Science.gov

Sample records for deep optical photometry

  1. Deep near-infrared and optical imaging photometry of the Serpens cloud core

    NASA Astrophysics Data System (ADS)

    Giovannetti, Philippe; Caux, Emmanuel

    few x 10^4 yrs) earliest protostellar stage. In this poster we present new deep optical and near-infrared observations of the Serpens cloud core using array detectors. We estimate our completeness limits to be 24, 23, 23, 19, 18.5 and 17.0 at V, R, I, J, H and K respectively, although sources as faint as K=17.6 were detected. We surveyed an area of 4'x4.8' centered approximately on the Serpens Reflexion Nebula at alpha(1950)=18h27m24s and delta(1950) = 1d 12'41". 165 sources are detected in the area surveyed which represents an increase of 60 objects. The fact that we have obtained near-infrared photometry of a fraction of the sample in three separate passbands (1.25, 1.65 and 2.2 microns) allows us to study via colour-colour and colour-magnitude diagrams, the combined effects of both the intrinsic properties of the sources and the overlaying extinction which, at near-infrared wavelengths, is obviously considerably smaller than in the optical. Added to this, such diagrams and other basic criteria were used to determine which stars are members of the embedded young stellar population, i.e. separating the young PMS stars from the population of "normal" background/foreground main sequence stars and giants. Additionally, high-resolution molecular line observations of the Serpens Nebula by White et al. (1995) were used to evaluate the extinction through each part of the cloud and allowed us to construct the dereddened K luminosity function of the cluster. To investigate the nature of the underlying Interstellar Mass Function (IMF), we calculated models which predict the evolution of the luminosity function of a cluster of PMS stars using the half-gaussian form of the Miller-Scalo IMF (Miller and Scalo 1979) and the slope of the mass-K luminosity relation as derived from transformed PMS tracks at each age and mass (d'Antona and Mazzitelli 1994). We then compared these models with the Serpens KLF to place constraints on the star-formation history and we found that a second

  2. WINGS: A WIde-field Nearby Galaxy-cluster Survey. II. Deep optical photometry of 77 nearby clusters

    NASA Astrophysics Data System (ADS)

    Varela, J.; D'Onofrio, M.; Marmo, C.; Fasano, G.; Bettoni, D.; Cava, A.; Couch, W. J.; Dressler, A.; Kjærgaard, P.; Moles, M.; Pignatelli, E.; Poggianti, B. M.; Valentinuzzi, T.

    2009-04-01

    Context: This is the second paper of a series devoted to the WIde Field Nearby Galaxy-cluster Survey (WINGS). WINGS is a long term project which is gathering wide-field, multi-band imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected, nearby clusters (0.04 < z < 0.07) located far from the galactic plane (|b|≥ 20°). The main goal of this project is to establish a local reference for evolutionary studies of galaxies and galaxy clusters. Aims: This paper presents the optical (B,V) photometric catalogs of the WINGS sample and describes the procedures followed to construct them. We have paid special care to correctly treat the large extended galaxies (which includes the brightest cluster galaxies) and the reduction of the influence of the bright halos of very bright stars. Methods: We have constructed photometric catalogs based on wide-field images in B and V bands using SExtractor. Photometry has been performed on images in which large galaxies and halos of bright stars were removed after modeling them with elliptical isophotes. Results: We publish deep optical photometric catalogs (90% complete at V ~ 21.7, which translates to ˜ M^*_V+6 at mean redshift), giving positions, geometrical parameters, and several total and aperture magnitudes for all the objects detected. For each field we have produced three catalogs containing galaxies, stars and objects of “unknown” classification (~6%). From simulations we found that the uncertainty of our photometry is quite dependent of the light profile of the objects with stars having the most robust photometry and de Vaucouleurs profiles showing higher uncertainties and also an additional bias of ~-0.2^m. The star/galaxy classification of the bright objects (V < 20) was checked visually making negligible the fraction of misclassified objects. For fainter objects, we found that simulations do not provide reliable estimates of the possible misclassification and therefore we have compared our data

  3. The ROSAT Deep Survey. 2; Optical Identification, Photometry and Spectra of X-Ray Sources in the Lockman Field

    NASA Technical Reports Server (NTRS)

    Schmidt, M.; Hasinger, G.; Gunn, J.; Schneider, D.; Burg, R.; Giacconi, R.; Lehmann, I.; MacKenty, J.; Truemper, J.; Zamorani, G.

    1998-01-01

    The ROSAT Deep Survey includes a complete sample of 50 X-ray sources with fluxes in the 0.5 - 2 keV band larger than 5.5 x 10(exp -15)erg/sq cm/s in the Lockman field (Hasinger et al., Paper 1). We have obtained deep broad-band CCD images of the field and spectra of many optical objects near the positions of the X-ray sources. We define systematically the process leading to the optical identifications of the X-ray sources. For this purpose, we introduce five identification (ID) classes that characterize the process in each case. Among the 50 X-ray sources, we identify 39 AGNs, 3 groups of galaxies, 1 galaxy and 3 galactic stars. Four X-ray sources remain unidentified so far; two of these objects may have an unusually large ratio of X-ray to optical flux.

  4. The ROSAT Deep Survey. 2; Optical Identification, Photometry and Spectra of X-Ray Sources in the Lockman Field

    NASA Technical Reports Server (NTRS)

    Schmidt, M.; Hasinger, G.; Gunn, J.; Schneider, D.; Burg, R.; Giacconi, R.; Lehmann, I.; MacKenty, J.; Truemper, J.; Zamorani, G.

    1998-01-01

    The ROSAT Deep Survey includes a complete sample of 50 X-ray sources with fluxes in the 0.5 - 2 keV band larger than 5.5 x 10(exp -15)erg/sq cm/s in the Lockman field (Hasinger et al., Paper 1). We have obtained deep broad-band CCD images of the field and spectra of many optical objects near the positions of the X-ray sources. We define systematically the process leading to the optical identifications of the X-ray sources. For this purpose, we introduce five identification (ID) classes that characterize the process in each case. Among the 50 X-ray sources, we identify 39 AGNs, 3 groups of galaxies, 1 galaxy and 3 galactic stars. Four X-ray sources remain unidentified so far; two of these objects may have an unusually large ratio of X-ray to optical flux.

  5. A Young Stellar Cluster within the RCW41 H II Region: Deep NIR Photometry and Optical/NIR Polarimetry

    NASA Astrophysics Data System (ADS)

    Santos, Fábio P.; Roman-Lopes, Alexandre; Franco, Gabriel A. P.

    2012-06-01

    The RCW41 star-forming region is embedded within the Vela Molecular Ridge, hosting a massive stellar cluster surrounded by a conspicuous H II region. Understanding the role of interstellar magnetic fields and studying the newborn stellar population is crucial to building a consistent picture of the physical processes acting on this kind of environment. We carried out a detailed study of the interstellar polarization toward RCW41 with data from an optical and near-infrared polarimetric survey. Additionally, deep near-infrared images from the 3.5 meter New Technology Telescope were used to study the photometric properties of the embedded young stellar cluster, revealing several YSO candidates. By using a set of pre-main-sequence isochrones, a mean cluster age in the range 2.5-5.0 million years was determined, and evidence of sequential star formation was revealed. An abrupt decrease in R-band polarization degree was noticed toward the central ionized area, probably due to low grain alignment efficiency caused by the turbulent environment and/or the weak intensity of magnetic fields. The distortion of magnetic field lines exhibits dual behavior, with the mean orientation outside the area approximately following the borders of the star-forming region and directed radially toward the cluster inside the ionized area, in agreement with simulations of expanding H II regions. The spectral dependence of polarization allowed a meaningful determination of the total-to-selective extinction ratio by fittings of the Serkowski relation. Furthermore, a large rotation of polarization angle as a function of wavelength was detected toward several embedded stars. Based on observations collected at the European Southern Observatory (La Silla, Chile), National Optical Astronomy Observatory (CTIO, Chile), and Observatório do Pico dos Dias, operated by Laboratório Nacional de Astrofísica (LNA/MCT, Brazil).

  6. A YOUNG STELLAR CLUSTER WITHIN THE RCW41 H II REGION: DEEP NIR PHOTOMETRY AND OPTICAL/NIR POLARIMETRY

    SciTech Connect

    Santos, Fabio P.; Franco, Gabriel A. P.; Roman-Lopes, Alexandre E-mail: franco@fisica.ufmg.br

    2012-06-01

    The RCW41 star-forming region is embedded within the Vela Molecular Ridge, hosting a massive stellar cluster surrounded by a conspicuous H II region. Understanding the role of interstellar magnetic fields and studying the newborn stellar population is crucial to building a consistent picture of the physical processes acting on this kind of environment. We carried out a detailed study of the interstellar polarization toward RCW41 with data from an optical and near-infrared polarimetric survey. Additionally, deep near-infrared images from the 3.5 meter New Technology Telescope were used to study the photometric properties of the embedded young stellar cluster, revealing several YSO candidates. By using a set of pre-main-sequence isochrones, a mean cluster age in the range 2.5-5.0 million years was determined, and evidence of sequential star formation was revealed. An abrupt decrease in R-band polarization degree was noticed toward the central ionized area, probably due to low grain alignment efficiency caused by the turbulent environment and/or the weak intensity of magnetic fields. The distortion of magnetic field lines exhibits dual behavior, with the mean orientation outside the area approximately following the borders of the star-forming region and directed radially toward the cluster inside the ionized area, in agreement with simulations of expanding H II regions. The spectral dependence of polarization allowed a meaningful determination of the total-to-selective extinction ratio by fittings of the Serkowski relation. Furthermore, a large rotation of polarization angle as a function of wavelength was detected toward several embedded stars.

  7. Hubble Deep Field guide star photometry

    NASA Astrophysics Data System (ADS)

    Zwintz, K.; Kuschnig, R.; Weiss, W. W.; Gray, R. O.; Jenkner, H.

    1999-03-01

    Since the advent of asteroseismology as a promising innovative tool for investigating internal stellar structure, numerous attempts to detect solar type oscillations in distant stars have been conducted. The three Fine Guidance Sensors of the Hubble Space Telescope can contribute to asteroseismology, but only after the data have been corrected for systematic effects, the South Atlantic Anomaly and terrestrial stray light being the most important. We have applied these corrections and obtained essentially photon noise-limited photometry for two guide stars used during the Hubble Deep Field program. Ground-based spectral classification has revealed that the brighter of the two guide stars is a solar-type star with a spectral type of G2mG0iv. Fine Guidance Sensor photometry for this star gives a noise level in the amplitude spectrum of only 23 ppm, which makes it a good candidate for detecting stochastically driven oscillations. We compare our result with theoretical predictions. The second guide star was classified as K1v and therefore is not a candidate for solar type oscillations. Based on observations made with the NASA/ESA {\\it Hubble Space Telescope}, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  8. The RINGS Survey: Optical Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Kuzio de Naray, Rachel; Mitchell, Carl; Spekkens, Kristine; Sellwood, Jerry; Williams, Ted

    2016-01-01

    We have targeted a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey (RINGS), for detailed study of their mass distributions. We have obtained Fabry-Perot Halpha velocity fields using the Southern African Large Telescope (SALT), 21-cm HI observations using the Very Large Array (VLA), and optical broadband BVRI photometry using the CTIO 0.9m and KPNO 2.1m telescopes. We present the results of the photometric component of the survey including multicolor images, surface brightness profiles, and DiskFit structural models.

  9. A REST-FRAME OPTICAL VIEW ON z {approx} 4 GALAXIES. I. COLOR AND AGE DISTRIBUTIONS FROM DEEP IRAC PHOTOMETRY OF THE IUDF10 AND GOODS SURVEYS

    SciTech Connect

    Oesch, P. A.; Illingworth, G. D.; Gonzalez, V.; Holden, B. P.; Magee, D.; Trenti, M.; Van Dokkum, P. G.

    2013-08-01

    We present a study of rest-frame UV-to-optical color distributions for z {approx} 4 galaxies based on the combination of deep HST/ACS+WFC3/IR data with Spitzer/IRAC imaging. In particular, we use new, ultra-deep data from the IRAC Ultradeep Field program (IUDF10), together with previous, public IRAC data over the GOODS fields. Our sample contains a total of {approx}2600 galaxies selected as B-dropout Lyman-break Galaxies in the HUDF and its deep parallel field HUDF09-2, as well as GOODS-North/South. This sample is used to investigate the UV continuum slopes {beta} and Balmer break colors (J{sub 125} - [4.5]) as a function of rest-frame optical luminosity (using [4.5] to avoid optical emission lines). We find that galaxies at M{sub z} < -21.5 (roughly corresponding to L{sup *}{sub z{approx}4}) are significantly redder than their lower luminosity counterparts. The UV continuum slopes and the J{sub 125} - [4.5] colors are well correlated, indicating that the dust reddening at these redshifts is better described by an SMC-like extinction curve, rather than the typically assumed Calzetti reddening. After dust correction, we find that the galaxy population shows mean stellar population ages in the range 10{sup 8.5} to 10{sup 9} yr, with a dispersion of {approx}0.5 dex, and only weak trends as a function of luminosity. Only a small fraction of galaxies shows Balmer break colors consistent with extremely young ages, younger than 100 Myr. Under the assumption of smooth star-formation histories, this fraction is 12%-19% for galaxies at M{sub z} < -19.75. Our results are consistent with a gradual build-up of stars and dust in galaxies at z > 4 with only a small fraction of stars being formed in short, intense bursts of star-formation.

  10. Deep Intermediate-Band Surface Photometry of NGC 5907

    NASA Astrophysics Data System (ADS)

    Zheng, Zhongyuan; Shang, Zhaohui; Su, Hongjun; Burstein, David; Chen, Jiansheng; Deng, Zugan; Byun, Yong-Ik; Chen, Rui; Chen, Wen-Ping; Deng, Licai; Fan, Xiaohui; Fang, Li-Zhi; Hester, J. Jeff; Jiang, Zhaoji; Li, Yong; Lin, Weipeng; Sun, Wei-Hsin; Tsay, Wean-Shun; Windhorst, Rogier A.; Wu, Hong; Xia, Xiaoyang; Xu, Wen; Xue, Suijian; Yan, Haojing; Zheng, Zheng; Zhou, Xu; Zhu, Jin; Zou, Zhenglong; Lu, Phillip

    1999-06-01

    Intrigued by the initial report of an extended luminosity distribution perpendicular to the disk of the edge-on Sc galaxy NGC 5907, we have obtained very deep exposures of this galaxy with a Schmidt telescope, large-format CCD, and intermediate-band filters centered at 6660 Å and 8020 Å. These two filters, part of a 15-filter set, are custom designed to avoid the brightest (and most variable) night skylines. As a result, our images are able to go deeper with lower sky noise than those taken with broadband filters at similar effective wavelengths: e.g., 0.6 e^- arcsec^-2 s^-1 for our observations versus 7.4 e^- arcsec^-2 s^-1 for the R-band measures of Morrison et al. In our assessment of both random and systematic errors, we show that the flux level where the errors of observation reach 1 mag arcsec^-2 are 29.00 mag arcsec^-2 in the 6660 Å image (corresponding to 28.7 in the R band) and 27.4 mag arcsec^-2 in the 8020 Å image (essentially on the I-band system). In a previous paper we have shown that NGC 5907 has a luminous ring around it, most plausibly caused by the tidal disruption of a dwarf spheroidal galaxy by the much more massive spiral. Here we show that, for values fainter than 27 R mag arcsec^-2, the surface brightness around NGC 5907 is strongly asymmetric, being mostly brighter on the northwest (ring) side of the galactic midplane. This asymmetry rules out a halo as the cause of the faint surface brightness we see. We find this asymmetry is likely an artifact resulting from a combination of ring light and residual surface brightness at faint levels from stars that our star-masking procedure cannot completely eliminate. The possible existence of an optical face-on warp in NGC 5907, suggested by our Very Large Array H I observations, is too confused with foreground star contamination to be independently studied. Good agreement with the surface photometry of NGC 5907 by other observers leads us to conclude that their data are similarly affected at faint

  11. The Spitzer Local Volume Legacy (LVL) global optical photometry

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Johnson, Benjamin D.; Van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Calzetti, Daniela; Staudaher, Shawn M.; Engelbracht, Charles W.

    2014-11-01

    We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D < 11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < MB < -20.7 mag. A composite optical (UBVR) data set is constructed from observed UBVR and Sloan Digital Sky Survey ugriz imaging, where the ugriz magnitudes are transformed into UBVR. We present photometry within three galaxy apertures defined at UV, optical, and IR wavelengths. Flux comparisons between these apertures reveal that the traditional optical R25 galaxy apertures do not fully encompass extended sources. Using the larger IR apertures, we find colour-colour relationships where later type spiral and irregular galaxies tend to be bluer than earlier type galaxies. These data provide the missing optical emission from which future LVL studies can construct the full panchromatic (UV-optical-IR) spectral energy distributions.

  12. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J. E-mail: janewman@pitt.edu E-mail: m.cooper@uci.edu

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  13. Southern Cosmology Survey. III. QSOs From Combined GALEX and Optical Photometry

    NASA Astrophysics Data System (ADS)

    Jimenez, Raul; Spergel, David N.; Niemack, Michael D.; Menanteau, Felipe; Hughes, John P.; Verde, Licia; Kosowsky, Arthur

    2009-04-01

    We present catalogs of QSO candidates selected using photometry from Galaxy Evolution Explorer (GALEX) combined with the Sloan Digital Sky Survey (SDSS) in the Stripe 82 region and Blanco Cosmology Survey (BCS) near declination -55°. The SDSS region contains sime700 objects with magnitude i < 20 and sime3600 objects with i < 21.5 in a sime60 deg2 sky region, while the BCS region contains sime280 objects with magnitude i < 20 and ~2000 objects with i < 21.5 for a 11 deg2 sky region that is being observed by three current microwave Sunyaev-Zeldovich surveys. Our QSO catalog is the first one in the BCS region. Deep GALEX exposures (gsim2000 s in F UV and N UV, except in three fields) provide high signal-to-noise photometry in the GALEX bands (F UV, N UV < 24.5 mag). From this data, we select QSO candidates using only GALEX and optical r-band photometry, using the method given by Atlee & Gould. In the Stripe 82 field, 60% (30%) of the GALEX-selected QSOs with optical magnitude i < 20 (i < 21.5) also appear in the Richards et al. QSO catalog constructed using five-band optical SDSS photometry. Comparison with the same catalog by Richards et al. shows that the completeness of the sample is approximately 40% (25%). However, for regions of the sky with very low dust extinction, like the BCS 23-hr field and the Stripe 82 between 0° and 10° in R.A., our completeness is close to 95%, demonstrating that deep GALEX observations are almost as efficient as multiwavelength observations at finding QSOs. GALEX observations thus provide a viable alternate route to QSO catalogs in sky regions where u-band optical photometry is not available. The full catalog is available at http://www.ice.csic.es/personal/jimenez/PHOTOZ.

  14. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  15. Adaptive Optics: A Pandora's box for Photometry

    NASA Astrophysics Data System (ADS)

    Roberts, L. C., Jr.; ten Brummelaar, T. A.; Mason, B. D.

    1998-01-01

    In conjunction with the long running CHARA speckle program, CHARA has begun using Adaptive Optics to study binary stars. Most of this work has focused on determining differential magnitudes for binary stars. CHARA was awarded six nights on the 1.5 meter at the Starfire Optical Range (SOR) in 1995. Since then CHARA has begun observing with the Mt Wilson Institute Adaptive Optics (MWI-AO) system on the Hooker 100-inch telescope at Mt. Wilson Observatory. While attempting to estimate error bars on the differential magnitudes it was noticed that frames of the same object taken sequentially produce discrepant images and results. As this may be related to the specific AO system comparisons between SOR and MWI-AO data are made for stars that were observed with both systems. Also, comparisons are made between stars observed multiple times with the MWI-AO system. The results of this investigation are presented.

  16. Optical Photometry of the Local Volume Legacy (LVL) Survey

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, D. A.; van Zee, L.; Johnson, B. D.; Lee, J. C.; Cales, S.; LVL Team

    2014-01-01

    We present new optical (UBVR) imaging of 258 nearby (D < 11 Mpc) galaxies in the Local Volume Legacy (LVL) survey. The volume limited sample is dominated by dwarf galaxies, however, the sample as a whole probes many global galaxy environments. This photometry completes the panchromatic data set which spans a wide wavelength range (1500 Å - 160 μm). This study focuses on GALEX (FUV & NUV), optical (UBVR), 2MASS (JHK), and Spitzer (3.6 μm, 4.5 μm, 5 um, 8 μm, & 24 μm) data. Photometry was performed with three separate apertures (defined from the FUV, 3.6 μm, and optical) to allow direct photometric comparisons between galaxies with consistent apertures. The wide wavelength coverage with uniform apertures across many environments will facilitate studying the effect of secular galaxy evolution and environment on galaxy-wide properties. Furthermore, the proximity of these galaxies will yield a wealth information on sub-kpc scales since individual star-forming regions can be identified and studied with the same wide wavelength coverage. We present the basic optical properties and SEDs of these galaxies and their relationships to the full panchromatic data set to evince underlying physical processes.

  17. SOUTHERN COSMOLOGY SURVEY. III. QSOs FROM COMBINED GALEX AND OPTICAL PHOTOMETRY

    SciTech Connect

    Jimenez, Raul; Verde, Licia; Spergel, David N.; Niemack, Michael D.; Menanteau, Felipe; Hughes, John P.; Kosowsky, Arthur

    2009-04-15

    We present catalogs of QSO candidates selected using photometry from Galaxy Evolution Explorer (GALEX) combined with the Sloan Digital Sky Survey (SDSS) in the Stripe 82 region and Blanco Cosmology Survey (BCS) near declination -55 deg. The SDSS region contains {approx_equal}700 objects with magnitude i < 20 and {approx_equal}3600 objects with i < 21.5 in a {approx_equal}60 deg{sup 2} sky region, while the BCS region contains {approx_equal}280 objects with magnitude i < 20 and {approx}2000 objects with i < 21.5 for a 11 deg{sup 2} sky region that is being observed by three current microwave Sunyaev-Zeldovich surveys. Our QSO catalog is the first one in the BCS region. Deep GALEX exposures ({approx}>2000 s in F {sub UV} and N {sub UV}, except in three fields) provide high signal-to-noise photometry in the GALEX bands (F {sub UV}, N {sub UV} < 24.5 mag). From this data, we select QSO candidates using only GALEX and optical r-band photometry, using the method given by Atlee and Gould. In the Stripe 82 field, 60% (30%) of the GALEX-selected QSOs with optical magnitude i < 20 (i < 21.5) also appear in the Richards et al. QSO catalog constructed using five-band optical SDSS photometry. Comparison with the same catalog by Richards et al. shows that the completeness of the sample is approximately 40% (25%). However, for regions of the sky with very low dust extinction, like the BCS 23-hr field and the Stripe 82 between 0{sup 0} and 10{sup 0} in R.A., our completeness is close to 95%, demonstrating that deep GALEX observations are almost as efficient as multiwavelength observations at finding QSOs. GALEX observations thus provide a viable alternate route to QSO catalogs in sky regions where u-band optical photometry is not available. The full catalog is available at http://www.ice.csic.es/personal/jimenez/PHOTOZ.

  18. Optical photometry and spectroscopy of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Tomov, T.; Ilkiewicz, K.; Swierczynski, E.; Belcheva, M.; Dimitrov, D.

    2013-08-01

    We report optical BV photometry and spectroscopy of Nova Del 2013, carried out between August 14.88 UT and August 15.08 UT. Using a 60 cm Cassegrain telescope at the Nicolaus Copernicus University Observatory (Torun, Poland) we estimated the V brightness of the Nova to be 6.31+/-0.02 mag and 6.18+/-0.03 mag on Aug. 14.94 UT and Aug. 15.02 UT respectively. HD 194113 (F2, V=8.00 mag) was used as a comparison star.

  19. Photometry of AM Herculis - A slow optical pulsar

    NASA Technical Reports Server (NTRS)

    Priedhorsky, W. C.; Krzeminski, W.

    1978-01-01

    Multicolor photometry of the X-ray binary AM Her suggests that the red component of the optical flux is closely related to the source of optical circular polarization in the system. It is concluded from the periodic modulation of flux in the U through R bands, which is particularly well-defined when plotted as color curves, that the primary and secondary minima are neither eclipses by a secondary star nor eclipses by a hot spot. It is suggested that the primary minimum in the visual light curve is the eclipse of a region of intense optical emission in the magnetic field near the surface of a degenerate dwarf by that dwarf itself.

  20. Macular pigment optical density measured by heterochromatic modulation photometry.

    PubMed

    Huchzermeyer, Cord; Schlomberg, Juliane; Welge-Lüssen, Ulrich; Berendschot, Tos T J M; Pokorny, Joel; Kremers, Jan

    2014-01-01

    To psychophysically determine macular pigment optical density (MPOD) employing the heterochromatic modulation photometry (HMP) paradigm by estimating 460 nm absorption at central and peripheral retinal locations. For the HMP measurements, two lights (B: 460 nm and R: 660 nm) were presented in a test field and were modulated in counterphase at medium or high frequencies. The contrasts of the two lights were varied in tandem to determine flicker detection thresholds. Detection thresholds were measured for different R:B modulation ratios. The modulation ratio with minimal sensitivity (maximal threshold) is the point of equiluminance. Measurements were performed in 25 normal subjects (11 male, 14 female; age: 30 ± 11 years, mean ± sd) using an eight channel LED stimulator with Maxwellian view optics. The results were compared with those from two published techniques - one based on heterochromatic flicker photometry (Macular Densitometer) and the other on fundus reflectometry (MPR). We were able to estimate MPOD with HMP using a modified theoretical model that was fitted to the HMP data. The resultant MPODHMP values correlated significantly with the MPODMPR values and with the MPODHFP values obtained at 0.25° and 0.5° retinal eccentricity. HMP is a flicker-based method with measurements taken at a constant mean chromaticity and luminance. The data can be well fit by a model that allows all data points to contribute to the photometric equality estimate. Therefore, we think that HMP may be a useful method for MPOD measurements, in basic and clinical vision experiments.

  1. Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics

    NASA Astrophysics Data System (ADS)

    Turri, P.; McConnachie, A. W.; Stetson, P. B.; Fiorentino, G.; Andersen, D. R.; Bono, G.; Massari, D.; Véran, J.-P.

    2017-04-01

    We present a detailed discussion of how to obtain precise stellar photometry in crowded fields using images from multi-conjugate adaptive optics (MCAO) systems, with the intent of informing the scientific development of this key technology for the Extremely Large Telescopes. We use deep J and K s exposures of NGC 1851 taken with the Gemini Multi-Conjugate Adaptive Optics System (GeMS) on Gemini South to quantify the performance of the instrument and to develop an optimal strategy for stellar photometry using point-spread function (PSF)-fitting techniques. We judge the success of the various methods we employ by using science-based metrics, particularly the width of the main sequence turnoff region. We also compare the GeMS photometry with the exquisite HST data in the visible of the same target. We show that the PSF produced by GeMS possesses significant spatial and temporal variability that must be accounted for during the analysis. We show that the majority of the variation of the PSF occurs within the “control radius” of the MCAO system and that the best photometry is obtained when the PSF radius is chosen to closely match this spatial scale. We identify photometric calibration as a critical issue for next-generation MCAO systems such as those on the Thirty Meter Telescope and European Extremely Large Telescope. Our final CMDs reach K s ˜ 22—below the main sequence knee—making it one of the deepest for a globular cluster available from the ground. Theoretical isochrones are in remarkable agreement with the stellar locus in our data from below the main sequence knee to the upper red giant branch.

  2. The Optical Afterglow of GRB 971214: R and J Photometry

    NASA Astrophysics Data System (ADS)

    Diercks, A. H.; Deutsch, E. W.; Castander, F. J.; Corson, C.; Gilmore, G.; Lamb, D. Q.; Tanvir, N.; Turner, E. L.; Wyse, R.

    1998-08-01

    We present an R- and J-band photometry of an optical transient that is likely to be associated with the gamma-ray burst event GRB 971214. Our first measurement took place 13 hr after the gamma-ray event. The brightness decayed with a power-law exponent α=-1.20+/-0.02, which is similar to those of GRB 970228 andGRB 970508, which had exponents of α=-1.10+/-0.04 and α=-1.141+/-0.014, respectively. The transient decayed monotonically during the first 4 days following the gamma-ray event in contrast with the optical transient associated with GRB 970508, which increased in brightness, peaking 2 days after the burst, before settling to a power-law decay.

  3. Macular Pigment Optical Density Measured by Heterochromatic Modulation Photometry

    PubMed Central

    Huchzermeyer, Cord; Schlomberg, Juliane; Welge-Lüssen, Ulrich; Berendschot, Tos T. J. M.; Pokorny, Joel; Kremers, Jan

    2014-01-01

    Purpose To psychophysically determine macular pigment optical density (MPOD) employing the heterochromatic modulation photometry (HMP) paradigm by estimating 460 nm absorption at central and peripheral retinal locations. Methods For the HMP measurements, two lights (B: 460 nm and R: 660 nm) were presented in a test field and were modulated in counterphase at medium or high frequencies. The contrasts of the two lights were varied in tandem to determine flicker detection thresholds. Detection thresholds were measured for different R:B modulation ratios. The modulation ratio with minimal sensitivity (maximal threshold) is the point of equiluminance. Measurements were performed in 25 normal subjects (11 male, 14 female; age: 30±11 years, mean ± sd) using an eight channel LED stimulator with Maxwellian view optics. The results were compared with those from two published techniques – one based on heterochromatic flicker photometry (Macular Densitometer) and the other on fundus reflectometry (MPR). Results We were able to estimate MPOD with HMP using a modified theoretical model that was fitted to the HMP data. The resultant MPODHMP values correlated significantly with the MPODMPR values and with the MPODHFP values obtained at 0.25° and 0.5° retinal eccentricity. Conclusions HMP is a flicker-based method with measurements taken at a constant mean chromaticity and luminance. The data can be well fit by a model that allows all data points to contribute to the photometric equality estimate. Therefore, we think that HMP may be a useful method for MPOD measurements, in basic and clinical vision experiments. PMID:25354049

  4. Optical and near infrared photometry of Butcher-Oemler clusters

    NASA Technical Reports Server (NTRS)

    Shier, Lisa M.; Rieke, Marcia J.

    1993-01-01

    Rich clusters of galaxies at moderate redshifts (z approx. .3) have a larger proportion of optically blue galaxies than their low redshift counterparts. Spectroscopic examination of the blue galaxies by various authors has shown that the blue galaxies are generally Seyferts, show evidence for recent star formation, or are foreground objects. Unfortunately, spectroscopy is too time consuming to be used on large samples. Thus, we have looked for a way to separate Seyferts, starbursts, ellipticals and nonmembers using photometry alone. Five moderate redshift clusters, Abell numbers 777, 963, 1758, 1961 and 2218, have been observed in the V, R and K bands. We model the spectral energy distributions of various kinds of galaxies found in clusters and derive observed colors. We have modeled the spectral energy distributions (SED) of several kinds of galaxies and compute their colors as a function of redshift. We expect to see ellipticals, spirals, starbursts, post-starburst and Seyfert galaxies. The SED of elliptical and Sbc galaxies was observed by Rieke and Rieke. The SEDs for the starburst galaxies was created by adding a reddened 10(exp 8) year old burst to a spiral galaxy SED. The post-starburst (E+A) galaxy SEDs are composed of a slightly reddened 10(exp 9) year old burst and elliptical galaxy SED. SEDs for the Seyferts were created by adding a v(exp -1.1) power law, and a hot dust thermal spectrum to the Sbc. From the SEDs the colors of galaxies at various redshifts with assorted filters were computed. Lilly & Gunn (1985) have optical and infrared photometry for a sample of galaxies in CL0024+1654 observed spectroscopically by Dressler, Gunn and Schneider (1985). We have used this data to choose the most appropriate SEDs for our starburst and post-starburst models. The most likely explanation for the optically blue colors in most cluster galaxies is star formation. Very few galaxies lie in the Seyfert locus. Abel 1758 has more Seyfert candidates than the other

  5. Thermal Emission Photometry of Deep Impact Flyby Target (163249) 2002 GT

    NASA Astrophysics Data System (ADS)

    Lim, Lucy F.; Moskovitz, N. A.; Licandro, J.; Emery, J. P.; Reddy, V.; Vilas, F.; 2002 GT Observing Team

    2013-10-01

    Near-Earth asteroid (163249) 2002 GT is now the target of a Deep Impact spacecraft flyby in Jan. 2020 (see Pittichova et al., this volume, for details of the flyby and observing campaign). Thermal emission photometry of 2002 GT was obtained from NIRI on Gemini-North in the L' and M' filters, which are centered at 3.76 and 4.68 microns respectively. J- and K-band reflectance photometry was also acquired in support of the thermal observations. The full JKL'M' set was acquired on UT 2013-Jun-13 at a solar phase angle of 53 degrees. A further set of photometry in J, K, and L' only was carried out on 2013-Jun-19 at a phase angle of 65 degrees. High water vapor conditions at Mauna Kea during this period unfortunately prevented acquisition of a second set of M' measurements. In addition, N-band photometry of 2002 GT was conducted on 2013-Jun-10 from CanariCam at the 10-meter Gran Telescopio Canarias using a beta version of the moving object guiding system. Data were acquired in three filters between 8.7 and 12.5 microns, although the limitations of the guiding are complicating the analysis. (We note that N-band observing was not offered by either Gemini or IRTF during this apparition.) Data analysis is ongoing and results will be discussed. We appreciate the efforts of the Gemini and GTC staff in support of these observing programs.

  6. Optical Photometry of BY Cam Modeled Using a Multipolar Magnetic Field Structure

    NASA Astrophysics Data System (ADS)

    Morales, John; Mason, P. A.; Zhilkin, A.; Bisikalo, D. V.; Robinson, E. L.

    2014-01-01

    We present new high-speed broad-band optical photometry of the asynchronous polar (magnetic cataclysmic variable) BY Cam. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald observatory with 3s integration times. In an attempt to understand the complex changes in accretion flow geometry, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry and various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are consistent with the optical photometry.

  7. Deep space optical communications experiment

    NASA Technical Reports Server (NTRS)

    Kinman, P.; Katz, J.; Gagliardi, R.

    1983-01-01

    An optical communications experiment between a deep space vehicle and an earth terminal is under consideration for later in this decade. The experimental link would be incoherent (direct detection) and would employ two-way cooperative pointing. The deep space optical transceiver would ride piggyback on a spacecraft with an independent scientific objective. Thus, this optical transceiver is being designed for minimum spacecraft impact - specifically, low mass and low power. The choices of laser transmitter, coding/modulation scheme, and pointing mechanization are discussed. A representative telemetry link budget is presented.

  8. VizieR Online Data Catalog: Deep VI photometry of Sgr dIrr (Beccari+, 2014)

    NASA Astrophysics Data System (ADS)

    Beccari, G.; Bellazzini, M.; Fraternali, F.; Battaglia, G.; Perina, S.; Sollima, A.; Oosterloo, T. A.; Testa, V.; Galleti, S.

    2014-10-01

    Photometric catalogue of the dwarf irregular galaxy Sagittarius. The catalogue is obtained from deep V and I band wide field photometry from VIMOS at VLT. Only sources having at least six independent magnitude estimates per filter were included in this catalogue. The average and the standard error of the mean of the independent measures obtained from the different images were adopted as the final values of the instrumental magnitude and of the uncertainty on the relative photometry. The instrumental v and i magnitudes were transformed into the Johnson-Kron-Cousins V,I photometric system using more than 70 bright stars (V<22.5) in common with the publicly available HST Wide Field and Planetary Camera 2 (WFPC2) photometry by Holtzman et al. (2006ApJS..166..534H). The instrumental coordinates were transformed into J2000 Equatorial coordinates with 2nd degree polynomials, using more than 1000 stars in common with the GSC2.2 catalog. Please see Section 2.2 for details. (1 data file).

  9. Optical microscopy aims deep

    NASA Astrophysics Data System (ADS)

    Gigan, Sylvain

    2017-01-01

    A new set of imaging techniques that take advantage of scattered light may soon lead to key advances in biomedical optics, providing access to depths well beyond what is currently possible with ballistic light.

  10. Optical Photometry of V404 Cyg (=GS2023+338)

    NASA Astrophysics Data System (ADS)

    Wagner, R. M.; Shrader, C. R.; Starrfield, S. G.

    2000-03-01

    In response to the request by Hjellming et al. in ATEL #54, Rose Finn (Steward Observatory/U. Arizona) obtained for us two R-band CCD images of V404 Cyg (=GS2023+338) on 2000 Mar 3.52 UT with the Steward Observatory Bok 2.3-m telescope and direct CCD (scale = 0.3 arcsec/pixel, airmass = 1.8, seeing = 1.7 arcsec FWHM). Photometry of V404 Cyg was obtained with respect to the comparison stars C1, C4, and C5 of Udalski and Kaluzny (1991, PASP, 103, 198), Casares et al. (1993, MNRAS, 265, 834), and our own photometry of C1 (R = 12.39).

  11. High Speed Optical Photometry of LMXBs and CVs

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Robinson, Edward L.; Gomez, Sebastian; Gonzalez, Emmanuel; Lopez, Isaac D.; Monroy, Lorena; Price, Alex

    2013-02-01

    High speed photometry of several accreting binaries was obtained using the McDonald Observatory 2.1m telescope and ARGOS CCD photometer. A broad-band filter (BVR) was used in order to maximize flux and maintain a short (1-10s) integration time on faint targets. Such observations obtained over several years allow for variability study over time scales covering many orders of magnitude. Observations and analysis for several binaries are summarized.

  12. DEEP, WIDE-FIELD CCD PHOTOMETRY FOR THE OPEN CLUSTER NGC 3532

    SciTech Connect

    Clem, James L.; Landolt, Arlo U.; Hoard, D. W.; Wachter, Stefanie E-mail: landolt@phys.lsu.edu E-mail: wachter@ipac.caltech.edu

    2011-04-15

    We present the results of a deep, wide-field CCD survey for the open cluster NGC 3532. Our new BV(RI){sub c} photometry effectively covers a one square degree area and reaches an unprecedented depth of V {approx} 21 to reveal that NGC 3532 is a rich open cluster that harbors a large number of faint, low-mass stars. We employ a number of methods to reduce the impact of field star contamination in the cluster color-magnitude diagrams (CMDs), including supplementing our photometry with JHK{sub s} data from the 2MASS catalog. These efforts allow us to define a robust sample of candidate main-sequence stars suitable for a purely empirical determination of the cluster's parameters by comparing them to the well-established Hyades main sequence. Our results confirm previous findings that NGC 3532 lies fairly near to the Sun [(m - M){sub 0} = 8.46 {+-} 0.05; 492{sup +12}{sub -11} pc] and has an extremely low reddening for its location near the Galactic plane [E(B - V) = 0.028 {+-} 0.006]. Moreover, an age of {approx}300 Myr has been derived for the cluster by fitting a set of overshooting isochrones to the well-populated upper main sequence. This new photometry also extends faint enough to reach the cluster white dwarf sequence, as confirmed by our photometric recovery of eight spectroscopically identified members of the cluster. Using the location of these eight members, along with the latest theoretical cooling tracks, we have identified {approx}30 additional white dwarf stars in the [V, (B - V)] CMD that have a high probability of belonging to NGC 3532. Reassuringly, the age we derive from fitting white dwarf isochrones to the locus of these stars, 300 {+-} 100 Myr, is consistent with the age derived from the turnoff. Our analysis of the photometry also includes an estimation of the binary star fraction as well as a determination of the cluster's luminosity and mass functions.

