods of quantifying the colour of the luminal surface of the equine endometrium and to relate the results to histopathological evidence of inflammation and fibrosis. The mucosal surfaces of 17 equine uteri obtained from an abattoir were assessed using a spectrophotometer and by computer-assisted analysis of photographs. Values were converted into L(*)a(*)b(*) colour space. Although there was significant correlation between the two methods of quantification, variations in 'brightness', 'red' and 'yellow' values were noted. Within a given uterus, measurements using the spectrophotometer did not differ significantly. Using photographic analysis, brightness differed between horns, although no differences in chromaticity were found. Histopathological classification of changes within endometria corresponded to measured differences in colour. Extensive fibrosis was associated with increased brightness and decreased chromaticity using both methods. Inflammation correlated with reduced chromaticity, when measured by spectrophotometry, and with reduced brightness and yellow values, when assessed photographically. For this technique to gain wider acceptance as a diagnostic tool, e.g. for the endoscopic evaluation of uterine mucosae in vivo, standardised illumination techniques will be required so that colours can be compared and interpreted accurately. Copyright © 2013 Elsevier Ltd. All rights reserved.

VizieR Online Data Catalog: Face-on disk galaxies photometry. I. (de Jong+, 1994)

NASA Astrophysics Data System (ADS)

de Jong, R. S.; van der Kruit, P. C.

1995-07-01

We present accurate surface photometry in the B, V, R, I, H and K passbands of 86 spiral galaxies. The galaxies in this statistically complete sample of undisturbed spirals were selected from the UGC to have minimum diameters of 2' and minor over major axis ratios larger than 0.625. This sample has been selected in such a way that it can be used to represent a volume limited sample. The observation and reduction techniques are described in detail, especially the not often used driftscan technique for CCDs and the relatively new techniques using near-infrared (near-IR) arrays. For each galaxy we present radial profiles of surface brightness. Using these profiles we calculated the integrated magnitudes of the galaxies in the different passbands. We performed internal and external consistency checks for the magnitudes as well as the luminosity profiles. The internal consistency is well within the estimated errors. Comparisons with other authors indicate that measurements from photographic plates can show large deviations in the zero-point magnitude. Our surface brightness profiles agree within the errors with other CCD measurements. The comparison of integrated magnitudes shows a large scatter, but a consistent zero-point. These measurements will be used in a series of forthcoming papers to discuss central surface brightnesses, scalelengths, colors and color gradients of disks of spiral galaxies. (9 data files).

Cratering and Grooved Terrain on Ganymede

NASA Technical Reports Server (NTRS)

1979-01-01

This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The image shows detail on the surface with a resolution of four and a half km. This picture is just south of PIA001515 (P21161) and shows more craters. It also shows the two distinctive types of terrain found by Voyager, the darker ungrooved regions and the lighter areas which show the grooves or fractures in abundance. The most striking features are the bright ray craters which havE a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the northern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejecta patterns. This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

Spectrophotometry of the Khonsu region on the comet 67P/Churyumov-Gerasimenko in the context of OSIRIS images

NASA Astrophysics Data System (ADS)

Prasanna Deshapriya, Jasinghege Don; Barucci, Maria Antonieta; Fornasier, Sonia; Feller, Clement; Hasselmann, Pedro Henrique; Sierks, Holger; Ramy El-Maarry, Mohammed; OSIRIS Team

2016-10-01

Since the Rosetta spacecraft rendezvoused with the comet 67P/Churyumov-Gerasimenko in August 2014, OSIRIS (Optical,Spectroscopic and Infrared Remote Imaging System) has been instrumental in characterising and studying both the nucleus as well as the coma of the comet. OSIRIS has thus far contributed to a plethora of scientific results. OSIRIS observations have revealed a bilobate nucleus accreted from a pair of cometesimals each having an irregular shape and a size, populated with numerous geomorphological features. Among the well defined 26 regions of the comet, Khonsu region inherits a heterogeneous terrain composed of smooth areas, scarps, outcroppings, large boulders, an intriguing 'pancake' feature, both transient and long-lived bright patches plus many other geological features.Our work focuses on the spectrophotometric analysis of some selected terrain and bright patches in the Khonsu region. Despite the variety of geological features, their spectrophotometric properties appear to share a similar composition. It is noticeable also that the smooth areas in Khonsu possess similar spectrophotometric behaviour to some other regions of the comet. By comparing the spectrophotometric characteristics of observed bright patches on Khonsu with those described and attributed to the presence of H2O ice on the comet by Barucci et al. (2016) utilising infrared data, we suggest that the bright patches we present could plausibly be derived from H2O ice. One of the studied bright patches has been observed to exist on the surface for more than 4 months without a major diminution of its size, which implies the existence of potential subsurface icy layers. The location of this feature is strongly correlated with a cometary outburst during the perihelion passage of the comet in August 2015, and we interpret it to have triggered the surface modifications necessary to unearth the stratified icy layers beneath the surface.

ARC-1990-A91-2001

NASA Image and Video Library

1990-02-19

Range : 60,000 miles These images are two versions of a near-infrafed map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft.The map shows the turbulent, cloudy middle atmosphere some 30-33 miles above the surface, 6-10 miles below the visible cloudtops. The image to the left shows the radiant heat from the lower atmosphere (about 400 degrees F) ahining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. This cloud layer is at about 170 degrees F, at a pressure about 1/2 Earth's atmospheric pressure. About 2/3 of the dark hemisphere is visible, centered on longitude 350 West, with bright slsivers of daylit high clouds visible at top and bottom left. The right image, a modified negative, represents what scientists believe would be the visual appearance of this mid-level cloud deck in daylight, with the clouds reflecting sunlight instead of clocking out infrared from the hot planet and lower atmosphere. Near the equator, the clouds appear fluffy and clocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick clouds at this altitude. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo is a combined mapping (imaging) and spectral instrument. It can sense 408 contiguous wavelengths from 0.7 microns (deep red) to 5.2 microns, and can construct a map or image by mechanical scanning. It can spectroscopic-ally analyze atmospheres and surfaces and construct thermal and chemical maps.

ARC-1990-A91-2002

NASA Image and Video Library

1990-02-10

Range : 60,000 miles These images are two versions of a near-infrafed map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft.The map shows the turbulent, cloudy middle atmosphere some 30-33 miles above the surface, 6-10 miles below the visible cloudtops. The image to the left shows the radiant heat from the lower atmosphere (about 400 degrees F) ahining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. This cloud layer is at about 170 degrees F, at a pressure about 1/2 Earth's atmospheric pressure. About 2/3 of the dark hemisphere is visible, centered on longitude 350 West, with bright slsivers of daylit high clouds visible at top and bottom left. The right image, a modified negative, represents what scientists believe would be the visual appearance of this mid-level cloud deck in daylight, with the clouds reflecting sunlight instead of clocking out infrared from the hot planet and lower atmosphere. Near the equator, the clouds appear fluffy and clocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick clouds at this altitude. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo is a combined mapping (imaging) and spectral instrument. It can sense 408 contiguous wavelengths from 0.7 microns (deep red) to 5.2 microns, and can construct a map or image by mechanical scanning. It can spectroscopic-ally analyze atmospheres and surfaces and construct thermal and chemical maps.

Retrieval and Validation of aerosol optical properties from AHI measurements: impact of surface reflectance assumption

NASA Astrophysics Data System (ADS)

Lim, H.; Choi, M.; Kim, J.; Go, S.; Chan, P.; Kasai, Y.

2017-12-01

This study attempts to retrieve the aerosol optical properties (AOPs) based on the spectral matching method, with using three visible and one near infrared channels (470, 510, 640, 860nm). This method requires the preparation of look-up table (LUT) approach based on the radiative transfer modeling. Cloud detection is one of the most important processes for guaranteed quality of AOPs. Since the AHI has several infrared channels, which are very advantageous for cloud detection, clouds can be removed by using brightness temperature difference (BTD) and spatial variability test. The Yonsei Aerosol Retrieval (YAER) algorithm is basically utilized on a dark surface, therefore a bright surface (e.g., desert, snow) should be removed first. Then we consider the characteristics of the reflectance of land and ocean surface using three visible channels. The known surface reflectivity problem in high latitude area can be solved in this algorithm by selecting appropriate channels through improving tests. On the other hand, we retrieved the AOPs by obtaining the visible surface reflectance using NIR to normalized difference vegetation index short wave infrared (NDVIswir) relationship. ESR tends to underestimate urban and cropland area, we improved the visible surface reflectance considering urban effect. In this version, ocean surface reflectance is using the new cox and munk method which considers ocean bidirectional reflectance distribution function (BRDF). Input of this method has wind speed, chlorophyll, salinity and so on. Based on validation results with the sun-photometer measurement in AErosol Robotic NETwork (AERONET), we confirm that the quality of Aerosol Optical Depth (AOD) from the YAER algorithm is comparable to the product from the Japan Aerospace Exploration Agency (JAXA) retrieval algorithm. Our future update includes a consideration of improvement land surface reflectance by hybrid approach, and non-spherical aerosols. This will improve the quality of YAER algorithm more, particularly retrieval for the dust particle over the bright surface in East Asia.

Syrtis Major

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 1 May 2002) The Science This image is from the region of Syrtis Major, which is dominated by a low-relief shield volcano. This area is believed to be an area of vigorous aeolian activity with strong winds in the east-west direction. The effects of these winds are observed as relatively bright streaks across the image, extending from topographic features such as craters. The brighter surface material probably indicates a smaller relative particle size in these areas, as finer particles have a higher albedo. The bright streaks seen off of craters are believed to have formed during dust storms. A raised crater rim can cause a reduction in the wind velocity directly behind it, which results in finer particles being preferentially deposited in this location. In the top half of the image, there is a large bright streak that crosses the entire image. There is no obvious topographic obstacle, therefore it is unclear whether it was formed in the same manner as described above. This image is located northwest of Nili Patera, a large caldera in Syrtis Major. Different flows from the caldera eruptions can be recognized as raised ridges, representing the edge of a flow lobe. The Story In the 17th century, Holland was in its Golden Age, a time of cultural greatness and immense political and economic influence in the world. In that time, lived a inquisitive person named Christian Huygens. As a boy, he loved to draw and to figure out problems in mathematics. As a man, he used these talents to make the first detailed drawings of the Martian surface - - only 50 years or so after Galileo first turned his telescope on Mars. Mars suddenly became something other than a small red dot in the sky. One of the drawings Huygens made was of a dark marking on the red planet's surface named Syrtis Major. Almost 350 years later, here we are with an orbiter that can show us this place in detail. Exploration lives! It's great we can study this area up close. In earlier periods of history, scientists were fascinated with Syrtis Major because this dark region varied so much through the seasons and years. Some people thought it might be a changing sea, and others thought it might be vegetation. Early spacecraft like Mariner and Viking revealed for the first time that the changes were caused by the wind blowing dust and sand across the surface. What we can see in this image is exactly that: evidence of a lot of wind action. Bright dust patches streak across this image, formed through wind interference from craters and other landforms. These wispy, bright streaks are spread on the surface by a vigorous, east-west wind that kicked up huge dust storms, scattering the fine particles of sand and dust in an almost etherial pattern. The bright streaks in the top part of the image might have formed in a slightly different way, because there is no landform standing in the wind's way. Beneath the bright surface dust are raised ridges that mark the edges of earlier lava flows from Nili Patera, a Martian 'caldera.' A caldera is a collapsed, bowl-shaped depression at the top of a volcano cone. Can you imagine how Christian Huygens would feel if he lived today and could see all of this knowledge unfold? Or how it would feel to be the first person to stand in this dark volcanic and cratered region, knowing how many discovers had paved the way to that moment? Yes, exploration lives!

Iapetus: Major discoveries from the Cassini imaging experiment

NASA Astrophysics Data System (ADS)

Denk, T.; Neukum, G.; Schmedemann, N.; Roatsch, Th.; Thomas, P. C.; Helfenstein, P.; Turtle, E. P.; Porco, C. C.

2008-09-01

Over the course of more than three years orbiting Saturn, the Imaging Subsystem (ISS) [1] of the Cassini spacecraft has acquired high-resolution images of the Saturnian moon Iapetus during a number of flybys. The most recent and only targeted Iapetus flyby occured on 10 September 2007, and allowed a >50x closer look at the surface than any previous observation. The surface of Iapetus is heavily cratered down to the resolution limit of ~10 meters per pixel. The crater size-frequency distribution shows no measurable difference between the leading and the trailing hemisphere, arguing for planetocentric projectiles as the main impactor source. The equatorial ridge can now be clearly tracked along half of Iapetus's circumference, from ~50°W to ~245°W; it is mainly absent on the other hemisphere. However, we argue that it presumably spanned the full globe shortly after formation. Very small bright-ray and bright-rim craters have been detected deep within the dark hemisphere, suggestive for a dark blanket with a thickness in the order of decimeters to meters only. On the trailing side at low and mid-latitudes, very dark terrain is located immediately adjacent to bright terrain, with almost no gray shading in between. In many cases, crater walls facing towards the equator are dark, while poleward-facing walls and slopes are bright. This effect vanishes at both north and south high latitudes. We interpret these observations to indicate that thermal segregation of water ice is responsible for these complex small-scale dark-bright patterns. On the trailing side, a bright polar cap has been observed at high latitudes on both hemispheres (north and south). A global color dichotomy has been detected in addition to the long-known global brightness dichotomy, with the leading side showing a significantly redder color than the trailing side. Unlike the more ellipsoidal-shaped brightness dichotomy, the color dichotomy is quite well separated into two different hemispheres, with the sub-Saturn (~0°W) and anti-Saturn (~180°W) meridians as the approximate boundaries [2]. This global pattern indicates an exogenic origin. Earlier hypotheses for the origin of the brightness dichotomy, like the infall of dust from retrograde outer moons, might actually offer a better explanation for the color dichotomy than for the brightness dichotomy. We propose that this so far unknown process forming the color dichotomy has also reddened and somewhat darkened Hyperion, another moon of Saturn. The color dichotomy also provides a key element to the explanation of the brightness dichotomy in the model of Spencer et al. [3]. References [1] Porco, C.C. et al. (2004) Space Sci. Rev.115, 363. [2] Denk, T. et al. (2006) EGU06-A-08352. [3] Spencer, J.R. et al. (2005) 37th DPS, abstract 39.08.

SMAP Data Assimilation at the GMAO

NASA Technical Reports Server (NTRS)

Reichle, R.; De Lannoy, G.; Liu, Q.; Ardizzone, J.

2016-01-01

The NASA Soil Moisture Active Passive (SMAP) mission has been providing L-band (1.4 GHz) passive microwave brightness temperature (Tb) observations since April 2015. These observations are sensitive to surface(0-5 cm) soil moisture. Several of the key applications targeted by SMAP, however, require knowledge of deeper-layer, root zone (0-100 cm) soil moisture, which is not directly measured by SMAP. The NASA Global Modeling and Assimilation Office (GMAO) contributes to SMAP by providing Level 4 data, including the Level 4 Surface and Root Zone Soil Moisture(L4_SM) product, which is based on the assimilation of SMAP Tb observations in the ensemble-based NASA GEOS-5 land surface data assimilation system. The L4_SM product offers global data every three hours at 9 km resolution, thereby interpolating and extrapolating the coarser- scale (40 km) SMAP observations in time and in space (both horizontally and vertically). Since October 31, 2015, beta-version L4_SM data have been available to the public from the National Snow and Ice Data Center for the period March 31, 2015, to near present, with a mean latency of approx. 2.5 days.

Self-deflection of a bright soliton in a separate bright-dark spatial soliton pair based on a higher-order space charge field

NASA Astrophysics Data System (ADS)

Liu, Jin-Song; Hao, Zhong-Hua

2003-10-01

The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (hat rho) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions. The deflection amount (Deltas0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function of hat rho. When hat rho is weak or strong enough, Deltas0 is, in fact, unchanged with hat rho, whereas Deltas0 increases or decreases monotonically with hat rho in a middle range of hat rho. The corresponding variation range (deltas) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of deltas versus r under some conditions. When hat rho increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.

Large-scale clustering of Lymanα emission intensity from SDSS/BOSS

DOE PAGES

Croft, Rupert A. C.; Miralda-Escudé, Jordi; Zheng, Zheng; ...

2016-01-27

Here we present a tentative detection of the large-scale structure of Ly α emission in the Universe at redshifts z = 2–3.5 by measuring the cross-correlation of Ly α surface brightness with quasars in Sloan Digital Sky Survey/Baryon Oscillation Spectroscopic Survey. We use a million spectra targeting luminous red galaxies at z < 0.8, after subtracting a best-fitting model galaxy spectrum from each one, as an estimate of the high-redshift Ly α surface brightness. The quasar–Ly α emission cross-correlation is detected on scales 1 ~ 15h ₋1 Mpc, with shape consistent with a ΛCDM model with Ω m =0.30± 0.10more » 0.07. The predicted amplitude of this cross- correlation is proportional to the product of the mean Lyα surface brightness, {μ α}, the amplitude of mass density fluctuations, and the quasar and Lyα emission bias factors. Using published cosmological observations to constrain the amplitude of mass fluctuations and the quasar bias factor, we infer the value of the product {μ α} (b α /3) = (3.9±0.9)×10 ₋21 erg s ₋1 cm ₋2 °A ₋1 arcsec ₋2, where b α is the Lyα emission linear bias factor. If the dominant sources of Lyα emission we measure are star forming galaxies, we infer a total mean star formation rate density of ρSFR = (0.28 ± 0.07)(3/b α ) yr ₋1 Mpc ₋3 at z = 2 ₋ 3.5. For b α = 3, this value is a factor of 21 ₋ 35 above previous estimates relying on individually detected Lyα emitters, although it is consistent with the total star-formation density derived from dust-corrected, continuum UV surveys. Our observations therefore imply that 97% of the Lyα emission in the Universe at these redshifts is undetected in previous surveys of Lyα emitters. Our detected Lyα emission is also much greater, by at least an order of magnitude, than that measured from stacking analyses of faint halos surrounding previously detected Lyα emitters, but we speculate that it arises from similar low surface brightness Lyα halos surrounding all luminous star-forming galaxies. We also detect a redshift space anisotropy of the quasar-Lyα emission cross-correlation, finding evidence at the 3.0σ level that it is radially elongated, contrary to the prediction for linear gravitational evolution, but consistent with distortions caused by radiative-transfer effects, as predicted by Zheng et al. (2011). Lastly, our measurements represent the first application of the intensity mapping technique to optical observations.« less

Multipass holographic interferometer improves image resolution

NASA Technical Reports Server (NTRS)

Brooks, R. E.; Heflinger, L. O.

1970-01-01

Multipass holographic interferometer forms a hologram of high diffraction efficiency, and hence provides a bright and high contrast interferogram. It is used to study any effect which changes the index of refraction and to study surface deformations of a flat reflecting surface.

All-metal meta-surfaces for narrowband light absorption and high performance sensing

NASA Astrophysics Data System (ADS)

Liu, Zhengqi; Liu, Guiqiang; Fu, Guolan; Liu, Xiaoshan; Huang, Zhenping; Gu, Gang

2016-11-01

We report an experimental scheme for high performance sensing by an all-metal meta-surface (AMMS) platform. A dual-band resonant absorption spectrum with a bandwidth down to a single-digit nanometer level and an absorbance up to 89% is achieved due to the surface lattice resonances supported by the resonators array and their hybridization coupling with the particle plasmon resonances. The sensing application in the analysis of the sodium chloride solution has been demonstrated, where remarkable changes from a spectral ‘dark state’ to ‘bright state’ and vice versa are observed. Sensing performance factors of the figure of merit exceeding 50 and the spectral intensity change related FoM* up to 1075 are simultaneously achieved. The corresponding detection limit is as low as 8.849  ×  10-6 RIU. These features make such an AMMS-based sensor a promising route for efficient bio-chemical sensing, etc.

Volcanism on Io: New insights from global geologic mapping

USGS Publications Warehouse

Williams, D.A.; Keszthelyi, L.P.; Crown, D.A.; Yff, J.A.; Jaeger, W.L.; Schenk, P.M.; Geissler, P.E.; Becker, T.L.

2011-01-01

We produced the first complete, 1:15M-scale global geologic map of Jupiter's moon Io, based on a set of monochrome and color Galileo-Voyager image mosaics produced at a spatial resolution of 1km/pixel. The surface of Io was mapped into 19 units based on albedo, color and surface morphology, and is subdivided as follows: plains (65.8% of surface), lava flow fields (28.5%), mountains (3.2%), and patera floors (2.5%). Diffuse deposits (DD) that mantle the other units cover ???18% of Io's surface, and are distributed as follows: red (8.6% of surface), white (6.9%), yellow (2.1%), black (0.6%), and green (???0.01%). Analyses of the geographical and areal distribution of these units yield a number of results, summarized below. (1) The distribution of plains units of different colors is generally geographically constrained: Red-brown plains occur >??30?? latitude, and are thought to result from enhanced alteration of other units induced by radiation coming in from the poles. White plains (possibly dominated by SO2+contaminants) occur mostly in the equatorial antijovian region (??30??, 90-230??W), possibly indicative of a regional cold trap. Outliers of white, yellow, and red-brown plains in other regions may result from long-term accumulation of white, yellow, and red diffuse deposits, respectively. (2) Bright (possibly sulfur-rich) flow fields make up 30% more lava flow fields than dark (presumably silicate) flows (56.5% vs. 43.5%), and only 18% of bright flow fields occur within 10km of dark flow fields. These results suggest that secondary sulfurous volcanism (where a bright-dark association is expected) could be responsible for only a fraction of Io's recent bright flows, and that primary sulfur-rich effusions could be an important component of Io's recent volcanism. An unusual concentration of bright flows at ???45-75??N, ???60-120??W could be indicative of more extensive primary sulfurous volcanism in the recent past. However, it remains unclear whether most bright flows are bright because they are sulfur flows, or because they are cold silicate flows covered in sulfur-rich particles from plume fallout. (3) We mapped 425 paterae (volcano-tectonic depressions), up from 417 previously identified by Radebaugh et al. (Radebaugh, J., Keszthelyi, L.P., McEwen, A.S., Turtle, E.P., Jaeger, W., Milazzo, M. [2001]. J. Geophys. Res. 106, 33005-33020). Although these features cover only 2.5% of Io's surface, they correspond to 64% of all detected hot spots; 45% of all hot spots are associated with the freshest dark patera floors, reflecting the importance of active silicate volcanism to Io's heat flow. (4) Mountains cover only ???3% of the surface, although the transition from mountains to plains is gradational with the available imagery. 49% of all mountains are lineated and presumably layered, showing evidence of linear structures supportive of a tectonic origin. In contrast, only 6% of visible mountains are mottled (showing hummocks indicative of mass wasting) and 4% are tholi (domes or shields), consistent with a volcanic origin. (5) Initial analyses of the geographic distributions of map units show no significant longitudinal variation in the quantity of Io's mountains or paterae, in contrast to earlier studies. This is because we use the area of mountain and patera materials as opposed to the number of structures, and our result suggests that the previously proposed anti-correlation of mountains and paterae (Schenk, P., Hargitai, H., Wilson, R., McEwen, A., Thomas, P. [2001]. J. Geophys. Res. 106, 33201-33222; Kirchoff, M.R., McKinnon, W.B., Schenk, P.M. [2011]. Earth Planet. Sci. Lett. 301, 22-30) is more complex than previously thought. There is also a slight decrease in surface area of lava flows toward the poles of Io, perhaps indicative of variations in volcanic activity. (6) The freshest bright and dark flows make up about 29% of all of Io's flow fields, suggesting active emplacement is occurring in less than a third of Io's

Attitude angle effects on Nimbus-7 Scanning Multichannel Microwave Radiometer radiances and geophysical parameter retrievals

NASA Technical Reports Server (NTRS)

Macmillan, Daniel S.; Han, Daesoo

1989-01-01

The attitude of the Nimbus-7 spacecraft has varied significantly over its lifetime. A summary of the orbital and long-term behavior of the attitude angles and the effects of attitude variations on Scanning Multichannel Microwave Radiometer (SMMR) brightness temperatures is presented. One of the principal effects of these variations is to change the incident angle at which the SMMR views the Earth's surface. The brightness temperatures depend upon the incident angle sensitivities of both the ocean surface emissivity and the atmospheric path length. Ocean surface emissivity is quite sensitive to incident angle variation near the SMMR incident angle, which is about 50 degrees. This sensitivity was estimated theoretically for a smooth ocean surface and no atmosphere. A 1-degree increase in the angle of incidence produces a 2.9 C increase in the retrieved sea surface temperature and a 5.7 m/sec decrease in retrieved sea surface wind speed. An incident angle correction is applied to the SMMR radiances before using them in the geophysical parameter retrieval algorithms. The corrected retrieval data is compared with data obtained without applying the correction.

ARC-1979-AC79-7104

NASA Image and Video Library

1979-07-07

Range : 1,094,666 km (677,000 mi.) This false color picture of Callisto was taken by Voyager 2 and is centered on 11 degrees N and 171 degrees W. This rendition uses an ultraviolet image for the blue component. Because the surface displays regional contrast in UV, variations in surface materials are apparent. Notice in particular the dark blue haloes which surround bright craters in the eastern hemisphere. The surface of Callisto is the most heavily cratered of the Galilean satellites and resembles ancient heavily cratered terrains on the moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture. The color version of this picture was constructed by compositing black and white images taken through the ultraviolet, clear and orange filters.

Spectral characteristics of the microwave emission from a wind-driven foam-covered sea

NASA Technical Reports Server (NTRS)

Webster, W. J., Jr.; Wilheit, T. T.; Gloersen, P.; Ross, D. B.

1976-01-01

Aircraft observations of the microwave emission from the wind-driven foam-covered Bering Sea substantiate earlier results and show that the combination of surface roughness and white water yields a significant microwave brightness temperature dependence on wind speed over a wide range of microwave wavelengths, with a decreasing dependence for wavelengths above 6 cm. The spectral characteristic of brightness temperature as a function of wind speed is consistent with a foam model in which the bubbles give rise to a cusped surface between the foam and the sea. In the fetch-limited situation the contribution of the wave structure at the surface appears to increase as the foam coverage decreases. Although the data show that the thin streaks are the most important part of the white water signature, there is some evidence for the contribution of whitecaps.

Surface modification of graphene using HBC-6ImBr in solution-processed OLEDs

NASA Astrophysics Data System (ADS)

Cheng, Tsung-Chin; Ku, Ting-An; Huang, Kuo-You; Chou, Ang-Sheng; Chang, Po-Han; Chang, Chao-Chen; Yue, Cheng-Feng; Liu, Chia-Wei; Wang, Po-Han; Wong, Ken-Tsung; Wu, Chih-I.

2018-01-01

In this work, we report a simple method for solution-processed organic light emitting devices (OLEDs), where single-layer graphene acts as the anode and the hexa-peri-hexabenzocoronene exfoliating agent (HBC-6ImBr) provides surface modification. In SEM images, the PEDOT:PSS solution fully covered the graphene electrode after coating with HBC-6ImBr. The fabricated solution-processed OLEDs with a single-layer graphene anode showed outstanding brightness at 3182 cd/m2 and current efficiency up to 6 cd/A which is comparable to that of indium tin oxide films, and the OLED device brightness performance increases six times compared to tri-layer graphene treated with UV-Ozone at the same driving voltage. This method can be used in a wide variety of solution-processed organic optoelectronics on surface-modified graphene anodes.

An analytic treatment of gravitational microlensing for sources of finite size at large optical depths

NASA Technical Reports Server (NTRS)

Deguchi, Shuji; Watson, William D.

1988-01-01

Statistical methods are developed for gravitational lensing in order to obtain analytic expressions for the average surface brightness that include the effects of microlensing by stellar (or other compact) masses within the lensing galaxy. The primary advance here is in utilizing a Markoff technique to obtain expressions that are valid for sources of finite size when the surface density of mass in the lensing galaxy is large. The finite size of the source is probably the key consideration for the occurrence of microlensing by individual stars. For the intensity from a particular location, the parameter which governs the importance of microlensing is determined. Statistical methods are also formulated to assess the time variation of the surface brightness due to the random motion of the masses that cause the microlensing.

Progress on complementary patterning using plasmon-excited electron beamlets (Conference Presentation)

NASA Astrophysics Data System (ADS)

Du, Zhidong; Chen, Chen; Pan, Liang

2017-04-01

Maskless lithography using parallel electron beamlets is a promising solution for next generation scalable maskless nanolithography. Researchers have focused on this goal but have been unable to find a robust technology to generate and control high-quality electron beamlets with satisfactory brightness and uniformity. In this work, we will aim to address this challenge by developing a revolutionary surface-plasmon-enhanced-photoemission (SPEP) technology to generate massively-parallel electron beamlets for maskless nanolithography. The new technology is built upon our recent breakthroughs in plasmonic lenses, which will be used to excite and focus surface plasmons to generate massively-parallel electron beamlets through photoemission. Specifically, the proposed SPEP device consists of an array of plasmonic lens and electrostatic micro-lens pairs, each pair independently producing an electron beamlet. During lithography, a spatial optical modulator will dynamically project light onto individual plasmonic lenses to control the switching and brightness of electron beamlets. The photons incident onto each plasmonic lens are concentrated into a diffraction-unlimited spot as localized surface plasmons to excite the local electrons to near their vacuum levels. Meanwhile, the electrostatic micro-lens extracts the excited electrons to form a focused beamlet, which can be rastered across a wafer to perform lithography. Studies showed that surface plasmons can enhance the photoemission by orders of magnitudes. This SPEP technology can scale up the maskless lithography process to write at wafers per hour. In this talk, we will report the mechanism of the strong electron-photon couplings and the locally enhanced photoexcitation, design of a SPEP device, overview of our proof-of-concept study, and demonstrated parallel lithography of 20-50 nm features.

Calibrating the Type Ia Supernova Distance Scale Using Surface Brightness Fluctuations

NASA Astrophysics Data System (ADS)

Potter, Cicely; Jensen, Joseph B.; Blakeslee, John; Milne, Peter; Garnavich, Peter M.; Brown, Peter

2018-06-01

We have observed 20 supernova host galaxies with HST WFC3/IR in the F110W filter, and prepared the data for Surface Brightness Fluctuation (SBF) distance measurements. The purpose of this study is to determine if there are any discrepancies between the SBF distance scale and the type-Ia SN distance scale, for which local calibrators are scarce. We have now measured SBF magnitudes to all early-type galaxies that have hosted SN Ia within 80 Mpc for which SBF measurements are possible. SBF is the only distance measurement technique with statistical uncertainties comparable to SN Ia that can be applied to galaxies out to 80 Mpc.

Ground temperature measurement by PRT-5 for maps experiment

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm and computer program were developed for determining the actual surface temperature from the effective brightness temperature as measured remotely by a radiation thermometer called PRT-5. This procedure allows the computation of atmospheric correction to the effective brightness temperature without performing detailed radiative transfer calculations. Model radiative transfer calculations were performed to compute atmospheric corrections for several values of the surface and atmospheric parameters individually and in combination. Polynomial regressions were performed between the magnitudes or deviations of these parameters and the corresponding computed corrections to establish simple analytical relations between them. Analytical relations were also developed to represent combined correction for simultaneous variation of parameters in terms of their individual corrections.