  13. A DEEP UBVRI CCD PHOTOMETRY OF SIX OPEN STAR CLUSTERS IN THE GALACTIC ANTICENTER REGION

    SciTech Connect

    Lata, Sneh; Pandey, Anil K.; Kumar, Brijesh; Bhatt, Himali; Pace, Giancarlo; Sharma, Saurabh

    2010-02-15

    We present deep UBVRI CCD photometry of six open star clusters situated in the Galactic anticenter region (l{approx} 120-200 deg.). The sample includes three unstudied (Be 6, Be 77, King 17) and three partly studied open clusters (Be 9, NGC 2186, and NGC 2304). The fundamental parameters have been determined by comparing color-color and color-magnitude diagrams with the theoretical models. The structural parameters and morphology of the clusters were discussed on the basis of radial density profiles and isodensity contours, respectively. The isodensity contours show that all the clusters have asymmetric shapes. An investigation of structural parameters indicates that the evolution of core and corona of the clusters is mainly controlled by internal relaxation processes.

  14. SPITZER OBSERVATIONS OF ABELL 1763. I. INFRARED AND OPTICAL PHOTOMETRY

    SciTech Connect

    Edwards, Louise O. V.; Fadda, Dario; Biviano, Andrea

    2010-02-15

    We present a photometric analysis of the galaxy cluster Abell 1763 at visible and infrared wavelengths. Included are fully reduced images in r', J, H, and K{sub s} obtained using the Palomar 200in telescope, as well as the IRAC and MIPS images from Spitzer. The cluster is covered out to approximately 3 virial radii with deep 24 {mu}m imaging (a 5{sigma} depth of 0.2 mJy). This same field of {approx}40' x 40' is covered in all four IRAC bands as well as the longer wavelength MIPS bands (70 and 160 {mu}m). The r' imaging covers {approx}0.8 deg{sup 2} down to 25.5 mag, and overlaps with most of the MIPS field of view. The J, H, and K{sub s} images cover the cluster core and roughly half of the filament galaxies, which extend toward the neighboring cluster, Abell 1770. This first, in a series of papers on Abell 1763, discusses the data reduction methods and source extraction techniques used for each data set. We present catalogs of infrared sources (with 24 and/or 70 {mu}m emission) and their corresponding emission in the optical (u', g', r', i', z'), and near- to far-IR (J, H, K{sub s} , IRAC, and MIPS 160 {mu}m). We provide the catalogs and reduced images to the community through the NASA/IPAC Infrared Science Archive.

  15. WIYN open cluster study. LXII. Comparison of isochrone systems using deep multi-band photometry of M35

    SciTech Connect

    Thompson, B.; Frinchaboy, P.; Kinemuchi, K.; Sarajedini, A.; Cohen, R.

    2014-11-01

    The current generation of stellar isochrone models exhibits non-negligible discrepancies due to variations in the input physics. The success of each model is determined by how well it fits the observations, and this paper aims to disentangle contributions from the various physical inputs. New deep, wide-field optical and near-infrared photometry (UBVRIJHK{sub S} ) of the cluster M35 is presented, against which several isochrone systems are compared: Padova, PARSEC, Dartmouth, and Y {sup 2}. Two different atmosphere models are applied to each isochrone: ATLAS9 and BT-Settl. For any isochrone set and atmosphere model, observed data are accurately reproduced for all stars more massive than 0.7 M {sub ☉}. For stars less massive than 0.7 M {sub ☉}, Padova and PARSEC isochrones consistently produce higher temperatures than observed. Dartmouth and Y{sup 2} isochrones with BT-Settl atmospheres reproduce optical data accurately; however, they appear too blue in IR colors. It is speculated that molecular contributions to stellar spectra in the near-infrared may not be fully explored, and that future study may reconcile these differences.

  16. SEDS: The Spitzer Extended Deep Survey. Survey Design, Photometry, and Deep IRAC Source Counts

    NASA Technical Reports Server (NTRS)

    Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Huang, J.-S.; Arendt, A.; Barmby, P.; Barro, G; Bell, E. F.; Bouwens, R.; Cattaneo, A.; hide

    2013-01-01

    The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46 deg(exp 2) to a depth of 26 AB mag (3sigma) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5 micron. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z = 2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six-month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300,000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6 +/- 1.0 and 4.4 +/- 0.8 nW / square m/sr at 3.6 and 4.5 micron to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.

  17. SEDS: THE SPITZER EXTENDED DEEP SURVEY. SURVEY DESIGN, PHOTOMETRY, AND DEEP IRAC SOURCE COUNTS

    SciTech Connect

    Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Huang, J.-S.; Hernquist, L.; Hora, J. L.; Arendt, R.; Barmby, P.; Barro, G.; Faber, S.; Guhathakurta, P.; Bouwens, R.; Cattaneo, A.; Croton, D.; Dave, R.; Dunlop, J. S.; Egami, E.; Finlator, K.; Grogin, N. A.; and others

    2013-05-20

    The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46 deg{sup 2} to a depth of 26 AB mag (3{sigma}) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5 {mu}m. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z = 2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six-month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300,000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6 {+-} 1.0 and 4.4 {+-} 0.8 nW m{sup -2} sr{sup -1} at 3.6 and 4.5 {mu}m to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.

  18. Photometry and polarimetry. [optical properties of Titan atmosphere

    NASA Technical Reports Server (NTRS)

    Veverka, J.

    1974-01-01

    A review of available information on the photometry, polarimetry, and narrow band spectrophotometry of Titan discusses five major categories: (1) brightness and color as a function of orbital position; (2) brightness and color as a function of solar phase angle; (3) geometric and bond albedo; (4) reflectance as a function of wavelength; and (5) polarization as a function of solar phase angle. It is concluded that a Saturn-like cloud model may be required to explain the sum of polarimetric and photometric observations.

  19. Stellar populations in edge-on galaxies from deep CCD surface photometry, 1: NGC 5907

    NASA Technical Reports Server (NTRS)

    Morrison, Heather L.; Boroson, Todd A.; Harding, Paul

    1994-01-01

    We present extremely deep charge coupled device (CCD) surface photometry of the edge-on Sc galaxy NGC 5907. Our data reach reliably to a surface brightness of R=27 mag/sq arcsec, some two magnitudes fainter than any previous work. We obtained this improvement using a 2048X2048 CCD with a wide (approximately 24 min) field, which made it possible to sky subtract directly from the galaxy frame, and by taking many dark sky flatfields. Our analysis of these data, using a full 2D model fitting procedure with a detailed error model, confirm the thin disk parameters of van der Kruit & Searle (1981). In particular, we confirm that the galaxy's disk has a radial cutoff and a constant scale height with radius. We find evidence for a stellar warp in this system, which has the same orientation as the H I warp. Our deep data also confirm that NGC 5907 has no thick disk. This suggests that theories of thick disk formation from star formation in the early stages of disk collapse, or by secular heating mechanisms, are unlikely to be correct, because they would predict that every galaxy would have a thick disk. Thick disk formation from the accretion of satellite galaxies is more likely.

  20. Optical BVRI photometry of common proper motion F/G/K+M wide separation binaries

    SciTech Connect

    Li, Ting; Marshall, Jennifer L.; Williams, Patrick; Chavez, Joy; Lépine, Sébastien

    2014-10-01

    We present optical (BVRI) photometric measurements of a sample of 76 common proper motion wide separation main-sequence binary pairs. The pairs are composed of a F-, G-, or K-type primary star and an M-type secondary. The sample is selected from the revised NLTT catalog and the LSPM catalog. The photometry is generally precise to 0.03 mag in all bands. We separate our sample into two groups, dwarf candidates and subdwarf candidates, using the reduced proper motion diagram constructed with our improved photometry. The M subdwarf candidates in general have larger V – R colors than the M dwarf candidates at a given V – I color. This is consistent with an average metallicity difference between the two groups, as predicted by the PHOENIX/BT-Settl models. The improved photometry will be used as input into a technique to determine the metallicities of the M-type stars.

  1. Deep NIR photometry of H I galaxies in the Zone of Avoidance

    NASA Astrophysics Data System (ADS)

    Williams, W. L.; Kraan-Korteweg, R. C.; Woudt, P. A.

    2014-09-01

    Current studies of the peculiar velocity flow field in the local Universe are limited by either the lack of detection or accurate photometry for galaxies at low Galactic latitudes. The contribution to the dynamics of the Local Group of the largely unknown mass distribution in this `Zone of Avoidance' (ZoA) remains controversial. We present here the results of a pilot project to obtain deep near-infrared (NIR) observations of galaxies detected in the systematic Parkes deep H I survey of the ZoA(HIZOA) - 578 galaxies with recession velocities out to 6000 km s-1 were observed with the 1.4 m InfraRed Survey Facility SIRIUS (Simultaneous InfraRed Imager for Unbiased Surveys) camera providing J, H and Ks imaging 2 mag deeper than 2MASS. After star subtraction, the resulting isophotal magnitudes and inclinations of ZoA galaxies are of sufficient accuracy (magnitude errors under 0.1 mag even at high extinction) to ultimately be used to determine cosmic flow fields `in' the ZoA via the NIR Tully-Fisher relation. We further used the observed NIR colours to assess the ratio of the true extinction to the Diffuse Infrared Background Experiment/IRAS extinction deep into the dust layers of the Milky Way. The derived ratio was found to be 0.87 across the HIZOA survey region with no significant variation with Galactic latitude or longitude. This value is in excellent agreement with the completely independently derived factor of 0.86 by Schlafly & Finkbeiner based on Sloan data far away from the Milky Way.

  2. Galaxy And Mass Assembly: accurate panchromatic photometry from optical priors using LAMBDAR

    NASA Astrophysics Data System (ADS)

    Wright, A. H.; Robotham, A. S. G.; Bourne, N.; Driver, S. P.; Dunne, L.; Maddox, S. J.; Alpaslan, M.; Andrews, S. K.; Bauer, A. E.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Clarke, C.; Cluver, M.; Davies, L. J. M.; Grootes, M. W.; Holwerda, B. W.; Hopkins, A. M.; Jarrett, T. H.; Kafle, P. R.; Lange, R.; Liske, J.; Loveday, J.; Moffett, A. J.; Norberg, P.; Popescu, C. C.; Smith, M.; Taylor, E. N.; Tuffs, R. J.; Wang, L.; Wilkins, S. M.

    2016-07-01

    We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high-resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending. Using simulated images, we demonstrate that the program is able to recover accurate photometric measurements in both high-resolution, low-confusion, and low-resolution, high-confusion, regimes. We apply the program to the 21-band photometric data set from the Galaxy And Mass Assembly (GAMA) Panchromatic Data Release (PDR; Driver et al. 2016), which contains imaging spanning the far-UV to the far-IR. We compare photometry derived from LAMBDAR with that presented in Driver et al. (2016), finding broad agreement between the data sets. None the less, we demonstrate that the photometry from LAMBDAR is superior to that from the GAMA PDR, as determined by a reduction in the outlier rate and intrinsic scatter of colours in the LAMBDAR data set. We similarly find a decrease in the outlier rate of stellar masses and star formation rates using LAMBDAR photometry. Finally, we note an exceptional increase in the number of UV and mid-IR sources able to be constrained, which is accompanied by a significant increase in the mid-IR colour-colour parameter-space able to be explored.

  3. Deep Washington photometry of inconspicuous star cluster candidates in the Large Magellanic Cloud

    SciTech Connect

    Choudhury, Samyaday; Subramaniam, Annapurni; Piatti, Andrés E.

    2015-02-01

    We present deep Washington photometry of 45 poorly populated star cluster candidates in the Large Magellanic Cloud (LMC). We have performed a systematic study to estimate the parameters of the cluster candidates by matching theoretical isochrones to the cleaned and dereddened cluster color–magnitude diagrams. We were able to estimate the basic parameters for 33 clusters, out of which 23 are identified as single clusters and 10 are found to be members of double clusters. The other 12 cluster candidates have been classified as possible clusters/asterisms. About 50% of the true clusters are in the 100–300 Myr age range, whereas some are older or younger. We have discussed the distribution of age, location, and reddening with respect to field, as well as the size of true clusters. The sizes and masses of the studied sample are found to be similar to that of open clusters in the Milky Way. Our study adds to the lower end of cluster mass distribution in the LMC, suggesting that the LMC, apart from hosting rich clusters, also has formed small, less massive open clusters in the 100–300 Myr age range.

  4. The RSA survey of dwarf galaxies, 1: Optical photometry

    NASA Technical Reports Server (NTRS)

    Vader, J. Patricia; Chaboyer, Brian

    1994-01-01

    We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are

  5. Optical Photometry of the flaring gamma-ray blazar AO 0235+164

    NASA Astrophysics Data System (ADS)

    Pursimo, Tapio; Losada, Illa R.; Messa, Matteo; Gafton, Emanuel; Ojha, Roopesh

    2016-03-01

    We report optical photometry of the blazar AO 0235+164 obtained with the 2.56m Nordic Optical Telescope in La Palma to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux seen in the public lightcurve of the Fermi/LAT instrument: http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/0235+164_86400.png Fermi/LAT first reported a detection of gamma-ray activity from this source in Sep, 2008 (ATel#1744) and a short timescale flare in Oct 14, 2008 (ATel#1784).

  6. VizieR Online Data Catalog: Optical & Spitzer photometry in IC 1805 (Sung+, 2017)

    NASA Astrophysics Data System (ADS)

    Sung, H.; Bessell, M. S.; Chun, M.-Y.; Yi, J.; Naze, Y.; Lim, B.; Karimov, R.; Rauw, G.; Park, B.-G.; Hur, H.

    2017-06-01

    For a study of the IMF and the star-formation history of the young open cluster IC 1805, we obtained deep wide-field VRI and Hα images of IC 1805 using the CFH12K mosaic CCD camera of the CFHT on 2002 January 6 and 7. We also observed several regions in IC 1805, for a study of the reddening and massive star content, using the SITe 2000x800 CCD (Maidanak 2k CCD) and standard UBVRI filters of the AZT-22 1.5m telescope at the Maidanak Astronomical Observatory in Uzbekistan on 2003 August 18 and 2004 december 25,30. Later, we obtained additional images of the central region of IC 1805 with the Fairchild 486 CCD (SNUCam) and UBVI and Hα filters of the AZT-22 telescope on 2007 October 7 and 2009 January 19. The Spitzer mapping observations were performed on 2006 September 20 under program ID 20052 (PI: S. Wolff). For complete photometry of stars in the CFH12K FOV in 3.6 and 4.5um, we also downloaded and reduced the GLIMPSE360 data (AOR: 38753280, 38763264, 38769408, 38799104, 38798592, 38784512, PI: B. A. Whitney). MIPS scans of IC 1805 were obtained on 2005 August 31 and 2005 September 2 (PID 3234, PI: J. S. Greeves). The Chandra X-ray Observatory Observations of IC 1805 (ObsID: 7033, PI: L. Townley) were made on 2006 November 25. The total exposure time was about 79ks. The properties of 647 X-ray sources were published in Townsley+ (2014,J/ApJS/213/1). We searched for the optical and MIR counterparts of these X-ray sources with a matching radius of up to 1.5". (4 data files).

  7. Multi-Site Simultaneous Time-Resolved Photometry with a Low Cost Electro-Optics System.

    PubMed

    Gasdia, Forrest; Barjatya, Aroh; Bilardi, Sergei

    2017-05-30

    Sunlight reflected off of resident space objects can be used as an optical signal for astrometric orbit determination and for deducing geometric information about the object. With the increasing population of small satellites and debris in low Earth orbit, photometry is a powerful tool in operational support of space missions, whether for anomaly resolution or object identification. To accurately determine size, shape, spin rate, status of deployables, or attitude information of an unresolved resident space object, multi-hertz sample rate photometry is required to capture the relatively rapid changes in brightness that these objects can exhibit. OSCOM, which stands for Optical tracking and Spectral characterization of CubeSats for Operational Missions, is a low cost and portable telescope system capable of time-resolved small satellite photometry, and is field deployable on short notice for simultaneous observation from multiple sites. We present the electro-optical design principles behind OSCOM and light curves of the 1.5 U DICE-2 CubeSat and simultaneous observations of the main body of the ASTRO-H satellite after its fragmentation event.

  8. Nighttime Aerosol Optical Depth Variability From Astronomical Photometry

    NASA Astrophysics Data System (ADS)

    Musat, I. C.; Ellingson, R. G.

    2006-12-01

    A technique for determination of the short-term (6 minutes intervals) variability of the aerosol optical depth (AOD) during nighttime from broadband visible measurements of star irradiances during clear nights was developed for the instrument called the Whole Sky Imager (WSI), placed at the Atmospheric Radiation Measurement (ARM) observation site in Oklahoma. The AOD is inferred indirectly from simultaneous observations of extinction of stars having different colors (spectra) and different elevations above the horizon, and takes into account the other sources for starlight attenuation in the atmosphere which might be present and which are measured by other instruments at the site at compatible timescales (e.g., precipitable water vapor content, columnar ozone amount, observed atmospheric stratification). The total error of the new method is a combination of the absolute star flux measurement error with the WSI and a systematic error in the models assumed for the other atmospheric components causing the starlight extinction. The relative error in the aerosol optical depth determined through this method is found to be below 4%. For the validation of the results, the comparison of the aerosol optical depth measured with the Lidar at 10 minutes intervals (at 355nm) with the AOD determined from WSI (in visible) shows a good agreement for the data in the interval studied (1999-2003).

  9. Photometry of BL Lac objects and optically violently variable quasars

    NASA Astrophysics Data System (ADS)

    Smith, N.; McBreen, B.; Ekins, R.; Grimley, P.

    1989-09-01

    A photon-counting photometer has been used to observe BL Lac objects and optically violently variable (OVV) quasars. The development, construction, and performance of the photometer are discussed and the photometer configuration is illustrated. The observations were made on five nights in September 1986 using a 1-m telescope. Results are presented for observations of seven OVV objects and the star Chi Persei. No statistically significant variation were detected in the sources on timescales ranging from 0.1 sec to 5 days.

  10. DEEP K{sub s} -NEAR-INFRARED SURFACE PHOTOMETRY OF 80 DWARF IRREGULAR GALAXIES IN THE LOCAL VOLUME

    SciTech Connect

    Fingerhut, Robin L.; McCall, Marshall L.; Argote, Mauricio; Cluver, Michelle E.; Nishiyama, Shogo; Rekola, Rami T. F.; Richer, Michael G.; Vaduvescu, Ovidiu; Woudt, Patrick A. E-mail: mccall@yorku.c E-mail: mcluver@ipac.caltech.ed E-mail: rareko@utu.f E-mail: ovidiuv@ing.iac.e

    2010-06-10

    We present deep near-infrared (K{sub s}) images and surface photometry for 80 dwarf irregular galaxies (dIs) within {approx}5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies.

  11. Asteroid shapes and thermal properties from combined optical and mid-infrared photometry inversion

    NASA Astrophysics Data System (ADS)

    Ďurech, J.; Delbo', M.; Carry, B.; Hanuš, J.; Alí-Lagoa, V.

    2017-07-01

    Context. Optical light-curves can be used to reconstruct the shape and spin of asteroids. Because the albedo is unknown, these models are scale free. When thermal infrared data are available, they can be used to scale the shape models and derive the thermophysical properties of the surface by applying a thermophysical model. Aims: We introduce a new method for simultaneously inverting optical and thermal infrared data that allows the size of an asteroid to be derived along with its shape and spin state. Methods: The method optimizes all relevant parameters (shape and size, spin state, light-scattering properties, thermal inertia, and surface roughness) by gradient-based optimization. The thermal emission is computed by solving the 1D heat diffusion equation. Calibrated optical photometry and thermal fluxes at different wavelengths are needed as input data. Results: We demonstrate the reliability and test the accuracy of the method on selected targets with different amounts and quality of data. Our results in general agree with those obtained by independent methods. Conclusions: Combining optical and thermal data into one inversion method opens a new possibility for processing photometry from large optical sky surveys with the data from WISE. It also provides more realistic error estimates of thermophysical parameters.

  12. Analysis of Mount St. Helens ash from optical photoelectric photometry

    NASA Technical Reports Server (NTRS)

    Cardelli, J. A.; Ackerman, T. P.

    1983-01-01

    The optical properties of suspended dust particles from the eruption of Mt. St. Helens on July 23, 1980 are investigated using photoelectric observations of standard stars obtained on the 0.76-m telescope at the University of Washington 48 hours after the eruption. Measurements were made with five broad-band filters centered at 3910, 5085, 5480, 6330, and 8050 A on stars of varying color and over a wide range of air masses. Anomalous extinction effects due to the volcanic ash were detected, and a significant change in the wavelength-dependent extinction parameter during the course of the observations was established by statistical analysis. Mean particle size (a) and column density (N) are estimated using the Mie theory, assuming a log-normal particle-size distribution: a = 0.18 micron throughout; N = 1.02 x 10 to the 9th/sq cm before 7:00 UT and 2.33 x 10 to the 9th/sq cm after 8:30 UT on July 25, 1980. The extinction is attributed to low-level, slowly migrating ash, possibly combined with products of gas-to-particle conversion and coagulation.

  13. The MIUSCAT stellar population models: constraints from optical photometry

    NASA Astrophysics Data System (ADS)

    Ricciardelli, E.; Vazdekis, A.; Cenarro, A. J.; Falcón-Barroso, J.

    2013-05-01

    We present the spectral extension of our stellar population synthesis models based on the MILES and CaT empirical stellar spectral libraries. For this purpose we combine these two libraries with the Indo-US to construct composite stellar spectra to feed our models. The spectral energy distributions (SEDs) computed with these models and the originally published models are combined to construct composite SEDs for single-age, single-metallicity stellar populations (SSPs) covering the range λλ3465 -- 9469 Å at resolution FWHM =2.51 Å. We also show a comprehensive comparison of the MIUSCAT models with photometric data of globular clusters and early-type galaxies. The models compare remarkably well with the integrated colours of Milky Way globular clusters in the optical range. On the other hand we find that the colour relations of nearby early-type galaxies are still a challenge for present-day stellar population synthesis models. We investigate a number of possible explanations and establish the importance of α-enhanced models to bring down the discrepancy with observations.

  14. Bayesian High-redshift Quasar Classification from Optical and Mid-IR Photometry

    NASA Astrophysics Data System (ADS)

    Richards, Gordon T.; Myers, Adam D.; Peters, Christina M.; Krawczyk, Coleman M.; Chase, Greg; Ross, Nicholas P.; Fan, Xiaohui; Jiang, Linhua; Lacy, Mark; McGreer, Ian D.; Trump, Jonathan R.; Riegel, Ryan N.

    2015-08-01

    We identify 885,503 type 1 quasar candidates to i≲ 22 using the combination of optical and mid-IR photometry. Optical photometry is taken from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from the Wide-field Infrared Survey Explorer (WISE) “AllWISE” data release and several large-area Spitzer Space Telescope fields. Selection is based on a Bayesian kernel density algorithm with a training sample of 157,701 spectroscopically confirmed type 1 quasars with both optical and mid-IR data. Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623 are objects that we have not previously classified as photometric quasar candidates). These candidates include 7874 objects targeted as high-probability potential quasars with 3.5\\lt z\\lt 5 (of which 6779 are new photometric candidates). Our algorithm is more complete to z\\gt 3.5 than the traditional mid-IR selection “wedges” and to 2.2\\lt z\\lt 3.5 quasars than the SDSS-III/BOSS project. Number counts and luminosity function analysis suggest that the resulting catalog is relatively complete to known quasars and is identifying new high-z quasars at z\\gt 3. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars and for further machine-learning quasar selection using Spitzer and WISE data combined with other large-area optical imaging surveys.

  15. A laboratory module on radiometry, photometry and colorimetry for an undergraduate optics course

    NASA Astrophysics Data System (ADS)

    Polak, Robert D.

    2014-07-01

    The bachelor's degree in Physics at Loyola University Chicago requires both an upper-division course in Optics as well as a companion Optics Laboratory course. Recently, the laboratory course has undergone dramatic changes. Traditional weekly laboratories have been replaced with three laboratory modules, where students focus on a single topic over several weeks after which the students submit a laboratory report written in the style of a journal article following American Institute of Physics style manual. With this method, students are able to gain a deeper understanding of the specific topic areas of radiometry, photometry and colorimetry, lens design and aberrations, and polarization and interference while using industry-standard equipment and simulation software. In particular, this work will provide the details of the laboratory module on radiometry, photometry and colorimetry where students use a photoradiometer and integrating sphere to characterize the optical properties of an LCD monitor, light bulb and a fiber optic light source calculating properties such as luminous flux, luminous intensity, luminance, CIE color coordinates, NTSC ratio, color temperature and luminous efficacy.

  16. Deep space optical communication via relay satellite

    NASA Technical Reports Server (NTRS)

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  17. Deep space optical communication via relay satellite

    NASA Technical Reports Server (NTRS)

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  18. High-Resolution Spectroscopy and Optical Photometry of MWC 349A and MWC 349B

    NASA Astrophysics Data System (ADS)

    Manset, N.; Miroshnichenko, A. S.; Zharikov, S. V.; Kusakin, A. V.

    2017-02-01

    MWC 349A is a V ˜ 13 mag object with the B[e] phenomenon, a very strong optical emission-line spectrum, maser and laser line emission, and a radio-bright bipolar nebula, attenuated by ˜10 mag of interstellar extinction. MWC 349B is a visual companion of MWC 349A with no previously reported signs of emission. The physical connection of the pair has been the subject of debates toward revealing the evolutionary state of MWC 349A. Only low-resolution spectra reported for MWC 349B resulted in estimating its parameters with a large uncertainty. We report the results of high-resolution optical spectroscopy of both objects as well as their optical photometry.

  19. Time-Resolved CubeSat Photometry with a Low Cost Electro-Optics System

    NASA Astrophysics Data System (ADS)

    Gasdia, F.; Barjatya, A.; Bilardi, S.

    2016-09-01

    Once the orbits of small debris or CubeSats are determined, optical rate-track follow-up observations can provide information for characterization or identification of these objects. Using the Celestron 11" RASA telescope and an inexpensive CMOS machine vision camera, we have obtained time-series photometry from dozens of passes of small satellites and CubeSats over sites in Florida and Massachusetts. The fast readout time of the CMOS detector allows temporally resolved sampling of glints from small wire antennae and structural facets of rapidly tumbling objects. Because the shape of most CubeSats is known, these light curves can be used in a mission support function for small satellite operators to diagnose or verify the proper functioning of an attitude control system or deployed antenna or instrument. We call this telescope system and the accompanying analysis tools OSCOM for Optical tracking and Spectral characterization of CubeSats for Operational Missions. We introduce the capability of OSCOM for space object characterization, and present photometric observations demonstrating the potential of high frame rate small satellite photometry.

  20. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, D.E.; Petrini, R.R.; Carter, G.W.

    An improved rod optic system for inspecting small diameter, deep bores is described. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90/sup 0/ to minimize optical distortion in examing the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable if examing 1/16 inch diameter and up to 4-inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and righ angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  1. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, David E.; Petrini, Richard R.; Carter, Gary W.

    1981-01-01

    An improved rod optic system for inspecting small diameter, deep bores. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90.degree. to minimize optical distortion in examining the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable of examining 1/16 inch diameter and up to 4 inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and right angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  2. Repeated measures of macular pigment optical density to test reproducibility of heterochromatic flicker photometry.

    PubMed

    Hagen, Stefan; Krebs, Ilse; Glittenberg, Carl; Binder, Susanne

    2010-03-01

    To report the reproducibility of macular pigment optical density (MPOD) values assessed with heterochromatic flicker photometry (HFP) in healthy individuals. Twenty-four volunteers from our department underwent MPOD testing of both eyes by flicker photometry on three separate occasions. To test reproducibility of MPOD, the coefficient of variance was calculated separately for right and left eyes. In addition, we investigated MPOD averages of right and left eyes and interocular correlations (Pearson's r) at every visit. The mean MPODs at the first visit were 0.61 +/- 0.24 and 0.72 +/- 0.27 in right and left eyes, respectively. Mean values of 0.58 +/- 0.29 and 0.60 +/- 0.21 (second visit) and 0.62 +/- 0.27 and 0.63 +/- 0.24 (third visit) were assessed for right and left eyes, respectively. Differences of the mean values between eyes were not significant. Correlations were weak at visits one and two (r = 0.49, p < 0.014 and r = 0.43, p < 0.038, respectively) and moderate at visit three (r = 0.58, p < 0.003). The coefficients of variance were 36.1% and 23% for right and left eyes, respectively. Our mean MPODs are higher and the interocular correlations weaker compared to the literature. The coefficient of variance in both eyes is high and does not imply good reproducibility of obtained MPOD values.

  3. Optical deep space communication via relay satellite

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.; Vilnrotter, V. A.; Dolinar, S. J., Jr.

    1981-01-01

    The possible use of an optical for high rate data transmission from a deep space vehicle to an Earth-orbiting relay satellite while RF links are envisioned for the relay to Earth link was studied. A preliminary link analysis is presented for initial sizing of optical components and power levels, in terms of achievable data rates and feasible range distances. Modulation formats are restricted to pulsed laser operation, involving bot coded and uncoded schemes. The advantage of an optical link over present RF deep space link capabilities is shown. The problems of acquisition, pointing and tracking with narrow optical beams are presented and discussed. Mathematical models of beam trackers are derived, aiding in the design of such systems for minimizing beam pointing errors. The expected orbital geometry between spacecraft and relay satellite, and its impact on beam pointing dynamics are discussed.

  4. Broad-Band Optical Photometry of the LMXB PSR J1023+0038

    NASA Astrophysics Data System (ADS)

    Gonzalez, Emmanuel; Mason, P. A.; Robinson, E. L.

    2013-01-01

    Optical observations of the low-mass X-ray binary PSR J1023+0038 are presented. CCD photometry was collected with 10s integrations using the Argos camera on the 2.1 m Otto Struve Telescope of McDonald Observatory. Data was obtained during seven nights in February 2011 and January 2012. The light curves are quite similar to those obtained in previous studies, allowing a systematic period study of new data combined with three epochs of published light curves, covering a span of 8 years. An unambiguous period of 0.1980962(4) days is derived. An O-C diagram of the residuals is constructed and does not clearly require a significant period change.

  5. Gallium arsenide deep-level optical emitter for fibre optics.

    PubMed

    Pan, Janet L; McManis, Joseph E; Osadchy, Thomas; Grober, Louise; Woodall, Jerry M; Kindlmann, Peter J

    2003-06-01

    Fibre-optic components fabricated on the same substrate as integrated circuits are important for future high-speed communications. One industry response has been the costly push to develop indium phosphide (InP) electronics. However, for fabrication simplicity, reliability and cost, gallium arsenide (GaAs) remains the established technology for integrated optoelectronics. Unfortunately, the GaAs bandgap wavelength (0.85 microm) is far too short for fibre optics at 1.3-1.5 microm. This has led to work on materials that have a large lattice mismatch on GaAs. Here we demonstrate the first light-emitting diode (LED) that emits at 1.5 microm fibre-optic wavelengths in GaAs using optical transitions from arsenic antisite (As(Ga)) deep levels. This is an enabling technology for fibre-optic components that are lattice-matched to GaAs integrated circuits. We present experimental results showing significant internal optical power (24 mW) and speed (in terahertz) from GaAs optical emitters using deep-level transitions. Finally, we present theory showing the ultimate limit to the efficiency-bandwidth product of semiconductor deep-level optical emitters.

  6. VizieR Online Data Catalog: Optical and UV photometry of SN 2013dy (Zhai+, 2016)

    NASA Astrophysics Data System (ADS)

    Zhai, Q.; Zhang, J.-J.; Wang, X.-F.; Zhang, T.-M.; Liu, Z.-W.; Brown, P. J.; Huang, F.; Zhao, X.-L.; Chang, L.; Yi, W.-M.; Wang, C.-J.; Xin, Y.-X.; Wang, J.-G.; Lun, B.-L.; Zhang, X.-L.; Fan, Y.-F.; Zheng, X.-M.; Bai, J.-M.

    2016-08-01

    SN2013dy, an Type Ia supernova (SNIa), was discovered at roughly a magnitude of ~17.2mag on UT July 10.45 2013 (Universal Time) in an unfiltered image of the galaxy NGC7250 by the Lick observatory supernova search (Casper et al., 2013CBET.3588....1C). Our first observation of SN 2013dy is in spectroscopy on 2013 July 14 (Zhang & Wang 2013CBET.3394....1Z; 4.76days after the first light and published in Zheng et al. 2013ApJ...778L..15Z) with the Yunnan Faint Object Spectrograph and Camera (YFOSC) mounted at the Li-Jiang 2.4m Telescope (LJT) of Yunnan Observatories (YNAO), China. About two weeks later, we started to monitor this transient intensively at LJT in both ground-based UBVRI photometry and spectroscopy spanning from t~+0 to t~+180days. Ten local standard stars (see Table1 in the paper) in the field of SN2013dy are used to transform the instrumental magnitudes of SN2013dy to the standard Johnson UBV and Kron-Cousins RI system, as listed in Table2. Optical photometry data are also collected with the Tsinghua-NAOC 0.8m telescope (TNT) at Xing-Long Observation of National Astronomical Observatories (NAOC), China, from t~-2days to t~+150days. Additionally, three spectra were obtained at the Xing-Long 2.16 m telescope (hereafter XLT) with the Bei-Jing Faint Object Spectrograph and Camera (BFOSC). Furthermore, this target was also observed by the Ultra-Violet/Optical Telescope (UVOT) on board the Swift satellite. The Swift observatory began observing SN 2013dy on 2013 July 17.09, about 10days (t~-10days) before the B band maximum, and continued for approximately 26days (t~+15days). These photometric observations are performed in three UV filters (uvw2, uvm2, and uvw1) and three broadband optical filters (uu, bb, and vv). Table3 lists the final UVOT UV/optical magnitudes of SN2013dy. (2 data files).

  7. DeepSurveyCam--A Deep Ocean Optical Mapping System.

    PubMed

    Kwasnitschka, Tom; Köser, Kevin; Sticklus, Jan; Rothenbeck, Marcel; Weiß, Tim; Wenzlaff, Emanuel; Schoening, Timm; Triebe, Lars; Steinführer, Anja; Devey, Colin; Greinert, Jens

    2016-01-28

    Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor), and the limitations of localization technologies (no GPS). The absence of natural light complicates energy budget considerations for deep diving flash-equipped drones. Refraction effects influence geometric image formation considerations with respect to field of view and focus, while attenuation and scattering degrade the radiometric image quality and limit the effective visibility. As an improvement on the stated issues, we present an AUV-based optical system intended for autonomous visual mapping of large areas of the seafloor (square kilometers) in up to 6000 m water depth. We compare it to existing systems and discuss tradeoffs such as resolution vs. mapped area and show results from a recent deployment with 90,000 mapped square meters of deep ocean floor.

  8. DeepSurveyCam—A Deep Ocean Optical Mapping System

    PubMed Central

    Kwasnitschka, Tom; Köser, Kevin; Sticklus, Jan; Rothenbeck, Marcel; Weiß, Tim; Wenzlaff, Emanuel; Schoening, Timm; Triebe, Lars; Steinführer, Anja; Devey, Colin; Greinert, Jens

    2016-01-01

    Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor), and the limitations of localization technologies (no GPS). The absence of natural light complicates energy budget considerations for deep diving flash-equipped drones. Refraction effects influence geometric image formation considerations with respect to field of view and focus, while attenuation and scattering degrade the radiometric image quality and limit the effective visibility. As an improvement on the stated issues, we present an AUV-based optical system intended for autonomous visual mapping of large areas of the seafloor (square kilometers) in up to 6000 m water depth. We compare it to existing systems and discuss tradeoffs such as resolution vs. mapped area and show results from a recent deployment with 90,000 mapped square meters of deep ocean floor. PMID:26828495

  9. Spin-Resolved Optical CCD Spectroscopy and Photometry of Bg-Canis

    NASA Astrophysics Data System (ADS)

    Garlick, M. A.; Rosen, S. R.; Mittaz, J. P. D.; Mason, K. O.; de Martino, D.

    1994-04-01

    We report spin-resolved optical photometry and spectroscopy of the intermediate polar BG Canis Minoris. New 913-s pulsation ephemerides are derived. We find that a cubic fit provides a better description of the 0-C values than the hitherto assumed quadratic ephemeris at a confidence level of 97.3 per cent. From the spectroscopy, we find that the violet-to-red (V/R) ratio of the emission lines varies with the 913-s period but not at the alternative period of 847s detected in the X-ray band. This suggests that 913 5 is the most probable spin period of the white dwarf. However, we do find evidence that the emission line intensities and equivalent widths are modulated at 847s. The morphology and phasing of the 913-s V/R ratio modulation with respect to the optical and X-ray light curves are similar to those of the spin modulation seen in other intermediate polars, and are consistent with the behaviour expected from material in an azimuthally extended magnetically constrained flow, formed at the inner edge of a truncated accretion disc. However, the confirmation of the 847-s period makes it difficult to accept this interpretation.

  10. Deep space optical communications development program

    NASA Technical Reports Server (NTRS)

    Lesh, James R.

    1987-01-01

    The technology development, spacecraft systems impact, design examples and overall development plan for optical deep space communications are described. Design examples include moderate distance links like ones from Mars to Earth, out through a potential mission to a distance of 1000 A.U. The technology development plan, which includes both ground-based as well as Earth orbit-based reception considerations, spans the period from 1985 to the year 2003. Past technology developments in high efficiency lasers, optical modulation and coding, and high power efficiency communications techniques at multiple bits of information per detected photon are also discussed.

  11. Deep Photometry of Galaxies in the VEGAS Survey: The Case of NGC 4472

    NASA Astrophysics Data System (ADS)

    Spavone, M.

    The VST-VEGAS project is aimed at observing and studying a rich sample of nearby early-type galaxies in order to systematically characterize their properties over a wide baseline of sizes and out to the faint outskirts where data are rather scarce so far. The external regions of galaxies more easily retain signatures about the formation and evolution mechanisms which shaped them, as their relaxation time are longer, and they are more weakly influenced by processes such as mergers, secular evolution, central black hole activity, and supernova feedback on the ISM, which tend to level age and metallicity gradients. The collection of a wide photometric dataset of a large number of galaxies in various environmental conditions, may help to shed light on these questions. To this end VEGAS exploits the potential of the VLT Survey Telescope (VST) which provides high quality images of 1 deg2 field of view in order to satisfy both the requirement of high resolution data and the need of studying nearby, and thus large, objects. We present a detailed study of the surface photometry of the elliptical galaxy NGC4472 and of smaller ETGs in its field, performed by using new g and i bands images to constrain the formation history of this nearby giant galaxy, and to investigate the presence of very faint substructures in its surroundings.

  12. EDGES: Deep Multi-Wavelength Photometry and Radial SED Analysis for UGC8303 and UGC8320

    NASA Astrophysics Data System (ADS)

    Phenicie, Christopher; Dale, Daniel A.; Barnes, Kate L.; Beltz-Mohrmann, Gillian; Egan, Arika; Hatlestad, Alan; Herzog, Laura; Kobulnicky, Henry A.; Leung, Andrew S.; McLane, Jacob; Roberts, Jareth; Staudaher, Shawn; van Zee, Liese

    2015-01-01

    New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for UGC8303 and UGC8320, two galaxies in the Extended Disk Galaxy Exploration Science survey. These data are coupled with deep GALEX ultraviolet and Spitzer infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software will be presented, including trends in the galaxy star formation histories. This work is supported by the National Science Foundation under REU grant AST 1063146.

  13. EDGES: Deep Multi-Wavelength Photometry and Radial SED Analysis for Six Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Mclane, Jacob Noel; Leung, Andrew S.; Dale, Daniel A.; Barnes, Kate L.; Beltz-Mohrmann, Gillian; Egan, Arika; Hatlestad, Alan; Herzog, Laura; Kobulnicky, Henry A.; Phenicie, Christopher; Roberts, Jareth; Staudaher, Shawn; van Zee, Liese

    2015-01-01

    New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for NGC4220, NGC4618, NGC5055, NGC5523 and NGC5608, five galaxies in the Extended Disk Galaxy Exploration Science Survey (EDGES). Additional imaging was obtained for NGC4625, a non-EDGES target of opportunity. These data are coupled with deep GALEX ultraviolet and Spitzer/WISE infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software will be presented, including trends in the galaxy star formation histories. This work is supported by the National Science Foundation under REU grant AST 1063146.

  14. EDGES: Deep Multi-Wavelength Photometry and Radial SED Analysis for NGC4242 and UGC7301

    NASA Astrophysics Data System (ADS)

    Egan, Arika; Dale, Daniel A.; Barnes, Kate L.; Beltz-Mohrmann, Gillian; Hatlestad, Alan; Herzog, Laura; Kobulnicky, Henry A.; Leung, Andrew S.; McLane, Jacob; Phenicie, Christopher; Roberts, Jareth; Staudaher, Shawn; van Zee, Liese

    2015-01-01

    New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for NGC4242 and UGC7301, two galaxies in the Extended Disk Galaxy Exploration Science survey. These data are coupled with deep GALEX ultraviolet and Spitzer/WISE infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software will be presented, including trends in the galaxy star formation histories. This work is supported by the National Science Foundation under REU grant AST 1063146.

  15. EDGES: Deep Multi-Wavelength Photometry and Radial SED Analysis for NGC4707 and NGC5229

    NASA Astrophysics Data System (ADS)

    Herzog, Laura; Dale, Daniel A.; Barnes, Kate L.; Beltz-Mohrmann, Gillian; Egan, Arika; Hatlestad, Alan; Kobulnicky, Henry A.; Leung, Andrew S.; McLane, Jacob; Phenicie, Christopher; Roberts, Jareth; Staudaher, Shawn; van Zee, Liese

    2015-01-01

    New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for NGC4707 and NGC5229, two galaxies in the Extended Disk Galaxy Exploration Science survey. These data are coupled with deep GALEX ultraviolet and Spitzer infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software will be presented, including trends in the galaxy star formation histories. This work is supported by the National Science Foundation under REU grant AST 1063146.

  16. Deep Stromvil Photometry for Star Formation in the Head of the Pelican Nebula

    NASA Astrophysics Data System (ADS)

    Boyle, Richard P.; J., S.; Stott, J.; J., S.; Janusz, R.; J., S.; Straizys, V.

    2010-01-01

    The North America and Pelican Nebulae, and specifically the dark cloud L935 contain regions of active star formation (Herbig, G. H. 1958, ApJ, 128,259). Previously we reported on Vatican telescope observations by Stromvil intermediate-band filters in a 12-arcmin field in the "Gulf of Mexico" region of L935. There we classify A, F, and G-type stars. However, the many faint K and M-type dwarf stars remain somewhat ambiguous in calibration and classification. But attaining reasonable progress, we turn to another part of L935 located near the Pelican head. This area includes the "bright rim" which is formed by dust and gas condensed by the light pressure of an unseen O-type star hidden behind the dense dark cloud. Straizys and Laugalys (2008 Baltic Astronomy, 17, 143 ) have identified this star to be one of the 2MASS objects with Av=23 mag. A few concentrations of faint stars, V 13 to 14 mag. are immersed in this dark region. Among these stars are a few known emission-line objects (T-Tauri or post T-Tauri stars). A half degree nearby are some photometric Vilnius standards we use to calibrate our new field. We call on 2MASS data for correlative information. Also the Stromvil photometry offers candidate stars for spectral observations. The aim of this study in the Vilnius and Stromvil photometric systems is to classify stars down to V = 18 mag., to confirm the existence of the young star clusters, and to determine the distance of the cloud covering the suspected hidden ionizing star.

  17. Deep Space 1 photometry of the nucleus of Comet P/19 Borrelly

    NASA Technical Reports Server (NTRS)

    Buratti, B. J.; Britt, D.; Oberst, J.; Soderblom, L. A.; Hillier, J. K.; Hicks, M. D.

    2002-01-01

    The NASA-JPL Deep Space 1 Mission (DS1) encountered the short-period Jupiter-family comet 19/P Borrelly on September 22, 2001, about 8 days after perihelion. DS1's payload contained a remote-sensing package that included a 1024 square CCD and a near IR spectrometer with 12nm resolution. Prior to its closest approach, the remote-sensing package on the spacecraft obtained 25 CCD images of the comet and 45 near-IR spectra.

  18. Deep Space 1 photometry of the nucleus of Comet P/19 Borrelly

    NASA Technical Reports Server (NTRS)

    Buratti, B. J.; Britt, D.; Oberst, J.; Soderblom, L. A.; Hillier, J. K.; Hicks, M. D.

    2002-01-01

    The NASA-JPL Deep Space 1 Mission (DS1) encountered the short-period Jupiter-family comet 19/P Borrelly on September 22, 2001, about 8 days after perihelion. DS1's payload contained a remote-sensing package that included a 1024 square CCD and a near IR spectrometer with 12nm resolution. Prior to its closest approach, the remote-sensing package on the spacecraft obtained 25 CCD images of the comet and 45 near-IR spectra.

  19. CANDELS MULTIWAVELENGTH CATALOGS: SOURCE IDENTIFICATION AND PHOTOMETRY IN THE CANDELS UKIDSS ULTRA-DEEP SURVEY FIELD

    SciTech Connect

    Galametz, Audrey; Grazian, Andrea; Fontana, Adriano; Castellano, Marco; Ferguson, Henry C.; Dahlen, Tomas; Grogin, Norman; Huang, Kuang-Han; Koekemoer, Anton M.; Ashby, M. L. N.; Willner, S. P.; Barro, Guillermo; Faber, Sandy M.; Guo, Yicheng; Kocevski, Dale D.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Peth, Michael; Almaini, Omar; Collaboration: CANDELS team; and others

    2013-06-01

    We present the multiwavelength-ultraviolet to mid-infrared-catalog of the UKIRT Infrared Deep Sky Survey (UKIDSS) Ultra-Deep Survey field observed as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). Based on publicly available data, the catalog includes the CANDELS data from the Hubble Space Telescope (near-infrared WFC3 F125W and F160W data and visible ACS F606W and F814W data); u-band data from CFHT/Megacam; B, V, R{sub c} , i', and z' band data from Subaru/Suprime-Cam; Y and K{sub s} band data from VLT/HAWK-I; J, H, and K band data from UKIDSS (Data Release 8); and Spitzer/IRAC data (3.6, 4.5 {mu}m from SEDS; 5.8 and 8.0 {mu}m from SpUDS). The present catalog is F160W-selected and contains 35, 932 sources over an area of 201.7 arcmin{sup 2} and includes radio- and X-ray-detected sources and spectroscopic redshifts available for 210 sources.

  20. CANDELS Multiwavelength Catalogs: Source Identification and Photometry in the CANDELS UKIDSS Ultra-deep Survey Field

    NASA Astrophysics Data System (ADS)

    Galametz, Audrey; Grazian, Andrea; Fontana, Adriano; Ferguson, Henry C.; Ashby, M. L. N.; Barro, Guillermo; Castellano, Marco; Dahlen, Tomas; Donley, Jennifer L.; Faber, Sandy M.; Grogin, Norman; Guo, Yicheng; Huang, Kuang-Han; Kocevski, Dale D.; Koekemoer, Anton M.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Peth, Michael; Willner, S. P.; Almaini, Omar; Cooper, Michael; Cooray, Asantha; Conselice, Christopher J.; Dickinson, Mark; Dunlop, James S.; Fazio, G. G.; Foucaud, Sebastien; Gardner, Jonathan P.; Giavalisco, Mauro; Hathi, N. P.; Hartley, Will G.; Koo, David C.; Lai, Kamson; de Mello, Duilia F.; McLure, Ross J.; Lucas, Ray A.; Paris, Diego; Pentericci, Laura; Santini, Paola; Simpson, Chris; Sommariva, Veronica; Targett, Thomas; Weiner, Benjamin J.; Wuyts, Stijn; the CANDELS Team

    2013-06-01

    We present the multiwavelength—ultraviolet to mid-infrared—catalog of the UKIRT Infrared Deep Sky Survey (UKIDSS) Ultra-Deep Survey field observed as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). Based on publicly available data, the catalog includes the CANDELS data from the Hubble Space Telescope (near-infrared WFC3 F125W and F160W data and visible ACS F606W and F814W data); u-band data from CFHT/Megacam; B, V, Rc , i', and z' band data from Subaru/Suprime-Cam; Y and Ks band data from VLT/HAWK-I; J, H, and K band data from UKIDSS (Data Release 8); and Spitzer/IRAC data (3.6, 4.5 μm from SEDS; 5.8 and 8.0 μm from SpUDS). The present catalog is F160W-selected and contains 35, 932 sources over an area of 201.7 arcmin2 and includes radio- and X-ray-detected sources and spectroscopic redshifts available for 210 sources.

  1. VizieR Online Data Catalog: Pan-STARRS1 transients optical photometry (Drout+, 2014)

    NASA Astrophysics Data System (ADS)

    Drout, M. R.; Chornock, R.; Soderberg, A. M.; Sanders, N. E.; McKinnon, R.; Rest, A.; Foley, R. J.; Milisavljevic, D.; Margutti, R.; Berger, E.; Calkins, M.; Fong, W.; Gezari, S.; Huber, M. E.; Kankare, E.; Kirshner, R. P.; Leibler, C.; Lunnan, R.; Mattila, S.; Marion, G. H.; Narayan, G.; Riess, A. G.; Roth, K. C.; Scolnic, D.; Smartt, S. J.; Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Jedicke, R.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Morgan, J. S.; Price, P. A.; Waters, C.

    2017-04-01

    PS1 is a wide-field imaging system dedicated to survey observations. Located on Haleakala, Hawaii, it possesses a 1.8 m diameter primary mirror and a 3.3° diameter field of view (Kaiser et al. 2010SPIE.7733E..0EK). The imager consists of an array of sixty 4800x4800 pixel detectors with a pixel scale of 0.258'', providing an instantaneous field of view of 7.1 deg2 (Tonry & Onaka 2009, Advanced Maui Optical and Space Surveillance Technologies Conference). Observations are obtained with a set of five broadband filters (gP1rP1iP1zP1yP1, hereafter grizyP1) which are similar, although not identical, to those used by the Sloan Digital Sky Survey (SDSS; Ahn et al. 2012ApJS..203...21A). Details of the filters and photometry system are given in Tonry et al. (2012, J/ApJ/750/99) and Stubbs et al. (2010ApJS..191..376S). (2 data files).

  2. Improving the repeatability of heterochromatic flicker photometry for measurement of macular pigment optical density.

    PubMed

    Howells, Olivia; Eperjesi, Frank; Bartlett, Hannah

    2013-03-01

    Heterochromatic flicker photometry (HFP) is a psychophysical technique used to measure macular pigment optical density (MPOD). We used the MPS 9000 (MPS) HFP device. Our aim was to determine if the repeatability of the MPS could be improved to make it more suitable for monitoring MPOD over time. Intra-session repeatability was assessed in 25 participants (aged 20-50 years). The resulting data was explored in detail, e.g., by examining the effect of removal and adjustment of data with less than optimal quality parameters. A protocol was developed for improved overall reliability, which was then tested in terms of inter-session repeatability in a separate group of 27 participants (aged 19-52 years). Removal and adjustment of data reduced the intra-session coefficient of repeatability (CR) by 0.04, on average, and the mean individual standard deviation by 0.004. Raw data observation offered further insight into ways of improving repeatability. The proposed protocol resulted in an inter-session CR of 0.08. Removal and adjustment of less than optimal data improved repeatability, and is therefore recommended. To further improve repeatability, in brief we propose that each patient perform each part of the test twice, and a third time where necessary (described in detail by the protocol). Doing so will make the MPS more useful in research and clinical settings.

  3. Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children.

    PubMed

    McCorkle, Sasha M; Raine, Lauren B; Hammond, Billy R; Renzi-Hammond, Lisa; Hillman, Charles H; Khan, Naiman A

    2015-10-16

    Macular pigment optical density (MPOD)-assessed using customized heterochromatic flicker photometry (cHFP)-is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7-10-year-olds (n = 66) underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46) with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59-session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27). There was no significant difference in the MPOD of boys vs. girls (p = 0.56). There was a significant correlation between sessions (Y = 0.52x + 0.31; R² = 0.29, p ≤ 0.005), with a reliability of 0.70 (Cronbach's α). Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R² = 0.32, p < 0.005), with a reliability of 0.72 (Cronbach's α). In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood.

  4. Ozone monitoring using differential optical absorption spectroscopy (DOAS) and UV photometry instruments in Sohar, Oman.

    PubMed

    Nawahda, Amin

    2015-08-01

    Ground level ozone (O3) concentrations were measured across Sohar highway in Oman during a four-month period from September to December 2014 by using an open-path deferential optical absorption spectroscopy (DOAS) instrument. The monthly average concentrations of O3 varied from 19.6 to 29.4 ppb. The measurements of O3 are compared with the measurements of a non-open-path UV photometry analyzer (UVP). The percent difference (PD) concept and linear regression methods were used to compare the readings of the two instruments. The findings show high correlation coefficients between the measurements of the DOAS and UVP instruments. The DOAS measurements of O3 are found to be less than those measured by the UVP instrument; the correlation coefficients between absolute PD values and meteorological parameters and PM2.5 were very low indicating a minor effect; therefore, titrations of O3 by traffic emissions and difference in elevation could be the reason for the difference in the measurements of the two instruments.

  5. Multi-Site Simultaneous Time-Resolved Photometry with a Low Cost Electro-Optics System †

    PubMed Central

    Gasdia, Forrest; Barjatya, Aroh; Bilardi, Sergei

    2017-01-01

    Sunlight reflected off of resident space objects can be used as an optical signal for astrometric orbit determination and for deducing geometric information about the object. With the increasing population of small satellites and debris in low Earth orbit, photometry is a powerful tool in operational support of space missions, whether for anomaly resolution or object identification. To accurately determine size, shape, spin rate, status of deployables, or attitude information of an unresolved resident space object, multi-hertz sample rate photometry is required to capture the relatively rapid changes in brightness that these objects can exhibit. OSCOM, which stands for Optical tracking and Spectral characterization of CubeSats for Operational Missions, is a low cost and portable telescope system capable of time-resolved small satellite photometry, and is field deployable on short notice for simultaneous observation from multiple sites. We present the electro-optical design principles behind OSCOM and light curves of the 1.5 U DICE-2 CubeSat and simultaneous observations of the main body of the ASTRO-H satellite after its fragmentation event. PMID:28556802

  6. Deep HST/ACS Photometry of an Arc of Young Stars in the Southern Halo of M82

    NASA Astrophysics Data System (ADS)

    Suwannajak, Chutipong

    2016-01-01

    We present deep HST/ACS photometry of an arclike, overdense region of stars in the southern halo of M82, located approximately 5 kpc from its disk. This arc feature was originally identified about a decade ago. The early ground-based studies suggested that it contains young stars with ages and metallicities similar to those that formed in the tidal tails between M81, M82, and NGC3077 during their interactions. The arc is clearly presented in the spatial distribution of stars in our field with significantly higher stellar density than the background M82 halo stars. The location of the tip of the red giant branch (RGB) reveals the arc to have a similar distance to M81 and M82, therefore confirming that it belongs to this interacting system. Combining our data with those from the ACS Nearby Galaxy Survey Treasury (ANGST), we construct a color-magnitude diagram (CMD) for the arc. A sequence of young stars is clearly presented on its CMD. This young main sequence is not seen in other parts of the M82 halo. Single-metallicity isochrones are used to derive the age of the young stars in the arc. We confirm that these stars exhibit ages consistent with young stars found in the HI bridges between M81, M82 and NGC3077. Furthermore, the mean metallicity of the RGB stars is also derived from their metallicity distribution function and found to be similar to that found in the HI bridges.

  7. Multi-colour optical photometry of V404 Cygni in outburst

    NASA Astrophysics Data System (ADS)

    Martí, Josep; Luque-Escamilla, Pedro L.; García-Hernández, María T.

    2016-02-01

    Context. This observational paper has been prepared in the context of the large multi-wavelength effort by many observers with the aim of following up the transient flaring event of V404 Cygni that took place for several weeks in 2015 June. Aims: Our main original aim was to contribute to the study of this transient source by acquiring broad-band photometric observations during its most active flaring phases. Nevertheless, after a detailed analysis of the data, several interesting results were obtained that encouraged a dedicated publication. Methods: The methodology used was based on broad-band differential CCD photometry. This outburst of V404 Cygni rendered the source a very bright target easily within reach of small educational telescopes. Therefore, the 41 cm telescope available at the Astronomical Observatory of the University of Jaén was used in this work. Results: We detected variability at different time scales, both in amplitude and colour. Individual optical flares appear every half hour on average during our 3 h long observation, although large-amplitude (~1 mag) variations are also observed to occur on intervals as short as 10 min. Also, colour variations appear to be highly correlated in a colour-colour diagram. Another remarkable finding is the detection of time lag, from about one to a fraction of a minute between light curves in different filters (VRcIc). Conclusions: The observed behaviour is tentatively interpreted in an scenario based on the ejection of non-thermal emitting, relativistic plasmons, with their synchrotron spectra extending up to optical wavelengths. This would render some of the V404 Cygni flares very similar to those of the well-know microquasar GRS 1915+105

  8. Discovery deep space optical communications (DSOC) transceiver

    NASA Astrophysics Data System (ADS)

    Roberts, W. Thomas

    2017-02-01

    NASA's 22 cm diameter Deep Space Optical Communications (DSOC) Transceiver is designed to provide a bidirectional optical link between a spacecraft in the inner solar system and an Earth-based optical ground station. This design, optimized for operation across a wide range of illumination conditions, is focused on minimizing blinding from stray light, and providing reliable, accurate attitude information to point its narrow communication beam accurately to the future location of the ground terminal. Though our transceiver will transmit in the 1550 nm waveband and receive in the 1064 nm waveband, the system design relies heavily on reflective optical elements, extending flexibility to be modified for use at different wavebands. The design makes use of common path propagation among transmit, receive and pointing verification optical channels to maintain precise alignment among its components, and to naturally correct for element misalignment resulting from launch or thermal element perturbations. This paper presents the results of trade studies showing the evolution of the design, unique operational characteristics of the design, elements that help to maintain minimal stray light contamination, and preliminary results from development and initial testing of a functional aluminum test model.

  9. THE HIGH A{sub V} Quasar Survey: Reddened Quasi-Stellar Objects selected from optical/near-infrared photometry. II

    SciTech Connect

    Krogager, J.-K.; Fynbo, J. P. U.; Vestergaard, M.; Geier, S.; Venemans, B. P.; Ledoux, C.; Møller, P.; Noterdaeme, P.; Kangas, T.; Pursimo, T.; Smirnova, O.; Saturni, F. G.

    2015-03-15

    Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2 μm flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2 μm relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs.

  10. Deep HST Photometry of NGC 6388: Age and Horizontal Branch Luminosity

    NASA Technical Reports Server (NTRS)

    Stetson, Peter B.; Catelan, M.; Pritzl, Barton J.; Smith, Horace A.; Kinemuchi, Karen; Layden, Andrew C.; Sweigart, Allen V.; Rich, R. M.

    2006-01-01

    We present the first deep color-magnitude diagram (CMD) of the Galactic globular cluster NGC 6388, obtained with the Hubble Space Telescope, that is able to reach the main-sequence turnoff point of the cluster. From a detailed comparison between the cluster CMD and that of 47 Tucanae (NGC 104), we find that the bulk of the stars in these two clusters have nearly the same age and chemical composition. On the other hand, our results indicate that the blue horizontal branch and RR Lyrae components in NGC 6388 are intrinsically over-luminous, which must be due to one or more, still undetermined, non-canonical second parameter(s) affecting a relatively minor fraction of the stars in NGC 6388.

  11. Deep-Space Optical Terminals (DOT)

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Farr, W. H.; Biswas, A.; Birnbaum, K. M.; Roberts, W. T.; Quirk, K.; Townes, S.

    2011-01-01

    A conceptual design study titled Deep-Space Optical Terminals was recently completed for an optical communication technology demonstration from Mars in the 2018 time frame. We report on engineering trades for the entire system, and for individual subsystems including the flight terminal, the ground receiver and the ground transmitter. A point design is described to meet the requirement for greater than 0.25 Gb/s downlink from the nearest distance to Mars of 0.42 AU with a maximum mass and power allocation of 40 kg and 110 W. Furthermore, the concept design addresses link closure at the farthest Mars range of 2.7 AU. Maximum uplink data-rate of 0.3 Mb/s and ranging with 30 cm precision are also addressed.

  12. Autonomous Deep-Space Optical Navigation Project

    NASA Technical Reports Server (NTRS)

    D'Souza, Christopher

    2014-01-01

    This project will advance the Autonomous Deep-space navigation capability applied to Autonomous Rendezvous and Docking (AR&D) Guidance, Navigation and Control (GNC) system by testing it on hardware, particularly in a flight processor, with a goal of limited testing in the Integrated Power, Avionics and Software (IPAS) with the ARCM (Asteroid Retrieval Crewed Mission) DRO (Distant Retrograde Orbit) Autonomous Rendezvous and Docking (AR&D) scenario. The technology, which will be harnessed, is called 'optical flow', also known as 'visual odometry'. It is being matured in the automotive and SLAM (Simultaneous Localization and Mapping) applications but has yet to be applied to spacecraft navigation. In light of the tremendous potential of this technique, we believe that NASA needs to design a optical navigation architecture that will use this technique. It is flexible enough to be applicable to navigating around planetary bodies, such as asteroids.

  13. Deep-Space Optical Terminals (DOT)

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Farr, W. H.; Biswas, A.; Birnbaum, K. M.; Roberts, W. T.; Quirk, K.; Townes, S.

    2011-01-01

    A conceptual design study titled Deep-Space Optical Terminals was recently completed for an optical communication technology demonstration from Mars in the 2018 time frame. We report on engineering trades for the entire system, and for individual subsystems including the flight terminal, the ground receiver and the ground transmitter. A point design is described to meet the requirement for greater than 0.25 Gb/s downlink from the nearest distance to Mars of 0.42 AU with a maximum mass and power allocation of 40 kg and 110 W. Furthermore, the concept design addresses link closure at the farthest Mars range of 2.7 AU. Maximum uplink data-rate of 0.3 Mb/s and ranging with 30 cm precision are also addressed.

  14. Deep photometry of two accreted families of globular clusters in the remote M31 halo

    NASA Astrophysics Data System (ADS)

    Mackey, Dougal

    2013-10-01

    Globular clusters {GCs} are fossil relics from which we can obtain critical insights into the merger and accretion events that underlie hierarchical galaxy assembly. As part of the major Pan-Andromeda Archaeological Survey {PAndAS} we have discovered two groups of GCs that closely trace narrow stellar debris streams in the M31 halo. These clearly represent two distinct accreted families of GCs - the only known examples apart from the few Galactic GCs arriving with the Sagittarius dwarf. We propose to obtain deep ACS imaging of 14 GCs spanning these two accreted families, allowing us to measure the constituent stellar populations, line-of-sight distance, and structural parameters of each object. We will, for the first time, quantify the typical properties of accreted GCs in the M31 halo as well as the degree of variation amongst them, and how closely they correspond to the suspected accreted GC population in the Milky Way. Combined with new radial velocity measurements for the GCs, our proposed observations will allow us to trace the 3D orbits of the two streams within the M31 halo, and thus break the main degeneracies that plague numerical models designed to probe the gravitational potential and distribution of dark mass.

  15. Deep Space Optical Link ARQ Performance Analysis

    NASA Technical Reports Server (NTRS)

    Clare, Loren; Miles, Gregory

    2016-01-01

    Substantial advancements have been made toward the use of optical communications for deep space exploration missions, promising a much higher volume of data to be communicated in comparison with present -day Radio Frequency (RF) based systems. One or more ground-based optical terminals are assumed to communicate with the spacecraft. Both short-term and long-term link outages will arise due to weather at the ground station(s), space platform pointing stability, and other effects. To mitigate these outages, an Automatic Repeat Query (ARQ) retransmission method is assumed, together with a reliable back channel for acknowledgement traffic. Specifically, the Licklider Transmission Protocol (LTP) is used, which is a component of the Disruption-Tolerant Networking (DTN) protocol suite that is well suited for high bandwidth-delay product links subject to disruptions. We provide an analysis of envisioned deep space mission scenarios and quantify buffering, latency and throughput performance, using a simulation in which long-term weather effects are modeled with a Gilbert -Elliot Markov chain, short-term outages occur as a Bernoulli process, and scheduled outages arising from geometric visibility or operational constraints are represented. We find that both short- and long-term effects impact throughput, but long-term weather effects dominate buffer sizing and overflow losses as well as latency performance.

  16. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  17. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  18. Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children

    PubMed Central

    McCorkle, Sasha M.; Raine, Lauren B.; Hammond, Billy R.; Renzi-Hammond, Lisa; Hillman, Charles H.; Khan, Naiman A.

    2015-01-01

    Macular pigment optical density (MPOD)—assessed using customized heterochromatic flicker photometry (cHFP)—is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7–10-year-olds (n = 66) underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46) with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59—session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27). There was no significant difference in the MPOD of boys vs. girls (p = 0.56). There was a significant correlation between sessions (Y = 0.52x + 0.31; R2 = 0.29, p ≤ 0.005), with a reliability of 0.70 (Cronbach’s α). Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R2 = 0.32, p < 0.005), with a reliability of 0.72 (Cronbach’s α). In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood. PMID:28231224

  19. Optical Photometry of the New Optical Transient SN 2010da in NGC 300

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.

    2010-05-01

    Multicolor images of the new optical transient in NGC 300, discovered by B. Monard (CBET #2289 and private communication), were obtained on 2010 May 25.37 by J. Espinoza with the SMARTS 1.3m telescope at Cerro Tololo and the ANDICAM camera. The transient has received the designation SN 2010da, although spectroscopic observations and the low luminosity suggest that it is most probably an LBV-like outburst on a dust-enshrouded massive star and not a true supernova (e.g., ATEL #2632, #2633, #2636, #2637, #2638).

  20. On the RR Lyrae Stars in Globulars. IV. ω Centauri Optical UBVRI Photometry

    NASA Astrophysics Data System (ADS)

    Braga, V. F.; Stetson, P. B.; Bono, G.; Dall'Ora, M.; Ferraro, I.; Fiorentino, G.; Freyhammer, L. M.; Iannicola, G.; Marengo, M.; Neeley, J.; Valenti, E.; Buonanno, R.; Calamida, A.; Castellani, M.; da Silva, R.; Degl'Innocenti, S.; Di Cecco, A.; Fabrizio, M.; Freedman, W. L.; Giuffrida, G.; Lub, J.; Madore, B. F.; Marconi, M.; Marinoni, S.; Matsunaga, N.; Monelli, M.; Persson, S. E.; Piersimoni, A. M.; Pietrinferni, A.; Prada-Moroni, P.; Pulone, L.; Stellingwerf, R.; Tognelli, E.; Walker, A. R.

    2016-12-01

    New accurate and homogeneous optical UBVRI photometry has been obtained for variable stars in the Galactic globular cluster ω Cen (NGC 5139). We secured 8202 CCD images covering a time interval of 24 years and a sky area of 84 × 48 arcmin. The current data were complemented with data available in the literature and provided new, homogeneous pulsation parameters (mean magnitudes, luminosity amplitudes, periods) for 187 candidate ω Cen RR Lyrae (RRLs). Among them we have 101 RRc (first overtone) and 85 RRab (fundamental) variables, and a single candidate RRd (double-mode) variable. Candidate Blazhko RRLs show periods and colors that are intermediate between the RRc and RRab variables, suggesting that they are transitional objects. A comparison of the period distribution and the Bailey diagram indicates that RRLs in ω Cen show a long-period tail not present in typical Oosterhoff II (OoII) globulars. The RRLs in dwarf spheroidals and in ultra-faint dwarfs have properties between Oosterhoff intermediate and OoII clusters. Metallicity plays a key role in shaping the above evidence. These findings do not support the hypothesis that ω Cen is the core remnant of a spoiled dwarf galaxy. Using optical period-Wesenheit relations that are reddening-free and minimally dependent on metallicity we find a mean distance to ω Cen of 13.71 ± 0.08 ± 0.01 mag (semi-empirical and theoretical calibrations). Finally, we invert the I-band period-luminosity-metallicity relation to estimate individual RRLs’ metal abundances. The metallicity distribution agrees quite well with spectroscopic and photometric metallicity estimates available in the literature. Based in part on proprietary data and on data obtained from the ESO Science Archive Facility under multiple requests by the authors; and in part upon data distributed by the NOAO Science Archive. NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National

  1. Highlights from the Center for Adaptive Optics Treasury Survey of Distant Galaxies, Including H-band Photometry of a z=1.3 Supernova

    NASA Astrophysics Data System (ADS)

    Melbourne, J.; Barczys, M.; Wright, S. A.; Max, C. E.; Larkin, J.; Koo, D. C.; Perlmutter, S.; Steinbring, E.; Metevier, A.; Chun, M.

    2005-12-01

    The Center for Adaptive Optics Treasury Survey (CATS) is observing the deep HST galaxy fields (e.g., GOODS-N and S, COSMOS, GEMS, and EGS) with high-resolution near-infrared imaging from ground-based adaptive optics on large telescopes. Initial results from the first ten Keck laser guide star pointings are presented. Highlights include, 1) H-band (rest-frame R) photometry over maximum of a z=1.32 Type Ia supernova from the HST cluster supernova search of Perlmutter et al. (see poster of Dawson et al.); 2) a near-infrared study of small bulges of distant disk galaxies (z ˜0.6); 3) Stellar population synthesis models of AGN cores to z=1; and 4) Detection of lensed arcs around a z=0.20 cluster. CATS plans its first public data release in Fall 2006. This work is funded by the NSF Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under the cooperative agreement No. AST-9876783.

  2. Optical ground station site diversity for Deep Space Optical Communications the Mars Telecom Orbiter optical link

    NASA Technical Reports Server (NTRS)

    Wilson, K.; Parvin, B.; Fugate, R.; Kervin, P.; Zingales, S.

    2003-01-01

    Future NASA deep space missions will fly advanced high resolution imaging instruments that will require high bandwidth links to return the huge data volumes generated by these instruments. Optical communications is a key technology for returning these large data volumes from deep space probes. Yet to cost effectively realize the high bandwidth potential of the optical link will require deployment of ground receivers in diverse locations to provide high link availability. A recent analysis of GOES weather satellite data showed that a network of ground stations located in Hawaii and the Southwest continental US can provide an average of 90% availability for the deep space optical link. JPL and AFRL are exploring the use of large telescopes in Hawaii, California, and Albuquerque to support the Mars Telesat laser communications demonstration. Designed to demonstrate multi-Mbps communications from Mars, the mission will investigate key operational strategies of future deep space optical communications network.

  3. Optical ground station site diversity for Deep Space Optical Communications the Mars Telecom Orbiter optical link

    NASA Technical Reports Server (NTRS)

    Wilson, K.; Parvin, B.; Fugate, R.; Kervin, P.; Zingales, S.

    2003-01-01

    Future NASA deep space missions will fly advanced high resolution imaging instruments that will require high bandwidth links to return the huge data volumes generated by these instruments. Optical communications is a key technology for returning these large data volumes from deep space probes. Yet to cost effectively realize the high bandwidth potential of the optical link will require deployment of ground receivers in diverse locations to provide high link availability. A recent analysis of GOES weather satellite data showed that a network of ground stations located in Hawaii and the Southwest continental US can provide an average of 90% availability for the deep space optical link. JPL and AFRL are exploring the use of large telescopes in Hawaii, California, and Albuquerque to support the Mars Telesat laser communications demonstration. Designed to demonstrate multi-Mbps communications from Mars, the mission will investigate key operational strategies of future deep space optical communications network.

  4. VizieR Online Data Catalog: WINGS: Deep optical phot. of 77 nearby clusters (Varela+, 2009)

    NASA Astrophysics Data System (ADS)

    Varela, J.; D'Onofrio, M.; Marmo, C.; Fasano, G.; Bettoni, D.; Cava, A.; Couch, J. W.; Dressler, A.; Kjaergaard, P.; Moles, M.; Pignatelli, E.; Poggianti, M. B.; Valentinuzzi, T.

    2009-05-01

    This is the second paper of a series devoted to the WIde Field Nearby Galaxy-cluster Survey (WINGS). WINGS is a long term project which is gathering wide-field, multi-band imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected, nearby clusters (0.04200deg). The main goal of this project is to establish a local reference for evolutionary studies of galaxies and galaxy clusters. This paper presents the optical (B,V) photometric catalogs of the WINGS sample and describes the procedures followed to construct them. We have paid special care to correctly treat the large extended galaxies (which includes the brightest cluster galaxies) and the reduction of the influence of the bright halos of very bright stars. We have constructed photometric catalogs based on wide-field images in B and V bands using SExtractor. Photometry has been performed on images in which large galaxies and halos of bright stars were removed after modeling them with elliptical isophotes. We publish deep optical photometric catalogs (90% complete at V21.7, which translates to ~ MV* + 6 at mean redshift), giving positions, geometrical parameters, and several total and aperture magnitudes for all the objects detected. For each field we have produced three catalogs containing galaxies, stars and objects of "unknown" classification (~16%). From simulations we found that the uncertainty of our photometry is quite dependent of the light profile of the objects with stars having the most robust photometry and de Vaucouleurs profiles showing higher uncertainties and also an additional bias of ~-0.2m. The star/galaxy classification of the bright objects (V<20) was checked visually making negligible the fraction of misclassified objects. For fainter objects, we found that simulations do not provide reliable estimates of the possible misclassification and therefore we have compared our data with that from deep counts of galaxies and star counts from models of our Galaxy. Both sets turned

  5. The VVDS-VLA deep field. IV. Radio-optical properties

    NASA Astrophysics Data System (ADS)

    Bardelli, S.; Zucca, E.; Bolzonella, M.; Ciliegi, P.; Gregorini, L.; Zamorani, G.; Bondi, M.; Zanichelli, A.; Tresse, L.; Vergani, D.; Gavignaud, I.; Bongiorno, A.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Adami, C.; Arnouts, S.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Iovino, A.; Lamareille, F.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Paltani, S.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Abbas, U.; Brinchmann, J.; Cucciati, O.; de La Torre, S.; de Ravel, L.; Memeo, P.; Perez-Montero, E.; Mellier, Y.; Merluzzi, P.; Temporin, S.; de Ruiter, H. R.; Parma, P.

    2009-02-01

    Aims: The availability of wide angle and deep surveys, both in the optical and the radio band, allows us to explore the evolution of radio sources with optical counterparts up to redshift z˜ 1.1 in an unbiased way using large numbers of radio sources and well defined control samples of radio-quiet objects. Methods: We use the 1.4 GHz VIMOS-VLA Deep Survey, the optical VIMOS-VLT Deep Survey and the CFHT Legacy Survey to compare the properties of radio-loud galaxies with respect to the whole population of optical galaxies. The availability of multiband photometry and high quality photometric redshifts allows us to derive rest-frame colors and radio luminosity functions to a limit of a B rest-frame magnitude of M_B=-20. We derive spectrophotometric types, following the classification of Zucca et al. (2006, A&A, 455, 879), in order to have a priori knowledge of the optical evolution of different galaxy classes. Results: Galaxy properties and luminosity functions are estimated up to z˜ 1 for radio-loud and radio-quiet early and late type galaxies. Radio-loud late type galaxies show significantly redder colors than radio-quiet objects of the same class and this is related to the presence of more dust in stronger star forming galaxies. We estimate the optical luminosity functions, stellar masses and star formation rate distributions for radio sources and compare them with those derived for a well defined control sample, finding that the probability of a galaxy to be a radio emitter significantly increases at high values of these parameters. Radio-loud early type galaxies exhibit luminosity evolution in their bivariate radio-optical luminosity function, due to evolution in the radio-optical ratio. The lack of evolution of the mass function of radio-loud early type galaxies means that no new AGN are formed at redshift z<1. In contrast, radio-loud late type objects exhibit a strong evolution, both in luminosity and density, of the radio luminosity function for z>0.7. This

  6. Optical photometry of GM Cep: evidence for UXor type of variability

    NASA Astrophysics Data System (ADS)

    Semkov, E. H.; Peneva, S. P.

    2012-03-01

    Results from optical photometric observations of the pre-main sequence star GM Cep are reported in the paper. The star is located in the field of the young open cluster Trumpler 37—a region of active star formation. GM Cep shows a large amplitude rapid variability interpreted as a possible outburst from EXor type in previous studies. Our data from BVRI CCD photometric observations of the star are collected from June 2008 to February 2011 in Rozhen observatory (Bulgaria) and Skinakas observatory (Crete, Greece). A sequence of sixteen comparison stars in the field of GM Cep was calibrated in the BVRI bands. Our photometric data for a 2.5 years period show a high amplitude variations (Δ V ˜2. m3) and two deep minimums in brightness are observed. The analysis of collected multicolor photometric data shows the typical of UX Ori variables a color reversal during the minimums in brightness. On the other hand, high amplitude rapid variations in brightness typical for the Classical T Tauri stars also present on the light curve of GM Cep. Comparing our results with results published in the literature, we conclude that changes in brightness are caused by superposition of both: (1) magnetically channeled accretion from the circumstellar disk, and (2) occultation from circumstellar clouds of dust or from features of a circumstellar disk.

  7. Second Workshop on Improvements to Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor)

    1988-01-01

    The papers in these proceedings show that a major effort is under way to improve all aspects of photometry. Astronomical multichannel photometry, photodiodes, analog-to-digital converters, data reduction techniques, interference filters and optical fibers are discussed.

  8. Reference-less Detection, Astrometry, and Photometry of Faint Companions with Adaptive Optics at 1, 2 and 5 ?m

    NASA Astrophysics Data System (ADS)

    Gladysz, S.; Christou, J.; Kenworthy, M.; Law, N.; Dekany, R.

    We propose a complete framework for detection, differential astrometry and photometry of faint companions, e.g. planets orbiting stars other than the Sun. The algorithms exploit the difference in statistics between the on-axis and off-axis intensity and in principle do not require the signal to be above the noise level. To test the accuracy of the proposed methods we used adaptive-optics short-exposure data from three observing campaigns: I-band observations with the 5m telescope at the Palomar Observatory, K-band data from the Lick Observatory's 3m telescope, and M-band images from the MMT Observatory's 6.5m telescope. We show that our algorithms outperform the classic procedures of PSF-subtraction for detection and PSF-fitting for photometry. All three proposed techniques are self-calibrating, i.e. they do not require observation of a calibration star after the science target thus improving the observing efficiency.

  9. Constrained coding for the deep-space optical channel

    NASA Technical Reports Server (NTRS)

    Moision, B. E.; Hamkins, J.

    2002-01-01

    We investigate methods of coding for a channel subject to a large dead-time constraint, i.e. a constraint on the minimum spacing between transmitted pulses, with the deep-space optical channel as the motivating example.

  10. Sub-microradian pointing for deep space optical telecommunications network

    NASA Technical Reports Server (NTRS)

    Ortiz, G.; Lee, S.; Alexander, J.

    2001-01-01

    This presentation will cover innovative hardware, algorithms, architectures, techniques and recent laboratory results that are applicable to all deep space optical communication links, such as the Mars Telecommunication Network to future interstellar missions.

  11. Space Station-based deep-space optical communication experiments

    NASA Technical Reports Server (NTRS)

    Chen, Chien-Chung; Schwartz, Jon A.

    1988-01-01

    A series of three experiments proposed for advanced optical deep-space communications is described. These proposed experiments would be carried out aboard the Space Station to test and evaluate the capability of optical instruments to conduct data communication and spacecraft navigation for deep-space missions. Techniques for effective data communication, precision spacecraft ranging, and accurate angular measurements will be developed and evaluated in a spaceborne environment.