Studies of the Virgo Cluster. I - Photometry of 109 galaxies near the cluster center to serve as standards

NASA Technical Reports Server (NTRS)

Sandage, A.; Tarenghi, M.; Binggeli, B.

1984-01-01

Attention is given to the technical aspects of photometric measurements of 109 galaxies near the center of the Virgo Cluster, noting various types of radii and surface brightness for about 50 E and dE galaxies in the sample that range in absolute magnitude from -20 to -12. These data are combined with data from the literature for giant E and dwarf E galaxies in the Local Group to study the systematic properties of E galaxies over a range of one million luminosities. The radial intensity profiles derived are fitted to the manifold of King (1978) models to derive model-dependent central surface brightness, core radii, and cutoff radii.

Investigating the surface brightness profiles, ejected mass and speed from the outburst events of comet 67P/Churyumov-Gerasmenko

NASA Astrophysics Data System (ADS)

Lin, Zhong-Yi; Vincent, Jean-Baptiste; A'Hearn, Mike; Lara, Luisa; Knollenberg, Joerg; Ip, Wing-Huen; Osiris Team

2016-04-01

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) WAC and NAC camera onboard the ESA Rosetta spacecraft orbiting 67P/Churyumov-Gersimenko has captured a lot of outbursts since July, 2015. Most of their source regions were located at southern hemisphere of comet C-G. Including the March- and perihelion-outbursts, the detected events show a variety of morphological features (i.e. broad fan, collimated jet and so on). In this work, we investigate these events and characterize the physical properties, including the surface brightness profiles, ejected mass and speed if there were two or more images acquired by the same filter during the outburst timeframe.

Surface brightness and color distributions in blue compact dwarf galaxies. I - Haro 2, an extreme example of a star-forming young elliptical galaxy

NASA Technical Reports Server (NTRS)

Loose, Hans-Hermann; Thuan, Trinh X.

1986-01-01

The first results of a large-scale program to study the morphology and structure of blue compact dwarf galaxies from CCD observations are presented. The observations and reduction procedures are described, and surface brightness and color profiles are shown. The results are used to discuss the morphological type of Haro 2 and its stellar populations. It is found that Haro 2 appears to be an extreme example of an elliptical galaxy undergoing intense star formation in its central regions, and that the oldest stars it contains were made only about four million yr ago. The 'missing' mass problem of Haro 2 is also discussed.

Satellite microwave and in situ observations of the Weddell Sea ice cover and its marginal ice zone

NASA Technical Reports Server (NTRS)

Comiso, J. C.; Sullivan, C. W.

1986-01-01

The radiative and physical characteristics of the Weddell Sea ice cover and its marginal ice zone are analyzed using multichannel satellite passive microwave data and ship and helicopter observations obtained during the 1983 Antarctic Marine Ecosystem Research. Winter and spring brightness temperatures are examined; spatial variability in the brightness temperatures of consolidated ice in winter and spring cyclic increases and decrease in brightness temperatures of consolidated ice with an amplitude of 50 K at 37 GHz and 20 K at 18 GHz are observed. The roles of variations in air temperature and surface characteristics in the variability of spring brightness temperatures are investigated. Ice concentrations are derived using the frequency and polarization techniques, and the data are compared with the helicopter and ship observations. Temporal changes in the ice margin structure and the mass balance of fresh water and of biological features of the marginal ice zone are studied.

High Energy Studies of Astrophysical Dust

NASA Astrophysics Data System (ADS)

Corrales, Lia Racquel

Astrophysical dust---any condensed matter ranging from tens of atoms to micron sized grains---accounts for about one third of the heavy elements produced in stars and disseminated into space. These tiny pollutants are responsible for producing the mottled appearance in the spray of light we call the "Milky Way." However these seemingly inert particles play a strong role in the physics of the interstellar medium, aiding star and planet formation, and perhaps helping to guide galaxy evolution. Most dust grains are transparent to X-ray light, leaving a signature of atomic absorption, but also scattering the light over small angles. Bright X-ray objects serendipitously situated behind large columns of dust and gas provide a unique opportunity to study the dust along the line of sight. I focus primarily on X-ray scattering through dust, which produces a diffuse halo image around a central point source. Such objects have been observed around X-ray bright Galactic binaries and extragalactic objects that happen to shine through the plane of the Milky Way. I use the Chandra X-ray Observatory, a space-based laboratory operated by NASA, which has imaging resolution ideal for studying X-ray scattering halos. I examine several bright X-ray objects with dust-free sight lines to test their viability as templates and develop a parametric model for the Chandra HETG point spread function (PSF). The PSF describes the instrument's imaging response to a point source, an understanding of which is necessary for properly measuring the surface brightness of X-ray scattering halos. I use an HETG observation of Cygnus X-3, one of the brightest objects available in the Chandra archive, to derive a dust grain size distribution. There exist degenerate solutions for the dust scattering halo, but with the aid of Bayesian analytics I am able to apply prior knowledge about the Cyg X-3 sight line to measure the relative abundance of dust in intervening Milky Way spiral arms. I also demonstrate how information from a single scattering halo can be used in conjunction with X-ray spectroscopy to directly measure the dust-to-gas mass ratio, laying the groundwork for future scattering halo surveys. Distant quasars also produce X-rays that pierce the intergalactic medium. These sources invite the unique opportunity to search for extragalactic dust, whether distributed diffusely throughout intergalactic space, surrounding other galaxies, or occupying reservoirs of cool intergalactic gas. I review X-ray scattering in a cosmological context, examining the range and sensitivity of Chandra to detect the low surface brightness levels of intergalactic scattering. Of particular interest is large "grey" dust, which would cause systematic errors in precision cosmology experiments at a level comparable to the size of the error bars sought. This requires using the more exact Mie scattering treatment, which reduces the scattering cross-section for soft X-rays by a factor of about ten, compared to the Rayleigh-Gans approximation used for interstellar X-ray scattering studies. This allows me to relax the limit on intergalactic dust imposed by previous X-ray imaging of a z=4.3 quasar, QSO 1508+5714, which overestimated the scattering intensity. After implementing the Mie solution with the cosmological integral for scattering halo intensity, I found that intergalactic dust will scatter 1-3% of soft X-ray light. Unfortunately the wings of the Chandra PSF are brighter than the surface brightness expected for these intergalactic scattering halos. The X-ray signatures of intergalactic dust may only be visible if a distant quasar suddenly dimmed by a factor of 1000 or more, leaving behind an X-ray scattering echo, or "ghost" halo.

Dark Material at the Surface of Polar Crater Deposits on Mercury

NASA Technical Reports Server (NTRS)

Neumann, Gregory A.; Cavanaugh, John F.; Sun, Xiaoli; Mazarico, Erwan; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.; Paige, Daid A.

2012-01-01

Earth-based radar measurements [1-3] have yielded images of radar-bright material at the poles of Mercury postulated to be near-surface water ice residing in cold traps on the permanently shadowed floors of polar impact craters. The Mercury Laser Altimeter (MLA) on board the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has now mapped much of the north polar region of Mercury [4] (Fig. 1). Radar-bright zones lie within polar craters or along poleward-facing scarps lying mainly in shadow. Calculations of illumination with respect to solid-body motion [5] show that at least 0.5% of the surface area north of 75deg N lies in permanent shadow, and that most such permanently shadowed regions (PSRs) coincide with radar-bright regions. MLA transmits a 1064-nm-wavelength laser pulse at 8 Hz, timing the leading and trailing edges of the return pulse. MLA can in some cases infer energy and thereby surface reflectance at the laser wavelength from the returned pulses. Surficial exposures of water ice would be optically brighter than the surroundings, but persistent surface water ice would require temperatures over all seasons to remain extremely low (<110 K). Thermal models [6,7] incorporating direct and scattered radiation, Mercury s eccentric orbit, 3:2 spin-orbit resonance, and near-zero obliquity generally do not support such conditions in all permanently shadowed craters but suggest that water ice buried near the surface (<0.5 m depth) could survive for > 1 Gy. We describe measurements of reflectivity derived from MLA pulse returns. These reflectivity data show that surface materials in the shadowed regions are darker than their surroundings, enough to strongly attenuate or extinguish laser returns. Such measurements appear to rule out widespread surface exposures of water ice. We consider explanations for the apparent low reflectivity of these regions involving other types of volatile deposit.

SMOS after 2 YEARS and a half in orbit

NASA Astrophysics Data System (ADS)

Kerr, Y.; Richaume, P.; Wigneron, J.-P.; Waldteufel, P.; Mecklenburg, S.; Cabot, F.; Boutin, J.; Font, J.; Reul, N.

2012-04-01

The SMOS (Soil Moisture and Ocean Salinity) satellite was successfully launched in November 2009. This ESA led mission for Earth Observation is dedicated to provide soil moisture over continental surface (with an accuracy goal of 0.04 m3/m3) and ocean salinity. These two geophysical features are important as they control the energy balance between the surface and the atmosphere. Their knowledge at a global scale is of interest for climatic and weather researches in particular in improving models forecasts. The purpose of this communication is to present the mission results after more than two years in orbit as well as some outstanding results already obtained. A special attention will be devoted to level 2 products. Modeling multi-angular brightness temperatures is not straightforward. The radiative model transfer model L-MEB (L-band Microwave Emission) is used over land while different models with different approaches as to the modeling of sea surface roughness are used over ocean surfaces. Over land the approach is based on semi-empirical relationships, adapted to different type of surface. The model computes a dielectric constant leading to surface emissivity. Surface features (roughness, vegetation) are also considered in the models. However, considering SMOS spatial resolution a wide area is seen by the instrument with strong heterogeneity. The L2 soil moisture retrieval scheme takes this into account. Brightness temperatures are computed for every classes composing a working area. A weighted function is applied for the incidence angle and the antenna beam. Once the brightness temperature is computed for the entire working area, the minimizing process starts. If no soil moisture is derived (not attempted or process failed) a dielectric constant is still derived from an simplified modeled (the cardioid model). SMOS data enabled very quickly to infer Sea surface salinity fields. As salinity retrieval is quite challenging, retrieving it enable to assess very finely the characteristics of the complete system in terms of stability, drift etc. Some anomalies such as the ascending descending temperature differences, temporal drifts or land sea contamination were used to infer issues and improve data quality. The modeling has to account for several perturbing factors 'galactic reflection, sea state, atmospheric path and Faraday rotation etc…as the useful signal is quite small when compared to the perturbing factors impact as well as the instrument sensitivity. Over sea ice several studies showed that it was possible to infer thin ice (first year ice, 50 cm or less) from SMOS measurements. Other studies focused on the Antarctic plateau with also very interesting new results. This presentation will show in detail the SMOS in flight results. The retrieval schemes have been developed to reach science requirements, that is to derive the surface soil moisture over continental surface with an accuracy better than 0,04m3/m3. Over the ocean the goals are not yet satisfied but results are already getting close to the requirements.

A surface brightness correlation between carbon monoxide and nonthermal radio continuum emission in the galaxy

NASA Technical Reports Server (NTRS)

Allen, R. J.

1992-01-01

The relation between the projected face-on velocity-integrated CO (1-0) brightness ICO and the 20 cm nonthermal radio continuum brightness T20 is examined as a function of radius in the Galactic disk. Averaged in 1 kpc annuli, the ratio ICO/T20 is nearly constant with a mean value of 1.51 +/- 0.34 km/s from 2 to 10 kpc. The manner in which ICO and T20 are derived for the Galaxy is different in several significant respects from the more direct observational determinations possible in nearby galaxies. The fact that the Galaxy also follows this correlation further strengthens the generality of the result.

LIRAS mission for lunar exploration by microwave interferometric radiometer: Moon's subsurface characterization, emission model and numerical simulator

NASA Astrophysics Data System (ADS)

Pompili, Sara; Silvio Marzano, Frank; Di Carlofelice, Alessandro; Montopoli, Mario; Talone, Marco; Crapolicchio, Raffaele; L'Abbate, Michelangelo; Varchetta, Silvio; Tognolatti, Piero

2013-04-01

The "Lunar Interferometric Radiometer by Aperture Synthesis" (LIRAS) mission is promoted by the Italian Space Agency and is currently in feasibility phase. LIRAS' satellite will orbit around the Moon at a height of 100 km, with a revisiting time period lower than 1 lunar month and will be equipped with: a synthetic aperture radiometer for subsurface sounding purposes, working at 1 and 3 GHz, and a real aperture radiometer for near-surface probing, working at 12 and 24 GHz. The L-band payload, representing a novel concept for lunar exploration, is designed as a Y-shaped thinned array with three arms less than 2.5 m long. The main LIRAS objectives are high-resolution mapping and vertical sounding of the Moon subsurface by applying the advantages of the antenna aperture synthesis technique to a multi-frequency microwave passive payload. The mission is specifically designed to achieve spatial resolutions less than 10 km at surface and to retrieve thermo-morphological properties of the Moon subsurface within 5 m of depth. Among LIRAS products are: lunar near-surface brightness temperature, subsurface brightness temperature gross profile, subsurface regolith thickness, density and average thermal conductivity, detection index of possible subsurface discontinuities (e.g. ice presence). The following study involves the preliminary design of the LIRAS payload and the electromagnetic and thermal characterization of the lunar subsoil through the implementation of a simulator for reproducing the LIRAS measurements in response to observations of the Moon surface and subsurface layers. Lunar physical data, collected after the Apollo missions, and LIRAS instrument parameters are taken as input for the abovementioned simulator, called "LIRAS End-to-end Performance Simulator" (LEPS) and obtained by adapting the SMOS End-to-end Performance Simulator to the different instrumental, orbital, and geophysical LIRAS characteristics. LEPS completely simulates the behavior of the satellite when it becomes operational providing the extrapolation of lunar brightness temperature maps in both Antenna frame (the cosine domain) and on the Moon surface and allowing an accurate analysis of the instrument performance. The Moon stratigraphy is reproduced in LEPS environment through three scenarios: a macro-layer of regolith; two subsequent macro-layers of regolith and rock; three subsequent macro-layers of regolith, ice and rock, respectively. These scenarios are studied using an incoherent approach, taking into account the interaction between the upwelling and downwelling radiation contributions from each layer to model the resulting brightness temperature at the surface level. It has been considered that the radiative behavior of the Moon varies over time, depending on solar illumination conditions, and it is also function of the material properties, layer thickness and specific position on the lunar crust; moreover it has been examined its variation with frequency, observation angle, and polarization. Using the proposed emission model it has been possible to derive a digital thermal model in the microwave frequency of the Moon, allowing in-depth analysis of the lunar soil consistency; this collected information could be related with a lunar digital elevation model in order to achieve global coverage information on topological aspects. The main results of the study will be presented at the conference.

Morphologic examination of CD3-CD4(bright) cells in rat liver.

PubMed

Yamamoto, Satoshi; Sato, Yosinobu; Abo, Toru; Hatakeyama, Katsuyosi

2002-01-01

Recently, we found CD3-CD4(bright) cells with comparative specificity for normal rat liver. In the current study, we investigated the type and form of both CD3-CD4(bright) cells and CD3-CD4(dull) cells in the rat liver. The surface phenotype of hepatic mononuclear cells in Lewis rats was identified by using monoclonal antibodies including anti-CD4, anti-CD3, and antimacrophage in conjunction with two- or three-color immunofluorescence analysis. CD3-CD4(bright) cells and CD3-CD4(dull) cells were examined morphologically using May-Giemsa staining and scanning electron microscopy. The distribution of CD3-CD4(bright) cells and CD3-CD4(dull) cells 48 hours after intravenous administration of liposome-encapsulated dichloromethylene diphosphate was also investigated. In comparison to CD3-CD4(dull) cells, CD3-CD4(bright) cells were slightly larger macrophages with abundant cytoplasmic granules, being present with comparative specificity for normal rat liver and showing negligible effects by intravenous liposome-encapsulated dichloromethylene diphosphate administration. These data suggest that in normal young rat liver these CD3-CD4(dull) and CD3-CD4(bright) cells may be dendritic cells and Kupffer cells that shift from the liver to the spleen or vice versa. These cells may also be able to locally proliferate in liver or spleen due to changes in the developing liver.

Morphologic and thermophysical characteristics of lava flows southwest of Arsia Mons, Mars

NASA Astrophysics Data System (ADS)

Crown, David A.; Ramsey, Michael S.

2017-08-01

The morphologic and thermophysical characteristics of part of the extensive lava flow fields southwest of Arsia Mons (22.5-27.5°S, 120-130°W) have been examined using a combination of orbital VNIR and TIR datasets. THEMIS images provide context for the regional geology and record diurnal temperature variability that is diverse and unusual for flow surfaces in such close proximity. CTX images were used to distinguish dominant flow types and assess local age relationships between individual lava flows. CTX and HiRISE images provide detailed information on flow surface textures and document aeolian effects as they reveal fine-grained deposits in many low-lying areas of the flow surfaces as well as small patches of transverse aeolian ridges. Although this region is generally dust-covered and has a lower overall thermal inertia, the THEMIS data indicate subtle spectral variations within the population of lava flows studied. These variations could be due to compositional differences among the flows or related to mixing of flow and aeolian materials. Specific results regarding flow morphology include: a) Two main lava flow types (bright, rugged and dark, smooth as observed in CTX images) dominate the southwest Arsia Mons/NE Daedalia Planum region; b) the bright, rugged flows have knobby, ridged, and/or platy surface textures, commonly have medial channel/levee systems, and may have broad distal lobes; c) the dark, smooth flows extend from distributary systems that consist of combinations of lava channels, lava tubes, and/or sinuous ridges and plateaus; and d) steep-sided, terraced margins, digitate breakout lobes, and smooth-surfaced plateaus along lava channel/tube systems are interpreted as signatures of flow inflation within the dark, smooth flow type. These flows exhibit smoother upper surfaces, are thinner, and have more numerous, smaller lobes, which, along with their the channel-/tube-fed nature, indicate a lower viscosity lava than for the bright, rugged flows. Flow patterns and local interfingering and overlapping relationships are delineated in CTX images and allow reconstruction of the complex flow field surfaces. Darker channel-/tube-fed flows are generally younger than adjacent thicker, bright, rugged flows; however, the diversity and complexity of temporal relationships observed, along with the thermophysical variability, suggests that lava sources with different eruptive styles and magnitudes and/or lavas that experienced different local emplacement conditions were active contemporaneously.

Image quality evaluation for smart-phone displays at lighting levels of indoor and outdoor conditions

NASA Astrophysics Data System (ADS)

Gong, Rui; Xu, Haisong; Wang, Binyu; Luo, Ming Ronnier

2012-08-01

The image quality of two active matrix organic light emitting diode (AMOLED) smart-phone displays and two in-plane switching (IPS) ones was visually assessed at two levels of ambient lighting conditions corresponding to indoor and outdoor applications, respectively. Naturalness, colorfulness, brightness, contrast, sharpness, and overall image quality were evaluated via psychophysical experiment by categorical judgment method using test images selected from different application categories. The experimental results show that the AMOLED displays perform better on colorfulness because of their wide color gamut, while the high pixel resolution and high peak luminance of the IPS panels help the perception of brightness, contrast, and sharpness. Further statistical analysis of ANOVA indicates that ambient lighting levels have significant influences on the attributes of brightness and contrast.

Giant Ly α Nebulae in the Illustris Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gronke, Max; Bird, Simeon, E-mail: maxbg@astro.uio.no

2017-02-01

Several “giant” Ly α nebulae with an extent ≳300 kpc and observed Ly α luminosity of ≳10{sup 44} erg s{sup −1} cm{sup −2} arcsec{sup −2} have recently been detected, and it has been speculated that their presence hints at a substantial cold gas reservoir in small cool clumps not resolved in modern hydrodynamical simulations. We use the Illustris simulation to predict the Ly α emission emerging from large halos ( M > 10{sup 11.5} M {sub ⊙}) at z ∼ 2 and thus test this model. We consider both active galactic nucleus (AGN) and star driven ionization, and compare themore » simulated surface brightness maps, profiles, and Ly α spectra to a model where most gas is clumped below the simulation resolution scale. We find that with Illustris, no additional clumping is necessary to explain the extents, luminosities, and surface brightness profiles of the “giant Ly α nebulae” observed. Furthermore, the maximal extents of the objects show a wide spread for a given luminosity and do not correlate significantly with any halo properties. We also show how the detected size depends strongly on the employed surface brightness cutoff, and predict that further examples of such objects will be found in the near future.« less

A population of faint low surface brightness galaxies in the Perseus cluster core

NASA Astrophysics Data System (ADS)

Wittmann, Carolin; Lisker, Thorsten; Ambachew Tilahun, Liyualem; Grebel, Eva K.; Conselice, Christopher J.; Penny, Samantha; Janz, Joachim; Gallagher, John S.; Kotulla, Ralf; McCormac, James

2017-09-01

We present the detection of 89 low surface brightness (LSB), and thus low stellar density galaxy candidates in the Perseus cluster core, of the kind named 'ultra-diffuse galaxies', with mean effective V-band surface brightnesses 24.8-27.1 mag arcsec-2, total V-band magnitudes -11.8 to -15.5 mag, and half-light radii 0.7-4.1 kpc. The candidates have been identified in a deep mosaic covering 0.3 deg2, based on wide-field imaging data obtained with the William Herschel Telescope. We find that the LSB galaxy population is depleted in the cluster centre and only very few LSB candidates have half-light radii larger than 3 kpc. This appears consistent with an estimate of their tidal radius, which does not reach beyond the stellar extent even if we assume a high dark matter content (M/L = 100). In fact, three of our candidates seem to be associated with tidal streams, which points to their current disruption. Given that published data on faint LSB candidates in the Coma cluster - with its comparable central density to Perseus - show the same dearth of large objects in the core region, we conclude that these cannot survive the strong tides in the centres of massive clusters.

Optical Properties of CdSe/ZnS Nanocrystals

PubMed Central

Gaigalas, Adolfas K; DeRose, Paul; Wang, Lili; Zhang, Yu-Zhong

2014-01-01

Measurements are presented of the absorbance, fluorescence emission, fluorescence quantum yield, and fluorescence lifetime of CdSe/ZnS nanocrystals, also known as quantum dots (QDs). The study included three groups of nanocrystals whose surfaces were either passivated with organic molecules, modified further with carboxyl groups, or conjugated with CD14 mouse anti-human antibodies. The surface modifications had observable effects on the optical properties of the nanocrystals. The oscillator strength (OS) of the band edge transition was about 1.0 for the nanocrystals emitting at 565 nm, 605 nm, and 655 nm. The OS could not be determined for QDs with emission at 700 nm and 800 nm. The fluorescence lifetimes varied from 26 ns for nanocrystals emitting near 600 nm to 150 ns for nanocrystals emitting near 800 nm. The quantum yield ranged between 0.4 and 0.9 for the nanocrystals in this study. A brightness index (BI) was used to evaluate the suitability of the nanocrystal labels for flow cytometer measurements. Most QD labels are at least as bright as fluorescein for applications in flow cytometer assays with 488 nm excitation. For optimal brightness the QDs should be excited with 405 nm light. We observed a strong dependence of the QD absorbance at 250 nm on the surface modification of the QD. PMID:26601047

Analysis of wave propagation and wavefront sensing in target-in-the-loop beam control systems

NASA Astrophysics Data System (ADS)

Vorontsov, Mikhail A.; Kolosov, Valeri V.

2004-10-01

Target-in-the-loop (TIL) wave propagation geometry represents perhaps the most challenging case for adaptive optics applications that are related with maximization of irradiance power density on extended remotely located surfaces in the presence of dynamically changing refractive index inhomogeneities in the propagation medium. We introduce a TIL propagation model that uses a combination of the parabolic equation describing outgoing wave propagation, and the equation describing evolution of the mutual intensity function (MIF) for the backscattered (returned) wave. The resulting evolution equation for the MIF is further simplified by the use of the smooth refractive index approximation. This approximation enables derivation of the transport equation for the returned wave brightness function, analyzed here using method characteristics (brightness function trajectories). The equations for the brightness function trajectories (ray equations) can be efficiently integrated numerically. We also consider wavefront sensors that perform sensing of speckle-averaged characteristics of the wavefront phase (TIL sensors). Analysis of the wavefront phase reconstructed from Shack-Hartmann TIL sensor measurements shows that an extended target introduces a phase modulation (target-induced phase) that cannot be easily separated from the atmospheric turbulence-related phase aberrations. We also show that wavefront sensing results depend on the extended target shape, surface roughness, and the outgoing beam intensity distribution on the target surface.

Investigating the Origin of Bright Materials on Vesta: Synthesis, Conclusions, and Implications

NASA Technical Reports Server (NTRS)

Li, Jian-Yang; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Schroder, S. E.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

2012-01-01

The Dawn spacecraft started orbiting the second largest asteroid (4) Vesta in August 2011, revealing the details of its surface at an unprecedented pixel scale as small as approx.70 m in Framing Camera (FC) clear and color filter images and approx.180 m in the Visible and Infrared Spectrometer (VIR) data in its first two science orbits, the Survey Orbit and the High Altitude Mapping Orbit (HAMO) [1]. The surface of Vesta displays the greatest diversity in terms of geology and mineralogy of all asteroids studied in detail [2, 3]. While the albedo of Vesta of approx.0.38 in the visible wavelengths [4, 5] is one of the highest among all asteroids, the surface of Vesta shows the largest variation of albedos found on a single asteroid, with geometric albedos ranging at least from approx.0.10 to approx.0.67 in HAMO images [5]. There are many distinctively bright and dark areas observed on Vesta, associated with various geological features and showing remarkably different forms. Here we report our initial attempt to understand the origin of the areas that are distinctively brighter than their surroundings. The dark materials on Vesta clearly are different in origin from bright materials and are reported in a companion paper [6].

Spectral identification of geological units on the surface of Mars related to the presence of silicates from Earth-based near-infrared telescopic charge-coupled device imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinet, P.; Chevrel, S.

1990-08-30

During the September 1988 Mars opposition, the authors obtained new high spatial (100-150 km) and spectral ({Delta}{lambda}/{lambda} = 1%) resolution near-IR telescopic charge-coupled device images of Mars from Pic-du-Midi Observatory. These images allow the association of spectral units with morphologic surface units on Mars, especially within the dark regions which exhibit much greater variability than the bright regions. Mineralogical interpretation of the data leads to a global description of the surface state of alteration consistent with the spatial distribution of bright and dark regions, with the bright regions being more altered than the dark. Within the less altered regions, Fe{supmore » 2+} crystal field absorption bands are detected, indicative of the presence of mafic minerals (Opx, Cpx, O1) in agreement with a likely crustal basaltic composition. The most conspicuous Fe{sup 2+} absorption features are clearly related to the volcanic regions of the Syrtis Major Shield and Hesperia Planum unit. The strongest observed absorptions due to olivine and clinopyroxene are spatially associated with the restricted central caldera complex of Nili-Meroe Paterae (within Syrtis Major) and the Tyrrhena Patera unit (within Hesperia Planum) and indicate an ultramafic composition.« less

Cerberus Wind Streaks

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 6 May 2002) The Science Cerberus is a dark region on Mars that has shrunk down from a continuous length of about 1000 km to roughly three discontinuous spots a few 100 kms in length in less than 20 years. There are two competing processes at work in the Cerberus region that produce the bright and dark features seen in this THEMIS image. Bright dust settles out of the atmosphere, especially after global dust storms, depositing a layer just thick enough to brighten the dark surfaces. Deposition occurs preferentially in the low wind 'shadow zones' within craters and downwind of crater rims, producing the bright streaks. The direction of the streaks clearly indicates that the dominant winds come from the northeast. Dust deposition would completely blot out the dark areas if it were not for the action of wind-blown sand grains scouring the surface and lifting the dust back into the atmosphere. Again, the shadow zones are protected from the blowing sand, preserving the bright layer of dust. Also visible in this image are lava flow features extending from the flanks of the huge Elysium volcanoes to the northwest. Two shallow channels and a raised flow lobe are just barely discernable. The lava channel in the middle of the image crosses the boundary of the bright and dark surfaces without any obvious change in its morphology. This demonstrates that the bright dust layer is very thin in this location, perhaps as little as a few millimeters. The Story Mars is an ever-changing land of spectacular contrasts. This THEMIS image shows the Cerberus region of Mars, a dark area located near the Elysium volcanoes and fittingly named after the three-headed, dragon-tailed dog who guards the door of the underworld. Two opposing processes are at work here: a thin layer of dust falling from the atmosphere and/or dust storms creating brighter surface areas (e.g. the top left portion of this image) and dust being scoured away by the action of the Martian wind disturbing the sand grains and freeing the lighter dust to fly away once more (the darker portions of this image). There are, however, some darker areas that are somewhat shielded and protected from the wind that have yielded bright, dusty crater floors and wind streaks that trail out behind the craters. These wind streaks tell a story all their own as to the prevailing wind direction coming from the northeast. This, added to the fact that this dark region was once 1000 km in length and has dwindled to just a few isolated dark splotches of 100 kilometers in the past 20 years, help us to see that the Martian environment is still quite dynamic and capable of changing. Finally, this being a volcanic region, a lobe of a lava flow from the immense Elysium volcanoes to the northwest is visible stretching across the bottom one-quarter of the image.

Shape-from-shading using Landsat 8 and airborne laser altimetry over ice sheets: toward new regional DEMs of Greenland and Antarctica

NASA Astrophysics Data System (ADS)

Moussavi, M. S.; Scambos, T.; Haran, T. M.; Klinger, M. J.; Abdalati, W.

2015-12-01

We investigate the capability of Landsat 8's Operational Land Imager (OLI) instrument to quantify subtle ice sheet topography of Greenland and Antarctica. We use photoclinometry, or 'shape-from-shading', a method of deriving surface topography from local variations in image brightness due to varying surface slope. Photoclinomeetry is applicable over ice sheet areas with highly uniform albedo such as regions covered by recent snowfall. OLI imagery is available from both ascending and descending passes near the summer solstice period for both ice sheets. This provides two views of the surface features from two distinct solar azimuth illumination directions. Airborne laser altimetry data from the Airborne Topographic Mapper (ATM) instrument (flying on the Operation Ice Bridge program) are used to quantitatively convert the image brightness variations of surface undulations to surface slope. To validate the new DEM products, we use additional laser altimetry profiles collected over independent sites from Ice Bridge and ICESat, and high-resolution WorldView-2 DEMs. The photoclinometry-derived DEM products will be useful for studying surface elevation changes, enhancing bedrock elevation maps through inversion of surface topography, and inferring local variations in snow accumulation rates.