  12. Standard Galactic Field RR Lyrae. I. Optical to Mid-infrared Phased Photometry

    NASA Astrophysics Data System (ADS)

    Monson, Andrew J.; Beaton, Rachael L.; Scowcroft, Victoria; Freedman, Wendy L.; Madore, Barry F.; Rich, Jeffrey A.; Seibert, Mark; Kollmeier, Juna A.; Clementini, Gisella

    2017-03-01

    We present a multi-wavelength compilation of new and previously published photometry for 55 Galactic field RR Lyrae variables. Individual studies, spanning a time baseline of up to 30 years, are self-consistently phased to produce light curves in 10 photometric bands covering the wavelength range from 0.4 to 4.5 microns. Data smoothing via the GLOESS technique is described and applied to generate high-fidelity light curves, from which mean magnitudes, amplitudes, rise times, and times of minimum and maximum light are derived. 60,000 observations were acquired using the new robotic Three-hundred MilliMeter Telescope (TMMT), which was first deployed at the Carnegie Observatories in Pasadena, CA, and is now permanently installed and operating at Las Campanas Observatory in Chile. We provide a full description of the TMMT hardware, software, and data reduction pipeline. Archival photometry contributed approximately 31,000 observations. Photometric data are given in the standard Johnson UBV, Kron-Cousins {R}C{I}C, 2MASS JHK, and Spitzer [3.6] and [4.5] bandpasses.

  13. Statistics of intensity in adaptive-optics images and their usefulness for detection and photometry of exoplanets.

    PubMed

    Gladysz, Szymon; Yaitskova, Natalia; Christou, Julian C

    2010-11-01

    This paper is an introduction to the problem of modeling the probability density function of adaptive-optics speckle. We show that with the modified Rician distribution one cannot describe the statistics of light on axis. A dual solution is proposed: the modified Rician distribution for off-axis speckle and gamma-based distribution for the core of the point spread function. From these two distributions we derive optimal statistical discriminators between real sources and quasi-static speckles. In the second part of the paper the morphological difference between the two probability density functions is used to constrain a one-dimensional, "blind," iterative deconvolution at the position of an exoplanet. Separation of the probability density functions of signal and speckle yields accurate differential photometry in our simulations of the SPHERE planet finder instrument.

  14. The calibration of read-out-streak photometry in the XMM-Newton Optical Monitor and the construction of a bright-source catalogue

    NASA Astrophysics Data System (ADS)

    Page, M. J.; Chan, N.; Breeveld, A. A.; Talavera, A.; Yershov, V.; Kennedy, T.; Kuin, N. P. M.; Hancock, B.; Smith, P. J.; Carter, M.

    2017-04-01

    The dynamic range of the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded from its micro-channel-plate (MCP) intensified charge-coupled device (CCD) detector. One way to overcome this limitation is to use photons that arrive during the frame transfer of the CCD, forming vertical read-out streaks for bright sources. We calibrate these read-out streaks for photometry of bright sources observed with XMM-OM. The bright-source limit for read-out-streak photometry is set by the recharge time of the MCPs. For XMM-OM, we find that the MCP recharge time is 5.5 × 10-4 s. We determine that the effective bright limits for read-out-streak photometry with XMM-OM are approximately 1.5 mag brighter than the bright-source limits for normal aperture photometry in full-frame images. This translates into bright-source limits in Vega magnitudes of UVW2=7.1, UVM2=8.0, UVW1=9.4, U=10.5, B=11.5, V=10.2, and White=12.5 for data taken early in the mission. The limits brighten by up to 0.2 mag, depending on filter, over the course of the mission as the detector ages. The method is demonstrated by deriving UVW1 photometry for the symbiotic nova RR Telescopii, and the new photometry is used to constrain the e-folding time of its decaying ultraviolet (UV) emission. Using the read-out-streak method, we obtain photometry for 50 per cent of the missing UV source measurements in version 2.1 of the XMM-Newton Serendipitous UV Source Survey catalogue.

  15. Exo-atmospheric telescopes for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Hurd, William J.; MacNeal, Bruce E.; Ortiz, Gerardo G.; Cheng, Edward S.; Moe, Rud V.; Walker, Jon Z.; Fairbrother, Debora A.; Dennis, Michael L.; Eegholm, Bente; Kasunic, Keith J.

    2006-01-01

    For deep space optical communications, optical telescopes located above the Earth's atmosphere would have significant performance advantages over telescopes mounted on the Earth's surface. Link outages due to could cover would be eliminated, atmospheric attenuation would be eliminated, and signal degradation due to stray light would be reduced.

  16. A note on deep space optical communication link parameters

    NASA Technical Reports Server (NTRS)

    Dolinar, S. J.; Yuen, J. H.

    1982-01-01

    Topical communication in the context of a deep space communication link. Communication link analysis at the optical frequencies differs significantly from that at microwave frequencies such as the traditional S and X-bands used in deep space applications, due to the different technology of transmitter, antenna, modulators, and receivers. In addition, the important role of quantum noise in limiting system performance is quite different than that of thermal noise. The optical link design is put in a design control table format similar to a microwave telecom link design. Key considerations unique to the optical link are discussed.

  17. Exo-atmospheric telescopes for Deep Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Hurd, William J.; Moe, Rud V.; Dennis, Michael L.; MacNeal, Bruce E.; Walker, Jon Z.; Ortiz, Gerardo G.; Eegholm, Bente; Fairbrother, debora A.; Cheng, Edward S.; Kasunic, Keith J.

    2006-01-01

    For deep space optical communications, optical telescopes located above the Earth's atmosphere would have significant performance advantages over telescopes mounted on the Earth's surface. Link outages due to cloud cover would be eliminated, atmospheric attenuation would be eliminated, and signal degradation due to stray light would be reduced. A study has been conducted to compare various exo-atmospheric platforms for the Earth end of the optical link.

  18. Quasi-stellar objects in the ALHAMBRA survey. I. Photometric redshift accuracy based on 23 optical-NIR filter photometry

    NASA Astrophysics Data System (ADS)

    Matute, I.; Márquez, I.; Masegosa, J.; Husillos, C.; del Olmo, A.; Perea, J.; Alfaro, E. J.; Fernández-Soto, A.; Moles, M.; Aguerri, J. A. L.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; Infante, L.; González Delgado, R. M.; Martínez, V. J.; Molino, A.; Prada, F.; Quintana, J. M.

    2012-06-01

    Context. Even the spectroscopic capabilities of today's ground and space-based observatories can not keep up with the enormous flow of detections (>105 deg-2) unveiled in modern cosmological surveys as: i) would be required enormous telescope time to perform the spectroscopic follow-ups and ii) spectra remain unattainable for the fainter detected population. In the past decade, the typical accuracy of photometric redshift (photo-z) determination has drastically improved. Nowdays, it has become a perfect complement to spectroscopy, closing the gap between photometric surveys and their spectroscopic follow-ups. The photo-z precision for active galactic nuclei (AGN) has always lagged behind that for the galaxy population owing to the lack of proper templates and their intrinsic variability. Aims: Our goal is to characterize the ability of the Advanced Large, Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey in assigning accurate photo-z's to broad-line AGN (BLAGN) and quasi-stellar objects (QSOs) based on their ALHAMBRA very-low-resolution optical-near-infrared (NIR) spectroscopy. This will serve as a benchmark for any future compilation of ALHAMBRA selected QSOs and the basis for the statistical analysis required to derive luminosity functions up to z ~ 5. Methods: We selected a sample of spectroscopically identified BLAGN and QSOs and used a library of templates (including the SEDs of AGN and both normal and starburst galaxies, as well as stars) to fit the 23 photometric data points provided by ALHAMBRA in the optical and NIR (20 medium-band optical filters plus the standard JHKs). Results: We find that the ALHAMBRA photometry is able to provide an accurate photo-z and spectral classification for ~88% of the 170 spectroscopically identified BLAGN/QSOs over 2.5 deg2 in different areas of the survey and brighter than m678 = 23.5 (equivalent to rSLOAN ~ 24.0). The derived photo-z accuracy is below 1% and is comparable to the most recent results in

  19. Asteroid photometry

    USGS Publications Warehouse

    Li, Jian-Yang; Helfenstein, Paul; Buratti, Bonnie J.; Takir, Driss; Beth Ellen Clark,; Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

    2015-01-01

    Asteroid photometry has three major applications: providing clues about asteroid surface physical properties and compositions, facilitating photometric corrections, and helping design and plan ground-based and spacecraft observations. The most significant advances in asteroid photometry in the past decade were driven by spacecraft observations that collected spatially resolved imaging and spectroscopy data. In the mean time, laboratory measurements and theoretical developments are revealing controversies regarding the physical interpretations of models and model parameter values. We will review the new developments in asteroid photometry that have occurred over the past decade in the three complementary areas of observations, laboratory work, and theory. Finally we will summarize and discuss the implications of recent findings.

  20. Retrieval of optical depth and particle size distribution of tropospheric and stratospheric aerosols by means of sun photometry

    SciTech Connect

    Schmid, B.; Maetzler, C.; Kaempfer, N.; Heimo, A.

    1997-01-01

    Aerosol optical depth measurements by means of ground-based Sun photometry were made in Bern, Switzerland during two and a half years primarily to provide quantitative corrections for atmospheric effects in remotely sensed data in the visible and near-infrared spectral region. An investigation of the spatial variability of tropospheric aerosol was accomplished in the summer of 1994 in the Swiss Central Plain, a region often covered by a thick aerosol layer. Intercomparisons are made with two Sun photometers operated by the Swiss Meteorological Institute in Payerne and Davos. By means of an inversion technique, columnar particle size distributions were derived from the aerosol optical depth spectra. Effective radius, columnar surface area, and columnar mass were computed from the inversion results. Most of the spectra measured in Bern exhibit an Angstroem-law dependence. Consequently, the inverted size distributions are very close to power-law distributions. Data collected during a four month calibration campaign in fall 1993 at a high-mountain station in the Swiss Alps allowed the authors to study optical properties of stratospheric aerosol. The extinction spectra measured have shown to be still strongly influenced by remaining aerosol of the June 1991 volcanic eruptions of Mount Pinatubo. Inverted particle size distributions can be characterized by a broad monodisperse peak with a mode radius around 0.25 {micro}m. Both aerosol optical depths and effective radii had not yet returned to pre-eruption values. Comparison of retrieved aerosol optical depth, columnar surface area and mass, with the values derived from lidar observations performed in Garmisch-Partenkirchen, Southern-Germany, yielded good agreement.

  1. Neptune's Increasing Brightness Since 1989: Inferences from Photometry, Voyager and HST Images, and Recent Keck Adapative Optics Images

    NASA Astrophysics Data System (ADS)

    Lockwood, G. W.; Hammel, H. B.

    2000-10-01

    The light curve of Neptune, measured on more than 300 nights since 1972 at the Lowell Observatory using b (472 nm) and y (551 nm) interference filters, displays two distinct patterns. Before 1989 the brightness rose and fell, seemingly in response to solar activity or some other low frequency stimulus (G. W.Lockwood and D. T. Thompson 1991, Nature 349, 593). Beginning around 1989 the brightness has increased steadily by 0.6-0.8% per year and the cumulative increase since 1971 is now more than 10%. Only a minuscule fraction can be accounted for by Neptune's changing aspect as seen from Earth; most of the variation is due to varying amounts of clouds and global haze. During the Voyager enounter in 1989, Neptune's appearance was dominated by the Great Dark Spot and its associated Bright Companion. Ground-based observations during the encounter allow comparison of these features with their photometric signatures. At visible wavelengths, the photometric effect of the GDS transit is quite small (no more than 1-2%), but changes in the methane bands are much larger and have been measured from Voyager images at 619 nm, Lowell spectrophotometry near 619 and 726 nm, Perth Observatory photometry at 726 nm, and Mauna Kea CCD images at 889 nm. Recent Hubble Space Telescope imaging from 1994 to 1998 and near-IR images obtained in August 2000 using the Keck Observatory adaptive optics system allow comparisons of photometry and images over much of the epoch of steadily rising planetary brightness. We expect this comparison to provide a more comprehensive view of Neptune's long term atmospheric changes. This work was supported by grants from NASA and STScI.

  2. The use of heterochromatic flicker photometry to determine macular pigment optical density in a healthy Australian population.

    PubMed

    Abell, Robin G; Hewitt, Alex W; Andric, Marko; Allen, Penelope L; Verma, Nitin

    2014-03-01

    To establish the normal macular pigment density (MPOD) in a healthy adult Australian sample using heterochromatic flicker photometry (HFP). Macular pigment density was measured using heterochromatic flicker photometry in a total of 201 subjects ranging in age from 21 to 84 years with healthy macula. Fifty-seven of the healthy subjects also completed a food-frequency dietary questionnaire. Best-corrected visual acuity (BCVA) was measured using logMAR, chart and macular morphological profiles were assessed using high-resolution integrated Fourier-domain optical coherence tomography (OCT). The average MPOD value was 0.41 ± 0.20 (range 0.07-0.79). There was no statistically significant difference between values in the left and right eye, with good interocular agreement (0.41 vs 0.40, r = 0.893, p < 0.01). Age significantly predicted MPOD score (R (2) = 0.07, p < 0.05). A subgroup analysis of patients who completed the dietary questionnaire revealed a close correlation between higher diet scores and higher MPOD (r = 0.720 p = 0.031). There was no effect of smoking, gender, or iris colour on MPOD values. There was no significant correlation between BCVA, macular OCT profiles, and MPOD. Given that MPOD values are potentially affected by geographical variation, we have determined a mean MPOD value for healthy subjects in a population south of the equator, providing a reference point for future studies on Caucasian samples.

  3. Optical Communications for Extreme Deep Space Missions

    NASA Technical Reports Server (NTRS)

    Lesh, James; Deutsch, Leslie; Edwards, Charles

    1996-01-01

    A recent study of deep space telecommunications systems was performed in support of NASA's Mission to the Solar System planing activity. The results show that high bandwidth communications (greater than 1Mbps) are feasible at high-value planetary targets provided there are investments in the ground and spacecraft communication infrastructure.

  4. Macular pigment optical density measurements: evaluation of a device using heterochromatic flicker photometry.

    PubMed

    de Kinkelder, R; van der Veen, R L P; Verbaak, F D; Faber, D J; van Leeuwen, T G; Berendschot, T T J M

    2011-01-01

    Accurate assessment of the amount of macular pigment (MPOD) is necessary to investigate the role of carotenoids and their assumed protective functions. High repeatability and reliability are important to monitor patients in studies investigating the influence of diet and supplements on MPOD. We evaluated the Macuscope (Macuvision Europe Ltd., Lapworth, Solihull, UK), a recently introduced device for measuring MPOD using the technique of heterochromatic flicker photometry (HFP). We determined agreement with another HFP device (QuantifEye; MPS 9000 series: Tinsley Precision Instruments Ltd., Croydon, Essex, UK) and a fundus reflectance method. The right eyes of 23 healthy subjects (mean age 33.9 ± 15.1 years) were measured. We determined agreement with QuantifEye and correlation with a fundus reflectance method. Repeatability of QuantifEye was assessed in 20 other healthy subjects (mean age 32.1 ± 7.3 years). Repeatability was also compared with measurements by a fundus reflectance method in 10 subjects. We found low agreement between test and retest measurements with Macuscope. The average difference and the limits of agreement were -0.041 ± 0.32. We found high agreement between test and retest measurements of QuantifEye (-0.02 ± 0.18) and the fundus reflectance method (-0.04 ± 0.18). MPOD data obtained by Macuscope and QuantifEye showed poor agreement: -0.017 ± 0.44. For Macuscope and the fundus reflectance method, the correlation coefficient was r = 0.05 (P = 0.83). A significant correlation of r = 0.87 (P<0.001) was found between QuantifEye and the fundus reflectance method. Because repeatability of Macuscope measurements was low (ie, wide limits of agreement) and MPOD values correlated poorly with the fundus reflectance method, and agreed poorly with QuantifEye, the tested Macuscope protocol seems less suitable for studying MPOD.

  5. Macular pigment optical density measurements: evaluation of a device using heterochromatic flicker photometry

    PubMed Central

    de Kinkelder, R; van der Veen, R L P; Verbaak, F D; Faber, D J; van Leeuwen, T G; Berendschot, T T J M

    2011-01-01

    Purpose Accurate assessment of the amount of macular pigment (MPOD) is necessary to investigate the role of carotenoids and their assumed protective functions. High repeatability and reliability are important to monitor patients in studies investigating the influence of diet and supplements on MPOD. We evaluated the Macuscope (Macuvision Europe Ltd., Lapworth, Solihull, UK), a recently introduced device for measuring MPOD using the technique of heterochromatic flicker photometry (HFP). We determined agreement with another HFP device (QuantifEye; MPS 9000 series: Tinsley Precision Instruments Ltd., Croydon, Essex, UK) and a fundus reflectance method. Methods The right eyes of 23 healthy subjects (mean age 33.9±15.1 years) were measured. We determined agreement with QuantifEye and correlation with a fundus reflectance method. Repeatability of QuantifEye was assessed in 20 other healthy subjects (mean age 32.1±7.3 years). Repeatability was also compared with measurements by a fundus reflectance method in 10 subjects. Results We found low agreement between test and retest measurements with Macuscope. The average difference and the limits of agreement were −0.041±0.32. We found high agreement between test and retest measurements of QuantifEye (−0.02±0.18) and the fundus reflectance method (−0.04±0.18). MPOD data obtained by Macuscope and QuantifEye showed poor agreement: −0.017±0.44. For Macuscope and the fundus reflectance method, the correlation coefficient was r=0.05 (P=0.83). A significant correlation of r=0.87 (P<0.001) was found between QuantifEye and the fundus reflectance method. Conclusions Because repeatability of Macuscope measurements was low (ie, wide limits of agreement) and MPOD values correlated poorly with the fundus reflectance method, and agreed poorly with QuantifEye, the tested Macuscope protocol seems less suitable for studying MPOD. PMID:21057522

  6. Optical Photometry of M31N 2008-12a Near Maximum Light

    NASA Astrophysics Data System (ADS)

    Shafter, A. W.; Horst, J. C.; Darnley, M. J.

    2015-08-01

    The remarkable recurrent nova in M31 with an unusually short recurrence time, M31N 2008-12a, has just been discovered to be undergoing its 8th recorded optical outburst since December 2008 (ATel #7964, ATel #7965).

  7. Research and development optical deep space antenna sizing study

    NASA Technical Reports Server (NTRS)

    Wonica, D.

    1994-01-01

    Results from this study provide a basis for the selection of an aperture size appropriate for a research and development ground-based receiver for deep space optical communications. Currently achievable or near-term realizable hardware performance capabilities for both a spacecraft optical terminal and a ground terminal were used as input parameters to the analysis. Links were analyzed using OPTI, our optical link analysis program. Near-term planned and current missions were surveyed and categorized by data rate and telecommunications-subsystems prime power consumption. The spacecraft optical-terminal transmitter power was selected by matching these (RF) data rates and prime power requirements and by applying power efficiencies suitable to an optical communications subsystem. The study was baselined on a Mars mission. Results are displayed as required ground aperture size for given spacecraft transmitter aperture size, parametrized by data rate, transmit optical power, and wavelength.

  8. Probing Accretion in Magnetic Cataclysmic Variables from High Time Resolution Optical Photometry and X-ray Observations from ASTROSAT

    NASA Astrophysics Data System (ADS)

    Buckley, David; Marsh, Tom; Revnivtsev, Mikhail; Bonnet-Bidaud, Jean-Marc; Mouchet, Martine; Pal Singh, Kulinder; Semena, Andrey; Dhillon, Vik; Breytenbach, Hannes; Irawati, Puji; Potter, Stephen

    2016-07-01

    We present results from an on-going program of high speed CCD photometry of magnetic cataclysmic variables (mCVs) aimed at characterizing their high frequency (˜0.1-10 Hz) optical variability. In particular, we have been actively attempting to detect Quasi-Periodic Oscillations in many Polars, indicative of shock instabilities in their accretion columns. We have used a variety of instruments for this purpose, including the EM-CCD based SHOC camera on the SAAO 1.9-m telescope, SALTICAM and BVIT on SALT and Ultraspec on the TNO 2.5-m telescope. While we have detected QPOs seen before in the systems V834 Cen and VV Pup, we have only found evidence for one new detection, namely for 2MASS J19283247-5001344, an eclipsing polar. This may indicate that QPOs are somewhat of a rarity in Polars. We have also seen evidence for lower frequency QPOs, with characteristic timescales of 10s of seconds to several minutes. In addition, we have been investigating the nature of the breaks in the Power Density Spectra (νF_ν) power law for Intermediate Polars (e.g. EX Hya). This may give clues to the size of the inner radius of the accretion disc, where the magnetosphere begins to dominate the accretion flow. Finally, results of our recent ASTROSAT program on mCVs will be discussed.

  9. Comparison between macular pigment optical density measurements using two-wavelength autofluorescence and heterochromatic flicker photometry techniques.

    PubMed

    Canovas, Renata; Lima, Verônica Castro; Garcia, Patricia; Morini, Chiara; Prata, Tiago S; Rosen, Richard B

    2010-06-01

    The association of macular pigment (MP) with age-related macular degeneration has been extensively studied in recent years, and interest in a rapid, objective, and accurate technique to measure MP optical density (MPOD) has increased. The purpose of this study was to compare the MPOD values at specific loci around the fovea using the heterochromatic flicker photometry (HFP) and the two-wavelength autofluorescence (AF) methods in a young, healthy population. Ten patients (20 eyes) were enrolled. Subjects with any ocular or systemic disease were excluded. All patients underwent HFP and AF examination. The AF examination was performed using a modified scanning laser ophthalmoscope. Values for both devices were measured at four eccentricities around the fovea (0.25 degrees , 0.5 degrees, 1.0 degrees, and 1.75 degrees). Each eye was tested three times with each Statistical analysis was based on paired t-test and linear regression analysis. At all retinal eccentricities, the HFP values were consistently lower than the HRA values (P < 0.001). There was, however, a significant correlation at almost all locations. The strongest correlation between two methods was found at 1.75 degrees from the center of the fovea (r = 0.73). The modified-HRA AF method for MPOD generated results that were highly correlated with the standard HPF method but consistently higher at all eccentricities. These findings suggest that HRA can be reliably used in patients unable to perform HPF, which is important for wider clinical application of MP testing.

  10. EDGES: Deep Multi-Wavelength Photometry and Radial SED Analysis for NGC4485, NGC4490 and NGC5273

    NASA Astrophysics Data System (ADS)

    Gillian, Beltz-Mohrmann; Dale, Daniel A.; Barnes, Kate L.; Egan, Arika; Hatlestad, Alan; Herzog, Laura; Kobulnicky, Henry A.; Leung, Andrew S.; McLane, Jacob; Phenicie, Christopher; Roberts, Jareth; Staudaher, Shawn; van Zee, Liese

    2015-01-01

    New deep ugr imaging was obtained on the Wyoming Infrared Observatory 2.3 meter telescope for NGC4485, NGC4490 and NGC5273, three galaxies in the Extended Disk Galaxy Exploration Science survey. These data are coupled with deep GALEX ultraviolet and Spitzer/Herschel infrared imaging to study the radial variations in the spectral energy distributions. Results from the CIGALE SED modeling software will be presented, including trends in the galaxy star formation histories. This work is supported by the National Science Foundation under REU grant AST 1063146.

  11. OPTICAL AND INFRARED PHOTOMETRY OF GLOBULAR CLUSTERS IN NGC 1399: EVIDENCE FOR COLOR-METALLICITY NONLINEARITY

    SciTech Connect

    Blakeslee, John P.; Ferrarese, Laura; Martel, Andre R.; Cho, Hyejeon; Peng, Eric W.; Jordan, Andres

    2012-02-10

    We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H{sub 160}) imaging data for NGC 1399, the central galaxy in the Fornax cluster, with archival F475W (g{sub 475}), F606W (V{sub 606}), F814W (I{sub 814}), and F850LP (z{sub 850}) optical data from the Advanced Camera for Surveys (ACS). The purely optical g{sub 475} - I{sub 814}, V{sub 606} - I{sub 814}, and g{sub 475} - z{sub 850} colors of NGC 1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I{sub 814} > 21.5. The optical-IR I{sub 814} - H{sub 160} color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V{sub 606} - H{sub 160} colors show marginal evidence for bimodality, consistent with bimodality in V{sub 606} - I{sub 814} and unimodality in I{sub 814} - H{sub 160}. If bimodality is imposed for I{sub 814} - H{sub 160} with a double Gaussian model, the preferred blue/red split differs from that for optical colors; these 'differing bimodalities' mean that the optical and optical-IR colors cannot both be linearly proportional to metallicity. Consistent with the differing color distributions, the dependence of I{sub 814} - H{sub 160} on g{sub 475} - I{sub 814} for the matched GC sample is significantly nonlinear, with an inflection point near the trough in the g{sub 475} - I{sub 814} color distribution; the result is similar for the I{sub 814} - H{sub 160} dependence on g{sub 475} - z{sub 850} colors taken from the ACS Fornax Cluster Survey. These g{sub 475} - z{sub 850} colors have been calibrated empirically against metallicity; applying this calibration yields a continuous, skewed, but single-peaked metallicity distribution. Taken together, these results indicate that nonlinear color-metallicity relations play an important role in shaping the observed bimodal distributions of optical colors in extragalactic GC systems.

  12. Deep space uplink receiver prototype for optical communications

    NASA Astrophysics Data System (ADS)

    Sburlan, S. E.; Birnbaum, K. M.; Farr, W. H.

    2011-03-01

    A hardware prototype of a flight receiver for deep space optical communications has been developed where a single detector array is used for acquisition, tracking, and high-speed data recovery. A counting algorithm accumulates pulses on every pixel in a photon-counting array and extracts signal information encoded with a nested modulation scheme.

  13. Design of stabilized platforms for deep space optical communications (DSOC)

    NASA Astrophysics Data System (ADS)

    Jacka, N.; Walter, R.; Laughlin, D.; McNally, J.

    2017-02-01

    Numerous Deep Space Optical Communications (DSOC) demonstrations are planned by NASA to provide the basis for future implementation of optical communications links in planetary science missions and eventually manned missions to Mars. There is a need for a simple, robust precision optical stabilization concept for long-range free space optical communications applications suitable for optical apertures and masses larger than the current state of the art. We developed a stabilization concept by exploiting the ultra-low noise and wide bandwidth of ATA-proprietary Magnetohydrodynamic (MHD) angular rate sensors and building on prior practices of flexure-based isolation. We detail a stabilization approach tailored for deep space optical communications, and present an innovative prototype design and test results. Our prototype system provides sub-micro radian stabilization for a deep space optical link such as NASA's integrated Radio frequency and Optical Communications (iROC) and NASA's DSOC programs. Initial test results and simulations suggest that >40 dB broadband jitter rejection is possible without placing unrealistic expectations on the control loop bandwidth and flexure isolation frequency. This approach offers a simple, robust method for platform stabilization without requiring a gravity offload apparatus for ground testing or launch locks to survive a typical launch environment. This paper reviews alternative stabilization concepts, their advantages and disadvantages, as well as, their applicability to various optical communications applications. We present results from testing that subjected the prototype system to realistic spacecraft base motion and confirmed predicted sub-micro radian stabilization performance with a realistic 20-cm aperture.

  14. Low-energy K- optical potentials: deep or shallow?

    NASA Astrophysics Data System (ADS)

    Cieplý, A.; Friedman, E.; Gal, A.; Mareš, J.

    2001-12-01

    The K- optical potential in the nuclear medium is evaluated self consistently from a free-space K-Nt matrix constructed within a coupled-channel chiral approach. The fit of model parameters gives a good description of the low-energy data plus the available K- atomic data. The resulting optical potential is relatively `shallow' in contradiction to the potentials obtained from phenomenological analysis. The calculated (Kstop-,π) hypernuclear production rates are very sensitive to the details of kaonic bound state wave function. The (Kstop-,π) reaction could thus serve as a suitable tool to distinguish between shallow and deep K- optical potentials.

  15. Optical Photometry and X-Ray Monitoring of the ``Cool Algol'' BD +05°706: Determination of the Physical Properties

    NASA Astrophysics Data System (ADS)

    Torres, Guillermo; Mader, Jeff A.; Marschall, Laurence A.; Neuhäuser, Ralph; Duffy, Alaine S.

    2003-06-01

    We present new photometric observations in the BVRI bands of the double-lined eclipsing binary BD +05°706 conducted over three observing seasons, as well as new X-ray observations obtained with ROSAT covering a full orbital cycle (P=18.9 days). A detailed light-curve analysis of the optical data shows the system to be semidetached, confirming indications from an earlier analysis by Torres et al. (published in 1998), with the less massive and cooler star filling its Roche lobe. The system is a member of the rare class of cool Algol systems, which are different from the ``classical'' Algol systems in that the mass-gaining component is also a late-type star rather than a B- or A-type star. By combining the new photometry with a reanalysis of the spectroscopic observations reported by Torres et al., we derive accurate absolute masses for the components of M1=2.633+/-0.028 Msolar and M2=0.5412+/-0.0093 Msolar, radii of R1=7.55+/-0.20 Rsolar and R2=11.02+/-0.21 Rsolar, as well as effective temperatures of 5000+/-100 and 4640+/-150 K, for the primary and secondary, respectively. There are obvious signs of activity (spottedness) in the optical light curve of the binary. Our X-ray light curve clearly shows the primary eclipse but not the secondary eclipse, suggesting that the primary star is the dominant source of the activity in the system. The depth and duration of the eclipse allow us to infer some of the properties of the X-ray-emitting region around that star.

  16. Ultraviolet spectrophotometry and optical and infrared photometry of the old nova GK Persei

    NASA Technical Reports Server (NTRS)

    Wu, Chi-Chao; Holm, Albert V.; Panek, Robert J.; Raymond, John C.; Hartmann, Lee W.; Swank, Jean H.

    1989-01-01

    IUE observations in the 1150-3250-A region were obtained of GK Per during the rise, at the maximum, and during the decline of the 2.5-mag optical outburst in 1981. The results support previous predictions for the interaction of an accretion disk with the magnetic field of an accretion star. The luminosity at minimum is found to be 2.3 solar luminosities, with 1/3 of this being attributed to the cool secondary star.

  17. Ultraviolet spectrophotometry and optical and infrared photometry of the old nova GK Persei

    NASA Technical Reports Server (NTRS)

    Wu, Chi-Chao; Holm, Albert V.; Panek, Robert J.; Raymond, John C.; Hartmann, Lee W.; Swank, Jean H.

    1989-01-01

    IUE observations in the 1150-3250-A region were obtained of GK Per during the rise, at the maximum, and during the decline of the 2.5-mag optical outburst in 1981. The results support previous predictions for the interaction of an accretion disk with the magnetic field of an accretion star. The luminosity at minimum is found to be 2.3 solar luminosities, with 1/3 of this being attributed to the cool secondary star.

  18. Photographic photometry of compact extragalactic objects Optical variability of the quasar 3C 345

    NASA Astrophysics Data System (ADS)

    Babadzhanyants, M. K.; Belokon, E. T.; Denisenko, N. S.; Semenova, E. V.

    1985-08-01

    The results of 11-years photographic observations of optical variability of the quasar 3C 345 are presented. A flare with a timescale of the order of one year, similar to those of 1967 and 1971, was observed in 1982. From a comparison of the obtained series of observations with those of the Rosemary Hill Observatory, a conclusion is drawn on the absence of systematic variability at a timescale of 5 - 20 hours exceeding 0m.2 in magnitude.

  19. Photographic photometry of compact extragalactic objects Optical variability of the quasar 3C 345

    SciTech Connect

    Babadzhaniants, M.K.; Belokon, E.T.; Denisenko, N.S.; Semenova, E.V.

    1985-08-01

    An 11-yr (1973-1983) program of photographic observations at the Leningrad Byurakan station is reported, tracing the optical variability of the quasar 3C 345. A roughly 1-yr flare resembling those of 1967 and 1971 occurred in 1982. Comparison with the concurrent observations at Rosemary Hill, Florida, shows no appreciable systematic B-band fluctuations on time scales of 5-20 h. 10 references.

  20. Optical dual-band photometry and spectroscopy of the WZ Sge-type dwarf nova EZ Lyn during the 2010 superoutburst

    NASA Astrophysics Data System (ADS)

    Isogai, Mizuki; Arai, Akira; Yonehara, Atsunori; Kawakita, Hideyo; Uemura, Makoto; Nogami, Daisaku

    2015-02-01

    We performed optical simultaneous dual-band (SDSS g'- and i'-bands) photometry and low-resolution spectroscopy for the WZ Sge-type dwarf nova EZ Lyn during its 2010 superoutburst. Dual-band photometry revealed that the g'- i' color reddened with a decrease in brightness during the main superoutburst and the following rebrightening phase, whereas the color became bluer with a further decrease in brightness during the slow, final decline phase. With a fit to our photometric results by a blackbody function, we estimated the disk radius ratio (ratio of the disk radius to the binary separation) and compared this with that of V455 And, a WZ Sge-type object that did not show any rebrightening in the 2007 superoutburst. The comparison revealed: (1) the disk radius ratio of EZ Lyn decreased more slowly than that of V455 And, and (2) the radius ratio of EZ Lyn at the end of the main superoutburst was larger than that of V455 And. These results favor the mass reservoir model for the mechanism of rebrightening. During both the superoutburst plateau and subsequent rebrightening phase, Hα and Hβ lines were detected. The Hα line showed a double-peak profile from which we estimated the disk radius ratio. The comparison of this ratio with that derived by photometry indicates that the Hα disk was larger than the photometric one, which suggests that the optically thin gas was extended to the outer region more than the optically thick gas disk and was possibly responsible for the rebrightening phenomenon. Time-series dual-band photometry during the main superoutburst revealed that color variations during the early superhump show roughly the same behavior as that of V455 And, whereas color variations during the ordinary superhump display clear anticorrelation with brightness, in contrast to that seen in V455 And. Here, we discuss different color behaviors.

  1. Photon counting detector array algorithms for deep space optical communications

    NASA Astrophysics Data System (ADS)

    Srinivasan, Meera; Andrews, Kenneth S.; Farr, William H.; Wong, Andre

    2016-03-01

    For deep-space optical communications systems utilizing an uplink optical beacon, a single-photon-counting detector array on the flight terminal can be used to simultaneously perform uplink tracking and communications as well as accurate downlink pointing at photon-starved (pW=m2) power levels. In this paper, we discuss concepts and algorithms for uplink signal acquisition, tracking, and parameter estimation using a photon-counting camera. Statistical models of detector output data and signal processing algorithms are presented, incorporating realistic effects such as Earth background and detector/readout blocking. Analysis and simulation results are validated against measured laboratory data using state-of-the-art commercial photon-counting detector arrays, demonstrating sub-microradian tracking errors under channel conditions representative of deep space optical links.

  2. S-CANDELS: The Spitzer-Cosmic Assembly Near-Infrared Deep Extragalactic Survey. Survey Design, Photometry, and Deep IRAC Source Counts

    NASA Astrophysics Data System (ADS)

    Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Dunlop, J. S.; Egami, E.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Hora, J. L.; Huang, J.-S.; Koekemoer, A. M.; Labbé, I.; Wang, Z.

    2015-06-01

    The Spitzer-Cosmic Assembly Deep Near-infrared Extragalactic Legacy Survey (S-CANDELS; PI G.Fazio) is a Cycle 8 Exploration Program designed to detect galaxies at very high redshifts (z\\gt 5). To mitigate the effects of cosmic variance and also to take advantage of deep coextensive coverage in multiple bands by the Hubble Space Telescope (HST) Multi-cycle Treasury Program CANDELS, S-CANDELS was carried out within five widely separated extragalactic fields: the UKIDSS Ultra-deep Survey, the Extended Chandra Deep Field South, COSMOS, the HST Deep Field North, and the Extended Groth Strip. S-CANDELS builds upon the existing coverage of these fields from the Spitzer Extended Deep Survey (SEDS), a Cycle 6 Exploration Program, by increasing the integration time from SEDS’ 12 hr to a total of 50 hr but within a smaller area, 0.16 deg2. The additional depth significantly increases the survey completeness at faint magnitudes. This paper describes the S-CANDELS survey design, processing, and publicly available data products. We present Infrared Array Camera (IRAC) dual-band 3.6+4.5 μ {{m}} catalogs reaching to a depth of 26.5 AB mag. Deep IRAC counts for the roughly 135,000 galaxies detected by S-CANDELS are consistent with models based on known galaxy populations. The increase in depth beyond earlier Spitzer/IRAC surveys does not reveal a significant additional contribution from discrete sources to the diffuse Cosmic Infrared Background (CIB). Thus it remains true that only roughly half of the estimated CIB flux from COBE/DIRBE is resolved.

  3. Deep NIR and Optical Study on RCW 34 and NGC 2626

    NASA Astrophysics Data System (ADS)

    Czanik, Robert

    2017-06-01

    An in-depth multi-wavelength has been performed on the two high mass star forming regions RCW 34 and NGC 2626 using NIR photometry from the IRSF, optical photometry from VPHAS+ and optical spectra from SALT. Customary NIR extinction laws were constructed using LINES linear regression method and extinction maps were constructed with the NICEST algorithm. Sources were dereddened and the amount of excess emission for each low-mass member could be tested. Synthesis of all of the data made it possible to construct a "big picture" star forming history for both regions.

  4. Optical Characterization of Deep-Space Object Rotation States

    DTIC Science & Technology

    2014-09-01

    In this regard, temporal photometry (i.e., measurements of whole-object brightness as a function of time) can be very valuable. For instance...be exploited to characterize stabilized GEO satellites [5-10]. The objective of this paper is to outline how temporal photometry can be used to...OBJECTS This analysis focuses on broad-band temporal photometry of Earth-orbiting satellites (i.e., time-series measurements of whole-object

  5. Architectural Options for a Future Deep Space Optical Communications Network

    NASA Technical Reports Server (NTRS)

    Edwards, B. L.; Benjamin, T.; Scozzafava, J.; Khatri, F.; Sharma, J.; Parvin, B.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  6. Architectural Options for a Future Deep Space Optical Communications Network

    NASA Technical Reports Server (NTRS)

    Edwards, B. L.; Benjamin, T.; Scozzafava, J.; Khatri, F.; Sharma, J.; Parvin, B.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  7. Optical spectroscopy and photometry of main-belt asteroids with a high orbital inclination

    NASA Astrophysics Data System (ADS)

    Iwai, Aya; Itoh, Yoichi; Terai, Tsuyoshi; Gupta, Ranjan; Sen, Asoke; Takahashi, Jun

    2017-02-01

    We carried out low-resolution optical spectroscopy of 51 main-belt asteroids, most of which have highly-inclined orbits. They are selected from D-type candidates in the SDSS-MOC 4 catalog. Using the University of Hawaii 2.2 m telescope and the Inter-University Centre for Astronomy and Astrophysics 2 m telescope in India, we determined the spectral types of 38 asteroids. Among them, eight asteroids were classified as D-type asteroids. Fractions of D-type asteroids are 3.0+/-1.1 for low orbital inclination main-belt asteroids and 7.3+/-2.0 for high orbital inclination main-belt asteroids. The results of our study indicate that some D-type asteroids were formed within the ecliptic region between the main belt and Jupiter, and were then perturbed by Jupiter.

  8. High Speed Optical Photometry of V1055 Orionis (=4U 0614+091)

    NASA Astrophysics Data System (ADS)

    Lopez, Isaac; Mason, P. A.; Robinson, E. L.

    2013-01-01

    V1055 Orionis (=4U 0614+091) is thought to be an ultra-compact binary containing a neutron star primary with a white dwarf companion. High-speed (10s) broad-band optical observations using the McDonald Observatory, 2.1m, Otto Struve Telescope were obtained on 13 nights in 2010, 2011, and 2012. The nightly mean brightness remained quite stable over the dataset. The light curve is dominated by complex oscillatory behavior reminiscent of the beating of hidden frequencies. A variety of photometric periods have been previously reported and none are found to be coherent periods in our dataset. Rather, a given night exhibits short lived quasi-periodic variations covering a variety of timescales, especially 10-40 min and even as long as two hours. This short period variability combined with recent spectroscopic abundance studies suggests that the likely donor in this binary is a white dwarf.

  9. Optical Photometry of the Black Hole Candidate SWIFT J1753.4-0126

    NASA Astrophysics Data System (ADS)

    Paez, Aurelio; Mason, P. A.; Robinson, E. L.; Bayless, A. J.

    2012-01-01

    We present optical observations of the black hole candidate LMXB SWIFT J1753.4-0126 with the 2.1m Otto Struve Telescope of McDonald Observatory. The Argos CCD photometer was used and 10s integrations were obtained on 19 nights in 2010 and 2011. We performed a period search using a Phase Dispersion Minimization (PDM) code and we obtain a period of 3.2448 +/- 0.0002hr. This new period is fully consistent with, and a factor of 5 improvement over, the PDM period of (Zurita et al. 2008). The individual light curves are complex and variable. This work is part of the NSF/PAARE program for Education and Research.

  10. Assessment of nocturnal aerosol optical depth from lunar photometry at the Izaña high mountain observatory

    NASA Astrophysics Data System (ADS)

    Barreto, África; Román, Roberto; Cuevas, Emilio; Berjón, Alberto J.; Almansa, A. Fernando; Toledano, Carlos; González, Ramiro; Hernández, Yballa; Blarel, Luc; Goloub, Philippe; Guirado, Carmen; Yela, Margarita

    2017-08-01

    This work is a first approach to correct the systematic errors observed in the aerosol optical depth (AOD) retrieved at nighttime using lunar photometry and calibration techniques dependent on the lunar irradiance model. To this end, nocturnal AOD measurements were performed in 2014 using the CE318-T master Sun-sky-lunar photometer (lunar Langley calibrated) at the Izaña high mountain observatory. This information has been restricted to 59 nights characterized as clean and stable according to lidar vertical profiles. A phase angle dependence as well as an asymmetry within the Moon's cycle of the Robotic Lunar Observatory (ROLO) model could be deduced from the comparison in this 59-night period of the CE318-T calibration performed by means of the lunar Langley calibration and the calibration performed every single night by means of the common Langley technique. Nocturnal AOD has also been compared in the same period with a reference AOD based on daylight AOD extracted from the AErosol RObotic NETwork (AERONET) at the same station. Considering stable conditions, the difference ΔAODfit, between AOD from lunar observations and the linearly interpolated AOD (the reference) from daylight data, has been calculated. The results show that ΔAODfit values are strongly affected by the Moon phase and zenith angles. This dependency has been parameterized using an empirical model with two independent variables (Moon phase and zenith angles) in order to correct the AOD for these residual dependencies. The correction of this parameterized dependency has been checked at four stations with quite different environmental conditions (Izaña, Lille, Carpentras and Dakar) showing a significant reduction of the AOD dependence on phase and zenith angles and an improved agreement with daylight reference data. After the correction, absolute AOD differences for day-night-day clean and stable transitions remain below 0.01 for all wavelengths.

  11. Microsecond Time Resolution Optical Photometry using a H.E.S.S. Cherenkov Telescope

    SciTech Connect

    Deil, Christoph; Domainko, Wilfried; Hermann, German

    2008-02-22

    We have constructed an optical photometer with microsecond time resolution, which is currently being operated on one of the H.E.S.S. telescopes. H.E.S.S. is an array of four Cherenkov telescopes, each with a 107 m{sup 2} mirror, located in the Khomas highland in Namibia. In its normal mode of operation H.E.S.S. observes Cherenkov light from air showers generated by very high energy gamma-rays in the upper atmosphere. Our detector consists of seven photomultipliers, one in the center to record the lightcurve from the target and six concentric photomultipliers as a veto system to reject disturbing signals e.g. from meteorites or lightning at the horizon. The data acquisition system has been designed to continuously record the signals with zero deadtime. The Crab pulsar has been observed to verify the performance of the instrument and the GPS timing system. Compact galactic targets were observed to search for flares on timescales of a few microseconds to {approx}100 ms. The design and sensitivity of the instrument as well as the data analysis method are presented.

  12. Beaconless Pointing for Deep-Space Optical Communication

    NASA Technical Reports Server (NTRS)

    Swank, Aaron J.; Aretskin-Hariton, Eliot; Le, Dzu K.; Sands, Obed S.; Wroblewski, Adam

    2016-01-01

    Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.

  13. Deep-space Optical Terminals (DOT) Systems Engineering

    NASA Astrophysics Data System (ADS)

    Biswas, A.; Hemmati, H.; Piazzolla, S.; Moision, B.; Birnbaum, K.; Quirk, K.

    2010-11-01

    Recently a conceptual design study titled Deep-space Optical Terminals (DOT) was completed for a deep-space optical communication technology demonstration in the 2018 timeframe. This article provides an overview of the system engineering portion of the study. The Level 1 requirements received from the NASA Space Communications and Navigation Program Manager emphasized an order of magnitude higher data rate from Mars closest range relative to the Ka-band telecommunication system flown on the Mars Reconnaissance Orbiter (MRO) mission but utilizing comparable mass and power. The system-level concept design motivated by this driving requirement and reported here describes link performance of 267 Mb/s from 0.42 AU within an allocated mass and power of 38 kg and 110 W. Furthermore, the concept design addresses link closure at the farthest Mars range of 2.7 AU. Maximum uplink data rates of 292 kb/s and ranging with 30-cm precision are also addressed.

  14. Estimation and tracking for deep-space optical communications

    NASA Technical Reports Server (NTRS)

    Win, Moe Zaw

    1989-01-01

    The importance of pointing and tracking is demonstrated with current deep-space optical communications system concepts. Maximum-likelihood (ML), minimum square counting-error (MSCE), and maximum product (MP) estimation algorithms (or decision rules) are derived to estimate the location of the receiving station to subpixel resolution. Comparisons of the above algorithms are made, via Monte Carlo computer simulation, in terms of estimator's bias and variance. Optical communication link analyses are made for a typical earth-Mars scenario, to gain engineering insights. It is observed that both the ML rule and the MSCE rule perform better than the MP rule.

  15. Optical communications for future deep-space missions

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.; Lesh, James R.

    1988-01-01

    The development of key technologies for an optical communications system for deep-space probes is discussed. Aspects of the technology include the pulse-position modulation technique for data transmission, a solid-state laser with a Nd:YAG crystal end, nondiffraction-limited receivers, and the application of avalanche photodiodes to improve photon detection. Mission benefits and flight opportunities and applications are discussed. Experiments to test optical communication systems are being planned for the Space Shuttle and the Mars Rover Sample Return misson. Future missions which will probably use the system include Cassini and the Mariner Mark II.

  16. Deep ultraviolet laser micromachining of novel fibre optic devices

    NASA Astrophysics Data System (ADS)

    Li, J.; Dou, J.; Herman, P. R.; Fricke-Begemann, T.; Ihlemann, J.; Marowsky, G.

    2007-04-01

    A deep ultraviolet F2 laser, with output at 157-nm wavelength, has been adopted for micro-shaping the end facets of single and multi-mode silica optical fibres. The high energy 7.9-eV photons drive strong interactions in the wide-bandgap silica fibres to enable the fabrication of surface-relief microstructures with high spatial resolution and smooth surface morphology. Diffraction gratings, focusing lenses, and Mach-Zehnder interferometric structures have been micromachined onto the cleaved-fibre facets and optically characterized. F2-laser micromachining is shown to be a rapid and facile means for direct-writing of novel infibre photonic components.

  17. An Array of Optical Receivers for Deep-Space Communications

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Chi-Wung; Srinivasan, Meera; Andrews, Kenneth

    2007-01-01

    An array of small optical receivers is proposed as an alternative to a single large optical receiver for high-data-rate communications in NASA s Deep Space Network (DSN). Because the telescope for a single receiver capable of satisfying DSN requirements must be greater than 10 m in diameter, the design, building, and testing of the telescope would be very difficult and expensive. The proposed array would utilize commercially available telescopes of 1-m or smaller diameter and, therefore, could be developed and verified with considerably less difficulty and expense. The essential difference between a single-aperture optical-communications receiver and an optical-array receiver is that a single-aperture receiver focuses all of the light energy it collects onto the surface of an optical detector, whereas an array receiver focuses portions of the total collected energy onto separate detectors, optically detects each fractional energy component, then combines the electrical signal from the array of detector outputs to form the observable, or "decision statistic," used to decode the transmitted data. A conceptual block diagram identifying the key components of the optical-array receiver suitable for deep-space telemetry reception is shown in the figure. The most conspicuous feature of the receiver is the large number of small- to medium-size telescopes, with individual apertures and number of telescopes selected to make up the desired total collecting area. This array of telescopes is envisioned to be fully computer- controlled via the user interface and prediction-driven to achieve rough pointing and tracking of the desired spacecraft. Fine-pointing and tracking functions then take over to keep each telescope pointed toward the source, despite imperfect pointing predictions, telescope-drive errors, and vibration caused by wind.

  18. A PUBLIC, K-SELECTED, OPTICAL-TO-NEAR-INFRARED CATALOG OF THE EXTENDED CHANDRA DEEP FIELD SOUTH (ECDFS) FROM THE MULTIWAVELENGTH SURVEY BY YALE-CHILE (MUSYC)

    SciTech Connect

    Taylor, Edward N.; Franx, Marijn; Quadri, Ryan F.; Damen, Maaike; Hildebrandt, Hendrik; Van Dokkum, Pieter G.; Herrera, David; Gawiser, Eric; Bell, Eric F.; Barrientos, L. Felipe; Blanc, Guillermo A.; Castander, Francisco J.; Gonzalez-Perez, Violeta; Hall, Patrick B.; Kriek, Mariska; Labbe, Ivo; Lira, Paulina; Maza, Jose; Rudnick, Gregory; Treister, Ezequiel

    2009-08-01

    We present a new, K-selected, optical-to-near infrared photometric catalog of the Extended Chandra Deep Field South (ECDFS), making it publicly available to the astronomical community.{sup 22}Imaging and spectroscopy data and catalogs are freely available through the MUSYC Public Data Release webpage: http://www.astro.yale.edu/MUSYC/. The data set is founded on publicly available imaging, supplemented by original z'JK imaging data collected as part of the MUltiwavelength Survey by Yale-Chile (MUSYC). The final photometric catalog consists of photometry derived from UU {sub 38} BVRIz'JK imaging covering the full 1/2 x 1/2 square circ of the ECDFS, plus H-band photometry for approximately 80% of the field. The 5{sigma} flux limit for point sources is K{sup (AB)}{sub tot}= 22.0. This is also the nominal completeness and reliability limit of the catalog: the empirical completeness for 21.75 < K < 22.00 is {approx}>85%. We have verified the quality of the catalog through both internal consistency checks, and comparisons to other existing and publicly available catalogs. As well as the photometric catalog, we also present catalogs of photometric redshifts and rest-frame photometry derived from the 10-band photometry. We have collected robust spectroscopic redshift determinations from published sources for 1966 galaxies in the catalog. Based on these sources, we have achieved a (1{sigma}) photometric redshift accuracy of {delta}z/(1 + z) = 0.036, with an outlier fraction of 7.8%. Most of these outliers are X-ray sources. Finally, we describe and release a utility for interpolating rest-frame photometry from observed spectral energy distributions, dubbed InterRest.{sup 23}InterRest is available via http://www.strw.leidenuniv.nl/{approx}ent/InterRest. Documentation and a complete walkthrough can be found at the same address.

  19. EUVE photometry of SS Cygni: Dwarf nova outbursts and oscillations

    SciTech Connect

    Mauche, C.W.

    1995-05-15

    The authors present EUVE Deep Survey photometry and AAVSO optical measurements of the 1993 August and 1994 June/July outbursts of the dwarf nova SS Cygni. The EUV and optical light curves are used to illustrate the different response of the accretion disk to outbursts which begin at the inner edge and propagate outward, and those which begin at the outer edge and propagate inward. Furthermore, the authors describe the properties of the quasi-coherent 7--9 s sinusoidal oscillations in the EUV flux detected during the rise and plateau stages of these outbursts.

  20. Optical subnet concepts for the deep space network

    NASA Technical Reports Server (NTRS)

    Shaik, K.; Wonica, D.; Wilhelm, M.

    1993-01-01

    This article describes potential enhancements to the Deep Space Network, based on a subnet of receiving stations that will utilize optical communications technology in the post-2010 era. Two optical subnet concepts are presented that provide full line-of-sight coverage of the ecliptic, 24 hours a day, with high weather availability. The technical characteristics of the optical station and the user terminal are presented, as well as the effects of cloud cover, transmittance through the atmosphere, and background noise during daytime or nighttime operation on the communications link. In addition, this article identifies candidate geographic sites for the two network concepts and includes a link design for a hypothetical Pluto mission in 2015.

  1. Deep-Space Optical Communications: Visions, Trends, and Prospects

    NASA Technical Reports Server (NTRS)

    Cesarone, R. J.; Abraham, D. S.; Shambayati, S.; Rush, J.

    2011-01-01

    Current key initiatives in deep-space optical communications are treated in terms of historical context, contemporary trends, and prospects for the future. An architectural perspective focusing on high-level drivers, systems, and related operations concepts is provided. Detailed subsystem and component topics are not addressed. A brief overview of past ideas and architectural concepts sets the stage for current developments. Current requirements that might drive a transition from radio frequencies to optical communications are examined. These drivers include mission demand for data rates and/or data volumes; spectrum to accommodate such data rates; and desired power, mass, and cost benefits. As is typical, benefits come with associated challenges. For optical communications, these include atmospheric effects, link availability, pointing, and background light. The paper describes how NASA's Space Communication and Navigation Office will respond to the drivers, achieve the benefits, and mitigate the challenges, as documented in its Optical Communications Roadmap. Some nontraditional architectures and operations concepts are advanced in an effort to realize benefits and mitigate challenges as quickly as possible. Radio frequency communications is considered as both a competitor to and a partner with optical communications. The paper concludes with some suggestions for two affordable first steps that can yet evolve into capable architectures that will fulfill the vision inherent in optical communications.

  2. Deep-Space Optical Communications: Visions, Trends, and Prospects

    NASA Technical Reports Server (NTRS)

    Cesarone, R. J.; Abraham, D. S.; Shambayati, S.; Rush, J.

    2011-01-01

    Current key initiatives in deep-space optical communications are treated in terms of historical context, contemporary trends, and prospects for the future. An architectural perspective focusing on high-level drivers, systems, and related operations concepts is provided. Detailed subsystem and component topics are not addressed. A brief overview of past ideas and architectural concepts sets the stage for current developments. Current requirements that might drive a transition from radio frequencies to optical communications are examined. These drivers include mission demand for data rates and/or data volumes; spectrum to accommodate such data rates; and desired power, mass, and cost benefits. As is typical, benefits come with associated challenges. For optical communications, these include atmospheric effects, link availability, pointing, and background light. The paper describes how NASA's Space Communication and Navigation Office will respond to the drivers, achieve the benefits, and mitigate the challenges, as documented in its Optical Communications Roadmap. Some nontraditional architectures and operations concepts are advanced in an effort to realize benefits and mitigate challenges as quickly as possible. Radio frequency communications is considered as both a competitor to and a partner with optical communications. The paper concludes with some suggestions for two affordable first steps that can yet evolve into capable architectures that will fulfill the vision inherent in optical communications.

  3. WINGS: a WIde-field nearby Galaxy-cluster survey. III. Deep near-infrared photometry of 28 nearby clusters

    NASA Astrophysics Data System (ADS)

    Valentinuzzi, T.; Woods, D.; Fasano, G.; Riello, M.; D'Onofrio, M.; Varela, J.; Bettoni, D.; Cava, A.; Couch, W. J.; Dressler, A.; Fritz, J.; Moles, M.; Omizzolo, A.; Poggianti, B. M.; Kjærgaard, P.

    2009-07-01

    Context: This is the third paper in a series devoted to the WIde-field Nearby Galaxy-cluster Survey (WINGS). WINGS is a long-term project aimed at gathering wide-field, multiband imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected, nearby clusters (0.04deep near-infrared photometric catalogs (90% complete in detection rate at total magnitudes J≈ 20.5, K≈ 19.4, and in classification rate at J≈19.5 and K≈ 18.5), giving positions, geometrical parameters, total and aperture magnitudes for all detected sources. For each field we classify the detected sources as stars, galaxies, and objects of “unknown” nature. Based on observations taken at the United Kingdom Infra-Red Telescope, operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the UK. J and K photometric catalogs are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/501/851

  4. Disk Galaxies in the Outer Local Supercluster: Optical CCD Surface Photometry and Distribution of Galaxy Disk Parameter

    NASA Technical Reports Server (NTRS)

    Lu, N. Y.

    1998-01-01

    We report new B-band CCD surface photometry on a sample of 76 disk galaxies brighter than BT = 14.5 mag in the Uppsala General Catalogue of Galaxies, which are confined within a volume located in the outer part of the Local Supercluster.

  5. Multicolor Optical Photometry of the 2015 Eruption of Recurrent Nova M31N 1963-09c

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Vrastil, J.; Wolf, M.; Kucakova, H.; Shafter, A. W.; Horst, J. C.; Rivera, D. I.

    2015-11-01

    We report additional multicolor photometry of the recurrent nova M31N 1963-09c (see ATel #8233, #8234, #8235, and CBAT TOCP) acquired with the 0.65-m telescope at Ondrejov and the Mount Laguna Observatory's 40-inch reflector.

  6. An ATP System for Deep-Space Optical Communication

    NASA Technical Reports Server (NTRS)

    Lee, Shinhak; Irtuzm Gerardi; Alexander, James

    2008-01-01

    An acquisition, tracking, and pointing (ATP) system is proposed for aiming an optical-communications downlink laser beam from deep space. In providing for a direction reference, the concept exploits the mature technology of star trackers to eliminate the need for a costly and potentially hazardous laser beacon. The system would include one optical and two inertial sensors, each contributing primarily to a different portion of the frequency spectrum of the pointing signal: a star tracker (<10 Hz), a gyroscope (<50 Hz), and a precise fluid-rotor inertial angular-displacement sensor (sometimes called, simply, "angle sensor") for the frequency range >50 Hz. The outputs of these sensors would be combined in an iterative averaging process to obtain high-bandwidth, high-accuracy pointing knowledge. The accuracy of pointing knowledge obtainable by use of the system was estimated on the basis of an 8-cm-diameter telescope and known parameters of commercially available star trackers and inertial sensors: The single-axis pointing-knowledge error was found to be characterized by a standard deviation of 150 nanoradians - below the maximum value (between 200 and 300 nanoradians) likely to be tolerable in deep-space optical communications.

  7. BV RI CCD photometry of 361,281 objects in the field of M 31

    NASA Technical Reports Server (NTRS)

    Magnier, E. A.; Lewin, W. H. G.; Van Paradijs, J.; Hasinger, G.; Jain, A.; Pietsch, W.; Truemper, J.

    1992-01-01

    Deep BV RI CCD photometry was performed on a 1 sq deg region of M 31. A catalog of photometry and astrometry of a total of 361,281 stars is presented, with typical completion limits of BV RI = (22.3, 22.2, 22.2, 20.9). Photometric accuracy is about 2 percent at V = 19. This catalog allows detailed studies of stellar populations and reddening. The data are currently being used to assist in finding the optical counterparts of Einstein and ROSAT X-ray sources.

  8. BV RI CCD photometry of 361,281 objects in the field of M 31

    NASA Technical Reports Server (NTRS)

    Magnier, E. A.; Lewin, W. H. G.; Van Paradijs, J.; Hasinger, G.; Jain, A.; Pietsch, W.; Truemper, J.

    1992-01-01

    Deep BV RI CCD photometry was performed on a 1 sq deg region of M 31. A catalog of photometry and astrometry of a total of 361,281 stars is presented, with typical completion limits of BV RI = (22.3, 22.2, 22.2, 20.9). Photometric accuracy is about 2 percent at V = 19. This catalog allows detailed studies of stellar populations and reddening. The data are currently being used to assist in finding the optical counterparts of Einstein and ROSAT X-ray sources.

  9. Deep and Clear Optical Imaging of Thick Inhomogeneous Samples

    PubMed Central

    Andilla, Jordi; Maandhui, Amina; Frongia, Céline; Lobjois, Valérie; Ducommun, Bernard; Lorenzo, Corinne

    2012-01-01

    Inhomogeneity in thick biological specimens results in poor imaging by light microscopy, which deteriorates as the focal plane moves deeper into the specimen. Here, we have combined selective plane illumination microscopy (SPIM) with wavefront sensor adaptive optics (wao). Our waoSPIM is based on a direct wavefront measure using a Hartmann-Shack wavefront sensor and fluorescent beads as point source emitters. We demonstrate the use of this waoSPIM method to correct distortions in three-dimensional biological imaging and to improve the quality of images from deep within thick inhomogeneous samples. PMID:22558226

  10. NEW EXTINCTION AND MASS ESTIMATES FROM OPTICAL PHOTOMETRY OF THE VERY LOW MASS BROWN DWARF COMPANION CT CHAMAELEONTIS B WITH THE MAGELLAN AO SYSTEM

    SciTech Connect

    Wu, Ya-Lin; Close, Laird M.; Males, Jared R.; Morzinski, Katie M.; Follette, Katherine B.; Bailey, Vanessa; Rodigas, Timothy J.; Hinz, Philip; Barman, Travis S.; Puglisi, Alfio; Xompero, Marco; Briguglio, Runa

    2015-03-01

    We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and Y{sub S}. With our new photometry and T {sub eff} ∼ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has A{sub V} = 3.4 ± 1.1 mag, and a mass of 14-24 M{sub J} according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates that the companion has significant Hα emission and a mass accretion rate ∼6 × 10{sup –10} M {sub ☉} yr{sup –1}, similar to some substellar companions. Proper motion analysis shows that another point source within 2'' of CT Cha A is not physical. This paper demonstrates how visible wavelength adaptive optics photometry (r', i', z', Y{sub S}) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions.

  11. Replication of deep micro-optical components prototyped by Deep Proton Writing

    NASA Astrophysics Data System (ADS)

    Van Erps, J.; Wissmann, M.; Guttmann, M.; Hartmann, M.; Desmet, L.; Debaes, C.; Mohr, J.; Thienpont, H.

    2008-04-01

    Using our rapid prototyping technology called Deep Proton Writing (DPW), we have in recent years made a wide range of micro-optical components with a large depth (500-μm) for a variety of applications. One of these components is a pluggable out-of-plane coupler for printed circuit board-level optical interconnections. Whereas DPW is capable of rapidly fabricating high-quality master components, the technology is not suitable for low-cost mass fabrication. Therefore, we investigate the replication of out-of-plane coupling components using hot embossing, through the fabrication of a metal mould of the DPW master by applying electroplating. We compare these hot embossed replicas with components replicated using the elastomeric mould vacuum casting technology.

  12. Downlink receiver algorithms for deep space optical communications

    NASA Astrophysics Data System (ADS)

    Srinivasan, Meera; Rogalin, Ryan; Lay, Norman; Shaw, Matthew; Tkacenko, Andre

    2017-02-01

    The goal of the Deep Space Optical Communications project at the Jet Propulsion Laboratory is to demonstrate laser communication links at ranges out to approximately 3 AU. In this paper, we discuss a downlink receiver concept capable of demodulating optical pulse-position modulated (PPM) waveforms with data rates varying from approximately 50 kbps up to 265 Mbps, using a range of PPM orders, slot widths, and code rates. The receiver operates on recorded timestamps corresponding to the times-of-arrival of photons detected by a photon-counting detector array followed by a commercial time-tagger. Algorithms are presented for slot, symbol, and frame synchronization as well as parameter estimation. Estimates of link performance are evaluated through Monte- Carlo simulation for an optical channel that includes optical losses, detector blocking, signal clock dynamics, and pointing-induced downlink fades. Based upon these simulation results, it is expected that link closure may be achieved with at least 3 dB of margin under a variety of relevant conditions.

  13. Holographic deep learning for rapid optical screening of anthrax spores

    PubMed Central

    Jo, YoungJu; Park, Sangjin; Jung, JaeHwang; Yoon, Jonghee; Joo, Hosung; Kim, Min-hyeok; Kang, Suk-Jo; Choi, Myung Chul; Lee, Sang Yup; Park, YongKeun

    2017-01-01

    Establishing early warning systems for anthrax attacks is crucial in biodefense. Despite numerous studies for decades, the limited sensitivity of conventional biochemical methods essentially requires preprocessing steps and thus has limitations to be used in realistic settings of biological warfare. We present an optical method for rapid and label-free screening of Bacillus anthracis spores through the synergistic application of holographic microscopy and deep learning. A deep convolutional neural network is designed to classify holographic images of unlabeled living cells. After training, the network outperforms previous techniques in all accuracy measures, achieving single-spore sensitivity and subgenus specificity. The unique “representation learning” capability of deep learning enables direct training from raw images instead of manually extracted features. The method automatically recognizes key biological traits encoded in the images and exploits them as fingerprints. This remarkable learning ability makes the proposed method readily applicable to classifying various single cells in addition to B. anthracis, as demonstrated for the diagnosis of Listeria monocytogenes, without any modification. We believe that our strategy will make holographic microscopy more accessible to medical doctors and biomedical scientists for easy, rapid, and accurate point-of-care diagnosis of pathogens. PMID:28798957

  14. Combining Fits of The Optical Photometry and X-ray Spectra of the Low Mass X-ray Binary V1408 Aquilae.

    NASA Astrophysics Data System (ADS)

    Gomez, Sebastian; Mason, Paul A.; Robinson, Edward L.

    2015-01-01

    V1408 Aquilae is a binary system with a black hole primary accreting matter from a low mass secondary. We observed the system at the McDonald Observatory and collected 126 hours of high speed optical photometry on the source. We modeled the optical light curve using the XRbinary light curve synthesis software. The best fits to the optical light curve seem to suggest that the primary is a low mass black hole, however we cannot exclude some high mass solutions. Our models slightly favor a 3 solar mass primary at an inclination of about 13 degrees. In order to further constrain these parameters, and verify their validity we compared the fits of the optical light curve to fits to the X-ray spectra of the source. Using data from the Chandra Transmission Grating Catalog and Archive and the ISIS software analysis package we modeled the spectra of the source with a multi-temperature blackbody for a relativistic accretion disk around a spinning black hole and an additional photon power law component. The fits to the optical lightcurve and X-ray spectra are in agreement, from this we conclude that the case for V1408 Aql to be at a low inclination and harbor a low mass black hole is plausible.

  15. Optical-communication systems for deep-space applications

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.; Gagliardi, R. M.

    1980-01-01

    The feasibility of using optical communication systems for data telemetry from deep space vehicles to Earth based receivers is evaluated. Performance analysis shows that practical, photon counting optical systems can transmit data reliably at 30 to 40 dB high rates than existing RF systems, or can be used to extend the communication range by 15 to 20 dB. The advantages of pulse-position modulation (PPM) formats are discussed, and photon counting receiver structures designed for PPM decoding are described. The effects of background interference and weather on receiver performance are evaluated. Some consideration is given to tracking and beam pointing operations, since system performance ultimately depends on the accuracy to which these operations can be carried out. An example of a tracking and pointing system utilizing an optical uplink beacon is presented, and it is shown that microradian beam pointing is within the capabilities of state-of-the-art technology. Recommendations for future theoretical studies and component development programs are presented.

  16. Deep-Space Optical Transceiver Uplink Detection Analysis

    NASA Astrophysics Data System (ADS)

    Tkacenko, A.; Quirk, J. J.; Srinivasan, M.

    2013-05-01

    In this article, we develop and analyze an uplink signal detection technique for the Deep-Space Optical Transceiver (DOT). Here, the detection is carried out using a set of test statistics obtained from up-down counter (UDC) photon detection systems. Specifically, we address two sets of statistics: the count outputs from a bank of uniformly temporally spaced UDCs as well as the counts from a single UDC that cycles through multiple uniformly spaced timing phases. From these test statistics, we derive the Neyman-Pearson decision rule under certain input conditions and analyze the performance of this hypothesis test. We show the performance trade-offs associated with both sets of test statistics, which can then be used to determine which set to use as well as the number of UDCs or timing phases required for implementation.

  17. Bioabsorbable polymer optical waveguides for deep-tissue photomedicine

    PubMed Central

    Nizamoglu, Sedat; Gather, Malte C.; Humar, Matjaž; Choi, Myunghwan; Kim, Seonghoon; Kim, Ki Su; Hahn, Sei Kwang; Scarcelli, Giuliano; Randolph, Mark; Redmond, Robert W.; Yun, Seok Hyun

    2016-01-01

    Advances in photonics have stimulated significant progress in medicine, with many techniques now in routine clinical use. However, the finite depth of light penetration in tissue is a serious constraint to clinical utility. Here we show implantable light-delivery devices made of bio-derived or biocompatible, and biodegradable polymers. In contrast to conventional optical fibres, which must be removed from the body soon after use, the biodegradable and biocompatible waveguides may be used for long-term light delivery and need not be removed as they are gradually resorbed by the tissue. As proof of concept, we demonstrate this paradigm-shifting approach for photochemical tissue bonding (PTB). Using comb-shaped planar waveguides, we achieve a full thickness (>10 mm) wound closure of porcine skin, which represents ∼10-fold extension of the tissue area achieved with conventional PTB. The results point to a new direction in photomedicine for using light in deep tissues. PMID:26783091

  18. Bioabsorbable polymer optical waveguides for deep-tissue photomedicine

    NASA Astrophysics Data System (ADS)

    Nizamoglu, Sedat; Gather, Malte C.; Humar, Matjaž; Choi, Myunghwan; Kim, Seonghoon; Kim, Ki Su; Hahn, Sei Kwang; Scarcelli, Giuliano; Randolph, Mark; Redmond, Robert W.; Yun, Seok Hyun

    2016-01-01

    Advances in photonics have stimulated significant progress in medicine, with many techniques now in routine clinical use. However, the finite depth of light penetration in tissue is a serious constraint to clinical utility. Here we show implantable light-delivery devices made of bio-derived or biocompatible, and biodegradable polymers. In contrast to conventional optical fibres, which must be removed from the body soon after use, the biodegradable and biocompatible waveguides may be used for long-term light delivery and need not be removed as they are gradually resorbed by the tissue. As proof of concept, we demonstrate this paradigm-shifting approach for photochemical tissue bonding (PTB). Using comb-shaped planar waveguides, we achieve a full thickness (>10 mm) wound closure of porcine skin, which represents ~10-fold extension of the tissue area achieved with conventional PTB. The results point to a new direction in photomedicine for using light in deep tissues.

  19. Deep-tissue optical imaging of decubitus ulcers

    NASA Astrophysics Data System (ADS)

    Moza, Rohin; DiMaio, J. Michael; Melendez, Jose

    2011-03-01

    Decubitus ulcers are a costly and widespread issue in healthcare today, that result from impaired blood flow in skin and underlying muscle and tissue. To address this need, a point of care multi-wavelength diagnostic imaging system has been developed to monitor hemodynamic processes via use of optical imaging of deep tissue. The resulting measurements demonstrate changes in light-tissue interaction to differentiate healthy and pathologic tissue without disturbing patients in a hospital setting. The identification of light source-detector illumination patterns uniquely map to spatial depths of tissue. The additional time dependent component, allows a novel four-dimensional analysis of tissue. The portable, noninvasive, and non-contact features provide quantitative in-situ measurements.

  20. Bioabsorbable polymer optical waveguides for deep-tissue photomedicine.

    PubMed

    Nizamoglu, Sedat; Gather, Malte C; Humar, Matjaž; Choi, Myunghwan; Kim, Seonghoon; Kim, Ki Su; Hahn, Sei Kwang; Scarcelli, Giuliano; Randolph, Mark; Redmond, Robert W; Yun, Seok Hyun

    2016-01-19

    Advances in photonics have stimulated significant progress in medicine, with many techniques now in routine clinical use. However, the finite depth of light penetration in tissue is a serious constraint to clinical utility. Here we show implantable light-delivery devices made of bio-derived or biocompatible, and biodegradable polymers. In contrast to conventional optical fibres, which must be removed from the body soon after use, the biodegradable and biocompatible waveguides may be used for long-term light delivery and need not be removed as they are gradually resorbed by the tissue. As proof of concept, we demonstrate this paradigm-shifting approach for photochemical tissue bonding (PTB). Using comb-shaped planar waveguides, we achieve a full thickness (>10 mm) wound closure of porcine skin, which represents ∼ 10-fold extension of the tissue area achieved with conventional PTB. The results point to a new direction in photomedicine for using light in deep tissues.

  1. Long-Term Optical Photometry of Selected Blazars: 3C 66A, 4C 29.45, ON 231 and 3C 345

    NASA Astrophysics Data System (ADS)

    Kurtanidze, O. M.; Nikolashvili, M. G.; Sigua, L. A.

    We present optical R band photometry of 3C 66A, 4C 29.45, ON 231 and 3C 345 from August 1997 to April 1999. Variability on long time scales in R band up to two magnitudes was found for 3C 66A and ON 231. The largest variation was observed for 3C 66A and equals to Delta(R)=1.90 (0.03) mag. Observational period includes the last great April 1998 outburst of ON 231 with overall amplitude 1.8 mag, IDV and IHV amplitudes are 0.82 and 0.2, respectively. 4C 29.45 and 3C 345 show variability of 1.6 and 1.02 mag.

  2. Irregular Variability In Kepler Photometry

    NASA Astrophysics Data System (ADS)

    Schlecker, Martin

    2016-12-01

    The transit method is the most successful tool for exoplanet discovery to date. With more than half of all known exoplanets discovered by Kepler using this method, the mission also revealed a number of objects with dimming events that defy the common explanations, the most prominent being KIC 8462852 aka ``Tabby's star''. I embarked on a search for objects with such irregular transit signatures in the data of K2, the two-wheeled successor mission of Kepler. My method is a combination of automated pre-selection of targets showing downward flux excursions and visual light curve inspection of the selected subset comprising about SI{1.5}% of the initial sample. In addition, I developed a tool to constrain the effective temperature of a planet-hosting star from photometry alone. This software finds broad application in any science case where a photometric spectral type estimate is necessary. I used existing transit models and Bayesian inference to perform a Markov Chain Monte Carlo (MCMC) analysis of a planetary candidate I discovered. This putative gas giant is in a SI{1.32}day circular orbit with an exceptionally tight orbital radius of a ≈ 0.012 AU. My analysis revealed a scaled planetary radius of R_{p}/R_star = 0.0927±0.0026 and an edge-on orientation with an inclination i=89.8+3.0-3.4. EPIC 217393088.01 is one of the closest-orbiting exoplanets ever detected and the first giant planet with such a small orbital radius. An additional major finding of my search is EPIC 220262993, which exhibits aperiodic, asymmetric dips in flux with rapid dimming rates and up to SI{˜25}% depth, lasting for SIrange{2}{4} day. In previous works based on optical and mid-infrared photometry, this object was inconsistently classified as a possible quasar or a white dwarf. We conducted follow-up observations both photometrically with GROND on the MPI/ESO SI{2.2} meter telescope in La Silla (Chile) and spectroscopically with FIRE on the Magellan/Baade SI{6.5} meter telescope. With

  3. Optimizing Parameters for Deep-Space Optical Communication

    NASA Technical Reports Server (NTRS)

    Moison, Bruce; Hamkins, Jon

    2005-01-01

    A paper discusses the optimization of the parameters of a high-rate, deep-space optical communication link that utilizes pulse-position modulation (PPM) and an error-correcting code (ECC). The parameters in question include the PPM order (number of pulse time slots in one symbol period), the ECC rate, and the uncoded symbol error rate. In simple terms, the optimization problem is to choose the combination of these parameters that maximizes the throughput data rate at a given bit-error-rate (BER), subject to several constraints, including limits on the average and peak power and possibly a limit on the uncoded symbol error rate. This is a complex, multidimensional optimization problem, the solution of which involves computation of channel capacities for various combinations of the parameters. The paper presents extensive theoretical analyses and numerical predictions that elucidate the many facets of the optimization problem. It shows how a nearly optimum solution can be obtained by choosing the optimum PPM order for the desired number of bits per slot and concatenating the PPM mapping with an error-correction code so that the decoded bits satisfy some BER threshold.

  4. Galaxy Evolution from Deep Optical and Near-Infrared Surveys

    NASA Astrophysics Data System (ADS)

    Moustakas, Leonidas Alexander

    1998-09-01

    We use very deep optical and near-infrared imaging surveys to set constraints on galaxy evolution models, based on the numbers, colors, and morphologies of infrared-excess galaxies that are found in the field. We concentrate on a curious population of extremely faint (K > 20) infrared-excess galaxies whose blue-optical colors are not consistent with the expectations of any passive evolution models. These ``faint red-outlier galaxies'' (FROGs) are distinct from the redder and brighter ``extremely red objects'' (EROs; R-K~=6 ). In a concerted effort to identify a good sample of FROG s and to study their properties, we used Keck/NIRC to image several independent high-galactic latitude fields. Much of the analysis presented here is drawn from a very deep 3.24 arcmin2 K-band ( Klim~24 at 3σ) mosaic in the deep Westphal HST/WFPC2 pointing of the Groth Survey Strip, for which F606W and F814W data were publically available. The surface density of FROGs is found to be ~ 3.3 +/- 1 arcmin-2, more than ten times that of EROs. Whereas reliable photometric redshifts are not forthcoming without the development of more relevant models, the colors are broadly consistent with the redshift range 1.2 < z < 2.3. If placed at z ~ 1.5, FROGs occur at space densities of about 10% of the local f* space density of K-selected galaxies. To map wavelength-dependent morphologies of two FROGs, we observed a portion of our main survey field with HST/NICMOS imaging through the F160W (1.6 μm) filter. The target was resolved into two r~=0''.6 objects with similar colors, separated by ~0''.7. This is suggestive of old and dynamically-relaxed systems. The colors of FROGs are not satisfactorily fit by dust-reddened Bruzual-Charlot models at any redshift and for a broad range of assumed star formation histories. The best possible fits are consistent with very large amounts of reddening, E(B - V) ~ 1. If the infrared-excess in EROs and FROGs is taken to be entirely due to the effects of dust, then we

  5. Active Optics for a Segmented Primary Mirror on a Deep-Space Optical Receiver Antenna (DSORA)

    NASA Technical Reports Server (NTRS)

    Clymer, B. D.

    1990-01-01

    This article investigates the active optical control of segments in the primary mirror to correct for wavefront errors in the Deep-Space Optical Receiver Antenna (DSORA). Although an exact assessment of improvement in signal blur radius cannot be made until a more detailed preliminary structural design is completed, analytical tools are identified for a time when such designs become available. A brief survey of appropriate sensing approaches is given. Since the choice of control algorithm and architecture depends on the particular sensing system used, typical control systems, estimated complexities, and the type of equipment required are discussed. Once specific sensor and actuator systems are chosen, the overall control system can be optimized using methods identified in the literature.

  6. Optical processing deep inside optical materials using counterpropagating pulse-shaped spatial solitons

    NASA Astrophysics Data System (ADS)

    Hisaka, Masaki

    2016-10-01

    Optical processing using a pair of counterpropagating pulse-shaped spatial solitons to control the molecular structure deep inside an optical material is investigated. A femtosecond pulsed laser focused at the surface of a strontium barium niobate single crystal induces a pulse-shaped self-focusing second-harmonic beam. The two counterpropagating beams are involved in a head-on collision. Locally reversed crystal domains are formed at the collision point, assisted by external threshold controls such as crystal temperature and an electric dc field. The nonlinear interaction between the soliton collision and the approximate nonperiodic reversed domains induces a change in the second-harmonic intensity of the scattered and transmitted beams, thereby enabling the detection of locally reversed crystal domains.