On The Missing Dwarf Problem In Clusters And Around The Nearby Galaxy M33

NASA Astrophysics Data System (ADS)

Keenan, Olivia Charlotte

2017-08-01

This thesis explores possible solutions to the dwarf galaxy problem. This is a discrepancy between the number of dwarf galaxies we observe, and the number predicted from cosmological computer simulations. Simulations predict around ten times more dwarf galaxy satellites than are currently observed. I have investigated two possible solutions: dark galaxies and the low surface brightness universe. Dark galaxies are dark matter halos which contain gas, but few or no stars, hence are optically dark. As part of the Arecibo Galaxy Environment Survey I surveyed the neutral hydrogen gas around the nearby galaxy M33. I found 32 gas clouds, 11 of which are new detections. Amongst these there was one particularly interesting cloud. AGESM33-32 is ring shaped and larger than M33 itself, if at the same distance. It has a velocity width which is similar to the velocity dispersion of gas in a disk galaxy, as well as having a clear velocity gradient across it which may be due to rotation. The fact that it also currently has no observed associated stars means it is a dark galaxy candidate. Optically, dwarf galaxies may be out there, but too faint for us to detect. This means that with newer, deeper, images we may be able to unveil a large, low surface brightness, population of dwarf galaxies. However, the question remains as to how these can be distinguished from background galaxies. I have used Next Generation Virgo Survey (NGVS) data to carry out photometry on 852 Virgo galaxies in four bands. I also measured the photometric properties of galaxies on a background (non-cluster) NGVS frame. I discovered that a combination of colour, magnitude and surface brightness information could be used to identify cluster dwarf galaxies from background field galaxies. The most effective method is to use the surface brightness-magnitude relation.

The local metallicity-surface brightness relationship in galactic disks

NASA Technical Reports Server (NTRS)

Ryder, Stuart D.

1995-01-01

We present the results of a first attempt to employ multiaperture masks to obtain spectrophotometry of H II regions in nearby galaxies. A total of 97 H II regions in six southern spiral galaxies were observed using a combination of multiaperture masks and conventional long-slit spectrophotometry. The oxygen abundances derived from the multiaperture mask observations using the empirical abundance diagnostic R(sub 23) are shown to be consistent with those from long-slit spectra and generally show better reproducibility and object definition. Although the number of objects that can be observed simultaneously with this particular system is still quite limited compared with either imaging spectrophotometry or fiber-fed spectrographs, the spectral resolution offered and high throughput in the blue help make multiaperture spectrophotometry a competitive technique for increasing the sampling of H II regions in both radial distance and luminosity. There is still no clear trend of abundance gradient with either the galaxy's luminosity or its Hubble type, although the extrapolated central abundance does appear to correlate with galaxy luminosity/mass. In order to avoid difficulty in choosing an appropriate normalizing radius, we instead plot the oxygen abundance against the underlying I-band surface brightness at the radial distance of the H II region and confirm the existence of a local metallicity-surface brightness reltaionship within the disks of spiral galaxies. Although the simple closed-boc model of galaxy evolution predicts almost the right form of this relationship, a more realistic multizone model employing expnentially decreasing gas infall provides a more satisfactory fit to the observational data, provided the expected enriched gas return from dying low-mass stars shedding their envelopes at late epochs is properly taken into account. This same model, with a star formation law based upon self-regulating star formation in a three-dimensional disk (Dopita & Ryder 1994), is equally capable of accounting for the observed relationship between recent massive star formation and stellar surface brightness (Ryder & Dopita 1994).

Tropical Pacific sea surface salinity variability derived from SMOS data: Comparison with in-situ observations.

NASA Astrophysics Data System (ADS)

Ballabrera, Joaquim; Hoareau, Nina; Umbert, Marta; Martínez, Justino; Turiel, Antonio

2013-04-01

Prediction of El Niño/Southern Oscillation (ENSO), and its relation with global climate anomalies, continues to be an important research effort in short-term climate forecasting. This task has become even more challenging as researchers are becoming more and more convinced that there is not a single archetypical El Niño (or La Niña) pattern, but several. During some events (called now Standard or East Pacific), the largest temperature anomalies are located at the eastern part of the Pacific. However, during some of the most recent events, the largest anomalies are restricted to the central part of the Pacific Ocean, and are now called Central Pacific or Modoki (a Japanese word for "almost") events. Although the role of salinity in operational ENSO forecasting was initially neglected (in contrast with temperature, sea level, or surface winds), recent studies have shown that salinity does play a role in the preconditioning of ENSO. Moreover, some researchers suggest that sea surface salinity might play a role (through the modulation of the western Pacific barrier layer) to favor the Standard or the Modoki nature of each event. Sea Surface Salinity maps are being operationally generated from microwave (L-band, 1.4 Ghz) brightness temperature maps. The L-band frequency was chosen because is the optimal one for ocean salinity measurements. However, after three years of satellite data, it has been found that noise in brightness temperatures (due to natural and artificial sources) is larger than expected. Moreover, the retrieval of SSS information requires special care because of the low sensitivity of the brightness temperature to SSS: from 0.2-0.8 K per salinity unit. Despite of all these facts, current accuracy of SS maps ranges from 0.2-0.4, depending on the processing level and the region being considered. We present here our study about the salinity variability in the tropical Pacific Ocean from the 9-day, 0.25 bins salinity maps derived from the SMOS reprocessing campaign released to the SMOS user community on March 2011. During the period under study, the equatorial Pacific has been in a quasi-continuous La Niña state. During the cold phases of ENSO, positive anomalies of SSS are expected with the largest anomalous values in the western warm-fresh pool. The anomalies derived from the SMOS data do indeed display a positive anomaly. The persistence of the feature, its geographical pattern, the time modulation of the anomaly amplitude indicate, and its resemblance with in situ observations indicate this novel observation technology is currently able to capture seasonal and interannual signatures of climate interest.

The impact of bottom brightness on spectral reflectance of suspended sediments

USGS Publications Warehouse

Tolk, Brian L.; Han, L.; Rundquist, D. C.

2000-01-01

Two experiments were conducted outdoors to investigate how bottom brightness impacts the spectral response of a water column under varied suspended sediment concentrations. A white aluminum panel placed at the bottom of the tank was used as the bright bottom, and a flat-black tank liner served as the dark bottom. Sixteen levels of suspended sediment from 25 to 400 mg litre -1 were used in each experiment. Spectral data were collected using a Spectron SE-590 spectroradiometer. The major findings include the following: the bright bottom had the greatest impact at visible wavelengths; when suspended sediment concentrations exceeded 100 mg litre -1, the bright bottom response was found to be negligible; and, substrate brightness has minimal impact between 740 and 900 nm, suggesting that these wavelengths are best for measuring suspended sediment concentrations by means of remote sensing.

A spectral k-means approach to bright-field cell image segmentation.

PubMed

Bradbury, Laura; Wan, Justin W L

2010-01-01

Automatic segmentation of bright-field cell images is important to cell biologists, but difficult to complete due to the complex nature of the cells in bright-field images (poor contrast, broken halo, missing boundaries). Standard approaches such as level set segmentation and active contours work well for fluorescent images where cells appear as round shape, but become less effective when optical artifacts such as halo exist in bright-field images. In this paper, we present a robust segmentation method which combines the spectral and k-means clustering techniques to locate cells in bright-field images. This approach models an image as a matrix graph and segment different regions of the image by computing the appropriate eigenvectors of the matrix graph and using the k-means algorithm. We illustrate the effectiveness of the method by segmentation results of C2C12 (muscle) cells in bright-field images.

Prospects for Near Ultraviolet Astronomical Observations from the Lunar Surface — LUCI

NASA Astrophysics Data System (ADS)

Mathew, J.; Kumar, B.; Sarpotdar, M.; Suresh, A.; Nirmal, K.; Sreejith, A. G.; Safonova, M.; Murthy, J.; Brosch, N.

2018-04-01

We have explored the prospects for UV observations from the lunar surface and developed a UV telescope (LUCI-Lunar Ultraviolet Cosmic Imager) to put on the Moon, with the aim to detect bright UV transients such as SNe, novae, TDE, etc.

L Band Brightness Temperature Observations over a Corn Canopy during the Entire Growth Cycle

PubMed Central

Joseph, Alicia T.; van der Velde, Rogier; O’Neill, Peggy E.; Choudhury, Bhaskar J.; Lang, Roger H.; Kim, Edward J.; Gish, Timothy

2010-01-01

During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (TB) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characterization of land surface variables including soil moisture, soil temperature, vegetation biomass, and surface roughness. In the period May 22 to August 30, ten days of radiometer and ground measurements are available for a corn canopy with a vegetation water content (W) range of 0.0 to 4.3 kg m−2. Using this data set, the effects of corn vegetation on surface emissions are investigated by means of a semi-empirical radiative transfer model. Additionally, the impact of roughness on the surface emission is quantified using TB measurements over bare soil conditions. Subsequently, the estimated roughness parameters, ground measurements and horizontally (H)-polarized TB are employed to invert the H-polarized transmissivity (γh) for the monitored corn growing season. PMID:22163585

L Band Brightness Temperature Observations Over a Corn Canopy During the Entire Growth Cycle

NASA Technical Reports Server (NTRS)

Joseph, Alicia T.; O'Neill, Peggy E.; Choudhury, Bhaskar J.; vanderVelde, Rogier; Lang, Roger H.; Gish, Timothy

2011-01-01

During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (T(sub B)) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characterization of land surface variables including soil moisture, soil temperature, vegetation biomass, and surface roughness. During the period from May 22, 2002 to August 30, 2002 a range of vegetation water content (W) of 0.0 to 4.3 kg/square m, ten days of radiometer and ground measurements were available. Using this data set, the effects of corn vegetation on surface emissions are investigated by means of a semi-empirical radiative transfer model. Additionally, the impact of roughness on the surface emission is quantified using T(sub B) measurements over bare soil conditions. Subsequently, the estimated roughness parameters, ground measurements and horizontally (H)-polarized T(sub B) are employed to invert the H-polarized transmissivity (gamma-h) for the monitored corn growing season.

DISENTANGLING THE ICL WITH THE CHEFs: ABELL 2744 AS A CASE STUDY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiménez-Teja, Y.; Dupke, R., E-mail: yojite@iaa.es

Measurements of the intracluster light (ICL) are still prone to methodological ambiguities, and there are multiple techniques in the literature to address them, mostly based on the binding energy, the local density distribution, or the surface brightness. A common issue with these methods is the a priori assumption of a number of hypotheses on either the ICL morphology, its surface brightness level, or some properties of the brightest cluster galaxy (BCG). The discrepancy in the results is high, and numerical simulations just place a boundary on the ICL fraction in present-day galaxy clusters in the range 10%–50%. We developed amore » new algorithm based on the Chebyshev–Fourier functions to estimate the ICL fraction without relying on any a priori assumption about the physical or geometrical characteristics of the ICL. We are able to not only disentangle the ICL from the galactic luminosity but mark out the limits of the BCG from the ICL in a natural way. We test our technique with the recently released data of the cluster Abell 2744, observed by the Frontier Fields program. The complexity of this multiple merging cluster system and the formidable depth of these images make it a challenging test case to prove the efficiency of our algorithm. We found a final ICL fraction of 19.17 ± 2.87%, which is very consistent with numerical simulations.« less

THE ALBEDOS OF KEPLER'S CLOSE-IN SUPER-EARTHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demory, Brice-Olivier, E-mail: bod21@cam.ac.uk

Exoplanet research focusing on the characterization of super-Earths is currently limited to the handful of targets orbiting bright stars that are amenable to detailed study. This Letter proposes to look at alternative avenues to probe the surface and atmospheric properties of this category of planets, known to be ubiquitous in our galaxy. I conduct Markov Chain Monte Carlo light-curves analyses for 97 Kepler close-in R{sub P} ≲ 2.0 R {sub ⊕} super-Earth candidates with the aim of detecting their occultations at visible wavelengths. Brightness temperatures and geometric albedos in the Kepler bandpass are constrained for 27 super-Earth candidates. A hierarchicalmore » Bayesian modeling approach is then employed to characterize the population-level reflective properties of these close-in super-Earths. I find median geometric albedos A{sub g} in the Kepler bandpass ranging between 0.16 and 0.30, once decontaminated from thermal emission. These super-Earth geometric albedos are statistically larger than for hot Jupiters, which have medians A{sub g} ranging between 0.06 and 0.11. A subset of objects, including Kepler-10b, exhibit significantly larger albedos (A{sub g} ≳ 0.4). I argue that a better understanding of the incidence of stellar irradation on planetary surface and atmospheric processes is key to explain the diversity in albedos observed for close-in super-Earths.« less

LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

2014-06-10

Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ({sup f}licker{sup )} of stars can be used to measure log g to a high accuracymore » of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T {sub eff} = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.« less

Thermal inertia mapping of Mars from 60°S to 60°N

USGS Publications Warehouse

Palluconi, Frank Don; Kieffer, Hugh H.

1981-01-01

Twenty-micrometer brightness temperatures are used to derive the thermal inertia for 81% of the Martian surface between latitudes ±60°. These data were acquired by the two Viking Infrared Thermal Mappers in 1977 and 1978 following the two global dust storms of 1977. The spatial resolution used is 2° in latitude by 2° in longitude and the total range in derived inertia is . The distribution of thermal inertia is strongly bimodal with all values of thermal inertia less than  being associated with three disjoint bright regions mostly in the northern hemisphere. Sufficient dust is raised in global storms to provide fine material adequate to produce these low-inertia areas but the specific deposition mechanism has not been defined. At the low resolution used, no complete exposures of clean rock were found. There is some tendency for darker material to be associated with higher thermal inertia, although the trend is far from one to one. The distribution of high- and low-inertia areas is sufficiently nonrandom to produce a variation in whole-disk brightness temperature with central meridian longitude. This variation and the change in surface kinetic temperature associated with dust storms are factors in establishing the whole-disk brightness temperature at radio and infrared wavelengths and will be important for those who use Mars as a calibration source.

Morphology and Dynamics of Jets of Comet 67P Churyumov-Gerasimenko: Early Phase Development

NASA Astrophysics Data System (ADS)

Lin, Zhong-Yi; Ip, Wing-Huen; Lai, Ian-Lin; Lee, Jui-Chi; Pajola, Maurizio; Lara, Luisa; Gutierrez, Pedro; Rodrigo, Rafael; Bodewits, Dennis; A'Hearn, Mike; Vincent, Jean-Baptiste; Agarwal, Jessica; Keller, Uwe; Mottola, Stefano; Bertini, Ivano; Lowry, Stephen; Rozek, Agata; Liao, Ying; Rosetta Osiris Coi Team

2015-04-01

The scientific camera, OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System), onboard the Rosetta spacecraft comprises a Narrow Angle Camera (NAC) for nucleus surface and dust studies and a Wide Angle Camera (WAC) for the wide field of dust and gas coma investigations. The dynamical behavior of jets in the dust coma continuously monitored by using dust filters from the arrival at the comet (August 2014) throughout the mapping phase (Oct. 2014) is described here. The analysis will cover the study of the time variability of jets, the source regions of these jets, the excess brightness of jets relative to the averaged coma brightness, and the brightness distribution of dust jets along the projected distance. The jets detected between August and September originated mostly from the neck region (Hapi). Morphological changes appeared over a time scale of several days in September. The brightness slope of the dust jets is much steeper than the background coma. This might be related to the sublimation or fragmentation of the emitted dust grains. Inter-comparison with results from other experiments will be necessary to understand the difference between the dust emitted from Hapi and those from the head and the body of the nucleus surface. The physical properties of the Hapi jets will be compared to dust jets (and their source regions) to emerge as comet 67P moves around the perihelion.

Arsia Mons by Day and Night

NASA Image and Video Library

2004-06-22

Released 22 June 2004 This pair of images shows part of Arsia Mons. Day/Night Infrared Pairs The image pairs presented focus on a single surface feature as seen in both the daytime and nighttime by the infrared THEMIS camera. The nighttime image (right) has been rotated 180 degrees to place north at the top. Infrared image interpretation Daytime: Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark. Nighttime: Infrared images taken during the nighttime exhibit only the thermophysical properties of the surface of Mars. The effect of sun-facing versus non-sun-facing energy dissipates quickly at night. Thermophysical effects dominate as different surfaces cool at different rates through the nighttime hours. Rocks cool slowly, and are therefore relatively bright at night (remember that rocks are dark during the day). Dust and other fine grained materials cool very quickly and are dark in nighttime infrared images. Image information: IR instrument. Latitude -19.6, Longitude 241.9 East (118.1 West). 100 meter/pixel resolution. http://photojournal.jpl.nasa.gov/catalog/PIA06399

Crater Ejecta by Day and Night

NASA Image and Video Library

2004-06-24

Released 24 June 2004 This pair of images shows a crater and its ejecta. Day/Night Infrared Pairs The image pairs presented focus on a single surface feature as seen in both the daytime and nighttime by the infrared THEMIS camera. The nighttime image (right) has been rotated 180 degrees to place north at the top. Infrared image interpretation Daytime: Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark. Nighttime: Infrared images taken during the nighttime exhibit only the thermophysical properties of the surface of Mars. The effect of sun-facing versus non-sun-facing energy dissipates quickly at night. Thermophysical effects dominate as different surfaces cool at different rates through the nighttime hours. Rocks cool slowly, and are therefore relatively bright at night (remember that rocks are dark during the day). Dust and other fine grained materials cool very quickly and are dark in nighttime infrared images. Image information: IR instrument. Latitude -9, Longitude 164.2 East (195.8 West). 100 meter/pixel resolution. http://photojournal.jpl.nasa.gov/catalog/PIA06445

Using Simplistic Shape/Surface Models to Predict Brightness in Estimation Filters

NASA Astrophysics Data System (ADS)

Wetterer, C.; Sheppard, D.; Hunt, B.

The prerequisite for using brightness (radiometric flux intensity) measurements in an estimation filter is to have a measurement function that accurately predicts a space objects brightness for variations in the parameters of interest. These parameters include changes in attitude and articulations of particular components (e.g. solar panel east-west offsets to direct sun-tracking). Typically, shape models and bidirectional reflectance distribution functions are combined to provide this forward light curve modeling capability. To achieve precise orbit predictions with the inclusion of shape/surface dependent forces such as radiation pressure, relatively complex and sophisticated modeling is required. Unfortunately, increasing the complexity of the models makes it difficult to estimate all those parameters simultaneously because changes in light curve features can now be explained by variations in a number of different properties. The classic example of this is the connection between the albedo and the area of a surface. If, however, the desire is to extract information about a single and specific parameter or feature from the light curve, a simple shape/surface model could be used. This paper details an example of this where a complex model is used to create simulated light curves, and then a simple model is used in an estimation filter to extract out a particular feature of interest. In order for this to be successful, however, the simple model must be first constructed using training data where the feature of interest is known or at least known to be constant.

Two-Dimensional Synthetic Aperture Radiometry over Land Surface During Soil Moisture Experiment in 2003 (SMEX03)

NASA Technical Reports Server (NTRS)

Ryu, Dongryeol; Jackson, Thomas J.; Bindlish, Rajat; Le Vine, David M.; Haken, Michael

2007-01-01

Microwave radiometry at low frequencies (L-band, approx. 1.4 GHz) has been known as an optimal solution for remote sensing of soil moisture. However, the antenna size required to achieve an appropriate resolution from space has limited the development of spaceborne L-band radiometers. This problem can be addressed by interferometric technology called aperture synthesis. The Soil Moisture and Ocean Salinity (SMOS) mission will apply this technique to monitor global-scale surface parameters in the near future. The first airborne experiment using an aircraft prototype of this approach, the Two-Dimensional Synthetic Aperture Radiometer (2D-STAR), was performed in the Soil Moisture Experiment in 2003 (SMEX03). The L-band brightness temperature data acquired in Alabama by the 2DSTAR was compared with ground-based measurements of soil moisture and with C-band data collected by the Polarimetric Scanning Radiometer (PSR). Our results demonstrate a good response of the 2D-STAR brightness temperature to changes in surface wetness, both in agricultural and forest lands. The behavior of the horizontally polarized brightness temperature data with increasing view-angle over the forest area was noticeably different than over bare soil. The results from the comparison of 2D-STAR and PSR indicate a better response of the 2D-STAR to the surface wetness under both wet and dry conditions. Our results have important implications for the performance of the future SMOS mission.

Fusion of Terra-MODIS and Landsat TM data for geothermal sites investigation in Jiangsu Province, China

NASA Astrophysics Data System (ADS)

Chen, Shengbo

2006-01-01

Geothermal resources are generally confined to areas of the Earth's crust where heat flow higher than in surrounding areas heats the water contained in permeable rocks (reservoirs) at depth. It is becoming one of attractive solutions for clean and sustainable energy future for the world. The geothermal fields commonly occurs at the boundaries of plates, and only occasionally in the middle of a plate. The study area, Jiangsu Province, as an example, located in the east of China, is a potential area of geothermal energy. In this study, Landsat thematic Mapper (TM) data were georeferenced to position spatially the geothermal energy in the study area. Multi-spectral infrared data of Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra platform were georeferenced to Landsat TM images. Based on the Wien Displacement Law, these infrared data indicate the surface emitted radiance under the same atmospheric condition, and stand for surface bright temperature respectively. Thus, different surface bright temperature data from Terra-MODIS band 20 or band 31 (R), together with Landsat TM band 4 (G) and band 3 (B) separately, were made up false color composite images (RGB) to generate the distribution maps of surface bright temperatures. Combing with geologic environment and geophysical anomalies, the potential area of geothermal energy with different geo-temperature were mapped respectively. Specially, one geothermal spot in Qinhu Lake Scenery Area in Taizhou city was validated by drilling, and its groundwater temperature is up to some 51°.

Size Dependence of Dust Distribution around the Earth Orbit

NASA Astrophysics Data System (ADS)

Ueda, Takahiro; Kobayashi, Hiroshi; Takeuchi, Taku; Ishihara, Daisuke; Kondo, Toru; Kaneda, Hidehiro

2017-05-01

In the solar system, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to Earth orbit due to Poynting-Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI. The observed surface brightness in the trailing direction of the Earth orbit is 3.7% greater than that in the leading direction in the 9 μm band and 3.0% in the 18 μm band. In order to reveal dust properties causing leading-trailing surface brightness asymmetry, we numerically integrated orbits of the Sun, the Earth, and a dust particle as a restricted three-body problem including radiation from the Sun. The initial orbits of particles are determined according to the orbits of main-belt asteroids or Jupiter-family comets. Orbital trapping in mean motion resonances results in a significant leading-trailing asymmetry so that intermediate sized dust (˜10-100 μm) produces a greater asymmetry than zodiacal light. The leading-trailing surface brightness difference integrated over the size distribution of the asteroidal dust is obtained to be 27.7% and 25.3% in the 9 μm and 18 μm bands, respectively. In contrast, the brightness difference for cometary dust is calculated as 3.6% and 3.1% in the 9 μm and 18 μm bands, respectively, if the maximum dust radius is set to be s max = 3000 μm. Taking into account these values and their errors, we conclude that the contribution of asteroidal dust to the zodiacal infrared emission is less than ˜10%, while cometary dust of the order of 1 mm mainly accounts for the zodiacal light in infrared.

Size Dependence of Dust Distribution around the Earth Orbit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueda, Takahiro; Takeuchi, Taku; Kobayashi, Hiroshi

In the solar system, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to Earth orbit due to Poynting–Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI . The observed surface brightness in the trailing direction of the Earth orbit is 3.7% greater than that in the leading direction in the 9 μ m band and 3.0% in the 18 μ m band. In order to reveal dust properties causing leading–trailing surface brightness asymmetry, we numerically integrated orbits of the Sun, the Earth, and amore » dust particle as a restricted three-body problem including radiation from the Sun. The initial orbits of particles are determined according to the orbits of main-belt asteroids or Jupiter-family comets. Orbital trapping in mean motion resonances results in a significant leading–trailing asymmetry so that intermediate sized dust (∼10–100 μ m) produces a greater asymmetry than zodiacal light. The leading–trailing surface brightness difference integrated over the size distribution of the asteroidal dust is obtained to be 27.7% and 25.3% in the 9 μ m and 18 μ m bands, respectively. In contrast, the brightness difference for cometary dust is calculated as 3.6% and 3.1% in the 9 μ m and 18 μ m bands, respectively, if the maximum dust radius is set to be s {sub max} = 3000 μ m. Taking into account these values and their errors, we conclude that the contribution of asteroidal dust to the zodiacal infrared emission is less than ∼10%, while cometary dust of the order of 1 mm mainly accounts for the zodiacal light in infrared.« less

Simulating galaxies in the reionization era with FIRE-2: morphologies and sizes

NASA Astrophysics Data System (ADS)

Ma, Xiangcheng; Hopkins, Philip F.; Boylan-Kolchin, Michael; Faucher-Giguère, Claude-André; Quataert, Eliot; Feldmann, Robert; Garrison-Kimmel, Shea; Hayward, Christopher C.; Kereš, Dušan; Wetzel, Andrew

2018-06-01

We study the morphologies and sizes of galaxies at z ≥ 5 using high-resolution cosmological zoom-in simulations from the Feedback In Realistic Environments project. The galaxies show a variety of morphologies, from compact to clumpy to irregular. The simulated galaxies have more extended morphologies and larger sizes when measured using rest-frame optical B-band light than rest-frame UV light; sizes measured from stellar mass surface density are even larger. The UV morphologies are usually dominated by several small, bright young stellar clumps that are not always associated with significant stellar mass. The B-band light traces stellar mass better than the UV, but it can also be biased by the bright clumps. At all redshifts, galaxy size correlates with stellar mass/luminosity with large scatter. The half-light radii range from 0.01 to 0.2 arcsec (0.05-1 kpc physical) at fixed magnitude. At z ≥ 5, the size of galaxies at fixed stellar mass/luminosity evolves as (1 + z)-m, with m ˜ 1-2. For galaxies less massive than M* ˜ 108 M⊙, the ratio of the half-mass radius to the halo virial radius is ˜ 10 per cent and does not evolve significantly at z = 5-10; this ratio is typically 1-5 per cent for more massive galaxies. A galaxy's `observed' size decreases dramatically at shallower surface brightness limits. This effect may account for the extremely small sizes of z ≥ 5 galaxies measured in the Hubble Frontier Fields. We provide predictions for the cumulative light distribution as a function of surface brightness for typical galaxies at z = 6.

Effects of bright and blue light on acoustic reaction time and maximum handgrip strength in male athletes: a randomized controlled trial.

PubMed

Knaier, Raphael; Schäfer, Juliane; Rossmeissl, Anja; Klenk, Christopher; Hanssen, Henner; Höchsmann, Christoph; Cajochen, Christian; Schmidt-Trucksäss, Arno

2017-08-01

To assess which type of evening light exposure has the greatest effect on reaction time and maximum handgrip strength. These were pre-specified secondary outcomes in a trial which primarily investigated the influence of light on cycling performance. Seventy-four male athletes were allocated at random to either bright light (BRIGHT), monochromatic blue light (BLUE), or a control condition (CONTROL). Light exposure lasted for 60 min and started 17 h after the individual midpoint of sleep. Reaction time, handgrip strength, and melatonin levels were measured before and after the light exposure. We used analysis of covariance to compare the groups with respect to the investigated outcomes. Two participants had to be excluded retrospectively. The remaining 72 participants had a median age of 23 years. The adjusted difference in reaction time was -1 ms [95% confidence interval (CI) -8, 6] for participants in BRIGHT and 2 ms (95% CI -5, 9) for participants in BLUE, both relative to participants in CONTROL. The adjusted difference in handgrip strength was 0.9 kg (95% CI -1.5, 3.3) for participants in BRIGHT and -0.3 kg (95% CI -2.7, 2.0) for participants in BLUE, both relative to participants in CONTROL. After the light exposure, 17% of participants in BRIGHT, 22% in BLUE, and 29% in CONTROL showed melatonin concentrations of 2 pg/ml or higher. The results suggest that bright light might reduce melatonin levels but neither bright nor blue light exposure in the evening seem to improve reaction time or handgrip strength in athletes.

ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwai, Kazumasa; Loukitcheva, Maria; Shimojo, Masumi

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are among the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a λ = 3 mm (100 GHz) mosaic image obtained by ALMA that includes a large sunspot within the active region AR12470, on 2015 December 16. The 3 mm map has a 300″ × 300″ field of view and 4.″9 × 2.″2 spatial resolution, which is the highest spatialmore » resolution map of an entire sunspot in this frequency range. We find a gradient of 3 mm brightness from a high value in the outer penumbra to a low value in the inner penumbra/outer umbra. Within the inner umbra, there is a marked increase in 3 mm brightness temperature, which we call an umbral brightness enhancement. This enhanced emission corresponds to a temperature excess of 800 K relative to the surrounding inner penumbral region and coincides with excess brightness in the 1330 and 1400 Å slit-jaw images of the Interface Region Imaging Spectrograph ( IRIS ), adjacent to a partial lightbridge. This λ = 3 mm brightness enhancement may be an intrinsic feature of the sunspot umbra at chromospheric heights, such as a manifestation of umbral flashes, or it could be related to a coronal plume, since the brightness enhancement was coincident with the footpoint of a coronal loop observed at 171 Å.« less

ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm

NASA Astrophysics Data System (ADS)

Iwai, K.; Loukitcheva, M.; Shimojo, M.; Solanki, S. K.; White, S. M.

2017-12-01

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are among the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a λ = 3 mm (100 GHz) mosaic image obtained by ALMA that includes a large sunspot within the active region AR12470, on 2015 December 16. The 3 mm map has a 300''×300'' field of view and 4.9''×2.2'' spatial resolution, which is the highest spatial resolution map of an entire sunspot in this frequency range. We find a gradient of 3 mm brightness from a high value in the outer penumbra to a low value in the inner penumbra/outer umbra. Within the inner umbra, there is a marked increase in 3 mm brightness temperature, which we call an umbral brightness enhancement. This enhanced emission corresponds to a temperature excess of 800 K relative to the surrounding inner penumbral region and coincides with excess brightness in the 1330 and 1400 Å slit-jaw images of the Interface Region Imaging Spectrograph (IRIS), adjacent to a partial lightbridge. This λ = 3 mm brightness enhancement may be an intrinsic feature of the sunspot umbra at chromospheric heights, such as a manifestation of umbral flashes, or it could be related to a coronal plume, since the brightness enhancement was coincident with the footpoint of a coronal loop observed at 171 Å.

ARC-1986-AC86-7018

NASA Image and Video Library

1986-01-25

P-29502C Range: 1.04 million kilometers (650,000 miles) This color photo of Umbriel, the darkest of Uranus' five large moons was synthesized from frames exposed with the Voyager narrow-angle camera's violet and clear filters and has a resolution of 19 km (12 mi.). Umbriel is characterized by the darkest surface and smallest brightness variations of any of the large satellites of Uranus. As seen here, the surface is also generally gray and colorless. Nevertheless, at this resolution, considerable topographic detail is revealed, showing that Umbriel's surface is covered by impact craters. The brightest spot (shown at top near the equator at approxiamately 270 ° longitude) appears as a bright ring. Its geological significance is not yet understood. Umbriel has a diameter of about 1,200 km (750 miles) and orbits 267,000 km (166,000 mi) from Uranus' center. The satellite's name, from Alexander Pope's 'Rape of the Lock,' means 'dark angel'.