  7. Optical and Infrared Photometry of the Type Ia Supernovae 1991T, 1991bg, 1999ek, 2001bt, 2001cn, 2001cz, and 2002bo

    NASA Astrophysics Data System (ADS)

    Krisciunas, Kevin; Suntzeff, Nicholas B.; Phillips, Mark M.; Candia, Pablo; Prieto, José Luis; Antezana, Roberto; Chassagne, Robin; Chen, Hsiao-Wen; Dickinson, Mark; Eisenhardt, Peter R.; Espinoza, Juan; Garnavich, Peter M.; González, David; Harrison, Thomas E.; Hamuy, Mario; Ivanov, Vladimir D.; Krzemiński, Wojtek; Kulesa, Craig; McCarthy, Patrick; Moro-Martín, Amaya; Muena, César; Noriega-Crespo, Alberto; Persson, S. E.; Pinto, Philip A.; Roth, Miguel; Rubenstein, Eric P.; Stanford, S. Adam; Stringfellow, Guy S.; Zapata, Abner; Porter, Alain; Wischnjewsky, Marina

    2004-12-01

    We present optical and/or infrared photometry of the Type Ia supernovae SN 1991T, SN 1991bg, SN 1999ek, SN 2001bt, SN 2001cn, SN 2001cz, and SN 2002bo. All but one of these supernovae have decline rate parameters, Δm15(B), close to the median value of 1.1 for the whole class of Type Ia supernovae. The addition of these supernovae to the relationship between the near-infrared absolute magnitudes and Δm15(B) strengthens the previous relationships we have found in that the maximum light absolute magnitudes are essentially independent of the decline rate parameter. (SN 1991bg, the prototype of the subclass of fast-declining Type Ia supernovae, is a special case.) The dispersion in the Hubble diagram in JHK is only ~0.15 mag. The near-infrared properties of Type Ia supernovae continue to be excellent measures of the luminosity distances to the supernova host galaxies because of the need for only small corrections from the epoch of observation to maximum light, low dispersion in absolute magnitudes at maximum light, and the minimal reddening effects in the near-infrared.

  8. Shape model of asteroid (130) Elektra from optical photometry and disk-resolved images from VLT/SPHERE and Nirc2/Keck

    NASA Astrophysics Data System (ADS)

    Hanuš, J.; Marchis, F.; Viikinkoski, M.; Yang, B.; Kaasalainen, M.

    2017-02-01

    Context. Asteroid (130) Elektra belongs to one of the six known triple asteroids in the main belt, so its mass has been reliably determined. Aims: We aim to use all available disk-resolved images of (130) Elektra obtained by the SPHERE instrument at VLT and by the Nirc2 of the Keck telescope together with the disk-integrated photometry to determine its shape model and its size. The volume can be then used in combination with the known mass to derive the bulk density of the primary. Methods: We have applied the All-Data Asteroid Modeling (ADAM) algorithm to the optical disk-integrated data, two disk-resolved images obtained by the SPHERE instrument, and 13 disk-resolved images from the Nirc2 of the Keck telescope. We have also derived the shape model and size of Elektra. Results: We present the shape model, volume-equivalent diameter (199 ± 7 km) and bulk density (1.60 ± 0.13 g cm-3) of the C-type asteroid Elektra.

  9. Optical coherence tomography and optical coherence domain reflectometry for deep brain stimulation probe guidance

    NASA Astrophysics Data System (ADS)

    Jeon, Sung W.; Shure, Mark A.; Baker, Kenneth B.; Chahlavi, Ali; Hatoum, Nagi; Turbay, Massud; Rollins, Andrew M.; Rezai, Ali R.; Huang, David

    2005-04-01

    Deep Brain Stimulation (DBS) is FDA-approved for the treatment of Parkinson's disease and essential tremor. Currently, placement of DBS leads is guided through a combination of anatomical targeting and intraoperative microelectrode recordings. The physiological mapping process requires several hours, and each pass of the microelectrode into the brain increases the risk of hemorrhage. Optical Coherence Domain Reflectometry (OCDR) in combination with current methodologies could reduce surgical time and increase accuracy and safety by providing data on structures some distance ahead of the probe. For this preliminary study, we scanned a rat brain in vitro using polarization-insensitive Optical Coherence Tomography (OCT). For accurate measurement of intensity and attenuation, polarization effects arising from tissue birefringence are removed by polarization diversity detection. A fresh rat brain was sectioned along the coronal plane and immersed in a 5 mm cuvette with saline solution. OCT images from a 1294 nm light source showed depth profiles up to 2 mm. Light intensity and attenuation rate distinguished various tissue structures such as hippocampus, cortex, external capsule, internal capsule, and optic tract. Attenuation coefficient is determined by linear fitting of the single scattering regime in averaged A-scans where Beer"s law is applicable. Histology showed very good correlation with OCT images. From the preliminary study using OCT, we conclude that OCDR is a promising approach for guiding DBS probe placement.

  10. Additional optical photometry of the recurrent nova M31N 1990-10a during its 2016 eruption

    NASA Astrophysics Data System (ADS)

    Goranskij, V.; Barsukova, E.; Henze, M.

    2016-08-01

    We report additional optical measurements of the declining light curve of the recurrent nova M31N 1990-10a (see ATels #9276,#9280,#9281,#9383,#9386). All data were obtained with the 50-cm Maksutov meniscus telescope of the Crimean Astronomical Station of the Moscow University.

  11. Periodic Brightness Modulation of the T Tauri Star V716 Per Based on Optical and Infrared Photometry

    NASA Astrophysics Data System (ADS)

    Barsunova, O. Yu.; Grinin, V. P.; Arharov, A. A.; Semenov, A. O.; Sergeev, S. G.; Efimova, N. V.

    2016-06-01

    Results of long-term optical and near infrared observations (VRI and JHK bands, respectively) of the T Tauri star V716 Per are reported. The previously discovered period of the optical brightness variation of the star is confirmed. Our data yield a period of 7.50 days. The period is stable over the entire interval of our observations (about 12 years), although the shape and amplitude of the brightness phase curves varied from season to season. For the first time it is shown that this period is also present in the variations of the JHK infrared fluxes. It is also shown that besides the short period, a slow wave with a duration comparable to the interval of our observations appears in the variations of the star's brightness. Two models of the star's variability are considered for analyzing its photometric behavior: (a) surface activity owing to the existence of cold (magnetic) spots on the star and (b) AA Tau type variability caused by periodic eclipsing of the star by its own circumstellar disk, the inner region of which is warped because of interactions with the star's magnetosphere. The latter model matches the optical observations better. In the infrared, that model only provides a partial fit to the observed variability. In the K band, the major contribution to the variability is from changes in the luminosity of the inner disk caused by fluctuations in the accretion rate.

  12. Photometry of a Sodium Laser Guide Star from the Starfire Optical Range. II. Compensating the Pump Beam

    NASA Astrophysics Data System (ADS)

    Drummond, Jack; Telle, John; Denman, Craig; Hillman, Paul; Spinhirne, Jim; Christou, Julian

    2004-10-01

    Measurements of the brightness and size of a mesospheric sodium guide star pumped by a laser launched through an adaptive optics (AO) system are reported from experiments conducted on 2003 July 22 at the Starfire Optical Range. The guide star was produced by a laser launched through a 0.5 m telescope with (closed loop) and without (open loop) higher order atmospheric compensation using an ~60 actuator AO system and with various laser polarization states. A 3.5 m telescope (without AO) 50 m away from the launch site recorded the closed- and open-loop images. Calibrated using standard stars, the maximum brightness observed for the 8.5 W of compensated pump laser power out of the top of the telescope for a 96% circularly polarized beam was V1=7.35 (840 photons s-1 cm-2 at the bottom of the atmosphere) for the open-loop beam (where V1 is the V magnitude corrected for the transmission of the V filter at the 589 nm wavelength of the sodium D2 absorption line) and V1=7.4 (800 photons s-1 cm-2) for the closed-loop beam. It appears that circular polarization enhances the brightness of the return by 75%. Open-loop tests produced an integrated guide star that was 11% brighter than closed-loop, but the guide star produced from a closed-loop circularly polarized pump beam was about 50% of the width of either the open-loop beam or the linearly polarized closed-loop beam. At 0.85" FWHM, or 38 cm at 92 km altitude, the guide star is suitable for many astronomical AO applications. The guide star spot sizes were measured from images reconstructed with multiframe blind deconvolution. Because of optical losses, only 8.5 W of laser power was transmitted out of the top of the telescope. Reducing this by atmospheric extinction, the ``power through the mesospheric footprint,'' or peak Gaussian intensity, was 3.9 mW cm-2 for the closed-loop circularly polarized laser beam. This is about 60% of the saturation intensity Isat for the optically pumped atom, and 20% of the Isat for the

  13. Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement

    NASA Astrophysics Data System (ADS)

    Li, Chen; Zhou, Tianwei; Zhai, Yueyang; Xiang, Jinggang; Luan, Tian; Huang, Qi; Yang, Shifeng; Xiong, Wei; Chen, Xuzong

    2017-05-01

    We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ˜ 6 nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

  14. Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement.

    PubMed

    Li, Chen; Zhou, Tianwei; Zhai, Yueyang; Xiang, Jinggang; Luan, Tian; Huang, Qi; Yang, Shifeng; Xiong, Wei; Chen, Xuzong

    2017-05-01

    We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ∼6nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

  15. Doppler and range determination for deep space vehicles using active optical transponders

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Gagliardi, Robert M.

    1988-01-01

    This paper describes and analyzes two types of laser system employing active transponders that could accurately determine Doppler and range to deep space vehicles from earth-orbiting satellites. The first is a noncoherent optical system in which the Doppler effect on an intensity-modulating subcarrier is measured. The second is a coherent optical system in which the Doppler effect of the optical carrier itself is measured. Doppler and range measurement errors are mathematically modeled and, for three example systems, numerically evaluated.

  16. Photutils: Photometry tools

    NASA Astrophysics Data System (ADS)

    Bradley, Larry; Sipocz, Brigitta; Robitaille, Thomas; Tollerud, Erik; Deil, Christoph; Vinícius, Zè; Barbary, Kyle; Günther, Hans Moritz; Bostroem, Azalee; Droettboom, Michael; Bray, Erik; Bratholm, Lars Andersen; Pickering, T. E.; Craig, Matt; Pascual, Sergio; Greco, Johnny; Donath, Axel; Kerzendorf, Wolfgang; Littlefair, Stuart; Barentsen, Geert; D'Eugenio, Francesco; Weaver, Benjamin Alan

    2016-09-01

    Photutils provides tools for detecting and performing photometry of astronomical sources. It can estimate the background and background rms in astronomical images, detect sources in astronomical images, estimate morphological parameters of those sources (e.g., centroid and shape parameters), and perform aperture and PSF photometry. Written in Python, it is an affiliated package of Astropy (ascl:1304.002).

  17. FAINT NEAR-ULTRAVIOLET/FAR-ULTRAVIOLET STANDARDS FROM SWIFT/UVOT, GALEX, AND SDSS PHOTOMETRY

    SciTech Connect

    Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.; Brown, Peter E-mail: hoversten@astro.psu.ed E-mail: brown@astro.psu.ed

    2010-12-10

    At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u {approx} 17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20, 000 < T{sub eff} < 50, 000 K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures. We find that the photometry provides good constraints on white dwarf temperatures, which demonstrates the ability of Swift/UVOT to investigate the properties of hot luminous stars. We further find that the models reproduce the photometric measures in all 11 passbands to within their systematic uncertainties. Within the limits of our photometry, we find the standard stars to be photometrically stable. This success indicates that the models can be used to calibrate additional filters to our standard system, permitting easier comparison of photometry from heterogeneous sources. The largest source of uncertainty in the model fitting is the uncertainty in the foreground reddening curve, a problem that is especially acute in the UV.

  18. Deep space optical communications link availability and data volume

    NASA Technical Reports Server (NTRS)

    Biswas, A.; Wilson, K. E.; Piazzolla, S.; Wu, J.; Farr, W. H.

    2004-01-01

    Optical links from a spacecraft at planetary distance to a ground-based receiver presume a cloud free line of site (CFLOS). Future ground-based optical reeiving networks, should they be implemented, will rely on site diversity of could cover to increase link availability.

  19. Macular pigment optical density measurements by one-wavelength reflection photometry--influence of cataract surgery on the measurement results.

    PubMed

    Komar, Bogdana; Rauscher, Franziska Georgia; Wiedemann, Renate; Dawczynski, Jens

    2014-11-01

    The main objective of the present study was the investigation of possible influence of lens opacification on macular pigment optical density (MPOD) measurements. Eighty-six eyes of 64 patients (mean age 73.4 ± 8.3 years) were included in the study. MPOD was prospectively measured using the one-wavelength reflection method (Visucam500, Carl Zeiss Meditec AG) before and after cataract extraction, with implantation of a blue-light filtering intraocular lens (AlconSN60WF). The median of the maximum optical density (MaxOD) and the median of the mean optical density (MeanOD) measurements of macular pigment across the subject group were evaluated. Statistically significant differences were noticed between pre-operative and post-operative measurements, the absolute values were generally lower after cataract extraction. The following median (lower/upper quartile) differences across the group were determined: MaxOD -33.8 % (-46.2 to -19.1 %), MeanOD -44.0 % (-54.6 to -26.6 %). Larger changes were observed in elderly patients [<70 years of age (n = 25 eyes): MaxOD -13.4 % (-20.5 to 3.6 %), MeanOD -23.6 % (-30.5 to -15.3 %) versus patients ≥70 years (n = 61 eyes) MaxOD -40.5 % (-53.2 to -30.1 %), MeanOD -47.2 % (-57.8 to -40.1 %)] and in patients with progressed stage of cataract. MaxOD for lens opacification grade 1 (n = 9 eyes): -27.4 % (-42.1 to -19.6 %), grade 2 (n = 26 eyes): -35.0 % (-44.2 to -25.3 %), grade 3 (n = 21 eyes): -34.4 % (-45.4 to -11.4 %), grade 4 (n = 25 eyes): -32.6 % (-53.2 to -6.4 %), and grade 5 (n = 5 eyes): -53.5 % (-61.7 to -38.7 %) and MeanOD for cataract stage 1 (n = 9 eyes): -42.6 % (-46.0 to -26.0 %), stage 2 (n = 26 eyes): -44.1 % (-51.8 to -26.2 %), stage 3 (n = 21 eyes): -45.7 % (-54.7 to -24.7 %), stage 4 (n = 25 eyes): -39.5 % (-59.4 to -26.1 %), and stage 5 (n = 5 eyes): -57.0 % (-66.1 to -51.4 %). As established by comparison of pre- to post-operative measurements, cataract presented a

  20. Absolute Optical Photometry and a Photometric Metallicity Relation for the Nearby Cool Stars from the MEarth Project

    NASA Astrophysics Data System (ADS)

    Dittmann, Jason; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R.

    2015-01-01

    There is renewed interest in understanding the low mass stars and brown dwarfs of the solar neighborhood. Since M dwarfs make up the vast majority of stars in the universe, it is essential that we understand their fundamental physical properties. Their ubiquitousness makes them excellent kinematic and chemical probes of the Galaxy, provided we can accurately measure their distances, absolute magnitudes, and metallicities. Additionally, current and future exoplanet surveys that are focused on M dwarfs, such as SPIRou, CARMENES, and the Habitable Zone Planet Finder will uncover a plethora of planetary systems around these stars. Unfortunately, many of the nearby low mass stars are poorly characterized with current data. The MEarth survey has been monitoring approximately 1800 mid-to-late M dwarfs since 2008 and each night also observes a set of Landolt standard stars. We measure a precise optical magnitude in our MEarth bandpass, a red broadband filter similar to the Bessel I filter, for 1500 of these systems. By combining this work with our recent work measuring the trigonometric parallaxes and metallicities of a subset of these M dwarfs, we construct a photometric metallicity relation. We then apply it to the full sample of MEarth-North M dwarfs.The MEarth project gratefully acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering, the National Science Foundation under grants AST-0807690, AST-1109468, and AST-1004488, and the John Templeton Foundation.

  1. Deep optical access on multi-core and multi-mode fiber for integrated wireless applications

    NASA Astrophysics Data System (ADS)

    Llorente, Roberto; Morant, Maria; Beltrán, Marta; Macho, Andrés.

    2015-01-01

    Deep integrated optical access networks target to provide great capillarity and multiple ONTs for cost- and energy-efficient pervasive connectivity seamless supporting integrated wireless. Several key optical technologies are herein reported supporting integrated deep optical access: Bundled radio-over-fiber transmission is proposed and demonstrated for the provision of quintuple-play services achieving 125 km SSMF optical reach. Bend-insensitive fiber in-building distribution is also proposed and demonstrated supporting joint legacy coaxial transmission. Multimode POF is also proposed and demonstrated suitable for joint in-building distribution of MATV and SMATV broadcasting signals. Optical comb technology us is also demonstrated suitable for mm-wave radio generation of multiband OFDM wireless signals. Finally, multicore fiber transmission is also proposed and demonstrated suitable for the transmission of LTE and WIMAX in wireless fronthaul applications in a minimized inter-core crosstalk penalty configuration.

  2. Technological status and future challenges of deep space optical communication

    NASA Technical Reports Server (NTRS)

    Lesh, James R.

    1987-01-01

    An account is given of the concepts, techniques, and system design features that may be used to realize an optical communications link for future planetary missions. Such a spacecraft subsystem would encompass a 10-30 cm aperture optical telescope for both transmitting and receiving. Uplink from a laser, in the form of pulsed ranging signals or command information, will be extracted by a tracking detector; downlink data, as well as detected ranging pulses, will be properly formatted and used to modulate the downlink laser. The optical receiving station may be either on the ground or in earth orbit.

  3. Heterochromatic flicker photometry.

    PubMed

    Bone, Richard A; Landrum, John T

    2004-10-15

    Measurement of the macular pigment optical density (MPOD) by heterochromatic flicker photometry (HFP) is accomplished by viewing a small circular stimulus that alternates between a test wavelength that is absorbed by the MP (typically--blue, 460 nm) and a reference wavelength that is not absorbed (typically-green, 540 nm). Flicker observed by the subject is reduced to a null point by adjusting the intensity of the former while viewing the stimulus centrally, and then peripherally. A higher intensity, I, of the blue component of the stimulus is needed under central viewing conditions owing to attenuation by the MP. The MPOD at the test wavelength is given by log (Icentral/Iperipheral). Variation of the test wavelength has been used to measure the MPOD spectrum. This in vitro MPOD spectrum matches that of the carotenoids present in the macular region of the retina and demonstrates the validity and specificity of this methodology. The distribution of MPOD in the retina can be determined with HFP using a series of annular stimuli of different diameters.

  4. On the Absolute Age of the Metal-rich Globular M71 (NGC 6838). I. Optical Photometry

    NASA Astrophysics Data System (ADS)

    Di Cecco, A.; Bono, G.; Prada Moroni, P. G.; Tognelli, E.; Allard, F.; Stetson, P. B.; Buonanno, R.; Ferraro, I.; Iannicola, G.; Monelli, M.; Nonino, M.; Pulone, L.

    2015-08-01

    We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u\\prime ,g\\prime ,r\\prime ,i\\prime ,z\\prime ) collected with the MegaCam camera at the Canada-France-Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new method based on the 3D (r\\prime ,u\\prime -g\\prime ,g\\prime -r\\prime ) color-color-magnitude diagram. A comparison between the color-magnitude diagram (CMD) of the candidate cluster stars and a new set of isochrones at the locus of the main sequence turn-off (MSTO) suggests an absolute age of 12 ± 2 Gyr. The absolute age was also estimated using the difference in magnitude between the MSTO and the so-called main sequence knee, a well-defined bending occurring in the lower main sequence. This feature was originally detected in the near-infrared bands and explained as a consequence of an opacity mechanism (collisionally induced absorption of molecular hydrogen) in the atmosphere of cool low-mass stars. The same feature was also detected in the r‧, u\\prime -g\\prime , and in the r\\prime ,g\\prime -r\\prime CMD, thus supporting previous theoretical predictions by Borysow et al. The key advantage in using the {{{Δ }}}{TO}{Knee} as an age diagnostic is that it is independent of uncertainties affecting the distance, the reddening, and the photometric zero point. We found an absolute age of 12 ± 1 Gyr that agrees, within the errors, with similar age estimates, but the uncertainty is on average a factor of two smaller. We also found that the {{{Δ }}}{TO}{Knee} is more sensitive to the metallicity than the MSTO, but the dependence vanishes when using the difference in color between the MSK and the MSTO.

  5. Andromeda (M31) optical and infrared disk survey. I. Insights in wide-field near-IR surface photometry

    SciTech Connect

    Sick, Jonathan; Courteau, Stéphane; Cuillandre, Jean-Charles; McDonald, Michael; De Jong, Roelof; Tully, R. Brent

    2014-05-01

    We present wide-field near-infrared J and K{sub s} images of the Andromeda Galaxy (M31) taken with WIRCam at the Canada-France-Hawaii Telescope as part of the Andromeda Optical and Infrared Disk Survey. This data set allows simultaneous observations of resolved stars and near-infrared (NIR) surface brightness across M31's entire bulge and disk (within R = 22 kpc), permitting a direct test of the stellar composition of near-infrared light in a nearby galaxy. Here we develop NIR observation and reduction methods to recover a uniform surface brightness map across the 3° × 1° disk of M31 with 27 WIRCam fields. Two sky-target nodding strategies are tested, and we find that strictly minimizing sky sampling latency cannot improve background subtraction accuracy to better than 2% of the background level due to spatio-temporal variations in the NIR skyglow. We fully describe our WIRCam reduction pipeline and advocate using flats built from night-sky images over a single night, rather than dome flats that do not capture the WIRCam illumination field. Contamination from scattered light and thermal background in sky flats has a negligible effect on the surface brightness shape compared to the stochastic differences in background shape between sky and galaxy disk fields, which are ∼0.3% of the background level. The most dramatic calibration step is the introduction of scalar sky offsets to each image that optimizes surface brightness continuity. Sky offsets reduce the mean surface brightness difference between observation blocks from 1% to <0.1% of the background level, though the absolute background level remains statistically uncertain to 0.15% of the background level. We present our WIRCam reduction pipeline and performance analysis to give specific recommendations for the improvement of NIR wide-field imaging methods.

  6. Finding the Next Deep-Ultraviolet Nonlinear Optical Material: NH4B4O6F.

    PubMed

    Shi, Guoqiang; Wang, Ying; Zhang, Fangfang; Zhang, Bingbing; Yang, Zhihua; Hou, Xueling; Pan, Shilie; Poeppelmeier, Kenneth R

    2017-08-09

    Nonlinear optical materials are essential for the development of solid-state lasers. KBe2BO3F2 (KBBF) is a unique nonlinear optical material for generation of deep-ultraviolet coherent light; however, its industrial application is limited. Here, we report a new material NH4B4O6F, which exhibits a wide deep-ultraviolet transparent range and suitable birefringence that enables frequency doubling below 200 nm. NH4B4O6F possesses large nonlinear coefficients about 2.5 times that of KBBF. In addition, it is easy to grow bulk crystals and does not contain toxic elements.

  7. Designing a Beryllium-Free Deep-Ultraviolet Nonlinear Optical Material without a Structural Instability Problem.

    PubMed

    Zhao, Sangen; Kang, Lei; Shen, Yaoguo; Wang, Xiaodong; Asghar, Muhammad Adnan; Lin, Zheshuai; Xu, Yingying; Zeng, Siyuan; Hong, Maochun; Luo, Junhua

    2016-03-09

    A beryllium-free deep-ultraviolet (deep-UV) nonlinear optical (NLO) material K3Ba3Li2Al4B6O20F is developed mainly by the element substitution of Be for Al and Li from Sr2Be2B2O7 that was considered as one of the most promising deep-UV NLO materials. K3Ba3Li2Al4B6O20F preserves the structural merits of Sr2Be2B2O7 and thus exhibits no layering growth tendency and possesses the optical properties required for deep-UV NLO applications, including deep-UV transparency, phase-matchability, and sufficiently large second-harmonic generation (1.5 × KH2PO4). Furthermore, it overcomes the structural instability problem of Sr2Be2B2O7, which is confirmed by the obtainment of large single crystals and phonon dispersion calculations. These attributes make it very attractive for next-generation deep-UV NLO materials. The substitution of Be for Al and Li in beryllium borates provides a new opportunity to design beryllium-free deep-UV NLO materials with good performance.

  8. Pure and syndromic optic atrophy explained by deep intronic OPA1 mutations and an intralocus modifier.

    PubMed

    Bonifert, Tobias; Karle, Kathrin N; Tonagel, Felix; Batra, Marion; Wilhelm, Christian; Theurer, Yvonne; Schoenfeld, Caroline; Kluba, Torsten; Kamenisch, York; Carelli, Valerio; Wolf, Julia; Gonzalez, Michael A; Speziani, Fiorella; Schüle, Rebecca; Züchner, Stephan; Schöls, Ludger; Wissinger, Bernd; Synofzik, Matthis

    2014-08-01

    The genetic diagnosis in inherited optic neuropathies often remains challenging, and the emergence of complex neurological phenotypes that involve optic neuropathy is puzzling. Here we unravel two novel principles of genetic mechanisms in optic neuropathies: deep intronic OPA1 mutations, which explain the disease in several so far unsolved cases; and an intralocus OPA1 modifier, which explains the emergence of syndromic 'optic atrophy plus' phenotypes in several families. First, we unravelled a deep intronic mutation 364 base pairs 3' of exon 4b in OPA1 by in-depth investigation of a family with severe optic atrophy plus syndrome in which conventional OPA1 diagnostics including gene dosage analyses were normal. The mutation creates a new splice acceptor site resulting in aberrant OPA1 transcripts with retained intronic sequence and subsequent translational frameshift as shown by complementary DNA analysis. In patient fibroblasts we demonstrate nonsense mediated messenger RNA decay, reduced levels of OPA1 protein, and impairment of mitochondrial dynamics. Subsequent site-specific screening of >360 subjects with unexplained inherited optic neuropathy revealed three additional families carrying this deep intronic mutation and a base exchange four nucleotides upstream, respectively, thus confirming the clinical significance of this mutational mechanism. Second, in all severely affected patients of the index family, the deep intronic mutation occurred in compound heterozygous state with an exonic OPA1 missense variant (p.I382M; NM_015560.2). The variant alone did not cause a phenotype, even in homozygous state indicating that this long debated OPA1 variant is not pathogenic per se, but acts as a phenotypic modifier if it encounters in trans with an OPA1 mutation. Subsequent screening of whole exomes from >600 index patients identified a second family with severe optic atrophy plus syndrome due to compound heterozygous p.I382M, thus confirming this mechanism. In summary

  9. Optical coupling of deep-subwavelength semiconductor nanowires.

    PubMed

    Cao, Linyou; Fan, Pengyu; Brongersma, Mark L

    2011-04-13

    Systems of coupled resonators manifest a myriad of exciting fundamental physical phenomena. Analogous to the synthesis of molecules from single atoms, the construction of photonic molecules from stand-alone optical resonators represents a powerful strategy to realize novel functionalities. The coupling of high quality factor (Q) dielectric and semiconductor microresonators is by now well-understood and chipscale applications are abound. The coupling behavior of low-Q nanometallic structures has also been exploited to realize high-performance plasmonic devices and metamaterials. Although dense arrays of semiconductor nanoparticles and nanowires (NWs) find increasing use in optoelectronic devices, their photonic coupling has remained largely unexplored. These high refractive index nano-objects can serve as low-Q optical antennas that can effectively receive and broadcast light. We demonstrate that the broad band antenna response of a pair of NWs can be tuned significantly by engineering their optical coupling and develop an intuitive coupled-mode theory to explain our observations.

  10. Design Reference Missions for Deep-Space Optical Communication

    NASA Astrophysics Data System (ADS)

    Breidenthal, J.; Abraham, D.

    2016-05-01

    We examined the potential, but uncertain, NASA mission portfolio out to a time horizon of 20 years, to identify mission concepts that potentially could benefit from optical communication, considering their communications needs, the environments in which they would operate, and their notional size, weight, and power constraints. A set of 12 design reference missions was selected to represent the full range of potential missions. These design reference missions span the space of potential customer requirements, and encompass the wide range of applications that an optical ground segment might eventually be called upon to serve. The design reference missions encompass a range of orbit types, terminal sizes, and positions in the solar system that reveal the chief system performance variables of an optical ground segment, and may be used to enable assessments of the ability of alternative systems to meet various types of customer needs.

  11. Quick acquisition and recognition method for the beacon in deep space optical communications.

    PubMed

    Wang, Qiang; Liu, Yuefei; Ma, Jing; Tan, Liying; Yu, Siyuan; Li, Changjiang

    2016-12-01

    In deep space optical communications, it is very difficult to acquire the beacon given the long communication distance. Acquisition efficiency is essential for establishing and holding the optical communication link. Here we proposed a quick acquisition and recognition method for the beacon in deep optical communications based on the characteristics of the deep optical link. To identify the beacon from the background light efficiently, we utilized the maximum similarity between the collecting image and the reference image for accurate recognition and acquisition of the beacon in the area of uncertainty. First, the collecting image and the reference image were processed by Fourier-Mellin. Second, image sampling and image matching were applied for the accurate positioning of the beacon. Finally, the field programmable gate array (FPGA)-based system was used to verify and realize this method. The experimental results showed that the acquisition time for the beacon was as fast as 8.1s. Future application of this method in the system design of deep optical communication will be beneficial.

  12. Results from the Galileo Laser Uplink: A JPL Demonstration of Deep-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Lesh, J. R.

    1993-01-01

    The successful completion of the Galileo Optical Experiment (GOPEX), represented the accomplishment of a significant milestone in JPL's optical communication plan. The experiment demonstrated the first transmission of a narrow laser beam to a deep-space vehicle. Laser pulses were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The experiment took place over an eight-day period (December 9 through December 16, 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1 to 6 million kilometers (15 times the Earth-Moon distance), the laser uplink from TMF covered the longest known range for laser beam transmission and detection. This demonstration is the latest in a series of accomplishments by JPL in the development of deep-space optical communications technology.

  13. Accessing deep optical properties of skin using diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Koenig, Anne; Roig, Blandine; Le Digabel, Jimmy; Josse, Gwendal; Dinten, Jean-Marc

    2015-07-01

    Diffuse reflectance spectroscopy characterizes composition and structure of tissues by determining their scattering and absorption properties. We have developed in our laboratory a low-cost spatially resolved diffuse reflectance spectroscopy instrument. We present in this study some results showing how to adapt this technology on multi-layered tissues. First of all, a method enabling determination of scattering and absorption properties of multi-layered phantoms is described; the adaptation of the initial methodology to focus on deep layers is especially detailed. Then some preliminary results obtained on a panel of volunteer's redness faces are presented.

  14. OAUNI photometry of ASASSN-16hw

    NASA Astrophysics Data System (ADS)

    Pereyra, A.; Ricra, J.; Zevallos, M.

    2016-09-01

    We report optical photometry of Type Ia SN ASASSN-16hw (=SN 2016ekt, ATel #9278, ATel #9289, ATel #9300) on 2016-08-06 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015;arXiv:1512.03104) at Huancayo Observatory, Peru.

  15. Optical Survey with KMTNet for Dusty Star-Forming Galaxies in the Akari Deep Field South

    NASA Astrophysics Data System (ADS)

    Jeong, Woong-Seob; Ko, Kyeongyeon; Kim, Minjin; Ko, Jongwan; Kim, Sam; Pyo, Jeonghyun; Kim, Seong Jin; Kim, Taehyun; Seo, Hyun Jong; Park, Won-Kee; Park, Sung-Joon; Kim, Min Gyu; Kim, Dong Jin; Cha, Sang-Mok; Lee, Yongseok; Lee, Chung-Uk; Kim, Seung-Lee; Matsuura, Shuji; Pearson, Chris; Matsuhara, Hideo

    2016-10-01

    We present an optical imaging survey of AKARI Deep Field South (ADF-S) using the Korea Microlensing Telescope Network (KMTNet), to find optical counterparts of dusty star-forming galaxies. The ADF-S is a deep far-infrared imaging survey region with AKARI covering around 12 deg^2, where the deep optical imaging data are not yet available. By utilizing the wide-field capability of the KMTNet telescopes (˜4 deg^2), we obtain optical images in B, R and I bands for three regions. The target depth of images in B, R and I bands is ˜24 mag (AB) at 5σ, which enables us to detect most dusty star-forming galaxies discovered by AKARI in the ADF-S. Those optical datasets will be helpful to constrain optical spectral energy distributions as well as to identify rare types of dusty star-forming galaxies such as dust-obscured galaxy, sub-millimeter galaxy at high redshift.}

  16. UBVJHKLM photometry of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Burlak, A. M.; Shenavrin, I. V.; Tatarnikov, M. A.; Tatarnikova, A. A.

    2013-08-01

    We present the results of the optical and IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. UBV photometry was carried out with 60-cm Zeiss telescope using a photoelectric photometer on August 15.94 UT: U=4.54+/-0.02, B=5.07+/-0.01, V=5.05+/-0.01; on August 16.80 UT: U=4.54+/-0.01, B=4.85+/-0.02, V=4.68+/-0.01; on August 16.86 UT: U=4.66+/-0.01, B=4.92+/-0.01, V=4.73+/-0.01.

  17. Optical spectroscopy of laser plasma in a deep crater

    SciTech Connect

    Kononenko, Taras V; Konov, Vitalii I; Walter, D; Dausinger, F

    2009-04-30

    The time dynamics of plasma-emission spectra is studied experimentally at different stages of the drilling of a steel plate by 100-fs and 5-ps laser pulses: from a shallow crater to a hole. The change in the time dependence of the plasma temperature caused by variations in the irradiated surface geometry is analysed. It is found that the time interval needed to reach a particular temperature (about 8000 K) drastically increases from 40-50 to 150-200 ns when a specific crater depth is achieved. The opposite tendency is observed as the crater depth grows further and a hole is produced. Strong self-absorption in a plasma plume inside a deep crater is experimentally confirmed which results in the appearance of line absorption against a continuous emission spectrum. (interaction of laser radiation with matter. laser plasma)

  18. A deep-UV optical frequency comb at 205 nm.

    PubMed

    Peters, E; Diddams, S A; Fendel, P; Reinhardt, S; Hänsch, T W; Udem, Th

    2009-05-25

    By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser at 820 nm we generate a frequency comb at 205 nm with nearly bandwidth-limited pulses. The nonlinear frequency conversion is accomplished by two successive frequency doubling stages that take place in resonant cavities that are matched to the pulse repetition rate of 82 MHz. This allows for an overall efficiency of 4.5 % and produces an output power of up to 70 mW for a few minutes and 25 mW with continuous operation for hours. Such a deep UV frequency comb may be employed for direct frequency comb spectroscopy in cases where it is less efficient to convert to these short wavelengths with continuous wave lasers.

  19. Optical Photometry of Parsamian 21

    NASA Astrophysics Data System (ADS)

    Semkov, E. H.; Peneva, S. P.

    2010-05-01

    Results from BVRI photometric observations of the FUor-like object Parsamian 21 are presented. Calibrated BVRcIc magnitudes of the comparison star sequence around Parsamian 21 are given. Comparing our CCD photometric observations of Parsamian 21 in the period 2003 - 2009 with the data from Palomar plates showed no significant change in the brightness of the star for a very long period (57 years). Our conclusion is that Parsamian 21 is probably a member of the group of long-lived FUors and that the time-scale of the FUor phenomenon in some cases is much longer than that predicted in previous studies.

  20. A plan for the development and demonstration of optical communications for deep space

    NASA Technical Reports Server (NTRS)

    Lesh, James R.; Deutsch, Leslie J.; Weber, William J.

    1991-01-01

    A development history, current status, and prospective development account are given for deep-space optical communications, giving attention to overall systems-related activities and to the generic technology developments required for their implementation. An account is given of the progression envisioned from laboratory subsystems demonstrations to the full-scale flight experiment for the Mars Communications Relay Orbiter missions.

  1. Deep wet etching on fused silica material for fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Chen, Xiaopei; Yu, Bing; Zhu, YiZheng; Wang, Anbo

    2004-01-01

    In this paper, deep microstructures on fused silica material, which are useful for fabrication of the fiber optic sensors, were obtained by using a wet chemical etching process. The etching solutions and the masking materials used for developing deep structure are described in this paper. The etch rate of a fused silica diaphragm in room temperature ranged from 46nm per minute to 83nm per minute with different concentrations of Buffered Hydrogen Fluoride (BHF). The etch depth of one step etching was 25μm with the surface roughness less than 20nm (peak-to-peak value). The optical reflectance from the deep etched surface was 4%, which is the same as a well-cleaved fiber end face. This result made the visibility of interference fringes from the single mode fiber optic sensors to be as high as 96%. Furthermore, two-step structures on the fused silica diaphragms with the total depth greater than 35μm are demonstrated. To the best knowledge of the authors, this is the deepest structure produced by wet etching process on fused silica material. Fiber optic pressure sensors based on deep etched diaphragms were fabricated and tested. Fabrication of microstructures on the fiber end faces by using this process is therefore possible.

  2. Microwave analog fiber-optic link for use in the deep space network

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.; Lutes, G. F.; Maleki, L.

    1990-01-01

    A novel fiber-optic system with dynamic range of up to 150 dB-Hz for transmission of microwave analog signals is described. The design, analysis, and laboratory evaluations of this system are reported, and potential applications in the NASA/JPL Deep Space Network are discussed.

  3. Results from the DOLCE (Deep Space Optical Link Communications Experiment) project

    NASA Astrophysics Data System (ADS)

    Baister, Guy; Kudielka, Klaus; Dreischer, Thomas; Tüchler, Michael

    2009-02-01

    Oerlikon Space AG has since 1995 been developing the OPTEL family of optical communications terminals. The optical terminals within the OPTEL family have been designed so as to be able to position Oerlikon Space for future opportunities open to this technology. These opportunities range from commercial optical satellite crosslinks between geostationary (GEO) satellites, deep space optical links between planetary probes and the Earth, as well as optical links between airborne platforms (either between the airborne platforms or between a platform and GEO satellite). The OPTEL terminal for deep space applications has been designed as an integrated RF-optical terminal for telemetry links between the science probe and Earth. The integrated architecture provides increased TM link capacities through the use of an optical link, while spacecraft navigation and telecommand are ensured by the classical RF link. The optical TM link employs pulsed laser communications operating at 1058nm to transmit data using PPM modulation to achieve a robust link to atmospheric degradation at the optical ground station. For deep space links from Lagrange (L1 / L2) data rates of 10 - 20 Mbps can be achieved for the same spacecraft budgets (mass and power) as an RF high gain antenna. Results of an inter-island test campaign to demonstrate the performance of the pulsed laser communications subsystem employing 32-PPM for links through the atmosphere over a distance of 142 km are presented. The transmitter of the communications subsystem is a master oscillator power amplifier (MOPA) employing a 1 W (average power) amplifier and the receiver a Si APD with a measured sensitivity of -70.9 dBm for 32-PPM modulation format at a user data rate of 10 Mbps and a bit error rate (BER) of 10-6.

  4. Development of a novel fiber-optic sensor to measure radon in the deep ocean

    NASA Astrophysics Data System (ADS)

    Monteiro, Catarina; Guimarães, Diana; Jorge, Pedro; Barbosa, Susana

    2017-04-01

    The radon concentration in the deep ocean has gained increasing interest in the last decades. The underwater monitoring of this natural radioactive gas can give important information about submarine groundwater discharges, groundwater migration and contamination. Radon concentration has also been studied as a possible indicator of earthquake events which can have devastating consequences when the epicenter is located at the sea. In contrast with radon monitoring studies in caves, mines, and underground soil, there is an utter lack of information about radon in deep-sea. These measurements are particularly difficult to attain due to the challenges that marine-like environments post to electronic sensing devices and their maintenance over time. Gamma rays emitted by radon's progeny can be easily detected when interacting with a scintillator material. Recently, optical fiber doped with scintillating material has emerged has an alternative for gamma ray detection. The lightweight, low transmission loss, immunity to electromagnetic interference and the cost effectiveness makes optical fiber a compelling solution for radiation detection when compared to conventional sensors. In this work a compact all-fiber optical sensor is developed for continuous gamma ray detection in the deep sea. This sensor is composed by a scintillating optical fiber coupled to a polymeric optical fiber that allows the detection of low levels of radiation.