Callisto False Color

NASA Image and Video Library

1996-09-26

This false color picture of Callisto was taken by NASA's Voyager 2 on July 7, 1979 at a range of 1,094,666 kilometers (677,000 miles) and is centered on 11 degrees N and 171 degrees W. This rendition uses an ultraviolet image for the blue component. Because the surface displays regional contrast in UV, variations in surface materials are apparent. Notice in particular the dark blue haloes which surround bright craters in the eastern hemisphere. The surface of Callisto is the most heavily cratered of the Galilean satellites and resembles ancient heavily cratered terrains on the moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture. The color version of this picture was constructed by compositing black and white images taken through the ultraviolet, clear and orange filters. http://photojournal.jpl.nasa.gov/catalog/PIA00457

Extraction of topographic and material contrasts on surfaces from SEM images obtained by energy filtering detection with low-energy primary electrons.

PubMed

Nagoshi, Masayasu; Aoyama, Tomohiro; Sato, Kaoru

2013-01-01

Secondary electron microscope (SEM) images have been obtained for practical materials using low primary electron energies and an in-lens type annular detector with changing negative bias voltage supplied to a grid placed in front of the detector. The kinetic-energy distribution of the detected electrons was evaluated by the gradient of the bias-energy dependence of the brightness of the images. This is divided into mainly two parts at about 500 V, high and low brightness in the low- and high-energy regions, respectively and shows difference among the surface regions having different composition and topography. The combination of the negative grid bias and the pixel-by-pixel image subtraction provides the band-pass filtered images and extracts the material and topographic information of the specimen surfaces. Copyright © 2012 Elsevier B.V. All rights reserved.

The wavelength dependence and an interpretation of the photometric parameters of Mars

NASA Technical Reports Server (NTRS)

Weaver, W. R.; Meador, W. E.

1976-01-01

The photometric function developed by Meador and Weaver has been used with photometric data from the bright desert areas of Mars to determine the wavelength dependence of the three photometric parameters of that function and to provide some predictions about the physical properties of the surface. Knowledge of the parameters permits the brightness of these areas of Mars to be determined for scattering geometry over the wavelength range of 0.45 to 0.70 micrometer. The changes in the photometric parameters with wavelength are shown to be consistent with qualitative theoretical predictions, and the predictions of surface properties are shown to be consistent with conditions that might exist in these regions of Mars. The photometric function is shown to have good potential as a diagnostic tool for the determination of surface properties, and the consistency of the behavior of the photometric parameters is shown to be good support for the validity of the photometric function.

Seasonal Changes in Titan's Surface Temperatures

NASA Technical Reports Server (NTRS)

Jennins, Donald E.; Cottini, V.; Nixon, C. A.; Flasar, F. M.; Kunde, V. G.; Samuelson, R. E.; Romani, P. N.; Hesman, B. E.; Carlson, R. C.; Gorius, N. J. P.;

Development of Yellow Sand Image Products Using Infrared Brightness Temperature Difference Method

NASA Astrophysics Data System (ADS)

Ha, J.; Kim, J.; Kwak, M.; Ha, K.

2007-12-01

A technique for detection of airborne yellow sand dust using meteorological satellite has been developed from various bands from ultraviolet to infrared channels. Among them, Infrared (IR) channels have an advantage of detecting aerosols over high reflecting surface as well as during nighttime. There had been suggestion of using brightness temperature difference (BTD) between 11 and 12¥ìm. We have found that the technique is highly depends on surface temperature, emissivity, and zenith angle, which results in changing the threshold of BTD. In order to overcome these problems, we have constructed the background brightness temperature threshold of BTD and then aerosol index (AI) has been determined from subtracting the background threshold from BTD of our interested scene. Along with this, we utilized high temporal coverage of geostationary satellite, MTSAT, to improve the reliability of the determined AI signal. The products have been evaluated by comparing the forecasted wind field with the movement fiend of AI. The statistical score test illustrates that this newly developed algorithm produces a promising result for detecting mineral dust by reducing the errors with respect to the current BTD method.

Multi-band Emission Light Curves of Jupiter: Insights on Brown Dwarfs and Directly Imaged Exoplanets

NASA Astrophysics Data System (ADS)

Zhang, Xi; Ge, Huazhi; Orton, Glenn S.; Fletcher, Leigh N.; Sinclair, James; Fernandes, Joshua; Momary, Thomas W.; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

2016-10-01

Many brown dwarfs exhibit significant infrared flux variability (e.g., Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750, 105), ranging from several to twenty percent of the brightness. Current hypotheses include temperature variations, cloud holes and patchiness, and cloud height and thickness variations (e.g., Apai et al. 2013, ApJ, 768, 121; Robinson and Marley 2014, ApJ, 785, 158; Zhang and Showman 2014, ApJ, 788, L6). Some brown dwarfs show phase shifts in the light curves among different wavelengths (e.g., Buenzli et al. 2012, ApJ, 760, L31; Yang et al. 2016, arXiv:1605.02708), indicating vertical variations of the cloud distribution. The current observational technique can barely detect the brightness changes on the surfaces of nearby brown dwarfs (Crossfield et al. 2014, Nature, 505, 654) let alone resolve detailed weather patterns that cause the flux variability. The infrared emission maps of Jupiter might shed light on this problem. Using COMICS at Subaru Telescope, VISIR at Very Large Telescope (VLT) and NASA's Infrared Telescope Facility (IRTF), we obtained infrared images of Jupiter over several nights at multiple wavelengths that are sensitive to several pressure levels from the stratosphere to the deep troposphere below the ammonia clouds. The rotational maps and emission light curves are constructed. The individual pixel brightness varies up to a hundred percent level and the variation of the full-disk brightness is around several percent. Both the shape and amplitude of the light curves are significantly distinct at different wavelengths. Variation of light curves at different epochs and phase shift among different wavelengths are observed. We will present principle component analysis to identify dominant emission features such as stable vortices, cloud holes and eddies in the belts and zones and strong emissions in the aurora region. A radiative transfer model is used to simulate those features to get a more quantitative understanding. This work provides rich insights on the relationship between observed light curves and weather on brown dwarfs and perhaps on directly imaged exoplanets in the future.

Proposal for Research on High-Brightness Cathodes for High-Power Free-Electron Lasers (FEL)

DTIC Science & Technology

2013-05-09

recent experiments involving single crystal diamond amplifier cathodes (DAC) at Brookhaven National Laboratory ( BNL ). While the emission surface of our...diamond grain in the entire structure, both surface and interior, is passivated with hydrogen. The aforementioned studies at BNL found that

Exploring the Surface Brightness Breaks and Star Formation in Disk Galaxies

NASA Astrophysics Data System (ADS)

Malko, Bradley Ann; Hunter, Deidre Ann

2018-06-01

Stellar surface brightness profiles of both spirals and dwarf irregular galaxies often show breaks in which the exponential fall-off abruptly changes slope. Most often the profile is down-bending (Type II) in the outer disk, but sometimes it is up-bending (Type III). Stellar disks extend a long ways beyond the profile breaks, but we do not understand what happens physically at the breaks. To explore this we are examining the star formation activity, as traced with FUV emission, interior to the break compared to that exterior to the break in both dwarf irregulars and spiral galaxies. We present the results for the spiral galaxy NGC 2500 and compare it to the LITTLE THINGS dwarf irregular galaxies.

Printing quality control automation

NASA Astrophysics Data System (ADS)

Trapeznikova, O. V.

2018-04-01

One of the most important problems in the concept of standardizing the process of offset printing is the control the quality rating of printing and its automation. To solve the problem, a software has been developed taking into account the specifics of printing system components and the behavior in printing process. In order to characterize the distribution of ink layer on the printed substrate the so-called deviation of the ink layer thickness on the sheet from nominal surface is suggested. The geometric data construction the surface projections of the color gamut bodies allows to visualize the color reproduction gamut of printing systems in brightness ranges and specific color sectors, that provides a qualitative comparison of the system by the reproduction of individual colors in a varying ranges of brightness.

Pole-equator difference and the variability of the brightness of the chromospheric CaII-K-network elements in quiet regions over the solar cycle

NASA Technical Reports Server (NTRS)

Kariyappa, R.

1995-01-01

The dependence of the brightness of chromospheric network elements on latitude was investigated for quiet solar regions. Calibrated photographic CaII K-spectroheliograms were used to compare the variation in brightness at the center of the disk with higher latitude of chromospheric network elements in a quiet region as a function of solar activity. It was found that there was no significant difference in brightness between the center of the solar disk and higher latitude. It is concluded that the brightness of the chromospheric network elements in a quiet region does not depend on the latitude, but that the variation in the intensity enhancement is related to the level of solar activity.

Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

PubMed

Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

2011-03-09

Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.

Properties of an H I-selected galaxy sample

NASA Technical Reports Server (NTRS)

Szomoru, Arpad; Guhathakurta, Puragra; Van Gorkom, Jacqueline H.; Knapen, Johan H.; Weinberg, David H.; Fruchter, Andrew S.

1994-01-01

We analyze the properties of a sample of galaxies identified in a 21cm, H I-line survey of selected areas in the Perseus-Pisces supercluster and its foreground void. Twelve fields were observed in the supercluster, five of them (target fields) centered on optically bright galaxies, and the other seven (blank fields) selected to contain no bright galaxies within 45 min. of their centers. We detected nine previously uncatalogued, gas-rich galaxies, six of them in the target fields. We also detected H I from seven previously catalogued galaxies in these fields. Observations in the void covered the same volume as the 12 supercluster fields at the same H I-mass sensitivity, but no objects were detected. Combining out H I data with optical broadband and H alpha imaging, we conclude that the properties of H I-selected galaxies do not differ substantially from those of late-type galaxies found in optical surveys. In particular, the galaxies in our sample do not appear to be unusually faint for their H I mass, or for their circular velocity. We find tentative evidence for a connection between optical surface brightness and degree of isolation, in the sense that low surface brightness galaxies tend to be more isolated. The previously catalogued, optically bright galaxies in our survey volume dominate the total H I mass density and cross section; the uncatalogued galaxies contribute only approximately 19 percent of the mass and approximately 12 percent of the cross section. Thus, existing estimates of the density and cross section of neutral hydrogen, most of which are based on optically selected galaxy samples, are probably accurate. Such estimates can be used to compare the nearby universe to the high-redshift universe probed by quasar absorption lines.

Topography and geomorphology of the Huygens landing site on Titan

USGS Publications Warehouse

Soderblom, L.A.; Tomasko, M.G.; Archinal, B.A.; Becker, T.L.; Bushroe, M.W.; Cook, D.A.; Doose, L.R.; Galuszka, D.M.; Hare, T.M.; Howington-Kraus, E.; Karkoschka, E.; Kirk, R.L.; Lunine, J.I.; McFarlane, E.A.; Redding, B.L.; Rizk, B.; Rosiek, M.R.; See, C.; Smith, P.H.

2007-01-01

The Descent Imager/Spectral Radiometer (DISR) aboard the Huygens Probe took several hundred visible-light images with its three cameras on approach to the surface of Titan. Several sets of stereo image pairs were collected during the descent. The digital terrain models constructed from those images show rugged topography, in places approaching the angle of repose, adjacent to flatter darker plains. Brighter regions north of the landing site display two styles of drainage patterns: (1) bright highlands with rough topography and deeply incised branching dendritic drainage networks (up to fourth order) with dark-floored valleys that are suggestive of erosion by methane rainfall and (2) short, stubby low-order drainages that follow linear fault patterns forming canyon-like features suggestive of methane spring-sapping. The topographic data show that the bright highland terrains are extremely rugged; slopes of order of 30?? appear common. These systems drain into adjacent relatively flat, dark lowland terrains. A stereo model for part of the dark plains region to the east of the landing site suggests surface scour across this plain flowing from west to east leaving ???100-m-high bright ridges. Tectonic patterns are evident in (1) controlling the rectilinear, low-order, stubby drainages and (2) the "coastline" at the highland-lowland boundary with numerous straight and angular margins. In addition to flow from the highlands drainages, the lowland area shows evidence for more prolific flow parallel to the highland-lowland boundary leaving bright outliers resembling terrestrial sandbars. This implies major west to east floods across the plains where the probe landed with flow parallel to the highland-lowland boundary; the primary source of these flows is evidently not the dendritic channels in the bright highlands to the north. ?? 2007 Elsevier Ltd. All rights reserved.

Modeling Self-subtraction in Angular Differential Imaging: Application to the HD 32297 Debris Disk

NASA Astrophysics Data System (ADS)

Esposito, Thomas M.; Fitzgerald, Michael P.; Graham, James R.; Kalas, Paul

2014-01-01

We present a new technique for forward-modeling self-subtraction of spatially extended emission in observations processed with angular differential imaging (ADI) algorithms. High-contrast direct imaging of circumstellar disks is limited by quasi-static speckle noise, and ADI is commonly used to suppress those speckles. However, the application of ADI can result in self-subtraction of the disk signal due to the disk's finite spatial extent. This signal attenuation varies with radial separation and biases measurements of the disk's surface brightness, thereby compromising inferences regarding the physical processes responsible for the dust distribution. To compensate for this attenuation, we forward model the disk structure and compute the form of the self-subtraction function at each separation. As a proof of concept, we apply our method to 1.6 and 2.2 μm Keck adaptive optics NIRC2 scattered-light observations of the HD 32297 debris disk reduced using a variant of the "locally optimized combination of images" algorithm. We are able to recover disk surface brightness that was otherwise lost to self-subtraction and produce simplified models of the brightness distribution as it appears with and without self-subtraction. From the latter models, we extract radial profiles for the disk's brightness, width, midplane position, and color that are unbiased by self-subtraction. Our analysis of these measurements indicates a break in the brightness profile power law at r ≈ 110 AU and a disk width that increases with separation from the star. We also verify disk curvature that displaces the midplane by up to 30 AU toward the northwest relative to a straight fiducial midplane.

Reconstructed images of 4 Vesta.

NASA Astrophysics Data System (ADS)

Drummond, J.; Eckart, A.; Hege, E. K.

The first glimpses of an asteroid's surface have been obtained from images of 4 Vesta reconstructed from speckle interferometric observations made with Harvard's PAPA camera coupled to Steward Observatory's 2.3 m telescope. Vesta is found to have a "normal" triaxial ellipsoid shape of 566(±15)×532(±15)×466(±15) km. Its rotational pole lies within 4° of ecliptic long. 327°, lat. = +55°. Reconstructed images obtained with the power spectra and Knox-Thompson cross-spectra reveal dark and bright patterns, reminiscent of the Moon. Three bright and three dark areas are visible, and when combined with an inferred seventh bright region not visible during the rotational phases covered during the authors' run, lead to lightcurves that match Vesta's lightcurve history.

Photographer : JPL Callisto , The outermost Galilean Satellite , or Moon , of Jupiter, as taken by

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Callisto , The outermost Galilean Satellite , or Moon , of Jupiter, as taken by Voyager I . Range : About 7 Million km (5 Million miles) . Callisto, the darkest of the Galilean Satellites, still nearly twice as bright as the Earth's Moon, is seen here from the face that always faces Jupiter. All of the Galilean Satellites always show the same face to Jupiter, as the Earth's moon does to Earth. The Surface shows a mottled appearance of bright and dark patches. The former reminds scientists of rayed or bright haloed craters, similiar to those seen on earth's Moon. This color photo is assembled from 3 black and wite images taken though violet, orange, & green filters

Tropical cyclone warm core analyses with FY-3 microwave temperature sounder data

NASA Astrophysics Data System (ADS)

Liu, Zhe; Bai, Jie; Zhang, Wenjun; Yan, Jun; Zhou, Zhuhua

2014-05-01

Space-borne microwave instruments are well suited to analyze Tropical Cyclone (TC) warm core structure, because certain wavelengths of microwave energy are able to penetrate the cirrus above TC. With the vector discrete-ordinate microwave radiative transfer model, the basic atmospheric parameters of Hurricane BOB are used to simulate the upwelling brightness temperatures on each channel of the Microwave Temperature Sounder (MWTS) onboard FY-3A/3B observation. Based on the simulation, the characteristic of 1109 super typhoon "Muifa" warm core structure is analyzed with the MWTS channel 3. Through the radiative and hydrostatic equation, TC warm core brightness temperature anomalies are related to surface pressure anomalies. In order to correct the radiation attenuation caused by MWTS scan geometric features, and improve the capability in capturing the relatively complete warm core radiation, a proposed algorithm is devised to correct the bias from receiving warm core microwave radiation, shows similar time-variant tendency with "Muifa" minimal sea level pressure as described by TC best track data. As the next generation of FY-3 satellite will be launched in 2012, this method will be further verified

First scattered-light image of the debris disk around HD 131835 with the Gemini Planet Imager

DOE PAGES

Hung, Li -Wei; Duchêne, Gaspard; Arriaga, Pauline; ...

2015-12-09

Here, we present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ~15 Myr old A2IV star at a distance of ~120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission, in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ~75 to ~210 AU in the disk plane with roughlymore » flat surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.« less

FIRST SCATTERED-LIGHT IMAGE OF THE DEBRIS DISK AROUND HD 131835 WITH THE GEMINI PLANET IMAGER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, Li-Wei; Arriaga, Pauline; Fitzgerald, Michael P.

2015-12-10

We present the first scattered-light image of the debris disk around HD 131835 in the H band using the Gemini Planet Imager. HD 131835 is a ∼15 Myr old A2IV star at a distance of ∼120 pc in the Sco-Cen OB association. We detect the disk only in polarized light and place an upper limit on the peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission,  in scattered light the disk shows similar orientation but different morphology. The scattered-light disk extends from ∼75 to ∼210 AU in the disk plane with roughly flatmore » surface density. Our Monte Carlo radiative transfer model can describe the observations with a model disk composed of a mixture of silicates and amorphous carbon. In addition to the obvious brightness asymmetry due to stronger forward scattering, we discover a weak brightness asymmetry along the major axis, with the northeast side being 1.3 times brighter than the southwest side at a 3σ level.« less

Retinal venous blood carbon monoxide response to bright light in male pigs: A preliminary study.

PubMed

Oren, Dan A; Duda, Magdalena; Kozioł, Katarzyna; Romerowicz-Misielak, Maria; Koziorowska, Anna; Sołek, Przemysław; Nowak, Sławomir; Kulpa, Magdalena; Koziorowski, Marek

2017-03-01

The physical mechanism by which light is absorbed in the eye and has antidepressant and energizing effects in Seasonal Affective Disorder and other forms of psychiatric major depression is of scientific interest. This study was designed to explore one specific aspect of a proposed humoral phototransduction mechanism, namely that carbon monoxide (CO) levels increase in retinal venous blood in response to bright light. Eleven mature male pigs approximately six months of age were kept for 7days in darkness and fasted for 12h prior to surgery. Following mild sedation, anesthesia was induced. Silastic catheters were inserted into the dorsal nasal vein through the angular vein of the eye to reach the ophthalmic sinus, from which venous blood outflowing from the eye area was collected. The animals were exposed to 5000lx of fluorescent-generated white light. CO levels in the blood were analyzed by gas chromatography before and after 80min of light exposure. At baseline, mean CO levels in the retinal venous blood were 0.43±0.05(SE)nmol/ml. After bright light, mean CO levels increased to 0.54±0.06nmol/ml (two-tailed t-test p<0.05). This study provides preliminary mammalian evidence that acute bright light exposure raises carbon monoxide levels in ophthalmic venous blood. Copyright © 2017 Elsevier B.V. All rights reserved.

Venus: estimates of the surface temperature and pressure from radio and radar measurements.

PubMed

Wood, A T; Wattson, R B; Pollack, J B

1968-10-04

The radio brightness temperature and radar cross section spectra of Venus are in much better accord with surface boundary conditions deduced from a combination of the Mariner V results and the radar radius than those obtained by the Venera 4 space probe. The average surface temperature and pressure are approximately 750 degrees K and 90 atmospheres.

Springtime microwave emissivity changes in the southern Kara Sea

NASA Technical Reports Server (NTRS)

Crane, Robert G.; Anderson, Mark R.

1994-01-01

Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest that the negative gradient ratios in spring 1982 result from increased scatter at 37 GHz due to the formation of a near-surface hoar layer. This interpretation is supported by the results of a surface radiation balance model that shows the melt signature occurring at below freezing temperatures but under clear-sky conditions with increased solar input to the surface. Published observations from the Greenland ice cap show a surface hoar layer forming under similar atmospheric conditions owing to the increased penetration and absorption of solar radiation just below the surface layer. In spring/early summer 1984 similar gradient ratio signatures occur. They appear to be due to several days of freeze-thaw cycling following the movement of a low-pressure system through the region. These changes in surface emissivity represent the transition from winter to summer conditions (as defined by the microwave response) and are shown to be regional in extent and to vary with the synoptic circulations.

What is a melody? On the relationship between pitch and brightness of timbre.

PubMed

Cousineau, Marion; Carcagno, Samuele; Demany, Laurent; Pressnitzer, Daniel

2013-01-01

Previous studies showed that the perceptual processing of sound sequences is more efficient when the sounds vary in pitch than when they vary in loudness. We show here that sequences of sounds varying in brightness of timbre are processed with the same efficiency as pitch sequences. The sounds used consisted of two simultaneous pure tones one octave apart, and the listeners' task was to make same/different judgments on pairs of sequences varying in length (one, two, or four sounds). In one condition, brightness of timbre was varied within the sequences by changing the relative level of the two pure tones. In other conditions, pitch was varied by changing fundamental frequency, or loudness was varied by changing the overall level. In all conditions, only two possible sounds could be used in a given sequence, and these two sounds were equally discriminable. When sequence length increased from one to four, discrimination performance decreased substantially for loudness sequences, but to a smaller extent for brightness sequences and pitch sequences. In the latter two conditions, sequence length had a similar effect on performance. These results suggest that the processes dedicated to pitch and brightness analysis, when probed with a sequence-discrimination task, share unexpected similarities.

SPIDERMAN: Fast code to simulate secondary transits and phase curves

NASA Astrophysics Data System (ADS)

Louden, Tom; Kreidberg, Laura

2017-11-01

SPIDERMAN calculates exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. The code uses a geometrical algorithm to solve exactly the area of sections of the disc of the planet that are occulted by the star. Approximately 1000 models can be generated per second in typical use, which makes making Markov Chain Monte Carlo analyses practicable. The code is modular and allows comparison of the effect of multiple different brightness distributions for a dataset.

ARC-1979-A79-7103

NASA Image and Video Library

1979-07-04

Range : 4.2 million km. ( 2.6 million miles ) Jupiter's moon Europa, the size of earth's moon, is apparently covered by water ice, as indicated by ground spectrometers and its brightness. In this view, global scale dark sreaks discovered by Voyager 1 that criss-cross the the satelite are becoming visible. Bright rayed impact craters, which are abundant on Ganymede and Callisto, would be easily visible at this range, suggesting that Europa's surface is young and that the streaks are reflections of currently active internal dynamic processes.

Space Radar Image of Altona, Manitoba, Canada

NASA Technical Reports Server (NTRS)

1994-01-01

This is an X-band seasonal image of the Altona test site in Manitoba, Canada, about 80 kilometers (50 miles) south of Winnipeg. The image is centered at approximately 49 degrees north latitude and 97.5 degrees west longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 11, 1994, during the first flight of the radar system, and on October 2, 1994, during the second flight of SIR-C/X-SAR. The image channels have the following color assignments: red represents data acquired on April 11, 1994; green represents data acquired on October 2, 1994; blue represents the ratio of the two data sets. The test site is located in the Red River Basin and is characterized by rich farmland where a variety of crops are grown, including wheat, barley, canola, corn, sunflowers and sugar beets. This SIR-C/X-SAR research site is applying radar remote sensing to study the characteristics of vegetation and soil moisture. The seasonal comparison between the April and October 1994 data show the dramatic differences between surface conditions on the two dates. At the time of the April acquisition, almost all agricultural fields were bare and soil moisture levels were high. In October, however, soils were drier and while most crops had been harvested, some standing vegetation was still present. The areas which are cyan in color are dark in April and bright in October. These represent fields of standing biomass (amount of vegetation in a specified area) and the differences in brightness within these cyan fields represent differences in vegetation type. The very bright fields in October represent standing broadleaf crops such as corn, which had not yet been harvested. Other standing vegetation which has less biomass, such as hay and grain fields, are less bright. The magenta indicates bare soil surfaces which were wetter (brighter) in April than in October. The variations in brightness of the magenta indicate differences in the degree of soil moisture change and differences in surface roughness. This seasonal composite demonstrates the sensitivity of radar to changes in agricultural surface conditions such as soil moisture, tillage, cropping and harvesting. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR.

Cassini ISS observations of Iapetus: Results from the primary mission

NASA Astrophysics Data System (ADS)

Denk, Tilmann; Schmedemann, Nico; Wagner, Roland; Giese, Bernd; Perry, Jason; Helfenstein, Paul; Turtle, Elizabeth; Neukum, Gerhard; Roatsch, Thomas; Porco, Carolyn

Cassini ISS images obtained over the past 4 years in orbit around Saturn provide new insights about the surface features, properties, processes and history of Iapetus, the outermost regular Saturnian moon. Particularly valuable are the non-targeted flyby on New-Year's Eve 2005 with a good view on the leading side, and the targeted flyby in September 2007 where especially the trailing side was seen in particularly fine detail. There are many questions about Iapetus to which imaging might contribute solutions: What is the reason for the unique global brightness dichotomy that has already been discovered in 1672 by G.D. Cassini? How is the global color dichotomy, which was detected by the Cassini spacecraft, related to the brightness dichotomy? How did the (also unique) equatorial ridge form, and what is its detailed morphology? What is the distribution of the craters and large basins on the surface, and how old is the surface? What geologic processes (besides cratering) took place on Iapetus? Why is there a very distinct patchy segregation of dark and bright material at local scales? What is the thickness of the dark blanket? Why are there no large bright craters within the dark hemisphere? What is the time scale for a fresh bright crater in the dark terrain to fade back to the darkness of the surrounding terrain? Attempts to answer these questions will be given in the presentation. Selected references: Buratti B.J. et al. (2002) Icarus 155, 375-381, doi:10.1006/icar.2001.6730. Castillo-Rogez J.C. et al. (2007) Icarus 190, 179-202, doi:10.1016/j.icarus.2007.02.018. Denk T. et al. (2006) EGU, abstract EGU06-A-08352. Denk T. et al. (2008) LPSC XXXIX, abstract #2533. Giese B. et al. (2008) Icarus 193, 359-371, doi:10.1016/j.icarus.2007.06.005. Porco C.C. et al. (2005) Science 307, 1243-1247. Schmedemann N. et al. (2008) LPSC XXXIX, abstract #2070. Spencer J.R. et al. (2005) 37th DPS, abstract 39.08.

Improved Land Use and Leaf Area Index Enhances WRF-3DVAR Satellite Radiance Assimilation: A Case Study Focusing on Rainfall Simulation in the Shule River Basin during July 2013

NASA Astrophysics Data System (ADS)

Yang, Junhua; Ji, Zhenming; Chen, Deliang; Kang, Shichang; Fu, Congshen; Duan, Keqin; Shen, Miaogen

2018-06-01

The application of satellite radiance assimilation can improve the simulation of precipitation by numerical weather prediction models. However, substantial quantities of satellite data, especially those derived from low-level (surface-sensitive) channels, are rejected for use because of the difficulty in realistically modeling land surface emissivity and energy budgets. Here, we used an improved land use and leaf area index (LAI) dataset in the WRF-3DVAR assimilation system to explore the benefit of using improved quality of land surface information to improve rainfall simulation for the Shule River Basin in the northeastern Tibetan Plateau as a case study. The results for July 2013 show that, for low-level channels (e.g., channel 3), the underestimation of brightness temperature in the original simulation was largely removed by more realistic land surface information. In addition, more satellite data could be utilized in the assimilation because the realistic land use and LAI data allowed more satellite radiance data to pass the deviation test and get used by the assimilation, which resulted in improved initial driving fields and better simulation in terms of temperature, relative humidity, vertical convection, and cumulative precipitation.

Snow Cover Mapping at the Continental to Global Scale Using Combined Visible and Passive Microwave Satellite Data

NASA Astrophysics Data System (ADS)

Armstrong, R. L.; Brodzik, M.; Savoie, M. H.

2007-12-01

Over the past several decades both visible and passive microwave satellite data have been utilized for snow mapping at the continental to global scale. Snow mapping using visible data has been based primarily on the magnitude of the surface reflectance, and in more recent cases on specific spectral signatures, while microwave data can be used to identify snow cover because the microwave energy emitted by the underlying soil is scattered by the snow grains resulting in a sharp decrease in brightness temperature and a characteristic negative spectral gradient. Both passive microwave and visible data sets indicate a similar pattern of inter-annual variability, although the maximum snow extents derived from the microwave data are consistently less than those provided by the visible satellite data and the visible data typically show higher monthly variability. We describe the respective problems as well as the advantages and disadvantages of these two types of satellite data for snow cover mapping and demonstrate how a multi-sensor approach is optimal. For the period 1978 to present we combine data from the NOAA weekly snow charts with snow cover derived from the SMMR and SSM/I brightness temperature data. For the period since 2002 we blend NASA EOS MODIS and AMSR-E data sets. Our current product incorporates MODIS data from the Climate Modelers Grid (CMG) at approximately 5 km (0.05 deg.) with microwave-derived snow water equivalent (SWE) at 25 km, resulting in a blended product that includes percent snow cover in the larger grid cell whenever the microwave SWE signal is absent. Validation of AMSR-E at the brightness temperature level is provided through the comparison with data from the well-calibrated heritage SSM/I sensor over large homogeneous snow-covered surfaces (e.g. Dome C region, Antarctica). We also describe how the application of the higher frequency microwave channels (85 and 89 GHz)enhances accurate mapping of shallow and intermittent snow cover.

Atmospheric correction for retrieving ground brightness temperature at commonly-used passive microwave frequencies.

PubMed

Han, Xiao-Jing; Duan, Si-Bo; Li, Zhao-Liang

2017-02-20

An analysis of the atmospheric impact on ground brightness temperature (Tg) is performed for numerous land surface types at commonly-used frequencies (i.e., 1.4 GHz, 6.93 GHz, 10.65 GHz, 18.7 GHz, 23.8 GHz, 36.5 GHz and 89.0 GHz). The results indicate that the atmosphere has a negligible impact on Tg at 1.4 GHz for land surfaces with emissivities greater than 0.7, at 6.93 GHz for land surfaces with emissivities greater than 0.8, and at 10.65 GHz for land surfaces with emissivities greater than 0.9 if a root mean square error (RMSE) less than 1 K is desired. To remove the atmospheric effect on Tg, a generalized atmospheric correction method is proposed by parameterizing the atmospheric transmittance τ and upwelling atmospheric brightness temperature Tba↑. Better accuracies with Tg RMSEs less than 1 K are achieved at 1.4 GHz, 6.93 GHz, 10.65 GHz, 18.7 GHz and 36.5 GHz, and worse accuracies with RMSEs of 1.34 K and 4.35 K are obtained at 23.8 GHz and 89.0 GHz, respectively. Additionally, a simplified atmospheric correction method is developed when lacking sufficient input data to perform the generalized atmospheric correction method, and an emissivity-based atmospheric correction method is presented when the emissivity is known. Consequently, an appropriate atmospheric correction method can be selected based on the available data, frequency and required accuracy. Furthermore, this study provides a method to estimate τ and Tba↑ of different frequencies using the atmospheric parameters (total water vapor content in observation direction Lwv, total cloud liquid water content Lclw and mean temperature of cloud Tclw), which is important for simultaneously determining the land surface parameters using multi-frequency passive microwave satellite data.