  5. TFIT: Mixed-resolution data set photometry package

    NASA Astrophysics Data System (ADS)

    Laidler, Victoria G.; Papovich, Casey; Grogin, Norman A.; Idzi, Rafal; Dickinson, Mark; Ferguson, Henry C.; Hilbert, Bryan; Clubb, Kelsey; Ravindranath, Swara

    2015-05-01

    TFIT measures galaxy photometry using prior knowledge of sources in a deep, high-resolution image (HRI) to improve photometric measurements of objects in a corresponding low-resolution image (LRI) of the same field, usually at a different wavelength. For background-limited data, this technique produces optimally weighted photometry that maximizes signal-to-noise ratio (S/N). For objects not significantly detected in the low-resolution image, it provides useful and quantitative information for setting upper limits.

  6. Structure and photometry of an I less than 20.5 galaxy sample from the Hubble Space Telescope medium deep survey

    NASA Astrophysics Data System (ADS)

    Phillips, Andrew C.; Bershady, Matthew A.; Forbes, Duncan A.; Koo, David C.; Illingworth, Garth D.; Reitzel, David B.; Griffiths, Richard E.; Windhorst, Rogier A.

    1995-05-01

    A set of 100 faint galaxies from nine Hubble Space Telescope (HST) Wide Field Camera (WFC) I-band images have been analyzed as part of the Medium Deep Survey (MDS) Key Project. This sample reaches a depth of I approximately less than or equal to 20.5 (corresponding to B approximately 22-23) and complements the first set of fainter galaxies analyzed by the MDS team. Images were deconvolved using the Lucy-Richardson algorithm and a newly developed procedure designed to yield a more reliable determination of structure in the low-S/N regime. These deconvolved images were used to characterize the structure of the galaxies through quantative measurements of total magnitudes, half-light radii, exponential disk scale lengths, and disk-to-total rations. Extensive testing was done to establish the validity of the procedures used and to characterize the degree of systematic errors present in the analysis techniques. The observed size-magnitude distribution appears consistent with a scenario in which luminous galaxies have evolved little in intrinsic luminosity, size, or structure over recent epochs in a 'normal' cosmology (0 less than q0 less than 0.5 and Lambda0 = 0). The predicted nonevolving distributions were based on models designed to fit existing counts, colors, and redshifts of faint galaxies and on the observed correlations between metric rest-frame size and luminosity found in a nearby galaxy sample studied by Kent (1984-1985). The typical galaxy in our sample is expected to be at z approximately equal to 0.3, and to have a luminosity approximately 0.5 mag fainter than L* and a half-light radius of approximately 1 sec or approximately 6 kpc (H 0 = 50 km/s Mpc). The observed distribution of disk-to-total ratios, while uncertain, is in agreement with that of Kent's sample and thus supports the view that substantial evolution has not occurred over the look-back times characteristic of our sample.

  7. Transmission in near-infrared optical windows for deep brain imaging.

    PubMed

    Shi, Lingyan; Sordillo, Laura A; Rodríguez-Contreras, Adrián; Alfano, Robert

    2016-01-01

    Near-infrared (NIR) radiation has been employed using one- and two-photon excitation of fluorescence imaging at wavelengths 650-950 nm (optical window I) for deep brain imaging; however, longer wavelengths in NIR have been overlooked due to a lack of suitable NIR-low band gap semiconductor imaging detectors and/or femtosecond laser sources. This research introduces three new optical windows in NIR and demonstrates their potential for deep brain tissue imaging. The transmittances are measured in rat brain tissue in the second (II, 1,100-1,350 nm), third (III, 1,600-1,870 nm), and fourth (IV, centered at 2,200 nm) NIR optical tissue windows. The relationship between transmission and tissue thickness is measured and compared with the theory. Due to a reduction in scattering and minimal absorption, window III is shown to be the best for deep brain imaging, and windows II and IV show similar but better potential for deep imaging than window I.

  8. Atomic force microscopy deep trench and sidewall imaging with an optical fiber probe.

    PubMed

    Xie, Hui; Hussain, Danish; Yang, Feng; Sun, Lining

    2014-12-01

    We report a method to measure critical dimensions of micro- and nanostructures using the atomic force microscope (AFM) with an optical fiber probe (OFP). This method is capable of scanning narrow and deep trenches due to the long and thin OFP tip, as well as imaging of steep sidewalls with unique profiling possibilities by laterally tilting the OFP without any modifications of the optical lever. A switch control scheme is developed to measure the sidewall angle by flexibly transferring feedback control between the Z- and Y-axis, for a serial scan of the horizontal surface (raster scan on XY-plane) and sidewall (raster scan on the YZ-plane), respectively. In experiments, a deep trench with tapered walls (243.5 μm deep) and a microhole (about 14.9 μm deep) have been imaged with the orthogonally aligned OFP, as well as a silicon sidewall (fabricated by deep reactive ion etching) has been characterized with the tilted OFP. Moreover, the sidewall angle of TGZ3 (AFM calibration grating) was accurately measured using the switchable scan method.

  9. Potential of vortex beams with orbital angular momentum modulation for deep-space optical communication

    NASA Astrophysics Data System (ADS)

    Wang, Xiaorui; Liu, Yejun; Guo, Lei; Li, Hui

    2014-05-01

    In order to achieve multigigabit transmission in deep-space optical communication, our study applies a new modulation mode named orbital angular momentum (OAM) modulation, and uses the encoded OAM states of single photon as data information carriers, thus providing a reliable and high-speed transmission of signals. According to the long link characteristic of deep-space communication, we conduct a reasonable deployment for communication nodes in deep-space environment. First, we present the reliability of deep-space channel and analyze the data rate and spectral efficiency of beams with OAM. Second, we study the characteristics and generations of vortex beams with OAM by simulation. Results show that vortex beams have better spatial multiplexing capability of realizing high capacity data transmission. Finally, we propose an encoding method with OAM states of single photon. The transceiver units are based on spatial light modulators to perform the modulation and demodulation of vortex beams. At the receiver, the charged-coupled device camera is used to detect the signal intensity and decodes the OAM states. Our proposal not only ensures the confidentiality of deep-space optical communication, but also greatly increases the transmission rate.

  10. Atomic force microscopy deep trench and sidewall imaging with an optical fiber probe

    SciTech Connect

    Xie, Hui Hussain, Danish; Yang, Feng; Sun, Lining

    2014-12-15

    We report a method to measure critical dimensions of micro- and nanostructures using the atomic force microscope (AFM) with an optical fiber probe (OFP). This method is capable of scanning narrow and deep trenches due to the long and thin OFP tip, as well as imaging of steep sidewalls with unique profiling possibilities by laterally tilting the OFP without any modifications of the optical lever. A switch control scheme is developed to measure the sidewall angle by flexibly transferring feedback control between the Z- and Y-axis, for a serial scan of the horizontal surface (raster scan on XY-plane) and sidewall (raster scan on the YZ-plane), respectively. In experiments, a deep trench with tapered walls (243.5 μm deep) and a microhole (about 14.9 μm deep) have been imaged with the orthogonally aligned OFP, as well as a silicon sidewall (fabricated by deep reactive ion etching) has been characterized with the tilted OFP. Moreover, the sidewall angle of TGZ3 (AFM calibration grating) was accurately measured using the switchable scan method.

  11. Low-cost, high-precision micro-lensed optical fiber providing deep-micrometer to deep-nanometer-level light focusing.

    PubMed

    Wen, Sy-Bor; Sundaram, Vijay M; McBride, Daniel; Yang, Yu

    2016-04-15

    A new type of micro-lensed optical fiber through stacking appropriate high-refractive microspheres at designed locations with respect to the cleaved end of an optical fiber is numerically and experimentally demonstrated. This new type of micro-lensed optical fiber can be precisely constructed with low cost and high speed. Deep micrometer-scale and submicrometer-scale far-field light spots can be achieved when the optical fibers are multimode and single mode, respectively. By placing an appropriate teardrop dielectric nanoscale scatterer at the far-field spot of this new type of micro-lensed optical fiber, a deep-nanometer near-field spot can also be generated with high intensity and minimum joule heating, which is valuable in high-speed, high-resolution, and high-power nanoscale detection compared with traditional near-field optical fibers containing a significant portion of metallic material.

  12. Color weight photometry.

    PubMed

    Koenderink, Jan; van Doorn, Andrea; Gegenfurtner, Karl

    2017-07-19

    We study the "color weight" for a number of rather different paradigms. In well researched heterochromatic photometry methods we find that the "weights" determined by settings of naive observers are closely determined by the CIE luminance functional. This is very different for tasks that involve mid- and high-level aspects of perception. In several cases we find equipollence for the display red, green and blue channels. Moreover, in such cases the very nonlinear maximum-rule fits the data rather better than a linear functional. These findings are of interest when photometry needs to be applied for stimuli that are different from the high temporal and low spatial frequency gratings typical for flicker photometry. These results are relevant for science, ergonomics and art. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. APT: Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  14. Hubble and Spitzer Follow-up for Two Strongly Lensed LBGs: (I) Optical-to-Mid-IR Photometry and Mid-IR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tucker, Douglas Lee; Allam, S. S.; SDSS Bright Arcs Search Team

    2009-05-01

    We present the HST and Spitzer photometry and Spitzer spectroscopy of two strongly lensed Lyman Break Galaxies LBGs that were recently discovered. These two LBGs -- the "8 O'Clock Arc" (Allam et al. 2007) and the "SDSS J1206+5142 Arc" (Lin et al. 2008)-- are currently the brightest known LBGs, roughly 3 times brighter than the former record-holder, MS1512-cB58 (a.k.a. "cB58").

  15. Design and development of a baseline deep-space optical PPM transceiver

    NASA Astrophysics Data System (ADS)

    Yan, Tsun-Yee; Chen, Chien-Chung

    1999-04-01

    One of the NASA technology development programs at the Jet Propulsion Laboratory aims to increase the information return capability while reducing the size of the spacecraft via laser communications. The deep space optical transceiver developed under this program employs pulse position modulation (PPM) for both uplink and downlink transmissions. An integral part of the transceiver is the development of signal acquisition and tracking subsystem. This paper describes the baseline design of the electronic assembly within the transceiver and modifications that are necessary for deep space communications. A two phase breadboard activity will be described to reduce technological risks associated with the development.

  16. QDPHOT: Quick & Dirty PHOTometry

    NASA Astrophysics Data System (ADS)

    Mighell, Kenneth

    2016-01-01

    QDPHOT is a fast CCD stellar photometry task which quickly produces CCD stellar photometry from two CCD images of a star field. It was designed to be a data mining tool for finding high-quality stellar observations in the data archives of the National Virtual Observatory. QDPHOT typically takes just a few seconds to analyze two Hubble Space Telescope WFPC2 observations of Local Group star clusters. It is also suitable for real-time data-quality analysis of CCD observations; on-the-fly instrumental color-magnitude diagrams can be produced at the telescope console during the few seconds between CCD readouts.

  17. THE MULTIWAVELENGTH SURVEY BY YALE-CHILE (MUSYC): DEEP MEDIUM-BAND OPTICAL IMAGING AND HIGH-QUALITY 32-BAND PHOTOMETRIC REDSHIFTS IN THE ECDF-S

    SciTech Connect

    Cardamone, Carolin N.; Van Dokkum, Pieter G.; Urry, C. Megan; Brammer, Gabriel; Taniguchi, Yoshi; Gawiser, Eric; Bond, Nicholas; Taylor, Edward; Damen, Maaike; Treister, Ezequiel; Cobb, Bethany E.; Schawinski, Kevin; Lira, Paulina; Murayama, Takashi; Saito, Tomoki; Sumikawa, Kentaro

    2010-08-15

    We present deep optical 18-medium-band photometry from the Subaru telescope over the {approx}30' x 30' Extended Chandra Deep Field-South, as part of the Multiwavelength Survey by Yale-Chile (MUSYC). This field has a wealth of ground- and space-based ancillary data, and contains the GOODS-South field and the Hubble Ultra Deep Field. We combine the Subaru imaging with existing UBVRIzJHK and Spitzer IRAC images to create a uniform catalog. Detecting sources in the MUSYC 'BVR' image we find {approx}40,000 galaxies with R {sub AB} < 25.3, the median 5{sigma} limit of the 18 medium bands. Photometric redshifts are determined using the EAzY code and compared to {approx}2000 spectroscopic redshifts in this field. The medium-band filters provide very accurate redshifts for the (bright) subset of galaxies with spectroscopic redshifts, particularly at 0.1 < z < 1.2 and at z {approx}> 3.5. For 0.1 < z < 1.2, we find a 1{sigma} scatter in {Delta}z/(1 + z) of 0.007, similar to results obtained with a similar filter set in the COSMOS field. As a demonstration of the data quality, we show that the red sequence and blue cloud can be cleanly identified in rest-frame color-magnitude diagrams at 0.1 < z < 1.2. We find that {approx}20% of the red sequence galaxies show evidence of dust emission at longer rest-frame wavelengths. The reduced images, photometric catalog, and photometric redshifts are provided through the public MUSYC Web site.

  18. Development of composite fiber-optic electric-power umbilical cable and optical feedthrough for deep ocean mining

    NASA Astrophysics Data System (ADS)

    Mitsui, T.; Gomi, T.; Ito, T.; Ushitani, S.; Yamaguchi, M.

    The development of mining systems for mineral resources from deep ocean floors is now progressing in many countries. In Japan, the Agency of Industrial Science and Technology, has conducted research and development for a manganese nodule mining system. In this project, it is planned to use a new composite fiber-optic electric power umbilical cable for electrical power and control signal transmission from a main vessel to subsea equipment such as lifting pumps and collecting devices at about 5,000 meters' depth. The umbilical cable system is required to have good resistance to repetitive bending, twisting, and other external forces and to be able to withstand water pressure of up to 550kgf/sq cm. A 100m long sample umbilical cable, electrical connectors, and optical feedthroughs for this system have been developed and successfully passed mechanical, electrical, and optical tests.

  19. Deep optical imaging of tissue using the second and third near-infrared spectral windows.

    PubMed

    Sordillo, Laura A; Pu, Yang; Pratavieira, Sebastião; Budansky, Yury; Alfano, Robert R

    2014-05-01

    Light at wavelengths in the near-infrared (NIR) region allows for deep penetration and minimal absorption through high scattering tissue media. NIR light has been conventionally used through the first NIR optical tissue window with wavelengths from 650 to 950 nm. Longer NIR wavelengths had been overlooked due to major water absorption peaks and a lack of NIR-CCD detectors. The second NIR spectral window from 1100 to 1350 nm and a new spectral window from 1600 to 1870 nm, known as the third NIR optical window, were investigated. Optical attenuation measurements from thin tissue slices of normal and malignant breast and prostate tissues, pig brain, and chicken tissue were obtained in the spectral range from 400 to 2500 nm. Optical images of chicken tissue overlying three black wires were also obtained using the second and third spectral windows. Due to a reduction in scattering and minimal absorption, longer attenuation lengths and clearer optical images could be seen in the second and third NIR optical windows compared to the conventional first NIR optical window. A possible fourth optical window centered at 2200 nm was noted.

  20. Unusual Long and Luminous Optical Transient in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Urata, Yuji; Tsai, Patrick P.; Huang, Kuiyun; Morokuma, Tomoki; Yasuda, Naoki; Tanaka, Masaomi; Motohara, Kentaro; Hayashi, Masao; Kashikawa, Nobunari; Ly, Chun; Malkan, Matthew A.

    2012-11-01

    We present observations of SDF-05M05, an unusual optical transient discovered in the Subaru Deep Field (SDF). The duration of the transient is > ~ 800 days in the observer frame, and the maximum brightness during observation reached approximately 23 mag in the i' and z' bands. The faint host galaxy is clearly identified in all five optical bands of the deep SDF images. The photometric redshift of the host yields z ~ 0.6 and the corresponding absolute magnitude at maximum is ~ - 20. This implies that this event shone with an absolute magnitude brighter than -19 mag for approximately 300 days in the rest frame, which is significantly longer than a typical supernova and ultraluminous supernova. The total radiated energy during our observation was 1 × 1051 erg. The light curves and color evolution are marginally consistent with some luminous IIn supernovae. We suggest that the transient may be a unique and peculiar supernova at intermediate redshift.

  1. A Plan for the Development and Demonstration of Optical Communications for Deep Space

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.; Deutsch, L. J.; Weber, W. J.

    1990-01-01

    In this article, an overall plan for the development and demonstration of optical communications for deep-space applications is presented. The current state of the technology for optical communications is presented. Then, the development and demonstration plan is presented in two parts: the overall major systems activities, followed by the generic technology developments that will enable them. The plan covers the path from laboratory subsystems demonstrations out to a full-scale flight experiment system for the proposed Mars Communications Relay Orbiter mission.

  2. Deep-space Optical Terminals (DOT) Ground Laser Transmitter (GLT) Trades and Conceptual Point Design

    NASA Astrophysics Data System (ADS)

    Roberts, W. T.; Wright, M. W.

    2010-11-01

    A conceptual design for the Deep-space Optical Terminals (DOT) Ground Laser Transmitter (GLT) has been developed. Two trade studies were performed: one to determine the most cost-effective uplink pointing system including the use of multiple and single apertures, and the second to determine the optimal type of laser transmitter for use as a beacon reference source. The baselined design resulting from the trade studies incorporated a single 1-m aperture capable of 16-microrad pointing accuracy with multiple fiber-laser sources providing up to 5 kW average optical power at 1030 nm.

  3. Photodamage in deep tissue two-photon optical biopsy of human skin.

    PubMed

    Dalbosco, Luca; Zanini, Giulia; D'Amato, Elvira; Tessarolo, Francesco; Boi, Sebastiana; Bauer, Paolo; Haase, Albrecht; Antolini, Renzo

    2015-10-01

    Photodamage, induced by femtosecond laser radiation, was studied in thick samples of human skin tissue (healthy skin and neoplastic lesions). Photobleaching, photoionization, and thermomechanical damage effects were characterized comparatively. The laser power dependence of the damage rates allowed to connect macroscopic effects to underlying molecular processes. Optical effects were correlated to histopathological changes. Tissue alterations were found only from thermomechanical cavitation and limited to superficial layers of the epidermis. From the depth-dependencies of all damage thresholds a depth-dependent power-compensation scheme was defined allowing for damage-free deep tissue optical biopsy. Damage-induced luminescence pattern for different excitation powers and a corresponding threshold analysis.

  4. Modulation techniques for deep-space pulse-position modulation (PPM) optical communication

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.; Robinson, Deborah L.

    1988-01-01

    The extremely energy-efficient pulse-position modulation (PPM) format is being actively developed as a basis for optical communications with deep-space probes. Attention is presently given to different modulation schemes for the efficient production of laser pulses over a broad range of repetition rates. Both Q-switching and cavity dumping modulation methods are available for the envisioned diode-pumped Nd:YAG laser source. Numerical calculation results are presented for cavity-dumping.

  5. A ten-meter optical telescope for deep-space communications

    NASA Technical Reports Server (NTRS)

    Shaik, Kamran; Kerr, Edwin L.

    1990-01-01

    Optical communications using laser light in the visible spectral range is being considered for future deep-space missions. Such a system will require a large telescope in earth vicinity to be used as a receiving station for data return from the spacecraft. A preliminary discussion for a ground-based receiving station consisting of a 10-meter hexagonally segmented primary with high surface tolerance and a unique sunshade is presented.

  6. Modulation techniques for deep-space pulse-position modulation (PPM) optical communication

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.; Robinson, Deborah L.

    1988-01-01

    The extremely energy-efficient pulse-position modulation (PPM) format is being actively developed as a basis for optical communications with deep-space probes. Attention is presently given to different modulation schemes for the efficient production of laser pulses over a broad range of repetition rates. Both Q-switching and cavity dumping modulation methods are available for the envisioned diode-pumped Nd:YAG laser source. Numerical calculation results are presented for cavity-dumping.

  7. A ten-meter optical telescope for deep-space communications

    NASA Technical Reports Server (NTRS)

    Shaik, Kamran; Kerr, Edwin L.

    1990-01-01

    Optical communications using laser light in the visible spectral range is being considered for future deep-space missions. Such a system will require a large telescope in earth vicinity to be used as a receiving station for data return from the spacecraft. A preliminary discussion for a ground-based receiving station consisting of a 10-meter hexagonally segmented primary with high surface tolerance and a unique sunshade is presented.

  8. Deep-UV Based Acousto-Optic Tunable Filter for Spectral Sensing Applications

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.

    2006-01-01

    In this paper, recent progress made in the development of quartz and KDP crystal based acousto-optic tunable filters (AOTF) are presented. These AOTFs are developed for operation over deep-UV to near-UV wavelengths of 190 nm to 400 nm. Preliminary output performance measurements of quartz AOTF and design specifications of KDP AOTF are presented. At 355 nm, the quartz AOTF device offered approx.15% diffraction efficiency with a passband full-width-half-maximum (FWHM) of less than 0.0625 nm. Further characterization of quartz AOTF devices at deep-UV wavelengths is progressing. The hermetic packaging of KDP AOTF is nearing completion. The solid-state optical sources being used for excitation include nonlinear optics based high-energy tunable UV transmitters that operate around 320 nm and 308 nm wavelengths, and a tunable deep-UV laser operating over 193 nm to 210 nm. These AOTF devices have been developed as turn-key devices for primarily for space-based chemical and biological sensing applications using laser induced Fluorescence and resonance Raman techniques.

  9. The Araucaria Project. The Distance to the Sculptor Group Galaxy NGC 7793 from Near-infrared Photometry of Cepheid Variables

    NASA Astrophysics Data System (ADS)

    Zgirski, Bartlomiej; Gieren, Wolfgang; Pietrzyński, Grzegorz; Karczmarek, Paulina; Gorski, Marek; Wielgorski, Piotr; Narloch, Weronika; Graczyk, Dariusz; Kudritzki, Rolf-Peter; Bresolin, Fabio

    2017-10-01

    Following the earlier discovery of classical Cepheid variables in the Sculptor Group spiral galaxy NGC 7793 from an optical wide-field imaging survey, we have performed deep near-infrared J- and K-band follow-up photometry of a subsample of these Cepheids to derive the distance to this galaxy with a higher accuracy than what was possible from optical photometry alone, by minimizing the effects of reddening and metallicity on the distance result. Combining our new near-infrared period–luminosity relations with previous optical photometry, we obtain a true distance modulus to NGC 7793 of (27.66 ± 0.04) mag (statistical) ±0.07 mag (systematic), i.e., a distance of (3.40 ± 0.17) Mpc. We also determine the mean reddening affecting the Cepheids to be E(B ‑ V) = (0.08 ± 0.02) mag, demonstrating that there is significant dust extinction intrinsic to the galaxy in addition to the small foreground extinction. A comparison of the new, improved Cepheid distance to earlier distance determinations of NGC 7793 from the Tully–Fisher and TRGB methods is in agreement within the reported uncertainties of these previous measurements.

  10. Lower bound on number and sizes of telescopes in an optical array receiver for deep space optical communication

    NASA Astrophysics Data System (ADS)

    Hashmi, Ali J.; Eftekhar, Ali A.; Adibi, Ali; Amoozegar, Farid

    2014-10-01

    Free-Space optical communication is expected to revolutionize the deep-space communication by providing the high bandwidth data support for future solar and planetary exploration missions. Due to the cost and up-gradation constraints, an earth-based receiver seems to be a viable option. A large telescope acting as an optical antenna is required at the receiver end to support the reasonable data rates (at least in 10s of Mbps range). An array of smaller telescopes connected to fabricate a larger photon-collecting aperture is an attractive architecture. In this research, performance analyses of different array architectures are evaluated for a deep-space interplanetary optical communication link between Mars and Earth with an objective to find a lower bound on the number and sizes of individual telescopes in the array receiver. The achievable data rates are calculated for opposition and conjunction phases of Mars-Earth orbit. Various deleterious factors, such as background noise and atmospheric turbulence are also modeled in the simulations. Total aperture size of various array architectures are kept at 10 m. The comparison of results for different array architectures show that the performance of a receiver employing an array comprising of 135 telescopes with 0.86 m aperture diameter each is almost equivalent to a single telescope with 10 m aperture diameter. Further, if the diameter is reduced below this limit, the performance degradation is substantial.

  11. Optical tracking of deep-space spacecraft in Halo L2 orbits and beyond: The Gaia mission as a pilot case

    NASA Astrophysics Data System (ADS)

    Buzzoni, Alberto; Altavilla, Giuseppe; Galleti, Silvia

    2016-04-01

    We tackle the problem of accurate optical tracking of distant man-made probes, on Halo orbit around the Earth-Sun libration point L2 and beyond, along interplanetary transfers. The improved performance of on-target tracking, especially when observing with small-class telescopes is assessed providing a general estimate of the expected S/N ratio in spacecraft detection. The on-going GAIA mission is taken as a pilot case for our analysis, reporting on fresh literature and original optical photometry and astrometric results. The probe has been located, along its projected nominal path, with quite high precision, within 0.13±0.09 arcsec, or 0.9±0.6 km. Spacecraft color appears to be red, with (V -Rc) =1.1±0.2 and a bolometric correction to the Rc band of (Bol -Rc) = -1.1±0.2 . The apparent magnitude, Rc =20.8±0.2 , is much fainter than originally expected. These features lead to suggest a lower limit for the Bond albedo α =0.11±0.05 and confirm that incident Sun light is strongly reddened by GAIA through its on-board MLI blankets covering the solar shield. Relying on the GAIA figures, we found that VLT-class telescopes could yet be able to probe distant spacecraft heading Mars, up to 30 million km away, while a broader optical coverage of the forthcoming missions to Venus and Mars could be envisaged, providing to deal with space vehicles of minimum effective area A ⩾106 cm2. In addition to L2 surveys, 2 m-class telescopes could also effectively flank standard radar-ranging techniques in deep-space probe tracking along Earth's gravity-assist maneuvers for interplanetary missions.

  12. Deep optical observations of the central X-ray source in the Puppis A supernova remnant

    NASA Astrophysics Data System (ADS)

    Mignani, R. P.; de Luca, A.; Mereghetti, S.; Caraveo, P. A.

    2009-06-01

    Context: X-ray observations revealed a group of radio-silent isolated neutron stars (INSs) at the centre of young supernova remnants (SNRs), dubbed central compact objects or CCOs, with properties different from those of classical rotation-powered pulsars. In at least three cases, evidence points towards CCOs being low-magnetized INSs, born with slow rotation periods, and possibly accreting from a debris disc of material formed out of the supernova event. Understanding the origin of the diversity of the CCOs can shed light on supernova explosion and neutron star formation models. Optical/infrared (IR) observations are crucial to test different CCO interpretations. Aims: The aim of our work is to perform a deep optical investigation of the CCO RX J0822.0-4300 in the Puppis A SNR, one of the most poorly understood in the CCO family. Methods: By using as a reference the Chandra X-ray coordinates of RX J0822.0-4300 we performed deep optical observations in the B, V and I bands with the Very Large Telescope (VLT). Results: We found no candidate optical counterpart within 3 σ of the computed Chandra X-ray position down to 5 σ limits of B ~ 27.2, V ~ 26.9, and I ~ 25.6, the deepest obtained in the optical band for this source. Conclusions: These limits confirm the non-detection of a companion brighter than an M 5 dwarf. At the same time, they do not constrain optical emission from the neutron star surface, while emission from the magnetosphere would require a spectral break in the optical/IR. Based on observations collected at ESO, Paranal, under Programme 78.D-0706(A).

  13. Remote Sensing Science and Instrument Development Paradigms Will Radically Change as Deep Space Optical Communications Infrastructure is Standardized

    NASA Astrophysics Data System (ADS)

    Retherford, K. D.

    2017-02-01

    Deep Space Optical Communications (DSOC) systems are already inducing a sea change on our approach to designing mission concepts. A revolution in instrument concepts and mission operations will ensue as we move to observatory probe type missions.

  14. A Ten-Meter Ground-Station Telescope for Deep-Space Optical Communications: A Preliminary Design

    NASA Technical Reports Server (NTRS)

    Britcliffe, M.; Hoppe, D.; Roberts, W.; Page, N.

    2001-01-01

    This article describes a telescope design for a 10-m optical ground station for deep-space communications. The design for a direct-detection optical communications telescope differs dramatically from a telescope for imaging applications. In general, the requirements for optical manufacturing and tracking performance are much less stringent for direct detection of optical signals. The technical challenge is providing a design that will operate in the daytime/nighttime conditions required for a Deep Space Network tracking application. The design presented addresses these requirements. The design will provide higher performance at lower cost than existing designs.

  15. Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source

  16. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  17. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  18. The Metal Abundances across Cosmic Time (MACT) Survey. I. Optical Spectroscopy in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malhotra, Sangeeta; Malkan, Matthew A.; Rigby, Jane R.; Kashikawa, Nobunari; de los Reyes, Mithi A.; Rhoads, James E.

    2016-09-01

    Deep rest-frame optical spectroscopy is critical for characterizing and understanding the physical conditions and properties of the ionized gas in galaxies. Here, we present a new spectroscopic survey called “Metal Abundances across Cosmic Time” or { M }{ A }{ C }{ T }, which will obtain rest-frame optical spectra for ˜3000 emission-line galaxies. This paper describes the optical spectroscopy that has been conducted with MMT/Hectospec and Keck/DEIMOS for ≈1900 z = 0.1-1 emission-line galaxies selected from our narrowband and intermediate-band imaging in the Subaru Deep Field. In addition, we present a sample of 164 galaxies for which we have measured the weak [O iii]λ4363 line (66 with at least 3σ detections and 98 with significant upper limits). This nebular emission line determines the gas-phase metallicity by measuring the electron temperature of the ionized gas. This paper presents the optical spectra, emission-line measurements, interstellar properties (e.g., metallicity, gas density), and stellar properties (e.g., star formation rates, stellar mass). Paper II of the { M }{ A }{ C }{ T } survey (Ly et al.) presents the first results on the stellar mass-gas metallicity relation at z ≲ 1 using the sample with [O iii]λ4363 measurements.

  19. Surface Photometry of NGC 4656/4657

    SciTech Connect

    Stayton, L.C.; Angione, R.J.; Talbert, F.D.

    1983-05-01

    An analysis by surface photometry of the galaxy system NGC 4656/4657 yields the following results. First, NGC 4656 and NGC 4657 appear to be parts of the same galaxy. Second, the system bears a strong resemblance to both the SMC and NGC 55. Third, although the outermost isophotes in B and G light show coincidences with radio continuum, we found no conclusive optical indications of an interaction with the galaxy NGC 4631.

  20. Optical Photometry of the Type Ia Supernova 1999ee and the Type Ib/c Supernova 1999ex in IC 5179

    NASA Astrophysics Data System (ADS)

    Stritzinger, Maximilian; Hamuy, Mario; Suntzeff, Nicholas B.; Smith, R. C.; Phillips, M. M.; Maza, José; Strolger, L.-G.; Antezana, Roberto; González, Luis; Wischnjewsky, Marina; Candia, Pablo; Espinoza, Juan; González, David; Stubbs, Christopher; Becker, A. C.; Rubenstein, Eric P.; Galaz, Gaspar

    2002-10-01

    We present UBVRIz light curves of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both located in the galaxy IC 5179. SN 1999ee has an extremely well-sampled light curve spanning from 10 days before Bmax through 53 days after peak. Near maximum, we find systematic differences of ~0.05 mag in photometry measured with two different telescopes, even though the photometry is reduced to the same local standards around the supernova using the specific color terms for each instrumental system. We use models for our bandpasses and spectrophotometry of SN 1999ee to derive magnitude corrections (S-corrections) and remedy this problem. This exercise demonstrates the need of accurately characterizing the instrumental system before great photometric accuracies of Type Ia supernovae can be claimed. It also shows that this effect can have important astrophysical consequences, since a small systematic shift of 0.02 mag in the B-V color can introduce a 0.08 mag error in the extinction-corrected peak B magnitude of a supernova and thus lead to biased cosmological parameters. The data for the Type Ib/c SN 1999ex present us with the first ever observed shock breakout of a supernova of this class. These observations show that shock breakout occurred 18 days before Bmax and support the idea that Type Ib/c supernovae are due to the core collapse of massive stars rather than thermonuclear disruption of white dwarfs.

  1. Three-dimensional deep sub-wavelength defect detection using λ = 193 nm optical microscopy.

    PubMed

    Barnes, Bryan M; Sohn, Martin Y; Goasmat, Francois; Zhou, Hui; Vladár, András E; Silver, Richard M; Arceo, Abraham

    2013-11-04

    Optical microscopy is sensitive both to arrays of nanoscale features and to their imperfections. Optimizing scattered electromagnetic field intensities from deep sub-wavelength nanometer scale structures represents an important element of optical metrology. Current, well-established optical methods used to identify defects in semiconductor patterning are in jeopardy by upcoming sub-20 nm device dimensions. A novel volumetric analysis for processing focus-resolved images of defects is presented using simulated and experimental examples. This new method allows defects as narrow as (16 ± 2) nm (k = 1) to be revealed using 193 nm light with focus and illumination conditions optimized for three-dimensional data analysis. Quantitative metrics to compare two-dimensional and three-dimensional imaging indicate possible fourfold improvements in sensitivity using these methods.

  2. Smart optical coherence tomography for ultra-deep imaging through highly scattering media.

    PubMed

    Badon, Amaury; Li, Dayan; Lerosey, Geoffroy; Boccara, A Claude; Fink, Mathias; Aubry, Alexandre

    2016-11-01

    Multiple scattering of waves in disordered media is a nightmare whether it is for detection or imaging purposes. So far, the best approach to get rid of multiple scattering is optical coherence tomography. This basically combines confocal microscopy and coherence time gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging-depth range remains limited to 1 mm at best in human soft tissues because of aberrations and multiple scattering. We propose a matrix approach of optical imaging to push back this fundamental limit. By combining a matrix discrimination of ballistic waves and iterative time reversal, we show, both theoretically and experimentally, an extension of the imaging-depth limit by at least a factor of 2 compared to optical coherence tomography. In particular, the reported experiment demonstrates imaging through a strongly scattering layer from which only 1 reflected photon out of 1000 billion is ballistic. This approach opens a new route toward ultra-deep tissue imaging.

  3. Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

    NASA Astrophysics Data System (ADS)

    Britcliffe, M. J.; Hoppe, D. J.

    2001-01-01

    The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

  4. Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

    NASA Technical Reports Server (NTRS)

    Britcliffe, M. J.; Hoppe, D. J.

    2001-01-01

    The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

  5. Optical variability and pigment biomass in the Sargasso Sea as determined using deep-sea optical mooring data

    NASA Technical Reports Server (NTRS)

    Smith, R. C.; Waters, K. J.; Baker, K. S.

    1991-01-01

    A 9-month time series of optical data, composed of three separate deployments, from the Biowatt 1987 deep-sea mooring located in the oligotrophic waters of the Sargasso Sea at 32 deg N, 70 deg W, is presented. These data were analyzed using several biooptical models for the purpose of providing a continuous estimate of the spectral diffuse attenuation coefficient and pigment biomass. Results of the first 70-day deployment demonstrate the utility of optical observations as proxy measures of biological parameters, and facilitate a preliminary analysis of the temporal variations and a comparison of the present biooptical observations with concurrent physical observations. Biooptical properties exhibit variation in response to physical forcings, such as diel variations of incident solar irradiance, episodic wind forcing, advective mesoscale eddy layer depth, and succession of phytoplankton. The mooring data are discussed in the context of contemporaneous shipboard observations as well as in terms of future ocean satellite observations.

  6. Deep optical and radio searches for a quiescent counterpart to the optical transient source OTS 1809+31

    NASA Technical Reports Server (NTRS)

    Ricker, George R.; Mock, Patrick C.; Ajhar, Edward A.; Vanderspek, Roland K.

    1989-01-01

    Hudec (1987) has reported the detection of three bright transient optical images from the same celestial location localized to alpha(1950) = 18 h 9 m 26.29 s + or - 0.03 s, delta (1950) = +31 deg 23 arcmin 19.7 arcsec + or - 0.6 arcsec. This paper reports the result of a deep CCD search in four colors undertaken to find the quiescent counterpart of the optical transients. No source is found at the location of the transients to m(B) = 24.5; however, 18 objects in the vicinity of the reported coordinates which are consistent with the source having a proper motion of 1 arcsec/yr. A search at 6 cm with the VLA revealed no source in the mu less than 1 arcsec/yr circle to a 3 sigma limiting flux of 83 micro-Jy.

  7. Optical variability and pigment biomass in the Sargasso Sea as determined using deep-sea optical mooring data

    NASA Technical Reports Server (NTRS)

    Smith, R. C.; Waters, K. J.; Baker, K. S.

    1991-01-01

    A 9-month time series of optical data, composed of three separate deployments, from the Biowatt 1987 deep-sea mooring located in the oligotrophic waters of the Sargasso Sea at 32 deg N, 70 deg W, is presented. These data were analyzed using several biooptical models for the purpose of providing a continuous estimate of the spectral diffuse attenuation coefficient and pigment biomass. Results of the first 70-day deployment demonstrate the utility of optical observations as proxy measures of biological parameters, and facilitate a preliminary analysis of the temporal variations and a comparison of the present biooptical observations with concurrent physical observations. Biooptical properties exhibit variation in response to physical forcings, such as diel variations of incident solar irradiance, episodic wind forcing, advective mesoscale eddy layer depth, and succession of phytoplankton. The mooring data are discussed in the context of contemporaneous shipboard observations as well as in terms of future ocean satellite observations.

  8. X-ray Normal, Optically Bright Galaxies in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Moran, Edward C.

    2017-08-01

    Absorbed active galactic nuclei (AGNs) represent the dominant class of extragalactic sources in deep hard X-ray surveys. However, their true nature is often unclear because of ambiguities in their optical spectra. As a result, several important questions concerning the diversity and cosmic evolution of the AGN population remain unanswered. To explore the possibility of evolution, we have analyzed the multiwavelength properties of nearby absorbed AGNs and their host galaxies in a way that facilitates a direct, meaningful comparison to distant absorbed AGNs detected in the Chandra Deep Field South (CDF-S). Specifically, we have assembled the integrated spectral energy distributions (SEDs) of (a) a large, unbiased sample of nearby Seyfert 2 galaxies and (b) a set of carefully selected absorbed AGNs from the CDF-S, many of which are classified as XBONGs (X-ray-bright, optically normal galaxies) due to their starlight-dominated optical spectra. Comparisons of the SEDs have been carried out in a manner that properly accounts for redshift effects and the way in which the intrinsic luminosity function is sampled in a flux-limited pencil-beam survey like the CDF-S. In general, the SEDs of nearby Seyfert 2s provide a good match to the SEDs of distant absorbed AGNs. However, while the X-ray luminosities of “optically normal” galaxies in the CDF-S are comparable to those of local Seyfert 2s, their stellar continuum luminosities are often much higher than those of the nearby objects. Thus, distant XBONGs are perhaps best characterized as XNOBGs: X-ray normal, optically bright galaxies. It is likely that their optical spectra suffer from severe host-galaxy dilution, which provides a natural explanation for their normal appearance.

  9. DOLPHOT: Stellar photometry

    NASA Astrophysics Data System (ADS)

    Dolphin, Andrew

    2016-08-01

    DOLPHOT is a stellar photometry package that was adapted from HSTphot for general use. It supports two modes; the first is a generic PSF-fitting package, which uses analytic PSF models and can be used for any camera. The second mode uses ACS PSFs and calibrations, and is effectively an ACS adaptation of HSTphot. A number of utility programs are also included with the DOLPHOT distribution, including basic image reduction routines.