Death of Darkness: Artificial Sky Brightness in the Anthropocene

NASA Astrophysics Data System (ADS)

Zender, C. S.

2016-12-01

Many species (including ours) need darkness to survive and thrive yet light pollution in the anthropocene has received scant attention in Earth System Models (ESMs). Anthropogenic aerosols can brighten background sky brightness and reduce the contrast between skylight and starlight. These are both aesthetic and health-related issues due to their accompanying disruption of circadian rhythms. We quantify aerosol contributions to light pollution using a single-column night sky model, NiteLite, suitable for implementation in ESMs. NiteLite accounts for physiologcal (photopic and scotopic vision, retinal diameter/age), anthropogenic (light and aerosol pollution properties), and natural (surface albedo, trace gases) effects on background brightness and threshold visibility. We find that stratospheric aerosol injection contemplated as a stop-gap measure to counter global warming would increase night-sky brightness by about 25%, and thus eliminate last pristine dark sky areas on Earth. Our results suggest that ESMs incorporate light pollution so that associated societal impacts can be better quantified and included in policy deliberations.

Posterior uncertainty of GEOS-5 L-band radiative transfer model parameters and brightness temperatures after calibration with SMOS observations

NASA Astrophysics Data System (ADS)

De Lannoy, G. J.; Reichle, R. H.; Vrugt, J. A.

2012-12-01

Simulated L-band (1.4 GHz) brightness temperatures are very sensitive to the values of the parameters in the radiative transfer model (RTM). We assess the optimum RTM parameter values and their (posterior) uncertainty in the Goddard Earth Observing System (GEOS-5) land surface model using observations of multi-angular brightness temperature over North America from the Soil Moisture Ocean Salinity (SMOS) mission. Two different parameter estimation methods are being compared: (i) a particle swarm optimization (PSO) approach, and (ii) an MCMC simulation procedure using the differential evolution adaptive Metropolis (DREAM) algorithm. Our results demonstrate that both methods provide similar "optimal" parameter values. Yet, DREAM exhibits better convergence properties, resulting in a reduced spread of the posterior ensemble. The posterior parameter distributions derived with both methods are used for predictive uncertainty estimation of brightness temperature. This presentation will highlight our model-data synthesis framework and summarize our initial findings.

An empirical study of the nuclear explosion-induced lightning seen on IVY-MIKE

NASA Astrophysics Data System (ADS)

Colvin, J. D.; Mitchell, C. K.; Greig, J. R.; Murphy, D. P.; Pechacek, R. E.; Raleigh, M.

1987-05-01

We report the results of a unique study of the lightninglike phenomena that were seen to accompany the MIKE shot of operation IVY on October 31 1952. MIKE was a thermonuclear surface burst yielding 10.4 MT, which took place on Enewetak Atoll. During the period of approximately 10 ms after detonation, five discrete luminous channels were seen to start from the ground or sea surface at a distance of approximately 1 km from the burst point and to grow up into the clouds. We have reexamined the original photographic records of IVY-MIKE, obtaining effective brightnesses (optical powers per unit length) for the luminous channels at different altitudes as functions of time. The absolute calibration for the MIKE records was deduced by comparison with the photographic records of other events of that era, laboratory measurements of film sensitivity, and use of atmospheric transmission data taken just prior to the MIKE event. Errors in this analysis lead to an uncertainty of a factor of ˜2 in the brightnesses of the luminous channels. In the laboratory we have used laser-guided electric discharges to create long (100 cm), arclike plasma channels to simulate the observed luminous channels and to allow determination of an empirical relation between the brightness of the channel and the electric current flowing in the channel. These laboratory discharges had peak currents up to 100 kA and periods of ˜2 ms. Spectroscopic analysis showed that the luminous channels consisted primarily of normal air plasma with typical ground-level contaminants. Photographic studies showed that these long-duration discharges are unstable to the m = 1 magnetohydrodynamic (MHD) instability and become severely distorted in less than 1 ms. By direct comparison of the luminous channels seen at MIKE and the laboratory discharges, we deduce: (1) the peak current in the prominent (brightest) channel at MIKE was between 200 and 600 kA. Here the most likely value of the peak current was 250±50 kA, but potential systematic errors in the film calibration and the comparison of MIKE and laboratory data make higher currents possible. (2) The rapid decline in the brightness of the luminous channels seen at MIKE is caused by a combination of the effects of the MHD instability, which eventually leads to a broadening of the current-carrying channel, and channel cooling by turbulent convective mixing.

Stellar Surface Brightness Profiles of Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Herrmann, Kimberly A.; LITTLE THINGS Team

2012-01-01

Radial stellar surface brightness profiles of spiral galaxies can be classified into three types: (I) single exponential, (II) truncated: the light falls off with one exponential out to a break radius and then falls off more steeply, and (III) anti-truncated: the light falls off with one exponential out to a break radius and then falls off less steeply. Stellar surface brightness profile breaks are also found in dwarf disk galaxies, but with an additional category: (FI) flat-inside: the light is roughly constant or increasing and then falls off beyond a break. We have been re-examining the multi-wavelength stellar disk profiles of 141 dwarf galaxies, primarily from Hunter & Elmegreen (2006, 2004). Each dwarf has data in up to 11 wavelength bands: FUV and NUV from GALEX, UBVJHK and H-alpha from ground-based observations, and 3.6 and 4.5 microns from Spitzer. In this talk, I will highlight results from a semi-automatic fitting of this data set, including: (1) statistics of break locations and other properties as a function of wavelength and profile type, (2) color trends and radial mass distribution as a function of profile type, and (3) the relationship of the break radius to the kinematics and density profiles of atomic hydrogen gas in the 41 dwarfs of the LITTLE THINGS subsample. We gratefully acknowledge funding for this research from the National Science Foundation (AST-0707563).

Analyses of tomato fruit brightness mutants uncover both cutin-deficient and cutin-abundant mutants and a new hypomorphic allele of GDSL lipase.

PubMed

Petit, Johann; Bres, Cécile; Just, Daniel; Garcia, Virginie; Mauxion, Jean-Philippe; Marion, Didier; Bakan, Bénédicte; Joubès, Jérôme; Domergue, Frédéric; Rothan, Christophe

2014-02-01

The cuticle is a protective layer synthesized by epidermal cells of the plants and consisting of cutin covered and filled by waxes. In tomato (Solanum lycopersicum) fruit, the thick cuticle embedding epidermal cells has crucial roles in the control of pathogens, water loss, cracking, postharvest shelf-life, and brightness. To identify tomato mutants with modified cuticle composition and architecture and to further decipher the relationships between fruit brightness and cuticle in tomato, we screened an ethyl methanesulfonate mutant collection in the miniature tomato cultivar Micro-Tom for mutants with altered fruit brightness. Our screen resulted in the isolation of 16 glossy and 8 dull mutants displaying changes in the amount and/or composition of wax and cutin, cuticle thickness, and surface aspect of the fruit as characterized by optical and environmental scanning electron microscopy. The main conclusions on the relationships between fruit brightness and cuticle features were as follows: (1) screening for fruit brightness is an effective way to identify tomato cuticle mutants; (2) fruit brightness is independent from wax load variations; (3) glossy mutants show either reduced or increased cutin load; and (4) dull mutants display alterations in epidermal cell number and shape. Cuticle composition analyses further allowed the identification of groups of mutants displaying remarkable cuticle changes, such as mutants with increased dicarboxylic acids in cutin. Using genetic mapping of a strong cutin-deficient mutation, we discovered a novel hypomorphic allele of GDSL lipase carrying a splice junction mutation, thus highlighting the potential of tomato brightness mutants for advancing our understanding of cuticle formation in plants.

Analyses of Tomato Fruit Brightness Mutants Uncover Both Cutin-Deficient and Cutin-Abundant Mutants and a New Hypomorphic Allele of GDSL Lipase[C][W][OPEN

PubMed Central

Petit, Johann; Bres, Cécile; Just, Daniel; Garcia, Virginie; Mauxion, Jean-Philippe; Marion, Didier; Bakan, Bénédicte; Joubès, Jérôme; Domergue, Frédéric; Rothan, Christophe

2014-01-01

The cuticle is a protective layer synthesized by epidermal cells of the plants and consisting of cutin covered and filled by waxes. In tomato (Solanum lycopersicum) fruit, the thick cuticle embedding epidermal cells has crucial roles in the control of pathogens, water loss, cracking, postharvest shelf-life, and brightness. To identify tomato mutants with modified cuticle composition and architecture and to further decipher the relationships between fruit brightness and cuticle in tomato, we screened an ethyl methanesulfonate mutant collection in the miniature tomato cultivar Micro-Tom for mutants with altered fruit brightness. Our screen resulted in the isolation of 16 glossy and 8 dull mutants displaying changes in the amount and/or composition of wax and cutin, cuticle thickness, and surface aspect of the fruit as characterized by optical and environmental scanning electron microscopy. The main conclusions on the relationships between fruit brightness and cuticle features were as follows: (1) screening for fruit brightness is an effective way to identify tomato cuticle mutants; (2) fruit brightness is independent from wax load variations; (3) glossy mutants show either reduced or increased cutin load; and (4) dull mutants display alterations in epidermal cell number and shape. Cuticle composition analyses further allowed the identification of groups of mutants displaying remarkable cuticle changes, such as mutants with increased dicarboxylic acids in cutin. Using genetic mapping of a strong cutin-deficient mutation, we discovered a novel hypomorphic allele of GDSL lipase carrying a splice junction mutation, thus highlighting the potential of tomato brightness mutants for advancing our understanding of cuticle formation in plants. PMID:24357602

Zernike analysis of all-sky night brightness maps.

PubMed

Bará, Salvador; Nievas, Miguel; Sánchez de Miguel, Alejandro; Zamorano, Jaime

2014-04-20

All-sky night brightness maps (calibrated images of the night sky with hemispherical field-of-view (FOV) taken at standard photometric bands) provide useful data to assess the light pollution levels at any ground site. We show that these maps can be efficiently described and analyzed using Zernike circle polynomials. The relevant image information can be compressed into a low-dimensional coefficients vector, giving an analytical expression for the sky brightness and alleviating the effects of noise. Moreover, the Zernike expansions allow us to quantify in a straightforward way the average and zenithal sky brightness and its variation across the FOV, providing a convenient framework to study the time course of these magnitudes. We apply this framework to analyze the results of a one-year campaign of night sky brightness measurements made at the UCM observatory in Madrid.

Warning signal brightness variation: sexual selection may work under the radar of natural selection in populations of a polytypic poison frog.

PubMed

Crothers, Laura R; Cummings, Molly E

2013-05-01

Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog Dendrobates pumilio is an exceptionally polytypic (populations are phenotypically distinct) aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that aposematic brightness variation within this population is likely visible to two putative predators (crabs, snakes) and conspecifics but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. Because signal brightness changes can ultimately lead to changes in hue, our findings at the within-population level can provide insights into understanding this polytypism at across-population scales.

Single bright light exposure decreases sweet taste threshold in healthy volunteers.

PubMed

Srivastava, Shrikant; Donaldson, Lucy F; Rai, Dheeraj; Melichar, Jan K; Potokar, John

2013-10-01

Bright light exposure can alter circulating serotonin levels, and alteration of available serotonin by acute selective serotonin reuptake inhibition significantly lowers sweet but not salt taste recognition thresholds. We tested the hypothesis that bright light exposure would increase sweet but not salt taste sensitivity in healthy adults. Fourteen healthy volunteers were exposed to bright (10,000 lux) and dim (<20 lux) light for 30 min each, in counterbalanced order. Measures of taste perception (salt and sweet) and mood were determined at baseline, and before and after each light exposure period. Recognition thresholds for sucrose were significantly lower after bright but not dim light exposure. Thresholds for salt were unaffected by either condition. There were no significant changes in taste acuity, intensity or pleasantness for both the taste modalities and on visual analogue scales (VASs) for mood, anxiety, sleepiness and alertness, under either light condition. Brief bright light exposure reduces sweet but not salt taste recognition thresholds in healthy humans.

The bidirectional congruency effect of brightness-valence metaphoric association in the Stroop-like and priming paradigms.

PubMed

Huang, Yanli; Tse, Chi-Shing; Xie, Jiushu

2017-11-04

The conceptual metaphor theory (Lakoff & Johnson, 1980, 1999) postulates a unidirectional metaphoric association between abstract and concrete concepts: sensorimotor experience activated by concrete concepts facilitates the processing of abstract concepts, but not the other way around. However, this unidirectional view has been challenged by studies that reported a bidirectional metaphoric association. In three experiments, we tested the directionality of the brightness-valence metaphoric association, using Stroop-like paradigm, priming paradigm, and Stroop-like paradigm with a go/no-go manipulation. Both mean and vincentile analyses of reaction time data were performed. We showed that the directionality of brightness-valence metaphoric congruency effect could be modulated by the activation level of the brightness/valence information. Both brightness-to-valence and valence-to-brightness metaphoric congruency effects occurred in the priming paradigm, which could be attributed to the presentation of prime that pre-activated the brightness or valence information. However, in the Stroop-like paradigm the metaphoric congruency effect was only observed in the brightness-to-valence direction, but not in the valence-to-brightness direction. When the go/no-go manipulation was used to boost the activation of word meaning in the Stroop-like paradigm, the valence-to-brightness metaphoric congruency effect was observed. Vincentile analyses further revealed that valence-to-brightness metaphoric congruency effect approached significance in the Stroop-like paradigm when participants' reaction times were slower (at around 490ms). The implications of the current findings on the conceptual metaphor theory and embodied cognition are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Arecibo radar imagery of Mars: The major volcanic provinces

NASA Astrophysics Data System (ADS)

Harmon, John K.; Nolan, Michael C.; Husmann, Diana I.; Campbell, Bruce A.

2012-08-01

We present Earth-based radar images of Mars obtained with the upgraded Arecibo S-band (λ = 12.6 cm) radar during the 2005-2012 oppositions. The imaging was done using the same long-code delay-Doppler technique as for the earlier (pre-upgrade) imaging but at a much higher resolution (˜3 km) and, for some regions, a more favorable sub-Earth latitude. This has enabled us to make a more detailed and complete mapping of depolarized radar reflectivity (a proxy for small-scale surface roughness) over the major volcanic provinces of Tharsis, Elysium, and Amazonis. We find that vast portions of these regions are covered by radar-bright lava flows exhibiting circular polarization ratios close to unity, a characteristic that is uncommon for terrestrial lavas and that is a likely indicator of multiple scattering from extremely blocky or otherwise highly disrupted flow surfaces. All of the major volcanoes have radar-bright features on their shields, although the brightness distribution on Olympus Mons is very patchy and the summit plateau of Pavonis Mons is entirely radar-dark. The older minor shields (paterae and tholi) are largely or entirely radar-dark, which is consistent with mantling by dust or pyroclastic material. Other prominent radar-dark features include: the "fan-shaped deposits", possibly glacial, associated with the three major Tharsis Montes shields; various units of the Medusae Fossae Formation; a region south and west of Biblis Patera where "Stealth" deposits appear to obscure Tharsis flows; and a number of "dark-halo craters" with radar-absorbing ejecta blankets deposited atop surrounding bright flows. Several major bright features in Tharsis are associated with off-shield lava flows; these include the Olympus Mons basal plains, volcanic fields east and south of Pavonis Mons, the Daedalia Planum flows south of Arsia Mons, and a broad expanse of flows extending east from the Tharsis Montes to Echus Chasma. The radar-bright lava plains in Elysium are concentrated mainly in Cerberus and include the fluvio-volcanic channels of Athabasca Valles, Grjotá Valles, and Marte Valles, as well as an enigmatic region at the southern tip of the Cerberus basin. Some of the Cerberus bright features correspond to the distinctive "platy-ridged" flows identified in orbiter images. The radar-bright terrain in Amazonis Planitia comprises two distinct but contiguous sections: a northern section formed of lavas and sediments debouched from Marte Valles and a southern section whose volcanics may derive, in part, from local sources. This South Amazonis region shows perhaps the most complex radar-bright structure on Mars and includes features that correspond to platy-ridged flows similar to those in Cerberus.

Subjective figures and texture perception.

PubMed

Zucker, S W; Cavanagh, P

1985-01-01

A texture discrimination task using the Ehrenstein illusion demonstrates that subjective brightness effects can play an essential role in early vision. The subjectively bright regions of the Ehrenstein can be organized either as discs or as stripes, depending on orientation. The accuracy of discrimination between variants of the Ehrenstein and control patterns was a direct function of the presence of the illusory brightness stripes, being high when they were present and low otherwise. It is argued that neither receptive field structure nor spatial-frequency content can adequately account for these results. We suggest that the subjective brightness illusions, rather than being a high-level, cognitive aspect of vision, are in fact the result of an early visual process.

One- to two-month oscillations in SSMI surface wind speed in western tropical Pacific Ocean

NASA Technical Reports Server (NTRS)

Collins, Michael L.; Stanford, John L.; Halpern, David

1994-01-01

The 10-m wind speed over the ocean can be estimated from microwave brightness temperature measurements recorded by the Special Sensor Microwave Imager (SSMI) instrument mounted on a polar-orbiting spacecraft. Four-year (1988-1991) time series of average daily 1 deg x 1 deg SSMI wind speeds were analyzed at selected sites in the western tropical Pacific Ocean. One- to two-month period wind speed oscillations with amplitudes statistically significant at the 95% confidence level were observed near Kanton, Eniwetok, Guam, and Truk. This is the first report of such an oscillation in SSMI wind speeds.

Dynamic interaction of CO/H 2O mixtures with gold nanocrystals: Real-time imaging and local chemical probing

NASA Astrophysics Data System (ADS)

Visart de Bocarmé, Thierry; Chau, Thoi-Dai; Kruse, Norbert

2006-09-01

The dynamic interaction of pure gold nanocrystals ("tips") with H 2O/CO gas mixtures was studied by means of video-field ion microscopy (FIM). While imaging with nano-scale resolution selected areas of the equivalent of ˜200 atomic Au sites were analysed for their chemical composition using short field pulses and injecting respective ions into a time-of-flight mass spectrometer (pulsed field desorption mass spectrometry, PFDMS). At room temperature the exposure of a clean Au sample to water gas at 10 -4 Pa, in the presence of an electric field of ˜10 V/nm, led to water adsorption and formation of bright patterns in FIM. Additional exposure to CO gas at 5 × 10 -3 Pa led to the removal of the water layer. This was associated with the occurrence of bright wave fronts which ignited simultaneously in several regions of the Au surface with no preference for a certain crystallographic surface plane. In some cases wave fronts were seen to collide resulting in more complicated patterns such as concentric rings. Surface areas free of water appeared with low brightness. The phenomena were completely reversible. PFDMS demonstrated water ions to be responsible for image formation. Surface hydroxyl was also detected mass spectrometrically and respective ion intensities decreased during the titration with CO. The results suggest that gold nanocrystals, in the absence of oxidic support materials, may be active in the reaction between water and CO at temperatures as low as 300 K and in the presence of an electric field of ˜10 V/nm.

Target-in-the-loop beam control: basic considerations for analysis and wave-front sensing

NASA Astrophysics Data System (ADS)

Vorontsov, Mikhail A.; Kolosov, Valeriy

2005-01-01

Target-in-the-loop (TIL) wave propagation geometry represents perhaps the most challenging case for adaptive optics applications that are related to maximization of irradiance power density on extended remotely located surfaces in the presence of dynamically changing refractive-index inhomogeneities in the propagation medium. We introduce a TIL propagation model that uses a combination of the parabolic equation describing coherent outgoing-wave propagation, and the equation describing evolution of the mutual correlation function (MCF) for the backscattered wave (return wave). The resulting evolution equation for the MCF is further simplified by use of the smooth-refractive-index approximation. This approximation permits derivation of the transport equation for the return-wave brightness function, analyzed here by the method of characteristics (brightness function trajectories). The equations for the brightness function trajectories (ray equations) can be efficiently integrated numerically. We also consider wave-front sensors that perform sensing of speckle-averaged characteristics of the wave-front phase (TIL sensors). Analysis of the wave-front phase reconstructed from Shack-Hartmann TIL sensor measurements shows that an extended target introduces a phase modulation (target-induced phase) that cannot be easily separated from the atmospheric-turbulence-related phase aberrations. We also show that wave-front sensing results depend on the extended target shape, surface roughness, and outgoing-beam intensity distribution on the target surface. For targets with smooth surfaces and nonflat shapes, the target-induced phase can contain aberrations. The presence of target-induced aberrations in the conjugated phase may result in a deterioration of adaptive system performance.

Target-in-the-loop beam control: basic considerations for analysis and wave-front sensing.

PubMed

Vorontsov, Mikhail A; Kolosov, Valeriy

2005-01-01

Target-in-the-loop (TIL) wave propagation geometry represents perhaps the most challenging case for adaptive optics applications that are related to maximization of irradiance power density on extended remotely located surfaces in the presence of dynamically changing refractive-index inhomogeneities in the propagation medium. We introduce a TIL propagation model that uses a combination of the parabolic equation describing coherent outgoing-wave propagation, and the equation describing evolution of the mutual correlation function (MCF) for the backscattered wave (return wave). The resulting evolution equation for the MCF is further simplified by use of the smooth-refractive-index approximation. This approximation permits derivation of the transport equation for the return-wave brightness function, analyzed here by the method of characteristics (brightness function trajectories). The equations for the brightness function trajectories (ray equations) can be efficiently integrated numerically. We also consider wave-front sensors that perform sensing of speckle-averaged characteristics of the wave-front phase (TIL sensors). Analysis of the wave-front phase reconstructed from Shack-Hartmann TIL sensor measurements shows that an extended target introduces a phase modulation (target-induced phase) that cannot be easily separated from the atmospheric-turbulence-related phase aberrations. We also show that wave-front sensing results depend on the extended target shape, surface roughness, and outgoing-beam intensity distribution on the target surface. For targets with smooth surfaces and nonflat shapes, the target-induced phase can contain aberrations. The presence of target-induced aberrations in the conjugated phase may result in a deterioration of adaptive system performance.

How visual illusions illuminate complementary brain processes: illusory depth from brightness and apparent motion of illusory contours

PubMed Central

Grossberg, Stephen

2014-01-01

Neural models of perception clarify how visual illusions arise from adaptive neural processes. Illusions also provide important insights into how adaptive neural processes work. This article focuses on two illusions that illustrate a fundamental property of global brain organization; namely, that advanced brains are organized into parallel cortical processing streams with computationally complementary properties. That is, in order to process certain combinations of properties, each cortical stream cannot process complementary properties. Interactions between these streams, across multiple processing stages, overcome their complementary deficiencies to compute effective representations of the world, and to thereby achieve the property of complementary consistency. The two illusions concern how illusory depth can vary with brightness, and how apparent motion of illusory contours can occur. Illusory depth from brightness arises from the complementary properties of boundary and surface processes, notably boundary completion and surface-filling in, within the parvocellular form processing cortical stream. This illusion depends upon how surface contour signals from the V2 thin stripes to the V2 interstripes ensure complementary consistency of a unified boundary/surface percept. Apparent motion of illusory contours arises from the complementary properties of form and motion processes across the parvocellular and magnocellular cortical processing streams. This illusion depends upon how illusory contours help to complete boundary representations for object recognition, how apparent motion signals can help to form continuous trajectories for target tracking and prediction, and how formotion interactions from V2-to-MT enable completed object representations to be continuously tracked even when they move behind intermittently occluding objects through time. PMID:25389399

GHOSTS IN THE ATTIC: MAPPING THE STELLAR CONTENT OF THE S0 GALAXY NGC 5102

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidge, T. J.

2010-02-15

The spatial distribution of stars in the nearby S0 galaxy NGC 5102 is investigated using images obtained with WIRCam and MegaCam on the Canada-France-Hawaii Telescope. With the exception of gaps between detector elements, the entire galaxy is surveyed in r' and i', while the J and Ks data extend out to R {sub GC} {approx} 6 kpc, which corresponds to almost 7 disk scale lengths. A modest population of main-sequence stars with M{sub V} < -3.5 and ages {approx}70 Myr are detected throughout the disk, with the majority located in the southern half of the galaxy. The stellar disk inmore » the northern half of the galaxy is warped, following structure that is also seen in H I. Objects with photometric properties that are consistent with those of bright asymptotic giant branch (AGB) stars are seen throughout the disk, and the ratio of C stars to bright M giants is consistent with an overall increase in the star formation rate within the past 1 Gyr. Star-forming activity during the interval 0.1-2 Gyr was more centrally concentrated than during the past {approx}100 Myr. The structure of the disk changes near R {sub GC} {approx} 5 kpc (5.5 disk scale lengths), in the sense that the radial surface density profile defined by red supergiants (RSGs) and bright AGB stars levels off at larger radii. RSGs and bright AGB stars are traced out to a radius of 14 kpc (15.6 scale lengths) along the southern portion of the major axis, while a tentative detection is also made of bright AGB stars at a projected distance of {approx}16 kpc along the southeast minor axis. A large clump of AGB stars that subtends {approx}1 arcmin is identified to the west of the galaxy center. It is argued that this is the remnant of a companion galaxy that triggered past episodes of elevated star-forming activity.« less

Deep g'r'i'z' GMOS Imaging of the Dwarf Irregular Galaxy Kar 50

NASA Astrophysics Data System (ADS)

Davidge, T. J.

2002-11-01

Images obtained with the Gemini Multi-Object Spectrograph (GMOS) are used to investigate the stellar content and distance of the dwarf irregular galaxy Kar 50. The brightest object is an H II region, and the bright stellar content is dominated by stars with g'-r'<0. The tips of the main sequence and the red giant branch (RGB) are tentatively identified near r'=24.9 and i'=25.5, respectively. The galaxy has a blue integrated color and no significant color gradient, and we conclude that Kar 50 has experienced a recent galaxy-wide episode of star formation. The distance estimated from the brightest blue stars indicates that Kar 50 is behind the M81 group, and this is consistent with the tentative RGB-tip brightness. Kar 50 has a remarkably flat central surface brightness profile, even at wavelengths approaching 1 μm, although there is no evidence of a bar. In the absence of another large star-forming episode, Kar 50 will evolve into a very low surface brightness galaxy. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council of Canada (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

IPC two-color analysis of x ray galaxy clusters

NASA Technical Reports Server (NTRS)

White, Raymond E., III

1990-01-01

The mass distributions were determined of several clusters of galaxies by using X ray surface brightness data from the Einstein Observatory Imaging Proportional Counter (IPC). Determining cluster mass distributions is important for constraining the nature of the dark matter which dominates the mass of galaxies, galaxy clusters, and the Universe. Galaxy clusters are permeated with hot gas in hydrostatic equilibrium with the gravitational potentials of the clusters. Cluster mass distributions can be determined from x ray observations of cluster gas by using the equation of hydrostatic equilibrium and knowledge of the density and temperature structure of the gas. The x ray surface brightness at some distance from the cluster is the result of the volume x ray emissivity being integrated along the line of sight in the cluster.

Descartes region - Evidence for Copernican-age volcanism.

NASA Technical Reports Server (NTRS)

Head, J. W., III; Goetz, A. F. H.

1972-01-01

A model that suggests that the high-albedo central region of the Descartes Formation was formed by Copernican-age volcanism was developed from Orbiter photography, Apollo 12 multispectral photography, earth-based spectrophotometry, and thermal IR and radar data. The bright surface either is abundant in centimeter-sized rocks or is formed from an insulating debris layer overlying a surface with an abundance of rocks in the 1- to 20-cm size range. On the basis of these data, the bright unit is thought to be a young pyroclastic deposit mantling older volcanic units of the Descartes Formation. Since the Apollo 16 target point is only 50 km NW of the central part of this unit, evidence for material associated with this unique highland formation should be searched for in returned soil and rock samples.

The surface brightness of reflection nebulae. Ph.D. Thesis, Dec. 1972

NASA Technical Reports Server (NTRS)

Rush, W. F.

1974-01-01

Hubble's equation relating the maximum apparent angular extent of a reflection nebula to the apparent magnitude of the illuminating star has been reconsidered under a set of less restrictive assumptions. A computational technique is developed which permits the use of fits to observed m, log a values to determine the albedo of the particles composing reflection nebulae, providing only that one assumes a particular phase function. Despite the fact that all orders of scattering, anisotropic phase functions, and illumination by the general stellar field are considered, the albedo which is determined for reflection nebulae by this method appears larger than that for interstellar particles in general. The possibility that the higher surface brightness might be due to a continuous fluorescence mechanism is considered both theoretically and observationally.

Strange doings on Io. [Jupiter radio emission modification, sodium cloud, ionized sulfur and extreme brightness

NASA Technical Reports Server (NTRS)

Goody, R.

1978-01-01

Some unusual properties of Io are discussed, and possible explanations for these are considered. The properties discussed include Io's ability to modify radio waves emitted by Jupiter in the decametric band, the satellite's ionosphere and sodium cloud, its extraordinary brightness, and the presence of ionized sulfur just inside the satellite's orbit. Io's ability to modulate Jovian decametric radio emission is explained on the basis of the hypothesis that the satellite conducts electricity and interacts with Jupiter's magnetic field. Characteristics of the sodium cloud are reviewed, and the probable mechanism responsible for this cloud is outlined. It is concluded that the only plausible explanation for the brightness of Io is the presence of cat's-eye-type reflectors, possibly composed of crystalline deposits, on the satellite's surface.

Automatic detection method for mura defects on display film surface using modified Weber's law

NASA Astrophysics Data System (ADS)

Kim, Myung-Muk; Lee, Seung-Ho

2014-07-01

We propose a method that automatically detects mura defects on display film surfaces using a modified version of Weber's law. The proposed method detects mura defects regardless of their properties and shapes by identifying regions perceived by human vision as mura using the brightness of pixel and image distribution ratio of mura in an image histogram. The proposed detection method comprises five stages. In the first stage, the display film surface image is acquired and a gray-level shift performed. In the second and third stages, the image histogram is acquired and analyzed, respectively. In the fourth stage, the mura range is acquired. This is followed by postprocessing in the fifth stage. Evaluations of the proposed method conducted using 200 display film mura image samples indicate a maximum detection rate of ˜95.5%. Further, the results of application of the Semu index for luminance mura in flat panel display (FPD) image quality inspection indicate that the proposed method is more reliable than a popular conventional method.

Inference of precipitation through thermal infrared measurements of soil moisture

NASA Technical Reports Server (NTRS)

Wetzel, P. J.; Atlas, D.

1981-01-01

The physics of microwave radiative transfer is well understood so that causal models can be assembled which relate the observed brightness temperatures to assumed distributions of hydrometeors (both liquid and ice), non-precipitating clouds, water vapor oxygen, and surface conditions. Present models assume a Marshall Palmer size distribution of liquid hydrometers from the surface to the freezing level (near the 0 C isotherm) and a variable thickness of frozen hydrometeors above that with various reasonable distribution of the other relevant constituents. The validity of such models is discussed. All uncertainties in the rain rate retrieval algorithms can be expressed in terms of specific model uncertainties which can be addressed through appropriate measurements. Those factors which must be known to achieve umambiguous results can be identified so that rainfall measuring algorithms can be developed and improved. The emissivity of the underlying surface significantly affects the contrast that may be measured between areas covered by rain and those which are dry. Sensing strategies for measuring rain over the ocean and rain over land are reviewed.

Improvements to the swath-level near-surface atmospheric state parameter retrievals within the NRL Ocean Surface Flux System (NFLUX)

NASA Astrophysics Data System (ADS)

May, J. C.; Rowley, C. D.; Meyer, H.

2017-12-01

The Naval Research Laboratory (NRL) Ocean Surface Flux System (NFLUX) is an end-to-end data processing and assimilation system used to provide near-real-time satellite-based surface heat flux fields over the global ocean. The first component of NFLUX produces near-real-time swath-level estimates of surface state parameters and downwelling radiative fluxes. The focus here will be on the satellite swath-level state parameter retrievals, namely surface air temperature, surface specific humidity, and surface scalar wind speed over the ocean. Swath-level state parameter retrievals are produced from satellite sensor data records (SDRs) from four passive microwave sensors onboard 10 platforms: the Special Sensor Microwave Imager/Sounder (SSMIS) sensor onboard the DMSP F16, F17, and F18 platforms; the Advanced Microwave Sounding Unit-A (AMSU-A) sensor onboard the NOAA-15, NOAA-18, NOAA-19, Metop-A, and Metop-B platforms; the Advanced Technology Microwave Sounder (ATMS) sensor onboard the S-NPP platform; and the Advanced Microwave Scannin Radiometer 2 (AMSR2) sensor onboard the GCOM-W1 platform. The satellite SDRs are translated into state parameter estimates using multiple polynomial regression algorithms. The coefficients to the algorithms are obtained using a bootstrapping technique with all available brightness temperature channels for a given sensor, in addition to a SST field. For each retrieved parameter for each sensor-platform combination, unique algorithms are developed for ascending and descending orbits, as well as clear vs cloudy conditions. Each of the sensors produces surface air temperature and surface specific humidity retrievals. The SSMIS and AMSR2 sensors also produce surface scalar wind speed retrievals. Improvement is seen in the SSMIS retrievals when separate algorithms are used for the even and odd scans, with the odd scans performing better than the even scans. Currently, NFLUX treats all SSMIS scans as even scans. Additional improvement in all of the surface retrievals comes from using a 3-hourly SST field, as opposed to a daily SST field.

Microwave emission measurements of sea surface roughness, soil moisture, and sea ice structure

NASA Technical Reports Server (NTRS)

Gloersen, P.; Wilheit, T. T.; Schmugge, T. J.

1972-01-01

In order to demonstrate the feasibility of the microwave radiometers to be carried aboard the Nimbus 5 and 6 satellites and proposed for one of the earth observatory satellites, remote measurements of microwave radiation at wavelengths ranging from 0.8 to 21 cm have been made of a variety of the earth's surfaces from the NASA CV-990 A/C. Brightness temperatures of sea water surfaces of varying roughness, of terrain with varying soil moisture, and of sea ice of varying structure were observed. In each case, around truth information was available for correlation with the microwave brightness temperature. The utility of passive microwave radiometry in determining ocean surface wind speeds, at least for values higher than 7 meters/second has been demonstrated. In addition, it was shown that radiometric signatures can be used to determine soil moisture in unvegetated terrain to within five percentage points by weight. Finally, it was demonstrated that first year thick, multi-year, and first year thin sea ice can be distinguished by observing their differing microwave emissivities at various wavelengths.

Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere

NASA Astrophysics Data System (ADS)

Calvo, F.; Steiner, O.; Freytag, B.

2016-11-01

Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims: Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods: Numerical radiation (magneto-)hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results: The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions: Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them. The movie associated to Fig. 1 is available at http://www.aanda.org

Life-threatening motor vehicle crashes in bright sunlight

PubMed Central

Redelmeier, Donald A.; Raza, Sheharyar

2017-01-01

Abstract Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight. This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later. The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9–24, P < 0.001). The increased risk was accentuated in the early afternoon, disappeared at night, extended to patients with different characteristics, involved crashes with diverse features, not apparent with cloudy weather, and contributed to about 5000 additional patient-days in hospital. The increased risk extended to patients with high crash severity as indicated by ambulance involvement, surgical procedures, length of hospital stay, intensive care unit admission, and patient mortality. The increased risk was not easily attributed to differences in alcohol consumption, driving distances, or anomalies of adverse weather. Bright sunlight is associated with an increased risk of a life-threatening motor vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash. Level of evidence: Epidemiologic Study, level III. PMID:28072708

Europa's Pwyll Crater

NASA Technical Reports Server (NTRS)

1998-01-01

This view of the Pwyll impact crater on Jupiter's moon Europa taken by NASA's Galileo spacecraft shows the interior structure and surrounding ejecta deposits. Pwyll's location is shown in the background global view taken by Galileo's camera on December 16, 1997. Bright rays seen radiating from Pwyll in the global image indicate that this crater is geologically young. The rim of Pwyll is about 26 kilometers (16 miles) in diameter, and a halo of dark material excavated from below the surface extends a few kilometers beyond the rim. Beyond this dark halo, the surface is bright and numerous secondary craters can be seen. The closeup view of Pwyll, which combines imaging data gathered during the December flyby and the flyby of February 20, 1997, indicates that unlike most fresh impact craters, which have much deeper floors, Pwyll's crater floor is at approximately the same level as the surrounding background terrain.

North is to the top of the picture and the sun illuminates the surface from the northeast. This closeup image, centered at approximately 26 degrees south latitude and 271 degrees west longitude, covers an area approximately 125 by 75 kilometers (75 by 45 miles). The finest details that can be discerned in this picture are about 250 meters (800 feet) across. This image was taken on at a range of 12,400 kilometers (7,400 miles), with the green filter of Galileo's solid state imaging system.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

The Faces of Vesta

NASA Image and Video Library

2010-10-08

NASA Hubble Space Telescope snapped these images of the asteroid Vesta in preparation for the Dawn spacecraft visit in 2011. The images show the difference in brightness and color on the asteroid surface.

Discovery of megaparsec-scale, low surface brightness nonthermal emission in merging galaxy clusters using the green bank telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farnsworth, Damon; Rudnick, Lawrence; Brown, Shea

2013-12-20

We present results from a study of 12 X-ray bright clusters at 1.4 GHz with the 100 m Green Bank Telescope. After subtraction of point sources using existing interferometer data, we reach a median (best) 1σ rms sensitivity level of 0.01 (0.006) μJy arcsec{sup –2}, and find a significant excess of diffuse, low surface brightness emission in 11 of 12 Abell clusters observed. We also present initial results at 1.4 GHz of A2319 from the Very Large Array. In particular, we find: (1) four new detections of diffuse structures tentatively classified as two halos (A2065, A2069) and two relics (A2067,more » A2073); (2) the first detection of the radio halo in A2061 at 1.4 GHz, which qualifies this as a possible ultra-steep spectrum halo source with a synchrotron spectral index of α ∼ 1.8 between 327 MHz and 1.4 GHz; (3) a ∼2 Mpc radio halo in the sloshing, minor-merger cluster A2142; (4) a >2× increase of the giant radio halo extent and luminosity in the merging cluster A2319; (5) a ∼7× increase to the integrated radio flux and >4× increase to the observed extent of the peripheral radio relic in A1367 to ∼600 kpc, which we also observe to be polarized on a similar scale; (6) significant excess emission of ambiguous nature in three clusters with embedded tailed radio galaxies (A119, A400, A3744). Our radio halo detections agree with the well-known X-ray/radio luminosity correlation, but they are larger and fainter than current radio power correlation studies would predict. The corresponding volume-averaged synchrotron emissivities are 1-2 orders of magnitude below the characteristic value found in previous studies. Some of the halo-like detections may be some type of previously unseen, low surface brightness radio halo or blend of unresolved shock structures and sub-Mpc-scale turbulent regions associated with their respective cluster merging activity. Four of the five tentative halos contain one or more X-ray cold fronts, suggesting a possible connection between gas sloshing and particle acceleration on large scales in some of these clusters. Additionally, we see evidence for a possible inter-cluster filament between A2061 and A2067. For our faintest detections, we note the possibility of residual contamination from faint radio galaxies not accounted for in our confusion subtraction procedure. We also quantify the sensitivity of the NVSS to extended emission as a function of size.« less

Perennial water ice identified in the south polar cap of Mars

NASA Astrophysics Data System (ADS)

Bibring, Jean-Pierre; Langevin, Yves; Poulet, François; Gendrin, Aline; Gondet, Brigitte; Berthé, Michel; Soufflot, Alain; Drossart, Pierre; Combes, Michel; Bellucci, Giancarlo; Moroz, Vassili; Mangold, Nicolas; Schmitt, Bernard; OMEGA Team; Erard, S.; Forni, O.; Manaud, N.; Poulleau, G.; Encrenaz, T.; Fouchet, T.; Melchiorri, R.; Altieri, F.; Formisano, V.; Bonello, G.; Fonti, S.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Kottsov, V.; Ignatiev, N.; Titov, D.; Zasova, L.; Pinet, P.; Sotin, C.; Hauber, E.; Hoffman, H.; Jaumann, R.; Keller, U.; Arvidson, R.; Mustard, J.; Duxbury, T.; Forget, F.

2004-04-01

The inventory of water and carbon dioxide reservoirs on Mars are important clues for understanding the geological, climatic and potentially exobiological evolution of the planet. From the early mapping observation of the permanent ice caps on the martian poles, the northern cap was believed to be mainly composed of water ice, whereas the southern cap was thought to be constituted of carbon dioxide ice. However, recent missions (NASA missions Mars Global Surveyor and Odyssey) have revealed surface structures, altimetry profiles, underlying buried hydrogen, and temperatures of the south polar regions that are thermodynamically consistent with a mixture of surface water ice and carbon dioxide. Here we present the first direct identification and mapping of both carbon dioxide and water ice in the martian high southern latitudes, at a resolution of 2km, during the local summer, when the extent of the polar ice is at its minimum. We observe that this south polar cap contains perennial water ice in extended areas: as a small admixture to carbon dioxide in the bright regions; associated with dust, without carbon dioxide, at the edges of this bright cap; and, unexpectedly, in large areas tens of kilometres away from the bright cap.

Infrared photometric behavior and opposition effect of Mars

NASA Technical Reports Server (NTRS)

Erard, S.; Bibring, J-P.; Drossart, P.

1992-01-01

Although the instrument wasn't designed for this purpose, data from the imaging spectrometer ISM may be used for studying photometric variations of Mars reflectance, that are related to the surface materials and aerosols physical properties. ISM flew aboard the Phobos-2 spacecraft which orbited Mars from January to March, 1989. About 40,000 spectra were acquired in 128 channels ranging from 0.76 to 3.16 micro-m, with a spatial resolution of 25 km and a signal-to-noise ratio ranging up to 1000. Analysis of the results leads to the following conclusions: width variations of the opposition surge can be related to differences in porosity or grain size distribution on the various domains, with little or no effect from suspended dust. As the biggest effects are observed on dark and bright materials, intermediate behaviors on average-bright regions cannot result from a mixing process, but are more likely to come from either cementation processes or modification of the grain size distribution under the influence of wind, which under Martian conditions preferentially removes the biggest particles. Thus, a surface dust consisting in big bright and small dark grains could explain the observations.

Morphology, stratigraphy, and surface roughness properties of Venusian lava flow fields

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey M.; Crown, David A.

2002-10-01

Morphologic characteristics, flow stratigraphy, and radar backscatter properties of five lava flow fields on Venus (Turgmam Fluctus, Zipaltonal Fluctus, Tuli Mons/Uilata Fluctus, Var Mons, and Mylitta Fluctus) were examined to understand flow field emplacement mechanisms and relationships to other surface processes. These analyses indicate that the flow fields studied developed through emplacement of numerous, thin flow units, presumably over extended periods of time. Although the Venusian fields display flow morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger and have a larger range of radar backscatter coefficients. Both simple and compound flow emplacement appear to have occurred within the flow fields. A potential correlation between flow rheology and radar brightness is suggested by differences in planform morphology, apparent flow thickness, and apparent sensitivity to topography between bright and dark flows. Distributary flow morphologies may result from tube-fed flows, and postemplacement modification by processes such as flow inflation and crustal foundering is consistent with discrete zones of increased radar brightness within individual flow lobes. Mapping of these flow fields does not indicate any simple evolutionary trend in eruptive/resurfacing style within the flow fields, or any consistent temporal sequence relative to other tectonic and volcanic features.

Flooding of Ganymede's bright terrains by low-viscosity water-ice lavas.

PubMed

Schenk, P M; McKinnon, W B; Gwynn, D; Moore, J M

2001-03-01

Large regions of the jovian moon Ganymede have been resurfaced, but the means has been unclear. Suggestions have ranged from volcanic eruptions of liquid water or solid ice to tectonic deformation, but definitive high-resolution morphological evidence has been lacking. Here we report digital elevation models of parts of the surface of Ganymede, derived from stereo pairs combining data from the Voyager and Galileo spacecraft, which reveal bright, smooth terrains that lie at roughly constant elevations 100 to 1,000 metres below the surrounding rougher terrains. These topographic data, together with new images that show fine-scale embayment and burial of older features, indicate that the smooth terrains were formed by flooding of shallow structural troughs by low-viscosity water-ice lavas. The oldest and most deformed areas (the 'reticulate' terrains) in general have the highest relative elevations, whereas units of the most common resurfaced type--the grooved terrain--lie at elevations between those of the smooth and reticulate terrains. Bright terrain, which accounts for some two-thirds of the surface, probably results from a continuum of processes, including crustal rifting, shallow flooding and groove formation. Volcanism plays an integral role in these processes, and is consistent with partial melting of Ganymede's interior.

The outbursts of the comet 29P/Schwassmann-Wachmann 1: A new approach to the old problem

NASA Astrophysics Data System (ADS)

Gronkowski, P.

2014-02-01

As far as outbursts activity is concerned, the 29P/Schwassmann-Wachmann 1 is the exceptional comet. This Centaur object shows quasi-regular flares with periodicities of 50 days eriodicity (Trigo-Rodriguez et al. 2010). In the introductory part of the presented paper the most well-known hypotheses which try to explain this cometary behaviour are reviewed. The second, actual part of this paper presents the new model for the outburst activity of this comet. The model is based on the idea of Ipatov (2012), according to which there are large cavities %%in comets %%with material under gas pressure, below a considerable fraction of the comet's surface containing material under high gas pressure. In favourite conditions the surface layers over the cavities are thrown away and the interior of these cavities is exposed. Consequently, an outburst of the comet's brightness may be observed. The main characteristics of an outburst of this comet, the brightness jump, %%in its brightness is calculated. Numerical simulations were carried out for wide range of possible cometary parameters. The obtained results are in good agreement with the real observations.

A robust generalized fuzzy operator approach to film contrast correction in digital subtraction radiography.

PubMed

Leung, Chung-Chu

2006-03-01

Digital subtraction radiography requires close matching of the contrast in each pair of X-ray images to be subtracted. Previous studies have shown that nonparametric contrast/brightness correction methods using the cumulative density function (CDF) and its improvements, which are based on gray-level transformation associated with the pixel histogram, perform well in uniform contrast/brightness difference conditions. However, for radiographs with nonuniform contrast/ brightness, the CDF produces unsatisfactory results. In this paper, we propose a new approach in contrast correction based on the generalized fuzzy operator with least square method. The result shows that 50% of the contrast/brightness errors can be corrected using this approach when the contrast/brightness difference between a radiographic pair is 10 U. A comparison of our approach with that of CDF is presented, and this modified GFO method produces better contrast normalization results than the CDF approach.

Photic effects on sustained performance

NASA Technical Reports Server (NTRS)

French, J.; Whitmore, J.; Hannon, P. J.; Brainard, G.; Schiflett, S.

1992-01-01

Research is described which evaluates manipulating environmental light intensity as a means to attenuate fatigue. A counter balanced, within-subjects design was used to compare nine male subjects exposed to dim (100 lux) and bright (3000 lux) light conditions. Oral temperature values were greater for the bright light group over the dim light condition. Melatonin levels were suppressed by bright light treatment. Also, the frequency of eye blink rate was less for subjects during bright over dim light exposure. Light exposure was without effect on subjective fatigue. However, irrespective of light condition, significant effects on confusion, fatigue, and vigor mood dimensions were found as a result of 30 hour sleep deprivation. The findings suggest that bright lights may be used to help sustain nocturnal activity otherwise susceptible to fatigue. Such findings may have implications for the lighting arrangements on space flights during the subjective night for astronauts.

Recent development on high-power tandem-pumped fiber laser

NASA Astrophysics Data System (ADS)

Zhou, Pu; Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Xu, Jiangmin; Wu, Jian

2016-11-01

High power fiber laser is attracting more and more attention due to its advantage in excellent beam quality, high electricto- optical conversion efficiency and compact system configuration. Power scaling of fiber laser is challenged by the brightness of pump source, nonlinear effect, modal instability and so on. Pumping active fiber by using high-brightness fiber laser instead of common laser diode may be the solution for the brightness limitation. In this paper, we will present the recent development of various kinds of high power fiber laser based on tandem pumping scheme. According to the absorption property of Ytterbium-doped fiber, Thulium-doped fiber and Holmium-doped fiber, we have theoretically studied the fiber lasers that operate at 1018 nm, 1178 nm and 1150 nm, respectively in detail. Consequently, according to the numerical results we have optimized the fiber laser system design, and we have achieved (1) 500 watt level 1018nm Ytterbium-doped fiber laser (2) 100 watt level 1150 nm fiber laser and 100 watt level random fiber laser (3) 30 watt 1178 nm Ytterbium-doped fiber laser, 200 watt-level random fiber laser. All of the above-mentioned are the record power for the corresponded type of fiber laser to the best of our knowledge. By using the high-brightness fiber laser operate at 1018 nm, 1178 nm and 1150 nm that we have developed, we have achieved the following high power fiber laser (1) 3.5 kW 1090 nm Ytterbium-doped fiber amplifier (2) 100 watt level Thulium-doped fiber laser and (3) 50 watt level Holmium -doped fiber laser.

What is a melody? On the relationship between pitch and brightness of timbre

PubMed Central

Cousineau, Marion; Carcagno, Samuele; Demany, Laurent; Pressnitzer, Daniel

2014-01-01

Previous studies showed that the perceptual processing of sound sequences is more efficient when the sounds vary in pitch than when they vary in loudness. We show here that sequences of sounds varying in brightness of timbre are processed with the same efficiency as pitch sequences. The sounds used consisted of two simultaneous pure tones one octave apart, and the listeners’ task was to make same/different judgments on pairs of sequences varying in length (one, two, or four sounds). In one condition, brightness of timbre was varied within the sequences by changing the relative level of the two pure tones. In other conditions, pitch was varied by changing fundamental frequency, or loudness was varied by changing the overall level. In all conditions, only two possible sounds could be used in a given sequence, and these two sounds were equally discriminable. When sequence length increased from one to four, discrimination performance decreased substantially for loudness sequences, but to a smaller extent for brightness sequences and pitch sequences. In the latter two conditions, sequence length had a similar effect on performance. These results suggest that the processes dedicated to pitch and brightness analysis, when probed with a sequence-discrimination task, share unexpected similarities. PMID:24478638

Titan's Surface Temperatures Maps from Cassini - CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Samuelson, R. E.; Irwin, P. G. J.; Flasar, F. M.

2009-09-01

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 μm (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature profile by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). In future, application of our methodology over wide areas should greatly increase the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

The intrinsic three-dimensional shape of galactic bars

NASA Astrophysics Data System (ADS)

Méndez-Abreu, J.; Costantin, L.; Aguerri, J. A. L.; de Lorenzo-Cáceres, A.; Corsini, E. M.

2018-06-01

We present the first statistical study on the intrinsic three-dimensional (3D) shape of a sample of 83 galactic bars extracted from the CALIFA survey. We use the galaXYZ code to derive the bar intrinsic shape with a statistical approach. The method uses only the geometric information (ellipticities and position angles) of bars and discs obtained from a multi-component photometric decomposition of the galaxy surface-brightness distributions. We find that bars are predominantly prolate-triaxial ellipsoids (68%), with a small fraction of oblate-triaxial ellipsoids (32%). The typical flattening (intrinsic C/A semiaxis ratio) of the bars in our sample is 0.34, which matches well the typical intrinsic flattening of stellar discs at these galaxy masses. We demonstrate that, for prolate-triaxial bars, the intrinsic shape of bars depends on the galaxy Hubble type and stellar mass (bars in massive S0 galaxies are thicker and more circular than those in less massive spirals). The bar intrinsic shape correlates with bulge, disc, and bar parameters. In particular with the bulge-to-total (B/T) luminosity ratio, disc g - r color, and central surface brightness of the bar, confirming the tight link between bars and their host galaxies. Combining the probability distributions of the intrinsic shape of bulges and bars in our sample we show that 52% (16%) of bulges are thicker (flatter) than the surrounding bar at 1σ level. We suggest that these percentages might be representative of the fraction of classical and disc-like bulges in our sample, respectively.

Magnetic field strength of a neutron-star-powered ultraluminous X-ray source

NASA Astrophysics Data System (ADS)

Brightman, M.; Harrison, F. A.; Fürst, F.; Middleton, M. J.; Walton, D. J.; Stern, D.; Fabian, A. C.; Heida, M.; Barret, D.; Bachetti, M.

2018-04-01

Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar remnant, or an intermediate mass ( 100-105M⊙) black hole1. Recently detected coherent pulsations coming from three bright ULXs2-5 demonstrate that some of these sources are powered by accretion onto a neutron star, implying accretion rates significantly in excess of the Eddington limit, a high degree of geometric beaming, or both. The physical challenges associated with the high implied accretion rates can be mitigated if the neutron star surface field is very high (1014 G)6, since this suppresses the electron scattering cross-section, reducing the radiation pressure that chokes off accretion for high luminosities. Surface magnetic field strengths can be determined through cyclotron resonance scattering features7,8 produced by the transition of charged particles between quantized Landau levels. Here, we present the detection at a significance of 3.8σ of an absorption line at 4.5 keV in the Chandra spectrum of a ULX in M51. This feature is likely to be a cyclotron resonance scattering feature produced by the strong magnetic field of a neutron star. Assuming scattering off electrons, the magnetic field strength is implied to be 1011 G, while protons would imply a magnetic field of B 1015 G.

An Investigation of Intracluster Light Evolution Using Cosmological Hydrodynamical Simulations

NASA Astrophysics Data System (ADS)

Tang, Lin; Lin, Weipeng; Cui, Weiguang; Kang, Xi; Wang, Yang; Contini, E.; Yu, Yu

2018-06-01

Intracluster light (ICL) in observations is usually identified through the surface brightness limit (SBL) method. In this paper, for the first time we produce mock images of galaxy groups and clusters, using a cosmological hydrodynamical simulation to investigate the ICL fraction and focus on its dependence on observational parameters, e.g., the SBL, the effects of cosmological redshift-dimming, point-spread function (PSF), and CCD pixel size. Detailed analyses suggest that the width of the PSF has a significant effect on the measured ICL fraction, while the relatively small pixel size shows almost no influence. It is found that the measured ICL fraction depends strongly on the SBL. At a fixed SBL and redshift, the measured ICL fraction decreases with increasing halo mass, while with a much fainter SBL, it does not depend on halo mass at low redshifts. In our work, the measured ICL fraction shows a clear dependence on the cosmological redshift-dimming effect. It is found that there is more mass locked in the ICL component than light, suggesting that the use of a constant mass-to-light ratio at high surface brightness levels will lead to an underestimate of ICL mass. Furthermore, it is found that the radial profile of ICL shows a characteristic radius that is almost independent of halo mass. The current measurement of ICL from observations has a large dispersion due to different methods, and we emphasize the importance of using the same definition when observational results are compared with theoretical predictions.

Aerosol in the Martian atmosphere

NASA Astrophysics Data System (ADS)

Dlugach, Zh. M.; Morozhenko, O. V.

2000-09-01

Our examination of the methods and results of available estimates of the optical characteristics of atmospheric aerosols allows us to draw the following conclusions. 1. When the morning and evening hazes are ignored in the analyses of the solar brightness weakening data obtained from the Martian surface, the solar intensity at the upper boundary of the atmosphere as well as its optical thickness may be significantly overestimated. For example, at the Viking-1 lander site the intensity may be overestimated by a factor of 1.7 and τ0 by a factor of 0.35. When these data are used in the analysies of the azimuthal dependence of the Martian sky brightness and when the presence of hazes is ignored, aerosol size and imaginary part of the refractive index are also overestimated. At wavelenghts shorter than 500 nm the spectral values of the imaginary part of the refractive index ni, show the best agreement with those obtained in laboratory for basalts, but for longer wavelengths they are much lower. 3. At the 1971 dust storm maximum the mean geometrical radius r0 of the particles proved to be in the range 3.5-5.7 μm with the dispersion σ2 = 0.2. 4. In October-November τ0 >15, whereas for the "clear" atmosphere τ0 < 0.02 at λ = 500 nm. 5. The turbulent diffusion coefficient at the mean level of the surface layer proved to be not lower than 3\\cdot107 cm2/s in October-November 1971.

The abundance properties of nearby late-type galaxies. II. The relation between abundance distributions and surface brightness profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pilyugin, L. S.; Grebel, E. K.; Zinchenko, I. A.

2014-12-01

The relations between oxygen abundance and disk surface brightness (OH–SB relation) in the infrared W1 band are examined for nearby late-type galaxies. The oxygen abundances were presented in Paper I. The photometric characteristics of the disks are inferred here using photometric maps from the literature through bulge-disk decomposition. We find evidence that the OH–SB relation is not unique but depends on the galactocentric distance r (taken as a fraction of the optical radius R{sub 25}) and on the properties of a galaxy: the disk scale length h and the morphological T-type. We suggest a general, four-dimensional OH–SB relation with themore » values r, h, and T as parameters. The parametric OH–SB relation reproduces the observed data better than a simple, one-parameter relation; the deviations resulting when using our parametric relation are smaller by a factor of ∼1.4 than that of the simple relation. The influence of the parameters on the OH–SB relation varies with galactocentric distance. The influence of the T-type on the OH–SB relation is negligible at the centers of galaxies and increases with galactocentric distance. In contrast, the influence of the disk scale length on the OH–SB relation is at a maximum at the centers of galaxies and decreases with galactocentric distance, disappearing at the optical edges of galaxies. Two-dimensional relations can be used to reproduce the observed data at the optical edges of the disks and at the centers of the disks. The disk scale length should be used as a second parameter in the OH–SB relation at the center of the disk while the morphological T-type should be used as a second parameter in the relation at optical edge of the disk. The relations between oxygen abundance and disk surface brightness in the optical B and infrared K bands at the center of the disk and at optical edge of the disk are also considered. The general properties of the abundance–surface brightness relations are similar for the three considered bands B, K, and W1.« less

Results of TV imaging of Phobos - Experiment VSK-Fregat

NASA Technical Reports Server (NTRS)

Avanesov, G.; Zhukov, B.; Ziman, IA.; Kostenko, V.; Kuz'min, A.; Duxbury, T.

1991-01-01

From February to March 1989 the Phobos 2 spacecraft took 37 TV images of Phobos at a distance of 190-1100 km. These images complement Mariner-9 and Viking data by providing higher-resolution coverage of a laarge region west of the crater Stickney (40-160 deg W) and by providing disk-resolved measurements of surface brightness at a greater range of wavelengths and additional phase angles. These images have supported updated mapping and characterization of large craters and grooves, and have provided additional observations of craters' and grooves' bright rims. Variations in surface visible/near-infrared color ratio of almost a factor of 2 have been recognized; these variations appear to be associated with the ejecta of specific large impact craters. Updated determinations of satellite mass and volume allow calculation of a more accurate value of bulk density, 1.90 + or - 0.1 g/cu cm. This is sigificantly lower than the density of meteoritic analogs to Phobos' surface, suggesting a porous interior perhaps containing interstitial ice.

Feasibility of spectro-photometry in X-rays (SPHINX) from the moon

NASA Astrophysics Data System (ADS)

Sarkar, Ritabrata; Chakrabarti, Sandip Kumar

2010-08-01

Doing space Astronomy on lunar surface has several advantages. We present here feasibility of an All Sky Monitoring Payload for Spectro-photometry in X-rays (SPHINX) which can be placed on a lander on the moon or in a space craft orbiting around the moon. The Si-PIN photo-diodes and CdTe crystals are used to detect solar flares, bright gamma bursts, soft gamma-ray repeaters from space and also X-ray fluorescence (XRF) from lunar surface. We present the complete Geant4 simulation to study the feasibility of such an instrument in presence of Cosmic Diffused X-Ray Background (CDXRB). We find that the signal to noise ratio is sufficient for moderate to bright GRBs (above 5 keV), for the quiet sun (up to 100 keV), solar flares, soft gamma-ray repeaters, X-ray Fluorescence (XRF) of lunar surface etc. This is a low-cost system which is capable of performing multiple tasks while stationed at the natural satellite of our planet.

Theoretical colours and isochrones for some Hubble Space Telescope colour systems. II

NASA Technical Reports Server (NTRS)

Paltoglou, G.; Bell, R. A.

1991-01-01

A grid of synthetic surface brightness magnitudes for 14 bandpasses of the Hubble Space Telescope Faint Object Camera is presented, as well as a grid of UBV, uvby, and Faint Object Camera surface brightness magnitudes derived from the Gunn-Stryker spectrophotometric atlas. The synthetic colors are used to examine the transformations between the ground-based Johnson UBV and Stromgren uvby systems and the Faint Object Camera UBV and uvby. Two new four-color systems, similar to the Stromgren system, are proposed for the determination of abundance, temperature, and surface gravity. The synthetic colors are also used to calculate color-magnitude isochrones from the list of theoretical tracks provided by VandenBerg and Bell (1990). It is shown that by using the appropriate filters it is possible to minimize the dependence of this color difference on metallicity. The effects of interstellar reddening on various Faint Object Camera colors are analyzed as well as the observational requirements for obtaining data of a given signal-to-noise for each of the 14 bandpasses.

ARC-1979-A79-7093

NASA Image and Video Library

1979-07-09

Range : 225,000 kilometers (140,625 miles) This image of the Jovian moon Europa was taken by Voyager 2 along the evening terminator, which best shows the surface topography of complex narrow ridges, seen as curved bright streaks, 5 to 10 kilometers wide, and typically 100 kilometers in length. The area shown is about 600 by 800 kilometers, and the smallest features visible are about 4 kilometers in size. Also visable are dark bands, more diffused in character, 20 to 40 kilometers wide and hundreds to thousands of kilometers in length. A few features are suggestive of impact craters but are rare, indication that the surface thought to be dominantly ice is still active, perhaps warmed by tidal heating like Io. The larger icy satellites, Callisto and Ganymede, are evidently colder with much more rigid crusts and ancient impact craters. The complex intersection of dark markings and bright ridges suggest that the surface has been fractured and material from beneath has welled up to fill the cracks.

Syrtis Major

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 6 June 2002) The Science This image, located near the equator and 288W (72E), is near the southern edge of a low, broad volcanic feature called Syrtis Major. A close look at this image reveals a wrinkly texture that indicates a very rough surface that is associated with the lava flows that cover this region. On a larger scale, there are numerous bright streaks that trail topographic features such as craters. These bright streaks are in the wind shadows of the craters where dust that settles onto the surface is not as easily scoured away. It is important to note that these streaks are only bright in a relative sense to the surrounding image. Syrtis Major is one of the darkest regions on Mars and it is as dark as fresh basalt flows or dunes are on Earth. The Story Cool! It almost looks as if nature has 'painted' comets on the surface of Mars, using craters as comet cores and dust as streaky tails. Of course, that's just an illusion. As in many areas of Mars, the wind is behind the creation of such fantastic landforms. The natural phenomenon seen here gives this particular surface of Mars a very dynamic, fast-moving, almost luminous 'cosmic personality.' The bright, powdery-looking streaks of dust are in the 'wind shadows' of craters, where dust that settles onto the surface is not as easily scoured away. That's because the wind moves across the land in a particular direction, and a raised surface like the rim of a crater 'protects' dust from being completely blown away on the other side. The raised landforms basically act as a buffer. From the streaks seen above, you can tell the wind was blowing in a northeast to southwest direction. Why are the streaks so bright? Because they contrast with the really dark underlying terrain in this volcanic area of Mars. Syrtis Major is one of the darkest regions on Mars because it is made of basalt. Basalt is typically dark gray or black, and forms when a certain type of molten lava cools. The meaning of the word basalt has been traced back to an ancient Ethiopian word 'basal,' which means 'a rock from which you can obtain iron.' That must have made it a very desired material with ancient Earth civilizations long ago. Basalt is actually one of the most abundant types of rock found on Earth. Most of the volcanic islands in the ocean are made of basalt, including the large shield volcano of Mauna Loa, Hawaii, which is often compared to Martian shield volcanoes. Shield volcanoes don't have high, steep, mountain-like sides, but are instead low and broad humps upon the surface. They're created when highly fluid, molten-basalt flows spread out over wide areas. Over several millennia of basaltic layering upon layering, these volcanoes can reach massive sizes like the ones seen on Mars. You can see the wrinkly texture of dark lava flows (now hard and cool) in the above image beneath the brighter dust.

Shadows cast on the transition disk of HD 135344B. Multiwavelength VLT/SPHERE polarimetric differential imaging

NASA Astrophysics Data System (ADS)

Stolker, T.; Dominik, C.; Avenhaus, H.; Min, M.; de Boer, J.; Ginski, C.; Schmid, H. M.; Juhasz, A.; Bazzon, A.; Waters, L. B. F. M.; Garufi, A.; Augereau, J.-C.; Benisty, M.; Boccaletti, A.; Henning, Th.; Langlois, M.; Maire, A.-L.; Ménard, F.; Meyer, M. R.; Pinte, C.; Quanz, S. P.; Thalmann, C.; Beuzit, J.-L.; Carbillet, M.; Costille, A.; Dohlen, K.; Feldt, M.; Gisler, D.; Mouillet, D.; Pavlov, A.; Perret, D.; Petit, C.; Pragt, J.; Rochat, S.; Roelfsema, R.; Salasnich, B.; Soenke, C.; Wildi, F.

2016-11-01

Context. The protoplanetary disk around the F-type star HD 135344B (SAO 206462) is in a transition stage and shows many intriguing structures both in scattered light and thermal (sub-)millimeter emission which are possibly related to planet formation processes. Aims: We aim to study the morphology and surface brightness of the disk in scattered light to gain insight into the innermost disk regions, the formation of protoplanets, planet-disk interactions traced in the surface and midplane layers, and the dust grain properties of the disk surface. Methods: We have carried out high-contrast polarimetric differential imaging (PDI) observations with VLT/SPHERE and obtained polarized scattered light images with ZIMPOL in the R and I-bands and with IRDIS in the Y and J-bands. The scattered light images and surface brightness profiles are used to study in detail structures in the disk surface and brightness variations. We have constructed a 3D radiative transfer model to support the interpretation of several detected shadow features. Results: The scattered light images reveal with unprecedented angular resolution and sensitivity the spiral arms as well as the 25 au cavity of the disk. Multiple shadow features are discovered on the outer disk with one shadow only being present during the second observation epoch. A positive surface brightness gradient is observed in the stellar irradiation corrected (r2-scaled) images in southwest direction possibly due to an azimuthally asymmetric perturbation of the temperature and/or surface density by the passing spiral arms. The disk integrated polarized flux, normalized to the stellar flux, shows a positive trend towards longer wavelengths which we attribute to large (2πa ≳ λ) aggregate dust grains in the disk surface. Part of the non-azimuthal polarization signal in the Uφ image of the J-band observation can be attributed to multiple scattering in the disk. Conclusions: The detected shadow features and their possible variability have the potential to provide insight into the structure of and processes occurring in the innermost disk regions. Possible explanations for the presence of the shadows include a 22° misaligned inner disk, a warped disk region that connects the inner disk with the outer disk, and variable or transient phenomena such as a perturbation of the inner disk or an asymmetric accretion flow. The spiral arms are best explained by one or multiple protoplanets in the exterior of the disk although no gap is detected beyond the spiral arms up to 1.''0. Based on observations collected at the European Southern Observatory, Chile, ESO No. 095.C-0273(A) and 095.C-0273(D).

UBVR observation of V1357 Cyg = Cyg X-1. Search of the optical radiation of the accretion disk

NASA Technical Reports Server (NTRS)

Shevchenko, V. S.

1979-01-01

Data from 30 nights of V 1357 Cyg observations in July, August, and September of 1977 are presented. The contribution of the disk to the optic brightness of the system is computed with regard for the heating of its surface by ultraviolet radiation from V 1357 Cyg and X-ray radiation from Cyg X-1. The disk radiation explains the irregular variability in the system brightness. The possibility of the eclipse of the star by the disk and the disk by the star is discussed.

Bright Loops at 171

NASA Technical Reports Server (NTRS)

2007-01-01

STEREO was able to capture bright loops in exquisite detail as they were arcing above an active region (May 26, 2007) over an 18 hour period. What we are actually seeing are charged particles spinning along magnetic field lines that extend above the Sun's surface. Active regions are areas of intense magnetic activity and often the source of solar storms. In fact, the clip ends with a flourish in which a small coronal mass ejection (CME) blows out into space. This is from the STEREO Ahead spacecraft at the 171 Angstroms wavelength in extreme ultraviolet light.

Grooved Terrain on Ganymede: A Galileo-based Synthesis

NASA Technical Reports Server (NTRS)

Pappalardo, Robert T.; Collins, Geoffrey C.; Head, James W.; Moore, Jeffrey M.; Schenk, Paul M.

2003-01-01

Swaths of bright "grooved terrain" (sulci) on Ganymede are 10s to 100s of kilometers wide and cross-cut the older dark terrain, forming an intricate patchwork across 2/3 of Ganymede's surface. The view of grooved terrain developed from Voyager images is that bright cells are broad graben infilled by extrusion of relatively clean (silicate-poor) liquid water, warm ice, or icy slush, and then extended and faulted. Galileo imaging has greatly improved understanding of the emplacement history and geological implications of grooved terrain, supporting a rift-like model for its formation.

VizieR Online Data Catalog: Galaxies and QSOs FIR size and surface brightness (Lutz+, 2016)

NASA Astrophysics Data System (ADS)

Lutz, D.; Berta, S.; Contursi, A.; Forster Schreiber, N. M.; Genzel, R.; Gracia-Carpio, J.; Herrera-Camus, R.; Netzer, H.; Sturm, E.; Tacconi, L. J.; Tadaki, K.; Veilleux, S.

2016-08-01

We use 70, 100, and 160um images from scan maps obtained with PACS on board Herschel, collecting archival data from various projects. In order to cover a wide range of galaxy properties, we first obtain an IR-selected local sample ranging from normal galaxies up to (ultra)luminous infrared galaxies. For that purpose, we searched the Herschel archive for all cz>=2000km/s objects from the IRAS Revised Bright Galaxy Sample (RBGS, Sanders et al., 2003, Cat. J/AJ/126/1607). (1 data file).

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

Microwave radiometer and scatterometer design for the aquarius sea surface Salinity Mission

NASA Technical Reports Server (NTRS)

Wilson, William J.; Yueh, Simon H.; Pellerano, Fernando

2004-01-01

The measurement of sea surface salinity with L-band microwave radiometers is a very challenging task. Since the L-band brightness temperature variations associated with salinity changes are small, it is necessary to have a very sensitive and stable radiometer. In addition, the corrections for the ocean surface roughness require real time scatterometer measurements. The designs of the Aquarius radiometer and scatterometer are described in this paper.

Active and Passive Remote Sensing of Ice

DTIC Science & Technology

1991-11-15

To demonstrate the use of polarimetry in passive remote sensing of azimuthally asymmetric features on a terrain surface, an experiment was designed...azimuthal asymmetry on the remotely sensed soil surface. It is also observed from the experiment that the brightness temperatures for all three Stokes...significant implication of this experiment is that the surface asymmetry can be detected with a measurement of U at a single azimuthal angle. -8

Directional Emissivity Effects on Martian Surface Brightness Temperatures

NASA Astrophysics Data System (ADS)

Pitman, K. M.; Wolff, M. J.; Bandfield, J. L.; Clancy, R. T.; Clayton, G. C.

2001-11-01

The angular dependence of thermal emission from the surface of Mars has not been well characterized. Although nadir sequences constitute most of the MGS/TES Martian surface observations [1,2], a significant number scans of Martian surfaces at multiple emission angles (emission phase function (EPF) sequences) also exist. Such data can provide insight into surface structures, thermal inertias, and non-isotropic corrections to thermal emission measurements [3]. The availability of abundant EPF data as well as the added utility of such observations for atmospheric characterization provide the impetus for examining the phenomenon of directional emissivity. We present examples of directional emissivity effects on brightness temperature spectra for a variety of typical Martian surfaces. We examine the theoretical development by Hapke (1993, 1996) [4,5] and compare his algorithm to that of Mishchenko et al. (1999) [6]. These results are then compared to relevant TES EPF data. This work is supported through NASA grant NAGS-9820 (MJW) and JPL contract no. 961471 (RTC). [1] Smith et al. (1998), AAS-DPS meeting # 30, # 11.P07. [2] Kieffer, Mullins, & Titus (1998), EOS, 79, 533. [3] Jakosky, Finiol, & Henderson (1990), JGR, 17, 985--988. [4] Hapke, B. (1993), Theory of Reflectance & Emittance Spectroscopy, Cambridge Univ. Press, NY. [5] Hapke, B. (1996), JGR, 101, E7, 16817--16831. [6] Mishchenko et al. (1999), JQSRT, 63, 409--432.

Leonids 2017 from Norway – A bright surprise!

NASA Astrophysics Data System (ADS)

Gaarder, K.

2018-01-01

I am very pleased to have been able to observe near maximum activity of the Leonids, and clearly witnessed the unequal mass distribution during these hours. A lot of bright Leonids were seen, followed by a short period of high activity of fainter meteors, before a sharp drop in activity. The Leonids is undoubtedly a shower to watch closely, with its many variations in activity level and magnitude distribution. I already look forward to observing the next years’ display, hopefully under a dark and clear sky, filled with bright meteors!

MAPIR: An Airborne Polarmetric Imaging Radiometer in Support of Hydrologic Satellite Observations

NASA Technical Reports Server (NTRS)

Laymon, C.; Al-Hamdan, M.; Crosson, W.; Limaye, A.; McCracken, J.; Meyer, P.; Richeson, J.; Sims, W.; Srinivasan, K.; Varnevas, K.

2010-01-01

In this age of dwindling water resources and increasing demands, accurate estimation of water balance components at every scale is more critical to end users than ever before. Several near-term Earth science satellite missions are aimed at global hydrologic observations. The Marshall Airborne Polarimetric Imaging Radiometer (MAPIR) is a dual beam, dual angle polarimetric, scanning L band passive microwave radiometer system developed by the Observing Microwave Emissions for Geophysical Applications (OMEGA) team at MSFC to support algorithm development and validation efforts in support of these missions. MAPIR observes naturally-emitted radiation from the ground primarily for remote sensing of land surface brightness temperature from which we can retrieve soil moisture and possibly surface or water temperature and ocean salinity. MAPIR has achieved Technical Readiness Level 6 with flight heritage on two very different aircraft, the NASA P-3B, and a Piper Navajo.

SDSS IV MaNGA: Deep observations of extra-planar, diffuse ionized gas around late-type galaxies from stacked IFU spectra

NASA Astrophysics Data System (ADS)

Jones, A.; Kauffmann, G.; D'Souza, R.; Bizyaev, D.; Law, D.; Haffner, L.; Bahé, Y.; Andrews, B.; Bershady, M.; Brownstein, J.; Bundy, K.; Cherinka, B.; Diamond-Stanic, A.; Drory, N.; Riffel, R. A.; Sánchez, S. F.; Thomas, D.; Wake, D.; Yan, R.; Zhang, K.

2017-03-01

We have conducted a study of extra-planar diffuse ionized gas using the first year data from the MaNGA IFU survey. We have stacked spectra from 49 edge-on, late-type galaxies as a function of distance from the midplane of the galaxy. With this technique we can detect the bright emission lines Hα, Hβ, [O II]λλ3726, 3729, [O III]λ5007, [N II]λλ6549, 6584, and [S II]λλ6717, 6731 out to about 4 kpc above the midplane. With 16 galaxies we can extend this analysis out to about 9 kpc, I.e. a distance of 2Re, vertically from the midplane. In the halo, the surface brightnesses of the [O II] and Hα emission lines are comparable, unlike in the disk where Hα dominates. When we split the sample by specific star-formation rate, concentration index, and stellar mass, each subsample's emission line surface brightness profiles and ratios differ, indicating that extra-planar gas properties can vary. The emission line surface brightnesses of the gas around high specific star-formation rate galaxies are higher at all distances, and the line ratios are closer to ratios characteristic of H II regions compared with low specific star-formation rate galaxies. The less concentrated and lower stellar mass samples exhibit line ratios that are more like H II regions at larger distances than their more concentrated and higher stellar mass counterparts. The largest difference between different subsamples occurs when the galaxies are split by stellar mass. We additionally infer that gas far from the midplane in more massive galaxies has the highest temperatures and steepest radial temperature gradients based on their [N II]/Hα and [O II]/Hα ratios between the disk and the halo. SDSS IV.

bioLights: light emitting wear for visualizing lower-limb muscle activity.

PubMed

Igarashi, Naoto; Suzuki, Kenji; Kawamoto, Hiroaki; Sankai, Yoshiyuki

2010-01-01

Analysis of muscle activity by electrophysiological techniques is commonly used to analyze biomechanics. Although the simultaneous and intuitive understanding of both muscle activity and body motion is important in various fields, it is difficult to realize. This paper proposes a novel technique for visualizing physiological signals related to muscle activity by means of surface electromyography. We developed a wearable light-emitting interface that indicates lower-limb muscle activity or muscular tension on the surface of the body in real time by displaying the shape of the activated muscle. The developed interface allows users to perceive muscle activity in an intuitive manner by relating the level of the muscle activity to the brightness level of the glowing interface placed on the corresponding muscle. In order to verify the advantage of the proposed method, a cognitive experiment was conducted to evaluate the system performance. We also conducted an evaluation experiment using the developed interface in conjunction with an exoskeleton robot, in order to investigate the possible applications of the developed interface in the field of neurorehabilitation.

Chemical waves in the O2 + H2 reaction on a Rh(111) surface alloyed with nickel. I. Photoelectron emission microscopy

NASA Astrophysics Data System (ADS)

Smolinsky, Tim; von Boehn, Bernhard; Imbihl, Ronald

2018-04-01

Chemical waves that arise in the H2 + O2 reaction on a bimetallic Rh(111)/Ni surface have been studied in the 10-6 and 10-5 mbar range at T = 773 K with photoelectron emission microscopy (PEEM), low-energy electron diffraction (LEED), and Auger electron spectroscopy (AES). Nickel coverages of 0.3, 0.6, and 1.0 monolayers were investigated. Coadsorbed with some oxygen, Ni starts to penetrate the Rh bulk region substantially only beyond 900 K. In the 10-5 mbar range, chemical waves are characterized by three distinct gray levels in PEEM. This number reduces to only two levels in the 10-6 mbar range. In situ LEED showed the periodic appearance of a (n × 1) (n = 8, 10) pattern during chemical waves which was assigned to a 2D-Ni oxide. With in situ AES, one observes that the bright phase in PEEM correlates with a high Ni coverage and the dark phase with a low Ni coverage.

Radarclinometry

USGS Publications Warehouse

Wildey, R.L.

1986-01-01

A mathematical theory and a corresponding algorithm have been developed to derive topographic maps from radar images as photometric arrays. Thus, as radargrammetry is to photogrammetry, so radarclinometry is to photoclinometry. Photoclinometry is endowed with a fundamental indeterminacy principle even for terrain homogeneous in normal albedo. This arises from the fact that the geometric locus of orientations of the local surface normal that is consistent with a given reflected specific-intensity of radiation is more complicated than a fixed line in space. For a radar image, the locus is a cone whose half-angle is the incidence angle and whose axis contains the radar. The indeterminacy is removed throughout a region if one possesses a control profile as a boundary-condition. In the absence of such ground-truth, a point-boundary-condition will suffice only in conjunction with a heuristic assumption, such as that the strike-line runs perpendicularly to the line-of-sight. In the present study I have implemented a more reasonable assumption which I call 'the hypothesis of local cylindricity'. Firstly, a general theory is derived, based solely on the implicit mathematical determinacy. This theory would be directly indicative of procedure if images were completely devoid of systematic error and noise. The theory produces topography by an area integration of radar brightness, starting from a control profile, without need of additional idealistic assumptions. But we have also theorized separately a method of forming this control profile, which method does require an additional assumption about the terrain. That assumption is that the curvature properties of the terrain are locally those of a cylinder of inferable orientation, within a second-order mathematical neighborhood of every point of the terrain. While local strike-and-dip completely determine the radar brightness itself, the terrain curvature determines the brightness-gradient in the radar image. Therefore, the control profile is formed as a line integration of brightness and its local gradient starting from a single point of the terrain where the local orientation of the strike-line is estimated by eye. Secondly, and independently, the calibration curve for pixel brightness versus incidence-angle is produced. I assume that an applicable curve can be found from the literature or elsewhere so that our problem is condensed to that of properly scaling the brightness-axis of the calibration curve. A first estimate is found by equating the average image brightness to the point on the brightness axis corresponding to the complement of the effective radar depression-angle, an angle assumed given. A statistical analysis is then used to correct, on the one hand, for the fact that the average brightness is not the brightness that corresponds to the average incidence angle, as a result of the non-linearity of the calibration curve; and on the other hand, we correct for the fact that the average incidence angle is not the same for a rough surface as it is for a flat surface (and therefore not the complement of the depression angle). Lastly, the practical modifications that were interactively evolved to produce an operational algorithm for treating real data are developed. They are by no means considered optimized at present. Such a possibility is thus far precluded by excessive computer-time. Most noteworthy in this respect is the abandonment of area integration away from a control profile. Instead, the topography is produced as a set of independent line integrations down each of the parallel range lines of the image, using the theory for control-profile formation. An adaptive technique, which now appears excessive, was also employed so that SEASAT images of sand dunes could be processed. In this, the radiometric calibration was iterated to force the endpoints of each profile to zero elevation. A secondary algorithm then employed line-averages of appropriate quantities to adjust the mean t

Iapetus: Unique Surface Properties and a Global Color Dichotomy from Cassini Imaging

NASA Astrophysics Data System (ADS)

Denk, Tilmann; Neukum, Gerhard; Roatsch, Thomas; Porco, Carolyn C.; Burns, Joseph A.; Galuba, Götz G.; Schmedemann, Nico; Helfenstein, Paul; Thomas, Peter C.; Wagner, Roland J.; West, Robert A.

2010-01-01

Since 2004, Saturn’s moon Iapetus has been observed repeatedly with the Imaging Science Subsystem of the Cassini spacecraft. The images show numerous impact craters down to the resolution limit of ~10 meters per pixel. Small, bright craters within the dark hemisphere indicate a dark blanket thickness on the order of meters or less. Dark, equator-facing and bright, poleward-facing crater walls suggest temperature-driven water-ice sublimation as the process responsible for local albedo patterns. Imaging data also reveal a global color dichotomy, wherein both dark and bright materials on the leading side have a substantially redder color than the respective trailing-side materials. This global pattern indicates an exogenic origin for the redder leading-side parts and suggests that the global color dichotomy initiated the thermal formation of the global albedo dichotomy.

Iapetus: unique surface properties and a global color dichotomy from Cassini imaging.

PubMed

Denk, Tilmann; Neukum, Gerhard; Roatsch, Thomas; Porco, Carolyn C; Burns, Joseph A; Galuba, Götz G; Schmedemann, Nico; Helfenstein, Paul; Thomas, Peter C; Wagner, Roland J; West, Robert A

2010-01-22

Since 2004, Saturn's moon Iapetus has been observed repeatedly with the Imaging Science Subsystem of the Cassini spacecraft. The images show numerous impact craters down to the resolution limit of approximately 10 meters per pixel. Small, bright craters within the dark hemisphere indicate a dark blanket thickness on the order of meters or less. Dark, equator-facing and bright, poleward-facing crater walls suggest temperature-driven water-ice sublimation as the process responsible for local albedo patterns. Imaging data also reveal a global color dichotomy, wherein both dark and bright materials on the leading side have a substantially redder color than the respective trailing-side materials. This global pattern indicates an exogenic origin for the redder leading-side parts and suggests that the global color dichotomy initiated the thermal formation of the global albedo dichotomy.

Weird Warm Spot on Exoplanet

NASA Image and Video Library

2010-10-19

This frame from an animation based on NASA Spitzer Space Telescope data illustrates an unexpected warm spot on the surface of a gaseous exoplanet.The bright orange patches are the hottest part of the planet.

The Unique Geomorphology and Physical Properties of the Vestalia Terra Plateau

NASA Technical Reports Server (NTRS)

Buczkowski, D.L.; Wyrick, D.Y.; Toplis, M.; Yingst, R. A.; Williams, D. A.; Garry, W. B.; Mest, S.; Kneissl, T.; Scully, J. E. C.; Nathues, A.;

Spottier targets are less attractive to tabanid flies: on the tabanid-repellency of spotty fur patterns.

PubMed

Blaho, Miklos; Egri, Adam; Bahidszki, Lea; Kriska, Gyorgy; Hegedus, Ramon; Akesson, Susanne; Horvath, Gabor

2012-01-01

During blood-sucking, female members of the family Tabanidae transmit pathogens of serious diseases and annoy their host animals so strongly that they cannot graze, thus the health of the hosts is drastically reduced. Consequently, a tabanid-resistant coat with appropriate brightness, colour and pattern is advantageous for the host. Spotty coats are widespread among mammals, especially in cattle (Bos primigenius). In field experiments we studied the influence of the size and number of spots on the attractiveness of test surfaces to tabanids that are attracted to linearly polarized light. We measured the reflection-polarization characteristics of living cattle, spotty cattle coats and the used test surfaces. We show here that the smaller and the more numerous the spots, the less attractive the target (host) is to tabanids. We demonstrate that the attractiveness of spotty patterns to tabanids is also reduced if the target exhibits spottiness only in the angle of polarization pattern, while being homogeneous grey with a constant high degree of polarization. Tabanid flies respond strongly to linearly polarized light, and we show that bright and dark parts of cattle coats reflect light with different degrees and angles of polarization that in combination with dark spots on a bright coat surface disrupt the attractiveness to tabanids. This could be one of the possible evolutionary benefits that explains why spotty coat patterns are so widespread in mammals, especially in ungulates, many species of which are tabanid hosts.

Spottier Targets Are Less Attractive to Tabanid Flies: On the Tabanid-Repellency of Spotty Fur Patterns

PubMed Central

Blaho, Miklos; Egri, Adam; Bahidszki, Lea; Kriska, Gyorgy; Hegedus, Ramon; Åkesson, Susanne; Horvath, Gabor

2012-01-01

During blood-sucking, female members of the family Tabanidae transmit pathogens of serious diseases and annoy their host animals so strongly that they cannot graze, thus the health of the hosts is drastically reduced. Consequently, a tabanid-resistant coat with appropriate brightness, colour and pattern is advantageous for the host. Spotty coats are widespread among mammals, especially in cattle (Bos primigenius). In field experiments we studied the influence of the size and number of spots on the attractiveness of test surfaces to tabanids that are attracted to linearly polarized light. We measured the reflection-polarization characteristics of living cattle, spotty cattle coats and the used test surfaces. We show here that the smaller and the more numerous the spots, the less attractive the target (host) is to tabanids. We demonstrate that the attractiveness of spotty patterns to tabanids is also reduced if the target exhibits spottiness only in the angle of polarization pattern, while being homogeneous grey with a constant high degree of polarization. Tabanid flies respond strongly to linearly polarized light, and we show that bright and dark parts of cattle coats reflect light with different degrees and angles of polarization that in combination with dark spots on a bright coat surface disrupt the attractiveness to tabanids. This could be one of the possible evolutionary benefits that explains why spotty coat patterns are so widespread in mammals, especially in ungulates, many species of which are tabanid hosts. PMID:22876282

IRAC Imaging of LSB Galaxies

NASA Astrophysics Data System (ADS)

Schombert, James; McGaugh, Stacy; Lelli, Federico

2017-04-01

We propose a program to observe a large sample of Low Surface Brightness (LSB) galaxies. Large galaxy surveys conducted with Spitzer suffer from the unavoidable selection bias against LSB systems (e.g., the S4G survey). Even those programs thathave specifically targeted LSB galaxies have usually been restricted objects of intermediate surface brightness (between 22 and 23 B mag/ []). Our sample is selected to be of a more extreme LSB nature (with central surface brightness fainter than 23 Bmag/[]). Even warm, Spitzer is the ideal instrument to image these low contrast targets in the near infrared: our sample goes a considerable way towards remedying this hole in the Spitzer legacy archive, also increasing coverage in terms of stellar mass, gas mass, and SFR. The sample will be used to address the newly discovered radial acceleration relation (RAR) in disk galaxies. While issues involving the connection between baryons and dark matter have been known since the development of the global baryonic Tully-Fisher (bTF) relation, it is only in the last six months that the particle physics and theoretical communities have recognized and responded to the local coupling between dark and baryonic matter represented by the RAR. This important new correlation is effectively a new natural law for galaxies. Spitzer photometry has been at the forefront of resolving the stellar mass component in galaxies that make-up the RAR and is the primary reason for the discovery of this new kinematic law.

Planetary Nebulae in the UWISH2 survey

NASA Astrophysics Data System (ADS)

Gledhill, T. M.; Froebrich, D.; Campbell-White, J.; Jones, A. M.

2018-06-01

Near-infrared imaging in the 1 - 0 S(1) emission line of molecular hydrogen is able to detect planetary nebulae (PNe) that are hidden from optical emission line surveys. We present images of 307 objects from the UWISH2 survey of the northern Galactic Plane, and with the aid of mid-infrared colour diagnostics draw up a list of 291 PN candidates. The majority, 183, are new detections and 85 per cent of these are not present in H α surveys of the region. We find that more than half (54 per cent) of objects have a bipolar morphology and that some objects previously considered as elliptical or point-source in H α imaging, appear bipolar in UWISH2 images. By considering a small subset of objects for which physical radii are available from the H α surface brightness-radius relation, we find evidence that the H2 surface brightness remains roughly constant over a factor 20 range of radii from 0.03 to 0.6 pc, encompassing most of the visible lifetime of a PN. This leads to the H α surface brightness becoming comparable to that of H2 at large radius (>0.5 pc). By combining the number of UWISH2 PNe without H α detection with an estimate of the PN detection efficiency in H2 emission, we estimate that PN numbers from H α surveys may underestimate the true PN number by a factor between 1.5 and 2.5 within the UWISH2 survey area.

Cutting Edge: Helicobacter pylori Induces Nuclear Hypersegmentation and Subtype Differentiation of Human Neutrophils In Vitro.

PubMed

Whitmore, Laura C; Weems, Megan N; Allen, Lee-Ann H

2017-03-01

Helicobacter pylori infects the human stomach and causes a spectrum of disease that includes gastritis, peptic ulcers, and gastric adenocarcinoma. A chronic, neutrophil-rich inflammatory response characterizes this infection. It is established that H. pylori stimulates neutrophil chemotaxis and a robust respiratory burst, but other aspects of this interaction are incompletely defined. We demonstrate here that H. pylori induces N1-like subtype differentiation of human neutrophils as indicated by profound nuclear hypersegmentation, a CD62L dim , CD16 bright , CD11b bright , CD66b bright , CD63 bright surface phenotype, proinflammatory cytokine secretion, and cytotoxicity. Hypersegmentation requires direct neutrophil- H. pylori contact as well as transcription and both host and bacterial protein synthesis, but not urease, NapA, VacA, CagA, or CagT. The concept of neutrophil plasticity is new and, to our knowledge, these data are the first evidence that neutrophils can undergo subtype differentiation in vitro in response to bacterial pathogen infection. We hypothesize that these changes favor H. pylori persistence and disease. Copyright © 2017 by The American Association of Immunologists, Inc.

Proof of Concept for a Simple Smartphone Sky Monitor

NASA Astrophysics Data System (ADS)

Kantamneni, Abhilash; Nemiroff, R. J.; Brisbois, C.

2013-01-01

We present a novel approach of obtaining a cloud and bright sky monitor by using a standard smartphone with a downloadable app. The addition of an inexpensive fisheye lens can extend the angular range to the entire sky visible above the device. A preliminary proof of concept image shows an optical limit of about visual magnitude 5 for a 70-second exposure. Support science objectives include cloud monitoring in a manner similar to the more expensive cloud monitors in use at most major astronomical observatories, making expensive observing time at these observatories more efficient. Primary science objectives include bright meteor tracking, bright comet tracking, and monitoring the variability of bright stars. Citizen science objectives include crowd sourcing of many networked sky monitoring smartphones typically in broader support of many of the primary science goals. The deployment of a citizen smartphone array in an active science mode could leverage the sky monitoring data infrastructure to track other non-visual science opportunities, including monitoring the Earth's magnetic field for the effects of solar flares and exhaustive surface coverage for strong seismic events.

Retrieval of Aerosol Microphysical Properties Based on the Optimal Estimation Method: Information Content Analysis for Satellite Polarimetric Remote Sensing Measurements

NASA Astrophysics Data System (ADS)

Hou, W. Z.; Li, Z. Q.; Zheng, F. X.; Qie, L. L.

2018-04-01

This paper evaluates the information content for the retrieval of key aerosol microphysical and surface properties for multispectral single-viewing satellite polarimetric measurements cantered at 410, 443, 555, 670, 865, 1610 and 2250 nm over bright land. To conduct the information content analysis, the synthetic data are simulated by the Unified Linearized Vector Radiative Transfer Model (UNLVTM) with the intensity and polarization together over bare soil surface for various scenarios. Following the optimal estimation theory, a principal component analysis method is employed to reconstruct the multispectral surface reflectance from 410 nm to 2250 nm, and then integrated with a linear one-parametric BPDF model to represent the contribution of polarized surface reflectance, thus further to decouple the surface-atmosphere contribution from the TOA measurements. Focusing on two different aerosol models with the aerosol optical depth equal to 0.8 at 550 nm, the total DFS and DFS component of each retrieval aerosol and surface parameter are analysed. The DFS results show that the key aerosol microphysical properties, such as the fine- and coarse-mode columnar volume concentration, the effective radius and the real part of complex refractive index at 550 nm, could be well retrieved with the surface parameters simultaneously over bare soil surface type. The findings of this study can provide the guidance to the inversion algorithm development over bright surface land by taking full use of the single-viewing satellite polarimetric measurements.

High contrast imaging through adaptive transmittance control in the focal plane

NASA Astrophysics Data System (ADS)

Dhadwal, Harbans S.; Rastegar, Jahangir; Feng, Dake

2016-05-01

High contrast imaging, in the presence of a bright background, is a challenging problem encountered in diverse applications ranging from the daily chore of driving into a sun-drenched scene to in vivo use of biomedical imaging in various types of keyhole surgeries. Imaging in the presence of bright sources saturates the vision system, resulting in loss of scene fidelity, corresponding to low image contrast and reduced resolution. The problem is exacerbated in retro-reflective imaging systems where the light sources illuminating the object are unavoidably strong, typically masking the object features. This manuscript presents a novel theoretical framework, based on nonlinear analysis and adaptive focal plane transmittance, to selectively remove object domain sources of background light from the image plane, resulting in local and global increases in image contrast. The background signal can either be of a global specular nature, giving rise to parallel illumination from the entire object surface or can be represented by a mosaic of randomly orientated, small specular surfaces. The latter is more representative of real world practical imaging systems. Thus, the background signal comprises of groups of oblique rays corresponding to distributions of the mosaic surfaces. Through the imaging system, light from group of like surfaces, converges to a localized spot in the focal plane of the lens and then diverges to cast a localized bright spot in the image plane. Thus, transmittance of a spatial light modulator, positioned in the focal plane, can be adaptively controlled to block a particular source of background light. Consequently, the image plane intensity is entirely due to the object features. Experimental image data is presented to verify the efficacy of the methodology.

FC colour images of dwarf planet Ceres reveal a complicated geological history

NASA Astrophysics Data System (ADS)

Nathues, A.; Hoffmann, M.; Platz, T.; Thangjam, G. S.; Cloutis, E. A.; Reddy, V.; Le Corre, L.; Li, J.-Y.; Mengel, K.; Rivkin, A.; Applin, D. M.; Schaefer, M.; Christensen, U.; Sierks, H.; Ripken, J.; Schmidt, B. E.; Hiesinger, H.; Sykes, M. V.; Sizemore, H. G.; Preusker, F.; Russell, C. T.

2016-12-01

The dwarf planet Ceres (equatorial diameter 963km) is the largest object that has remained in the main asteroid belt (Russell and Raymond, 2012), while most large bodies have been destroyed or removed by dynamical processes (Petit et al. 2001; Minton and Malhotra, 2009). Pre-Dawn investigations (McCord and Sotin, 2005; Castillo-Rogez and McCord, 2010; Castillo-Rogez et al., 2011) suggest that Ceres is a thermally evolved, but still volatile-rich body with potential geological activity, that was never completely molten, but possibly differentiated into a rocky core, an ice-rich mantle, and may contain remnant internal liquid water. Thermal alteration should contribute to producing a (dark) carbonaceous chondritic-like surface (McCord and Sotin, 2005; Castillo-Rogez and McCord, 2010; Castillo-Rogez et al., 2011; Nathues et al., 2015) containing ammoniated phyllosilicates (King et al., 1992; De Sanctis et al., 2015 and 2016). Here we show and analyse global contrast-rich colour mosaics, derived from a camera on-board Dawn at Ceres (Russell et al., 2016). Colours are unexpectedly more diverse on global scale than anticipated by Hubble Space Telescope (Li et al., 2006) and ground-based observations (Reddy et al. 2015). Dawn data led to the identification of five major colour units. The youngest units identified by crater counting, termed bright and bluish units, are exclusively found at equatorial and intermediate latitudes. We identified correlations between the distribution of the colour units, crater size, and formation age, inferring a crustal stratigraphy. Surface brightness and spectral properties are not correlated. The youngest surface features are the bright spots at crater Occator ( Ø 92km). Their colour spectra are highly consistent with the presence of carbonates while most of the remaining surface resembles modifications of various types of ordinary carbonaceous chondrites.

Changing patterns of the long-term activity of the intermediate polar V1223 Sgr

NASA Astrophysics Data System (ADS)

Šimon, Vojtěch

2014-11-01

High and low states represent a large variety of features in the optical activity of some types of cataclysmic variables. Here, we examine them in the intermediate polar V1223 Sgr. We use the photographic observations from the Bamberg Observatory and from Garnavich and Szkody, and the CCD ASAS-3 and NSVS data. One plate or CCD image was usually obtained per night. These data span 78 years. We use the histograms of brightness to set the separation between the high and low states in V1223 Sgr at the level of 13.9 mag(B). The profile of this statistical distribution is dominated by a broad bump with the peak-to-peak amplitude of more than 1 mag(B). This is the result of co-adding various episodes of the high states, sometimes with the brightness varying on a timescale of months even during a single episode. The high state is not any uniquely defined level of brightness. Groups of the low states represent tails from such bumps rather than forming specific levels of brightness. The fuzzy boundaries of the bright side of the statistical distributions of brightness show that the system cannot find equilibrium of the mass transfer even in the high state. We show that V1223 Sgr underwent a large change of its high/low state activity; we ascribe it to the changes of the stellar activity of the donor. The episodes of the low states with mutually similar depth and profile were observed to recur with a cycle of 1092 days in the data mapping the years from 1999 to 2009; this behavior was discordant with the typical recurrence times present before. In our scenario, this cycle is driven by the changing aspect of some structure (e.g. a sequence of star spots migrating across the L1 point) on the donor. Because of the differential rotation of the donor, this configuration cyclically influences the mass flow to the accretion disk.

A New Scientific use of Total Eclipses of the Moon: Studies of the Generation and Loss of Atmospheres of Primitives Bodies

NASA Technical Reports Server (NTRS)

Mendillo, Michael

1999-01-01

This grant supported observational campaigns to record the size and brightness of the lunar atmosphere as seen in sodium gas (Na) emissions during the totality phase of lunar eclipses. Three eclipse events were attempted, two from the Mc Donald Observatory in Fort Davis Texas, and one from the site of Italy's Galileo National Telescope (GNT) in La Palma, in the Canary Islands. In all three cases, clear skies prevailed and excellent datasets were obtained. Following the observational component of the grant, a period of detailed processing and analysis began. Eclipse events were chosen for study because when the moon is in full phase it has been within the terrestrial magnetosphere for a few days, thereby shielded from solar wind impact upon its surface. Since sputtering of Na from the lunar regolith by solar wind particles had been proposed as a source of the Moon's atmosphere, this was a test of the mechanism. If the lunar Na appeared to be diminished in comparison to abundances seen at other phases (e.g., at quarter phase when the moon is directly in the solar wind), the solar wind sputtering would indeed be a major source of lunar Na. These experiments could not be conducted during any full moon night because scattering of bright moonlight is so strong that low-light-level imaging of the lunar atmosphere could not be achieved. Hence, the use of eclipses. The final result of these experiments was, for once, clear and unambiguous. The robust size and Na brightness levels measured during all of the eclipses showed that solar wind sputtering could not be a major source of the lunar atmosphere. A major paper on this conclusion was published in ICARUS, and an oral presentation of partial results given at the The Three Galileos conference in Padova (Italy) in January 1997 and at the DPS meeting in Cambridge, MA, in July 1997.

Statistical Measures of Large-Scale Structure

NASA Astrophysics Data System (ADS)

Vogeley, Michael; Geller, Margaret; Huchra, John; Park, Changbom; Gott, J. Richard

1993-12-01

\\inv Mpc} To quantify clustering in the large-scale distribution of galaxies and to test theories for the formation of structure in the universe, we apply statistical measures to the CfA Redshift Survey. This survey is complete to m_{B(0)}=15.5 over two contiguous regions which cover one-quarter of the sky and include ~ 11,000 galaxies. The salient features of these data are voids with diameter 30-50\\hmpc and coherent dense structures with a scale ~ 100\\hmpc. Comparison with N-body simulations rules out the ``standard" CDM model (Omega =1, b=1.5, sigma_8 =1) at the 99% confidence level because this model has insufficient power on scales lambda >30\\hmpc. An unbiased open universe CDM model (Omega h =0.2) and a biased CDM model with non-zero cosmological constant (Omega h =0.24, lambda_0 =0.6) match the observed power spectrum. The amplitude of the power spectrum depends on the luminosity of galaxies in the sample; bright (L>L(*) ) galaxies are more strongly clustered than faint galaxies. The paucity of bright galaxies in low-density regions may explain this dependence. To measure the topology of large-scale structure, we compute the genus of isodensity surfaces of the smoothed density field. On scales in the ``non-linear" regime, <= 10\\hmpc, the high- and low-density regions are multiply-connected over a broad range of density threshold, as in a filamentary net. On smoothing scales >10\\hmpc, the topology is consistent with statistics of a Gaussian random field. Simulations of CDM models fail to produce the observed coherence of structure on non-linear scales (>95% confidence level). The underdensity probability (the frequency of regions with density contrast delta rho //lineρ=-0.8) depends strongly on the luminosity of galaxies; underdense regions are significantly more common (>2sigma ) in bright (L>L(*) ) galaxy samples than in samples which include fainter galaxies.

Cytotoxicity of cadmium-free quantum dots and their use in cell bioimaging.

PubMed

Soenen, Stefaan J; Manshian, Bella B; Aubert, Tangi; Himmelreich, Uwe; Demeester, Jo; De Smedt, Stefaan C; Hens, Zeger; Braeckmans, Kevin

2014-06-16

The use of quantum dots (QDots) as bright and photostable probes for long-term fluorescence imaging is gaining more interest. Thus far, (pre)clinical use of QDots remains limited, which is primarily caused by the potential toxicity of QDots. Most QDots consist of Cd2+ ions, which are known to cause high levels of toxicity. In order to overcome this problem, several strategies have been tested, such as the generation of cadmium-free QDots. In the present study, two types of cadmium-free QDots, composed of ZnSe/ZnS (QDotZnSe) and InP/ZnS (QDotInP), were studied with respect to their cytotoxicity and cellular uptake in a variety of cell types. A multiparametric cytotoxicity approach is used, where the QDots are studied with respect to cell viability, oxidative stress, cell morphology, stem cell differentiation, and neurite outgrowth. The data reveal slight differences in uptake levels for both types of QDots (maximal for QDotZnSe), but clear differences in cytotoxicity and cell functionality effects exist, with highest toxicity for QDotZnSe. Differences between cell types and between both types of QDots can be explained by the intrinsic sensitivity of certain cell types and chemical composition of the QDots. At concentrations at which no toxic effects can be observed, the functionality of the QDots for fluorescence cell visualization is evaluated, revealing that the higher brightness of QDotZnSe overcomes most of the toxicity issues compared to that of QDotInP. Comparing the results obtained with common Cd2+-containing QDots tested under identical conditions, the importance of particle functionality is demonstrated, revealing that cadmium-free QDots tested in this study are not significantly better than Cd2+-containing QDots for long-term cell imaging and that more work needs to be performed in optimizing the brightness and surface chemistry of cadmium-free QDots for them to replace currently used Cd2+-containing QDots.

Diode lasers optimized in brightness for fiber laser pumping

NASA Astrophysics Data System (ADS)

Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

2018-02-01

In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

An enhanced structure tensor method for sea ice ridge detection from GF-3 SAR imagery

NASA Astrophysics Data System (ADS)

Zhu, T.; Li, F.; Zhang, Y.; Zhang, S.; Spreen, G.; Dierking, W.; Heygster, G.

2017-12-01

In SAR imagery, ridges or leads are shown as the curvilinear features. The proposed ridge detection method is facilitated by their curvilinear shapes. The bright curvilinear features are recognized as the ridges while the dark curvilinear features are classified as the leads. In dual-polarization HH or HV channel of C-band SAR imagery, the bright curvilinear feature may be false alarm because the frost flowers of young leads may show as bright pixels associated with changes in the surface salinity under calm surface conditions. Wind roughened leads also trigger the backscatter increasing that can be misclassified as ridges [1]. Thus the width limitation is considered in this proposed structure tensor method [2], since only shape feature based method is not enough for detecting ridges. The ridge detection algorithm is based on the hypothesis that the bright pixels are ridges with curvilinear shapes and the ridge width is less 30 meters. Benefited from GF-3 with high spatial resolution of 3 meters, we provide an enhanced structure tensor method for detecting the significant ridge. The preprocessing procedures including the calibration and incidence angle normalization are also investigated. The bright pixels will have strong response to the bandpass filtering. The ridge training samples are delineated from the SAR imagery in the Log-Gabor filters to construct structure tensor. From the tensor, the dominant orientation of the pixel representing the ridge is determined by the dominant eigenvector. For the post-processing of structure tensor, the elongated kernel is desired to enhance the ridge curvilinear shape. Since ridge presents along a certain direction, the ratio of the dominant eigenvector will be used to measure the intensity of local anisotropy. The convolution filter has been utilized in the constructed structure tensor is used to model spatial contextual information. Ridge detection results from GF-3 show the proposed method performs better compared to the direct threshold method.

The time variation of atomic oxygen emission around Io during a volcanic event observed with Hisaki/EXCEED

NASA Astrophysics Data System (ADS)

Koga, Ryoichi; Tsuchiya, Fuminori; Kagitani, Masato; Sakanoi, Takeshi; Yoneda, Mizuki; Yoshioka, Kazuo; Kimura, Tomoki; Murakami, Go; Yamazaki, Atsushi; Yoshikawa, Ichiro; Smith, H. Todd

2018-01-01

Io has an atmosphere produced by volcanism and sublimation of frosts deposited around active volcanoes. However, the time variation of atomic oxygen escaping Io's atmosphere is not well known. In this paper, we show a significant increase in atomic oxygen around Io during a volcanic event. Brightening of Io's extended sodium nebula was observed in the spring of 2015. We used the Hisaki satellite to investigate the time variation of atomic oxygen emission around Io during the same period. This investigation reveals that the duration of atomic oxygen brightness increases from a volcanically quiet level to a maximum level during the same approximate time period of 30 days as the observed sodium brightness. On the other hand, the recovery of the atomic oxygen brightness from the maximum to the quiet level (60 days) was longer than that of the sodium nebula decreasing (40 days). Additionally, a dawn-dusk asymmetry of the atomic oxygen emission is observed.

Active and passive microwave measurements in Hurricane Allen

NASA Technical Reports Server (NTRS)

Delnore, V. E.; Bahn, G. S.; Grantham, W. L.; Harrington, R. F.; Jones, W. L.

1985-01-01

The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods.

Electrodeposition Painting of Metal Substrates: Pinholing in Surface Films,

DTIC Science & Technology

1978-08-01

a bright surface and rubbed clean with a moist cloth to remove the fine dust of metal adhering to the surface, dried, degrea.ed and desmutted by...rubbing with mineral turpentine . This procedure conforms to Australian Standards AS 1580 (May 1975), ‘Pretreatment of Metal Test Panels’. 2.3...deposition, the panels were carefully washed with clean water to remove loosely adhering excess paint which resulted solely from contact of the panel with

Determination of washout performance of various monochrome displays under simulated flight ambient and solar lighting conditions

NASA Technical Reports Server (NTRS)

Batson, Vernon M.; Robertson, James B.; Parrish, Russell V.

1990-01-01

The aircraft cockpit ambient lighting simulation system (ACALSS) has been developed to study display readability and associated pilot/vehicle performance effects in a part-task simulator cockpit. In the study reported here, the ACALSS was used to determine the illumination levels at which subjects lose the ability to maintain aircraft states when using three display technologies as display media for primary flight displays: a standard monochrome EL (electroluminescent) flat-panel, a laboratory-class monochrome CRT, and an enhanced-brightness EL flat-panel. The multivariate statistical technique of modified profile analysis was used to test for performance differences between display devices as functions of illumination levels. The standard monochrome EL flat-panel display began to washout after the 2500 foot-candle level of illumination. The monochrome CRT began to washout after the 5500 foot-candle level of illumination. No performance decrements by increased illumination up to the 12,000 foot-candle level were found for the enhanced-brightness EL flat-panel display. What was not anticipated was that half the subjects would subjectively prefer the CRT over the enhanced-brightness EL, even though their performance errors would have indicated the opposite.

VEGAS: A VST Early-type GAlaxy Survey. I. Presentation, wide-field surface photometry, and substructures in NGC 4472

NASA Astrophysics Data System (ADS)

Capaccioli, Massimo; Spavone, Marilena; Grado, Aniello; Iodice, Enrichetta; Limatola, Luca; Napolitano, Nicola R.; Cantiello, Michele; Paolillo, Maurizio; Romanowsky, Aaron J.; Forbes, Duncan A.; Puzia, Thomas H.; Raimondo, Gabriella; Schipani, Pietro

2015-09-01

Context. We present the VST Early-type GAlaxy Survey (VEGAS), which is designed to obtain deep multiband photometry in g,r,i, of about one hundred nearby galaxies down to 27.3, 26.8, and 26 mag/arcsec2 respectively, using the ESO facility VST/OmegaCAM. Aims: The goals of the survey are 1) to map the light distribution up to ten effective radii, re; 2) to trace color gradients and surface brightness fluctuation gradients out to a few re for stellar population characterization; and 3) to obtain a full census of the satellite systems (globular clusters and dwarf galaxies) out to 20% of the galaxy virial radius. The external regions of galaxies retain signatures of the formation and evolution mechanisms that shaped them, and the study of nearby objects enables a detailed analysis of their morphology and interaction features. To clarify the complex variety of formation mechanisms of early-type galaxies (ETGs), wide and deep photometry is the primary observational step, which at the moment has been pursued with only a few dedicated programs. The VEGAS survey has been designated to provide these data for a volume-limited sample with exceptional image quality. Methods: In this commissioning photometric paper we illustrate the capabilities of the survey using g- and i-band VST/OmegaCAM images of the nearby galaxy NGC 4472 and of smaller ETGs in the surrounding field. Results: Our surface brightness profiles reach rather faint levels and agree excellently well with previous literature. Genuine new results concern the detection of an intracluster light tail in NGC 4472 and of various substructures at increasing scales. We have also produced extended (g - i) color profiles. Conclusions: The VST/OmegaCAM data that we acquire in the context of the VEGAS survey provide a detailed view of substructures in the optical emission from extended galaxies, which can be as faint as a hundred times below the sky level. Appendices are available in electronic form at http://www.aanda.org

Accommodating brightness and exposure levels in densitometry of stained polyacrylamide electrophoresis gels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Han Yen; Ng, Tuck Wah; Liew, Oi Wah

2010-03-20

Flatbed scanner densitometers can be operated under various illumination and recording exposure levels. In this work, we show that optical density measurement accuracy, sensitivity, and stability of stained polyacrylamide electrophoresis gel densitometry are crucially dependent on these two factors (brightness and exposure level), notwithstanding that the source is monochromatic, spatially uniform, and the measurements are made using an accurately calibrated step wedge in tandem. We further outline a method to accommodate the intensity deviations over a range of illumination and exposure levels in order to maintain sensitivity and repeatability in the computed optical densities. Comparisons were also made with resultsmore » from a commercial densitometer.« less

Artificial light alters natural regimes of night-time sky brightness

PubMed Central

Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

2013-01-01

Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

View of Callisto at Increasing Resolutions

NASA Technical Reports Server (NTRS)

1998-01-01

These four views of Jupiter's second largest moon, Callisto, highlight how increasing resolutions enable interpretation of the surface. In the global view (top left) the surface is seen to have many small bright spots, while the regional view (top right) reveals the spots to be the larger craters. The local view (bottom right) not only brings out smaller craters and detailed structure of larger craters, but also shows a smooth dark layer of material that appears to cover much of the surface. The close-up frame (bottom left) presents a surprising smoothness in this highest resolution (30 meters per picture element) view of Callisto's surface.

North is to the top of these frames which were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft between November 1996 and November 1997. Even higher resolution images (better than 20 meters per picture element) of Callisto will be taken on June 30, 1999 during the 21st orbit of the spacecraft around Jupiter.

The top left frame is scaled to 10 kilometers (km) per picture element (pixel) and covers an area about 4400 by 2500 km. The moon Callisto, which has a diameter of 4806 km, appears to be peppered with many bright spots. Images at this resolution of other cratered moons in the Solar System indicate that the bright spots could be impact craters. The ring structure of Valhalla, the largest impact structure on Callisto, is visible in the center of the frame. This color view combines images obtained in November 1997 taken through the green, violet, and 1 micrometer filters of the SSI system.

The top right frame is ten times higher resolution (about 1 km per pixel) and covers an area approximately 440 by 250 km. Craters, which are clearly recognizable, appear to be the dominant landform on Callisto. The crater rims appear bright, while the adjacent area and the crater interiors are dark. This resolution is comparable to the best data available from the 1979 flyby's of NASA's two Voyager spacecraft; it reflects the understanding of Callisto prior to new data from Galileo. This Galileo image was taken in November 1996.

The resolution of the bottom right image is again ten times better (100 meters per pixel) and covering an area of about 44 by 25 km. This resolution reveals that some crater rims are not complete rings, but are composed of bright isolated segments. Steep slopes near crater rims reveal dark material that appears to have slid down to reveal bright material. The thickness of the dark layer could be tens of meters. The image was taken in June 1997.

The bottom left image at about 29 meters per pixel is the highest resolution available for Callisto. It covers an area about 4.4 by 2.5 km and is somewhat oblique. Craters are visible but no longer dominate the surface. The image was taken in November 1996.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Surface cleanliness measurement procedure

DOEpatents

Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

2002-01-01

A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

Tools for measuring surface cleanliness

DOEpatents

Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

2002-01-01

A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

Evaluation of the Multi-Angle Implementation of Atmospheric Correction (MAIAC) Aerosol Algorithm through Intercomparison with VIIRS Aerosol Products and AERONET

NASA Technical Reports Server (NTRS)

Superczynski, Stephen D.; Kondragunta, Shobha; Lyapustin, Alexei I.

2017-01-01

The Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is under evaluation for use in conjunction with the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission. Column aerosol optical thickness (AOT) data from MAIAC are compared against corresponding data. from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument over North America during 2013. Product coverage and retrieval strategy, along with regional variations in AOT through comparison of both matched and un-matched seasonally gridded data are reviewed. MAIAC shows extended coverage over parts of the continent when compared to VIIRS, owing to its pixel selection process and ability to retrieve aerosol information over brighter surfaces. To estimate data accuracy, both products are compared with AERONET Level 2 measurements to determine the amount of error present and discover if there is any dependency on viewing geometry and/or surface characteristics. Results suggest that MAIAC performs well over this region with a relatively small bias of -0.01; however there is a tendency for greater negative biases over bright surfaces and at larger scattering angles. Additional analysis over an expanded area and longer time period are likely needed to determine a comprehensive assessment of the products capability over the Western Hemisphere. and meet the levels of accuracy needed for aerosol monitoring.

High brightness electrodeless Z-Pinch EUV source for mask inspection tools

NASA Astrophysics Data System (ADS)

Horne, Stephen F.; Partlow, Matthew J.; Gustafson, Deborah S.; Besen, Matthew M.; Smith, Donald K.; Blackborow, Paul A.

2012-03-01

Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinchTM light source since 1995. The source is currently being used for metrology, mask inspection, and resist development. Energetiq's higher brightness source has been selected as the source for pre-production actinic mask inspection tools. This improved source enables the mask inspection tool suppliers to build prototype tools with capabilities of defect detection and review down to 16nm design rules. In this presentation we will present new source technology being developed at Energetiq to address the critical source brightness issue. The new technology will be shown to be capable of delivering brightness levels sufficient to meet the HVM requirements of AIMS and ABI and potentially API tools. The basis of the source technology is to use the stable pinch of the electrodeless light source and have a brightness of up to 100W/mm(carat)2-sr. We will explain the source design concepts, discuss the expected performance and present the modeling results for the new design.

The global SMOS Level 3 daily soil moisture and brightness temperature maps

NASA Astrophysics Data System (ADS)

Bitar, Ahmad Al; Mialon, Arnaud; Kerr, Yann H.; Cabot, François; Richaume, Philippe; Jacquette, Elsa; Quesney, Arnaud; Mahmoodi, Ali; Tarot, Stéphane; Parrens, Marie; Al-Yaari, Amen; Pellarin, Thierry; Rodriguez-Fernandez, Nemesio; Wigneron, Jean-Pierre

2017-06-01

The objective of this paper is to present the multi-orbit (MO) surface soil moisture (SM) and angle-binned brightness temperature (TB) products for the SMOS (Soil Moisture and Ocean Salinity) mission based on a new multi-orbit algorithm. The Level 3 algorithm at CATDS (Centre Aval de Traitement des Données SMOS) makes use of MO retrieval to enhance the robustness and quality of SM retrievals. The motivation of the approach is to make use of the longer temporal autocorrelation length of the vegetation optical depth (VOD) compared to the corresponding SM autocorrelation in order to enhance the retrievals when an acquisition occurs at the border of the swath. The retrieval algorithm is implemented in a unique operational processor delivering multiple parameters (e.g. SM and VOD) using multi-angular dual-polarisation TB from MO. A subsidiary angle-binned TB product is provided. In this study the Level 3 TB V310 product is showcased and compared to SMAP (Soil Moisture Active Passive) TB. The Level 3 SM V300 product is compared to the single-orbit (SO) retrievals from the Level 2 SM processor from ESA with aligned configuration. The advantages and drawbacks of the Level 3 SM product (L3SM) are discussed. The comparison is done on a global scale between the two datasets and on the local scale with respect to in situ data from AMMA-CATCH and USDA ARS Watershed networks. The results obtained from the global analysis show that the MO implementation enhances the number of retrievals: up to 9 % over certain areas. The comparison with the in situ data shows that the increase in the number of retrievals does not come with a decrease in quality, but rather at the expense of an increased time lag in product availability from 6 h to 3.5 days, which can be a limiting factor for applications like flood forecast but reasonable for drought monitoring and climate change studies. The SMOS L3 soil moisture and L3 brightness temperature products are delivered using an open licence and free of charge using a web application (https://www.catds.fr/sipad/). The RE04 products, versions 300 and 310, used in this paper are also available at ftp://ext-catds-cpdc:catds2010@ftp.ifremer.fr/Land_products/GRIDDED/L3SM/RE04/.

Photographer : JPL Range : 862,200 km. ( 500,000 miles ) This photograph shows subspacecraft

NASA Technical Reports Server (NTRS)

1979-01-01

Photographer : JPL Range : 862,200 km. ( 500,000 miles ) This photograph shows subspacecraft longitude of approximately 146 degrees of Jupiter's moon Io. Circular features are seen that may be meteorite impact craters or features of internal origins. Irregular depressions are seen that indicate surface modifications. The bright irregular patches appear to be younger deposits masking the surface detail.

Determining the Thickness and Refractive Index of a Mirror

ERIC Educational Resources Information Center

Uysal, Ahmet

2010-01-01

When a laser beam reflects from a back surface glass mirror and falls on a screen, a pattern of discrete bright spots is created by partial reflection and refraction of the light at the air-glass interface and reflection at the mirror surface (Fig. 1). This paper explains how this phenomenon can be used to determine the refractive index and the…

Starspots and Activity of the Flare Star GJ 1243

NASA Astrophysics Data System (ADS)

Savanov, I. S.; Dmitrienko, E. S.

2018-04-01

The photometric variability of the uniqueMdwarf flare star GJ 1243 (KIC 9726699) is investigated using the most complete set of observationalmaterial obtained with the Kepler Space Telescope. The analysis is based on 49 487 individual brightness measurements obtained during an interval of 1460 days (nearly four years). The periodicity of the brightness variations with the period P phot = 0.59261 ± 0.00060d is confirmed. The temperature inhomogeneities on the stellar surface reconstructed from the light curve are used to drive maps of these surface-temperature inhomogeneities (of the filling factor f). The resulting maps are used to determine the positions of active regions. Analysis of the surface-temperature maps for GJ 1243 led to the conclusion that the positions of spots on the stellar surface displayed appreciable evolution during the analyzed time interval. The maximum value for the lower limit on the differentialrotation parameter ΔΩ is 0.0022 rad/day. This more accurate estimate of ΔΩ is lower than the values presented earlier by Davenport et al. [1] (0.0058 and 0.0036 rad/day), due to the more accurate account of variations in the positions of the most active longitude in the current study. However, the differentialrotation estimate obtained in [1] using a method based on fitting the evolution of spots using twodimensional Gaussian functions essentially coincides with the new estimate presented here. The fractional area of the total spotted surface S of the star during the observing interval considered varied from 7 to 2%. The amplitude of the brightness variability of the star slowly decreased, varying in the range 1.6-0.5%. Overall, the position of GJ 1243 in spottedness-age, spottedness-rotation period, and spottedness-Rossby number diagrams agrees very well with the general character of the dependences displayed in earlier studies of M dwarfs.

Liquid Hydrocarbons on Titan's Surface? How Cassini ISS Observations Fit into the Story (So Far)

NASA Technical Reports Server (NTRS)

Turtle, E. P.; Dawson, D. D.; Fussner, S.; Hardegree-Ullman, E.; Ewen, A. S.; Perry, J.; Porco, C. C.; West, R. A.

2005-01-01

Titan is the only satellite in our Solar System with a substantial atmosphere, the origins and evolution of which are still not well understood. Its primary (greater than 90%) component is nitrogen, with a few percent methane and lesser amounts of other species. Methane and ethane are stable in the liquid state under the temperature and pressure conditions in Titan s lower atmosphere and at the surface; indeed, clouds, likely composed of methane, have been detected. Photochemical processes acting in the atmosphere convert methane into more complex hydrocarbons, creating Titan s haze and destroying methane over relatively short timescales. Therefore, it has been hypothesized that Titan s surface has reservoirs of liquid methane which serve to resupply the atmosphere. Early observations of Titan s surface revealed albedo patterns which have been interpreted as dark hydrocarbon liquids occupying topographically low regions between higher-standing exposures of bright, water-ice bedrock, although this is far from being the only explanation for the observed albedo contrast. Observations made by the Imaging Science Subsystem during Cassini's approach to Saturn and its first encounters with Titan show the bright and dark regions in greater detail but have yet to resolve the question of whether there are liquids on the surface.