  10. Third Workshop on Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor); Lasher, Lawrence E. (Editor)

    2001-01-01

    The discoveries of extrasolar planets by Wolszczan, Mayor and Queloz, Butler et al., and others have stimulated a widespread effort to obtain a body of data sufficient to understand their occurrence and characteristics. Doppler velocity techniques have found dozens of extrasolar planets with masses similar to that of Jupiter. Approximately ten percent of the stars that show planets with orbital periods of a few days to a week are expected to show transits. With the mass obtained from Doppler velocity measurements and the size from transit photometry, the densities of the planets can be determined. Theoretical models of the structure of "hot Jupiters" (i.e., those planets within a tenth of an astronomical unit (AU) of the parent star) indicate that these planets should be substantially larger in size and lower in density than Jupiter. Thus the combination of transit and Doppler velocity measurements provide a critical test of the theories of planetary structure. Furthermore, because photometry can be done with small-aperture telescopes rather than requiring the use of much larger telescopes, transit photometry should also reduce the cost of discovering extrasolar planets.

  11. Third Workshop on Photometry

    NASA Astrophysics Data System (ADS)

    Borucki, William J.; Lasher, Lawrence E.

    2001-02-01

    The discoveries of extrasolar planets by Wolszczan, Mayor and Queloz, Butler et al., and others have stimulated a widespread effort to obtain a body of data sufficient to understand their occurrence and characteristics. Doppler velocity techniques have found dozens of extrasolar planets with masses similar to that of Jupiter. Approximately ten percent of the stars that show planets with orbital periods of a few days to a week are expected to show transits. With the mass obtained from Doppler velocity measurements and the size from transit photometry, the densities of the planets can be determined. Theoretical models of the structure of "hot Jupiters" (i.e., those planets within a tenth of an astronomical unit (AU) of the parent star) indicate that these planets should be substantially larger in size and lower in density than Jupiter. Thus the combination of transit and Doppler velocity measurements provide a critical test of the theories of planetary structure. Furthermore, because photometry can be done with small-aperture telescopes rather than requiring the use of much larger telescopes, transit photometry should also reduce the cost of discovering extrasolar planets.

  12. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy.

    PubMed

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Boccara, A Claude; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  13. Single myelin fiber imaging in living rodents without labeling by deep optical coherence microscopy

    NASA Astrophysics Data System (ADS)

    Ben Arous, Juliette; Binding, Jonas; Léger, Jean-François; Casado, Mariano; Topilko, Piotr; Gigan, Sylvain; Claude Boccara, A.; Bourdieu, Laurent

    2011-11-01

    Myelin sheath disruption is responsible for multiple neuropathies in the central and peripheral nervous system. Myelin imaging has thus become an important diagnosis tool. However, in vivo imaging has been limited to either low-resolution techniques unable to resolve individual fibers or to low-penetration imaging of single fibers, which cannot provide quantitative information about large volumes of tissue, as required for diagnostic purposes. Here, we perform myelin imaging without labeling and at micron-scale resolution with >300-μm penetration depth on living rodents. This was achieved with a prototype [termed deep optical coherence microscopy (deep-OCM)] of a high-numerical aperture infrared full-field optical coherence microscope, which includes aberration correction for the compensation of refractive index mismatch and high-frame-rate interferometric measurements. We were able to measure the density of individual myelinated fibers in the rat cortex over a large volume of gray matter. In the peripheral nervous system, deep-OCM allows, after minor surgery, in situ imaging of single myelinated fibers over a large fraction of the sciatic nerve. This allows quantitative comparison of normal and Krox20 mutant mice, in which myelination in the peripheral nervous system is impaired. This opens promising perspectives for myelin chronic imaging in demyelinating diseases and for minimally invasive medical diagnosis.

  14. Accretion and Magnetic Reconnection in the Pre-Main Sequence Binary DQ Tau as Revealed through High-Cadence Optical Photometry

    NASA Astrophysics Data System (ADS)

    Tofflemire, Benjamin M.; Mathieu, Robert D.; Ardila, David R.; Akeson, Rachel L.; Ciardi, David R.; Herczeg, Gregory; Johns-Krull, Christopher M.; Vodniza, Alberto

    2016-01-01

    Protostellar disks are integral to the formation and evolution of low-mass stars and planets. A paradigm for the star-disk interaction has been extensively developed through theory and observation in the case of single stars. Most stars, however, form in binaries or higher order systems where the distribution of disk material and mass flows are more complex. Pre-main sequence (PMS) binary stars can have up to three accretion disks: two circumstellar disks and a circumbinary disk separated by a dynamically cleared gap. Theory suggests that mass may periodically flow in an accretion stream from a circumbinary disk across the gap onto circumstellar disks or stellar surfaces.The archetype for this theory is the eccentric, PMS binary DQ Tau. Moderate-cadence broadband photometry (~10 observations per orbital period) has shown pulsed brightening events near most periastron passages, just as numerical simulations would predict for a binary of similar orbital parameters. While this observed behavior supports the accretion stream theory, it is not exclusive to variable accretion rates. Magnetic reconnection events (flares) during the collision of stellar magnetospheres at periastron (when separated by 8 stellar radii) could produce the same periodic, broadband behavior when observed at a one-day cadence. Further evidence for magnetic activity comes from gyrosynchrotron, radio flares (typical of stellar flares) observed near multiple periastron passages. To reveal the physical mechanism seen in DQ Tau's moderate-cadence observations, we have obtained continuous, moderate-cadence, multi-band photometry over 10 orbital periods (LCOGT 1m network), supplemented with 32 nights of minute-cadence photometry centered on 4 separate periastron passages (WIYN 0.9m; APO ARCSAT). With detailed lightcurve morphologies we distinguish between the gradual rise and fall on multi-day time-scales predicted by the accretion stream theory and the hour time-scale, rapid-rise and exponential

  15. Precision Multiband Photometry with a DSLR Camera

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Bakos, G. Á.; Penev, K.; Csubry, Z.; Hartman, J. D.; Bhatti, W.; de Val-Borro, M.

    2016-03-01

    Ground-based exoplanet surveys such as SuperWASP, HAT Network of Telescopes (HATNet), and KELT have discovered close to two hundred transiting extrasolar planets in the past several years. The strategy of these surveys is to look at a large field of view and measure the brightnesses of its bright stars to around half a percent per point precision, which is adequate for detecting hot Jupiters. Typically, these surveys use CCD detectors to achieve high precision photometry. These CCDS, however, are expensive relative to other consumer-grade optical imaging devices, such as digital single-lens reflex cameras (DSLRs). We look at the possibility of using a DSLR camera for precision photometry. Specifically, we used a Canon EOS 60D camera that records light in three colors simultaneously. The DSLR was integrated into the HATNet survey and collected observations for a month, after which photometry was extracted for 6600 stars in a selected stellar field. We found that the DSLR achieves a best-case median absolute deviation of 4.6 mmag per 180 s exposure when the DSLR color channels are combined, and 1000 stars are measured to better than 10 mmag (1%). Also, we achieve 10 mmag or better photometry in the individual colors. This is good enough to detect transiting hot Jupiters. We performed a candidate search on all stars and found four candidates, one of which is KELT-3b, the only known transiting hot Jupiter in our selected field. We conclude that the Canon 60D is a cheap, lightweight device capable of useful photometry in multiple colors.

  16. Experimental Evaluation of Optically Polished Aluminum Panels on the Deep Space Network's 34 Meter Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.

    2011-01-01

    The potential development of large aperture ground?based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation is to polish the aluminum reflector panels of 34?meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by state of?the?art polished aluminum panels. Theoretical analyses of receiving antenna pointing, temporal synchronization and data detection have been addressed in previous papers. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. Two polished aluminum panels (a standard DSN panel polished to high reflectance, and a custom designed aluminum panel with much better surface quality) have been mounted on the 34 meter research antenna at Deep?Space Station 13 (DSS?13), and a remotely controlled CCD camera with a large CCD sensor in a weather?proof container has been installed next to the subreflector, pointed directly at the custom polished panel. The point?spread function (PSF) generated by the Vertex polished panel has been determined to be smaller than the sensor of the CCD camera, hence a detailed picture of the PSF can be obtained every few seconds, and the sensor array data processed to determine the center of the intensity distribution. In addition to estimating the center coordinates, expected communications performance can also been evaluated with the recorded data. The results of preliminary pointing experiments with the Vertex polished panel receiver using the planet Jupiter to simulate the PSF generated by a deep?space optical transmitter are presented and discussed in this paper.

  17. Near Earth Architectural Options for a Future Deep Space Optical Communications Network

    NASA Technical Reports Server (NTRS)

    Edwards, B. L.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    In the near future the National Aeronautics and Space Administration anticipates a significant increase in demand for long-haul communications services from deep space to Earth. Distances will range from 0.1 to 40 AU, with data rate requirements in the 1's to 1000's of Mbits/second. The near term demand is driven by NASA's Space Science Enterprise which wishes to deploy more capable instruments onboard spacecraft and increase the number of deep space missions. The long term demand is driven by missions with extreme communications challenges such as very high data rates from the outer planets, supporting sub-surface exploration, or supporting NASA's Human Exploration and Development of Space Enterprise beyond Earth orbit. Laser communications is a revolutionary communications technology that will dramatically increase NASA's ability to transmit information across the solar system. Lasercom sends information using beams of light and optical elements, such as telescopes and optical amplifiers, rather than RF signals, amplifiers, and antennas. This paper provides an overview of different network options at Earth to meet NASA's deep space lasercom requirements. It is based mainly on work done for the Mars Laser Communications Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It reports preliminary conclusions from the Mars Lasercom Study conducted at MIT/LL and on additional work done for the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telesat Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  18. Experimental Evaluation of Optically Polished Aluminum Panels on the Deep Space Network's 34 Meter Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.

    2011-01-01

    The potential development of large aperture ground?based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation is to polish the aluminum reflector panels of 34?meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by state of?the?art polished aluminum panels. Theoretical analyses of receiving antenna pointing, temporal synchronization and data detection have been addressed in previous papers. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. Two polished aluminum panels (a standard DSN panel polished to high reflectance, and a custom designed aluminum panel with much better surface quality) have been mounted on the 34 meter research antenna at Deep?Space Station 13 (DSS?13), and a remotely controlled CCD camera with a large CCD sensor in a weather?proof container has been installed next to the subreflector, pointed directly at the custom polished panel. The point?spread function (PSF) generated by the Vertex polished panel has been determined to be smaller than the sensor of the CCD camera, hence a detailed picture of the PSF can be obtained every few seconds, and the sensor array data processed to determine the center of the intensity distribution. In addition to estimating the center coordinates, expected communications performance can also been evaluated with the recorded data. The results of preliminary pointing experiments with the Vertex polished panel receiver using the planet Jupiter to simulate the PSF generated by a deep?space optical transmitter are presented and discussed in this paper.

  19. Joint deep shape and appearance learning: application to optic pathway glioma segmentation

    NASA Astrophysics Data System (ADS)

    Mansoor, Awais; Li, Ien; Packer, Roger J.; Avery, Robert A.; Linguraru, Marius George

    2017-03-01

    Automated tissue characterization is one of the major applications of computer-aided diagnosis systems. Deep learning techniques have recently demonstrated impressive performance for the image patch-based tissue characterization. However, existing patch-based tissue classification techniques struggle to exploit the useful shape information. Local and global shape knowledge such as the regional boundary changes, diameter, and volumetrics can be useful in classifying the tissues especially in scenarios where the appearance signature does not provide significant classification information. In this work, we present a deep neural network-based method for the automated segmentation of the tumors referred to as optic pathway gliomas (OPG) located within the anterior visual pathway (AVP; optic nerve, chiasm or tracts) using joint shape and appearance learning. Voxel intensity values of commonly used MRI sequences are generally not indicative of OPG. To be considered an OPG, current clinical practice dictates that some portion of AVP must demonstrate shape enlargement. The method proposed in this work integrates multiple sequence magnetic resonance image (T1, T2, and FLAIR) along with local boundary changes to train a deep neural network. For training and evaluation purposes, we used a dataset of multiple sequence MRI obtained from 20 subjects (10 controls, 10 NF1+OPG). To our best knowledge, this is the first deep representation learning-based approach designed to merge shape and multi-channel appearance data for the glioma detection. In our experiments, mean misclassification errors of 2:39% and 0:48% were observed respectively for glioma and control patches extracted from the AVP. Moreover, an overall dice similarity coefficient of 0:87+/-0:13 (0:93+/-0:06 for healthy tissue, 0:78+/-0:18 for glioma tissue) demonstrates the potential of the proposed method in the accurate localization and early detection of OPG.

  20. A wideband connection to sperm whales: A fiber-optic, deep-sea hydrophone array

    NASA Astrophysics Data System (ADS)

    Heerfordt, Anders; Møhl, Bertel; Wahlberg, Magnus

    2007-03-01

    A 10-element, 950 m long, vertical hydrophone array based on fiber-optic data transmission has been developed primarily for studying the beam pattern from deep diving cetaceans emitting sonar pulses. The array elements have a configurable sampling rate and resolution with a maximum signal bandwidth of 90 kHz and a maximum dynamic range of 133 dB. The array has been deployed from a 14 m ketch with a crew of four. In the course of the development a number of mechanical and electrical problems have been solved.

  1. Earth-Image Tracking in the IR for Deep Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Chen, Yinging; Lee, Shinhak; Ortiz, Gerard G.

    2005-01-01

    Sub-microradian level laser beam pointing to an Earth-based receiver is required for deep space optical communications. This requires a beacon emanated from Earth towards the spacecraft. The beacon could be a laser or reflected sunlight from Earth. Earth image tracking in the visible is hampered by significant albedo variations and/or crescent Earth image yielding large central errors. Here, we report results of Earth-image tracking in the infrared (8 to 13 micron) region of the spectrum with the aim of substantially alleviating the two challenges mentioned earlier.

  2. In vivo deep tissue imaging using wavefront shaping optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Yu, Hyeonseung; Lee, Peter; Lee, KyeoReh; Jang, Jaeduck; Lim, Jaeguyn; Jang, Wooyoung; Jeong, Yong; Park, YongKeun

    2016-10-01

    Multiple light scattering in tissue limits the penetration of optical coherence tomography (OCT) imaging. Here, we present in vivo OCT imaging of a live mouse using wavefront shaping (WS) to enhance the penetration depth. A digital micromirror device was used in a spectral-domain OCT system for complex WS of an incident beam which resulted in the optimal delivery of light energy into deep tissue. Ex vivo imaging of chicken breasts and mouse ear tissues showed enhancements in the strength of the image signals and the penetration depth, and in vivo imaging of the tail of a live mouse provided a multilayered structure inside the tissue.

  3. Routing of deep-subwavelength optical beams without reflection and diffraction using infinitely anisotropic metamaterials

    NASA Astrophysics Data System (ADS)

    Catrysse, Peter B.; Fan, Shanhui

    2015-03-01

    Media that are described by extreme electromagnetic parameters, such as very large/small permittivity/permeability, have generated significant fundamental and applied interest in recent years. Notable examples include epsilon-near-zero, ultra-low refractive-index, and ultra-high refractive-index materials. Many photonic structures, such as waveguides, lenses, and photonic band gap materials, benefit greatly from the large index contrast provided by such media. In this paper, I discuss our recent work on media with infinite anisotropy, i.e., infinite permittivity (permeability) in one direction and finite in the other directions. As an illustration of the unusual optical behaviors that result from infinite anisotropy, I describe efficient light transport in deep-subwavelength apertures filled with infinitely anisotropic media. I then point out some of the opportunities that exist for controlling light at the nano-scale using infinitely anisotropic media by themselves. First, I show that a single medium with infinite anisotropy enables diffraction-free propagation of deep-subwavelength beams. Next, I demonstrate interfaces between two infinitely anisotropic media that are impedancematched for complete deep-subwavelength beams and enable reflection-free routing with zero bend radius that is entirely free from diffraction effects even when deep-subwavelength information is encoded on the beams. These behaviors indicate an unprecedented possibility to use media with infinite anisotropy to manipulate beams with deepsubwavelength features, including complete images. To illustrate physical realizability, I demonstrate a metamaterial design using existing materials in a planar geometry, which can be implemented using well-established nanofabrication techniques. This approach provides a path to deep-subwavelength routing of information-carrying beams and far-field imaging unencumbered by diffraction and reflection.

  4. Effects of nonspherical dust optical models on the VIIRS Deep Blue over-water aerosol product

    NASA Astrophysics Data System (ADS)

    Lee, J.; Hsu, N. Y. C.; Sayer, A. M.; Bettenhausen, C.; Yang, P.

    2016-12-01

    Aerosol Robotic Network (AERONET)-based nonspherical dust optical models are developed for the Version 1 Visible Infrared Imaging Radiometer Suite (VIIRS) Deep Blue over-water algorithm (also known as Satellite Ocean Aerosol Retrieval algorithm). The optical models are created at six distinct AERONET sites influenced by frequent dust aerosols from different source regions. We assume the same spheroid shape distribution as used in the Version 2 AERONET inversion algorithm to account for the nonsphericity of dust, which makes the developed optical models consistent with the AERONET-retrieved microphysical and optical properties. For the initial data processing, the optical models representing the Capo Verde site are used due to the strong influence of Saharan dust over the global ocean. Comparisons of the VIIRS-retrieved aerosol data products against AERONET at three island/coastal sites suggest that the use of nonspherical dust optical models significantly mitigates the well-known, artificial scattering angle dependence of aerosol optical depth (AOD), which is observed when incorrectly assuming spherical dust. Ångström exponent is also greatly improved, showing a noticeable reduction of high biases as compared to the spherical assumption. The improvement in AOD results in a more natural AOD gradient of Saharan dust along the transport path to the Atlantic Ocean; i.e., AOD decreases with increasing distance transported, whereas the spherical model assumption leads to a strong wave pattern in AOD due to the artificial scattering angle dependence of AOD. Although further investigation is required, the present study can be applied to similar sensors such as Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to produce a long-term, consistent aerosol data product.

  5. Optical focusing deep inside dynamic scattering media with near-infrared time-reversed ultrasonically encoded (TRUE) light

    PubMed Central

    Liu, Yan; Lai, Puxiang; Ma, Cheng; Xu, Xiao; Grabar, Alexander A.; Wang, Lihong V.

    2015-01-01

    Focusing light deep inside living tissue has not been achieved despite its promise to play a central role in biomedical imaging, optical manipulation and therapy. To address this challenge, internal-guide-star-based wavefront engineering techniques—for example, time-reversed ultrasonically encoded (TRUE) optical focusing—were developed. The speeds of these techniques, however, were limited to no greater than 1 Hz, preventing them from in vivo applications. Here we improve the speed of optical focusing deep inside scattering media by two orders of magnitude, and focus diffuse light inside a dynamic scattering medium having a speckle correlation time as short as 5.6 ms, typical of living tissue. By imaging a target, we demonstrate the first focusing of diffuse light inside a dynamic scattering medium containing living tissue. Since the achieved focusing speed approaches the tissue decorrelation rate, this work is an important step towards in vivo deep tissue noninvasive optical imaging, optogenetics and photodynamic therapy. PMID:25556918

  6. Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Ortiz, Gerry G.; Lee, Shinhak

    2003-01-01

    The feasibility of using long wavelength Earth thermal (infrared) images for telescope tracking/pointing application. for both Deep Space Free- pace Optical Communications has been investigated and is reported her. The advantage of this technology rests on using full Earth images in this band, which yield more accurate estimates of geometric centroids than that of Earth images in the visible band. Another major advantage is that these images are nearly independent of Earth phase angle. The results of the study show that at a Mars range, with currently available sensors, a noise equivalent angle of 10 to 150 nanoradians and a bias error of better than 80 nanoradians can be obtained. This enables precise pointing of the optical communications beam for high data rate links.

  7. Fluoride antireflection coatings for deep ultraviolet optics deposited by ion-beam sputtering.

    PubMed

    Yoshida, Toshiya; Nishimoto, Keiji; Sekine, Keiichi; Etoh, Kazuyuki

    2006-03-01

    Optically high quality coatings of fluoride materials are required in deep ultraviolet (DUV) lithography. We have applied ion-beam sputtering (IBS) to obtain fluoride films with smooth surfaces. The extinction coefficients were of the order of 10(-4) at the wavelength of 193 nm due to the reduction of their absorption loss. The transmittance of the MgF2/GdF3 antireflection coating was as high as 99.7% at the wavelength of 193 nm. The surfaces of the IBS deposited films were so smooth that the surface roughness of the A1F3/GdF3 film was comparable with that of the CaF2 substrate. The MgF2/GdF3 coating fulfilled the temperature and humidity requirements of military specification. Thus, the IBS deposited fluoride films are promising candidate for use in the DUV lithography optics.

  8. Deep sea tests of a prototype of the KM3NeT digital optical module

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Ageron, M.; Aharonian, F.; Aiello, S.; Albert, A.; Ameli, F.; Anassontzis, E. G.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; de Asmundis, R.; Balasi, K.; Band, H.; Barbarino, G.; Barbarito, E.; Barbato, F.; Baret, B.; Baron, S.; Belias, A.; Berbee, E.; van den Berg, A. M.; Berkien, A.; Bertin, V.; Beurthey, S.; van Beveren, V.; Beverini, N.; Biagi, S.; Bianucci, S.; Billault, M.; Birbas, A.; Boer Rookhuizen, H.; Bormuth, R.; Bouché, V.; Bouhadef, B.; Bourlis, G.; Bouwhuis, M.; Bozza, C.; Bruijn, R.; Brunner, J.; Cacopardo, G.; Caillat, L.; Calamai, M.; Calvo, D.; Capone, A.; Caramete, L.; Caruso, F.; Cecchini, S.; Ceres, A.; Cereseto, R.; Champion, C.; Château, F.; Chiarusi, T.; Christopoulou, B.; Circella, M.; Classen, L.; Cocimano, R.; Colonges, S.; Coniglione, R.; Cosquer, A.; Costa, M.; Coyle, P.; Creusot, A.; Curtil, C.; Cuttone, G.; D'Amato, C.; D'Amico, A.; De Bonis, G.; De Rosa, G.; Deniskina, N.; Destelle, J.-J.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti-Hasankiadeh, Q.; Drakopoulou, E.; Drouhin, D.; Drury, L.; Durand, D.; Eberl, T.; Eleftheriadis, C.; Elsaesser, D.; Enzenhöfer, A.; Fermani, P.; Fusco, L. A.; Gajana, D.; Gal, T.; Galatà, S.; Gallo, F.; Garufi, F.; Gebyehu, M.; Giordano, V.; Gizani, N.; Gracia Ruiz, R.; Graf, K.; Grasso, R.; Grella, G.; Grmek, A.; Habel, R.; van Haren, H.; Heid, T.; Heijboer, A.; Heine, E.; Henry, S.; Hernández-Rey, J. J.; Herold, B.; Hevinga, M. A.; van der Hoek, M.; Hofestädt, J.; Hogenbirk, J.; Hugon, C.; Hößl, J.; Imbesi, M.; James, C.; Jansweijer, P.; Jochum, J.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Kappos, E.; Katz, U.; Kavatsyuk, O.; Keller, P.; Kieft, G.; Koffeman, E.; Kok, H.; Kooijman, P.; Koopstra, J.; Korporaal, A.; Kouchner, A.; Koutsoukos, S.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lamare, P.; Larosa, G.; Lattuada, D.; Le Provost, H.; Leisos, A.; Lenis, D.; Leonora, E.; Lindsey Clark, M.; Liolios, A.; Llorens Alvarez, C. D.; Löhner, H.; Lo Presti, D.; Louis, F.; Maccioni, E.; Mannheim, K.; Manolopoulos, K.; Margiotta, A.; Mariş, O.; Markou, C.; Martínez-Mora, J. A.; Martini, A.; Masullo, R.; Michael, T.; Migliozzi, P.; Migneco, E.; Miraglia, A.; Mollo, C.; Mongelli, M.; Morganti, M.; Mos, S.; Moudden, Y.; Musico, P.; Musumeci, M.; Nicolaou, C.; Nicolau, C. A.; Orlando, A.; Orzelli, A.; Papageorgiou, K.; Papaikonomou, A.; Papaleo, R.; Păvălaş, G. E.; Peek, H.; Pellegrino, C.; Pellegriti, M. G.; Perrina, C.; Petridou, C.; Piattelli, P.; Pikounis, K.; Popa, V.; Pradier, Th.; Priede, M.; Pühlhofer, G.; Pulvirenti, S.; Racca, C.; Raffaelli, F.; Randazzo, N.; Rapidis, P. A.; Razis, P.; Real, D.; Resvanis, L.; Reubelt, J.; Riccobene, G.; Rovelli, A.; Royon, J.; Saldaña, M.; Samtleben, D. F. E.; Sanguineti, M.; Santangelo, A.; Sapienza, P.; Savvidis, I.; Schmelling, J.; Schnabel, J.; Sedita, M.; Seitz, T.; Sgura, I.; Simeone, F.; Siotis, I.; Sipala, V.; Solazzo, M.; Spitaleri, A.; Spurio, M.; Stavropoulos, G.; Steijger, J.; Stolarczyk, T.; Stransky, D.; Taiuti, M.; Terreni, G.; Tézier, D.; Théraube, S.; Thompson, L. F.; Timmer, P.; Trapierakis, H. I.; Trasatti, L.; Trovato, A.; Tselengidou, M.; Tsirigotis, A.; Tzamarias, S.; Tzamariudaki, E.; Vallage, B.; Van Elewyck, V.; Vermeulen, J.; Vernin, P.; Viola, S.; Vivolo, D.; Werneke, P.; Wiggers, L.; Wilms, J.; de Wolf, E.; van Wooning, R. H. L.; Yatkin, K.; Zachariadou, K.; Zonca, E.; Zornoza, J. D.; Zúñiga, J.; Zwart, A.

    2014-09-01

    The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deep waters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same $^{40}$K decay and the localization bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.

  9. Results in speckle photometry

    NASA Astrophysics Data System (ADS)

    Bagnuolo, W. G., Jr.; Barry, D. J.; Mason, B.; Dombrowski, E. G.

    1990-08-01

    Algorithms for reconstruction of isoplanically blurred point source pairs are considerably simpler and faster than full-blown image reconstruction techniques. Traditional autocorrelation approaches suffer from a 180 degree ambiguity, however, and only yield order of magnitude estimates for brightness ratios. A new asymmetric algorithm is here presented: the "Directed Vector Autocorrelation" (DVA), which is a rapid alternative to vector autocorrelation. Together with the 'Fork algorithm", a directional filter for estimating brightness ratios, the DVA algorithm has been used to resolve ambiguous orbits and produce differential color photometry for several binary stars.

  10. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    SciTech Connect

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.

  11. Predicting Global Minimum in Complex Beryllium Borate System for Deep-ultraviolet Functional Optical Applications

    PubMed Central

    Bian, Qiang; Yang, Zhihua; Wang, Ying; Cao, Chao; Pan, Shilie

    2016-01-01

    Searching for high performance materials for optical communication and laser industry in deep-ultraviolet (DUV) region has been the subject of considerable interest. Such materials by design from scratching on multi-component complex crystal systems are challenging. Here, we predict, through density function calculations and unbiased structure searching techniques, the formation of quaternary NaBeBO3 compounds at ambient pressure. Among the four low-energy phases, the P63/m structure exhibits a DUV cutoff edge of 20 nm shorter than α-BaB2O4 (189 nm) – the best-known DUV birefringent material. While the P-6 structure exhibits one time second-harmonic generation efficiency of KH2PO4 and possesses excellent crystal growth habit without showing any layer habit as observed in the only available DUV nonlinear optical material KBe2BO3F2, whose layer habit limits its wide industrial applications. These NaBeBO3 structures are promising candidates for the next generation of DUV optical materials, and the structure prediction technique will shed light on future optical materials design. PMID:27734901

  12. Predicting Global Minimum in Complex Beryllium Borate System for Deep-ultraviolet Functional Optical Applications

    NASA Astrophysics Data System (ADS)

    Bian, Qiang; Yang, Zhihua; Wang, Ying; Cao, Chao; Pan, Shilie

    2016-10-01

    Searching for high performance materials for optical communication and laser industry in deep-ultraviolet (DUV) region has been the subject of considerable interest. Such materials by design from scratching on multi-component complex crystal systems are challenging. Here, we predict, through density function calculations and unbiased structure searching techniques, the formation of quaternary NaBeBO3 compounds at ambient pressure. Among the four low-energy phases, the P63/m structure exhibits a DUV cutoff edge of 20 nm shorter than α-BaB2O4 (189 nm) – the best-known DUV birefringent material. While the P-6 structure exhibits one time second-harmonic generation efficiency of KH2PO4 and possesses excellent crystal growth habit without showing any layer habit as observed in the only available DUV nonlinear optical material KBe2BO3F2, whose layer habit limits its wide industrial applications. These NaBeBO3 structures are promising candidates for the next generation of DUV optical materials, and the structure prediction technique will shed light on future optical materials design.

  13. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna.

    PubMed

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H; Pagliano, Francesco; Fiore, Andrea; Schuck, P James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the "campanile tip", a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.

  14. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    DOE PAGES

    Caselli, Niccolò; La China, Federico; Bao, Wei; ...

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magneticmore » intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.« less

  15. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    PubMed Central

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-01-01

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions. PMID:26045401

  16. Interior radiances in optically deep absorbing media. 3: Scattering from Haze L

    NASA Technical Reports Server (NTRS)

    Kattawar, G. W.; Plass, G. N.

    1974-01-01

    The interior radiances are calculated within an optically deep absorbing medium scattering according to the Haze L phase function. The dependence on the solar zenith angle, the single scattering albedo, and the optical depth within the medium is calculated by the matrix operator method. The development of the asymptotic angular distribution of the radiance in the diffusion region is illustrated through a number of examples; it depends only on the single scattering albedo and on the phase function for single scattering. The exact values of the radiance in the diffusion region are compared with values calculated from the approximate equations proposed by Van de Hulst. The variation of the radiance near the lower boundary of an optically thick medium is illustrated with examples. The attenuation length is calculated for various single scattering albedos and compared with the corresponding values for Rayleigh scattering. The ratio of the upward to the downward flux is found to be remarkably constant within the medium. The heating rate is calculated and found to have a maximum value at an optical depth of two within a Haze L layer when the sun is at the zenith.

  17. Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

    PubMed

    Djordjevic, Ivan B

    2011-07-18

    In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

  18. Deep proton writing: a powerful rapid prototyping technology for various micro-optical components

    NASA Astrophysics Data System (ADS)

    Van Erps, Jürgen; Vervaeke, Michael; Debaes, Christof; Ottevaere, Heidi; Van Overmeire, Sara; Hermanne, Alex; Thienpont, Hugo

    2010-05-01

    One of the important challenges for the deployment of the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. For the fabrication of this kind of micro-optical modules, we make use of deep proton writing (DPW) as a generic rapid prototyping technology. DPW consists of bombarding polymer samples with swift protons, which results after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we give an overview of the process steps of the technology and we present several examples of micro-optical and micro-mechanical components, fabricated through DPW, targeting applications in optical interconnections and in bio-photonics. These include: high-precision 2-D fiber connectors, out-of-plane coupling structures featuring high-quality 45° and curved micro-mirrors, arrays of high aspect ratio micro-pillars, and fluorescence and absorption detection bio-photonics modules. While DPW is clearly not a mass fabrication technique as such, one of its assets is that once the master component has been prototyped, a metal mould can be generated from the DPW master by applying electroplating. After removal of the plastic master, this metal mould can be used as a shim in a final microinjection moulding or hot embossing step. This way, the master component can be mass-produced at low cost in a wide variety of high-tech plastics.

  19. Deep brain optical measurements of cell type–specific neural activity in behaving mice

    PubMed Central

    Cui, Guohong; Jun, Sang Beom; Jin, Xin; Luo, Guoxiang; Pham, Michael D; Lovinger, David M; Vogel, Steven S; Costa, Rui M

    2014-01-01

    Recent advances in genetically encoded fluorescent sensors enable the monitoring of cellular events from genetically defined groups of neurons in vivo. In this protocol, we describe how to use a time-correlated single-photon counting (tcspc)–based fiber optics system to measure the intensity, emission spectra and lifetime of fluorescent biosensors expressed in deep brain structures in freely moving mice. When combined with cre-dependent selective expression of genetically encoded ca2+ indicators (GecIs), this system can be used to measure the average neural activity from a specific population of cells in mice performing complex behavioral tasks. as an example, we used viral expression of GcaMps in striatal projection neurons (spns) and recorded the fluorescence changes associated with calcium spikes from mice performing a lever-pressing operant task. the whole procedure, consisting of virus injection, behavior training and optical recording, takes 3–4 weeks to complete. With minor adaptations, this protocol can also be applied to recording cellular events from other cell types in deep brain regions, such as dopaminergic neurons in the ventral tegmental area. the simultaneously recorded fluorescence signals and behavior events can be used to explore the relationship between the neural activity of specific brain circuits and behavior. PMID:24784819

  20. Deep brain optical measurements of cell type-specific neural activity in behaving mice.

    PubMed

    Cui, Guohong; Jun, Sang Beom; Jin, Xin; Luo, Guoxiang; Pham, Michael D; Lovinger, David M; Vogel, Steven S; Costa, Rui M

    2014-01-01

    Recent advances in genetically encoded fluorescent sensors enable the monitoring of cellular events from genetically defined groups of neurons in vivo. In this protocol, we describe how to use a time-correlated single-photon counting (TCSPC)-based fiber optics system to measure the intensity, emission spectra and lifetime of fluorescent biosensors expressed in deep brain structures in freely moving mice. When combined with Cre-dependent selective expression of genetically encoded Ca(2+) indicators (GECIs), this system can be used to measure the average neural activity from a specific population of cells in mice performing complex behavioral tasks. As an example, we used viral expression of GCaMPs in striatal projection neurons (SPNs) and recorded the fluorescence changes associated with calcium spikes from mice performing a lever-pressing operant task. The whole procedure, consisting of virus injection, behavior training and optical recording, takes 3-4 weeks to complete. With minor adaptations, this protocol can also be applied to recording cellular events from other cell types in deep brain regions, such as dopaminergic neurons in the ventral tegmental area. The simultaneously recorded fluorescence signals and behavior events can be used to explore the relationship between the neural activity of specific brain circuits and behavior.

  1. Deep Retinal Layer Microvasculature Dropout Detected by the Optical Coherence Tomography Angiography in Glaucoma.

    PubMed

    Suh, Min Hee; Zangwill, Linda M; Manalastas, Patricia Isabel C; Belghith, Akram; Yarmohammadi, Adeleh; Medeiros, Felipe A; Diniz-Filho, Alberto; Saunders, Luke J; Weinreb, Robert N

    2016-12-01

    To investigate factors associated with dropout of the parapapillary deep retinal layer microvasculature assessed by optical coherence tomography angiography (OCTA) in glaucomatous eyes. Cross-sectional study. Seventy-one eyes from 71 primary open-angle glaucoma (POAG) patients with β-zone parapapillary atrophy (βPPA) enrolled in the Diagnostic Innovations in Glaucoma Study. Parapapillary deep-layer microvasculature dropout was defined as a complete loss of the microvasculature located within the deep retinal layer of the βPPA from OCTA-derived optic nerve head vessel density maps by standardized qualitative assessment. Circumpapillary vessel density (cpVD) within the retinal nerve fiber layer (RNFL) also was calculated using OCTA. Choroidal thickness and presence of focal lamina cribrosa (LC) defects were determined using swept-source optical coherence tomography. Presence of parapapillary deep-layer microvasculature dropout. Parameters including age, systolic and diastolic blood pressure, axial length, intraocular pressure, disc hemorrhage, cpVD, visual field (VF) mean deviation (MD), focal LC defects βPPA area, and choroidal thickness were analyzed. Parapapillary deep-layer microvasculature dropout was detected in 37 POAG eyes (52.1%). Eyes with microvasculature dropout had a higher prevalence of LC defects (70.3% vs. 32.4%), lower cpVD (52.7% vs. 58.8%), worse VF MD (-9.06 dB vs. -3.83 dB), thinner total choroidal thickness (126.5 μm vs. 169.1 μm), longer axial length (24.7 mm vs. 24.0 mm), larger βPPA (1.2 mm(2) vs. 0.76 mm(2)), and lower diastolic blood pressure (74.7 mmHg vs. 81.7 mmHg) than those without dropout (P < 0.05, respectively). In the multivariate logistic regression analysis, higher prevalence of focal LC defects (odds ratio [OR], 6.27; P = 0.012), reduced cpVD (OR, 1.27; P = 0.002), worse VF MD (OR, 1.27; P = 0.001), thinner choroidal thickness (OR, 1.02; P = 0.014), and lower diastolic blood pressure (OR, 1.16; P = 0.003) were

  2. Remote-Sensing Reflectance and Inherent Optical Properties for Optically Deep Waters: A Revisit

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.; Du, Ke-Ping

    2001-01-01

    Remote-sensing reflectance (r(rs)) is defined as the ratio of upwelling radiance to downwelling irradiance. Relationships between remote-sensing reflectance and inherent optical properties serve as the basis for ocean-color modeling, as well as for spectral deduction of oceanic constituents through analytical/semi-analytical models of ocean color. A decade ago, a simple and concise formula based on Monte Carlo simulations was developed by relating rrs to a property u, the ratio of backscattering (b(b)) to the sum of absorption (a) and backscattering (u = b(b)/(a+b(b))). This relationship generally ignored the shape differences in phase functions between molecular scattering and particle scattering. In this study, the relationship is updated with separate parameters for molecular and particle scattering, based on the Radiative Transfer Equation through use of Hydrolight numerical solutions. The new approach fits r(rs) better than an earlier traditional formula, for both clear and turbid waters.

  3. Remote-Sensing Reflectance and Inherent Optical Properties for Optically Deep Waters: A Revisit

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.; Du, Ke-Ping

    2001-01-01

    Remote-sensing reflectance (r(rs)) is defined as the ratio of upwelling radiance to downwelling irradiance. Relationships between remote-sensing reflectance and inherent optical properties serve as the basis for ocean-color modeling, as well as for spectral deduction of oceanic constituents through analytical/semi-analytical models of ocean color. A decade ago, a simple and concise formula based on Monte Carlo simulations was developed by relating rrs to a property u, the ratio of backscattering (b(b)) to the sum of absorption (a) and backscattering (u = b(b)/(a+b(b))). This relationship generally ignored the shape differences in phase functions between molecular scattering and particle scattering. In this study, the relationship is updated with separate parameters for molecular and particle scattering, based on the Radiative Transfer Equation through use of Hydrolight numerical solutions. The new approach fits r(rs) better than an earlier traditional formula, for both clear and turbid waters.

  4. Deep optical imaging of the γ-ray pulsar J1048-5832 with the VLT

    NASA Astrophysics Data System (ADS)

    Danilenko, A.; Kirichenko, A.; Sollerman, J.; Shibanov, Yu.; Zyuzin, D.

    2013-04-01

    Context. PSR J1048-5832 is a young radio-pulsar that has recently been detected in γ-rays with Fermi, and also in X-rays with Chandra and XMM-Newton. It powers a compact pulsar wind nebula visible in X-rays and is in many ways similar to the Vela pulsar. Aims: We present deep optical observations made with the ESO Very Large Telescope to search for optical counterparts of the pulsar and its nebula and to explore their multi-wavelength emission properties. Methods: The data were obtained in the V and R bands and were compared with archival data in other spectral domains. Results: We do not detect the pulsar in the optical and derive informative upper limits of R ≳ 28.m1 and V ≳ 28.m4 for its brightness. Using a red-clump star method, we estimate an interstellar extinction towards the pulsar of AV ≈ 2 mag, which is consistent with the absorbing column density derived from X-rays. The respective distance agrees with the dispersion measure distance. We reanalysed the Chandra X-ray data and compared the dereddened upper limits with the unabsorbed X-ray spectrum of the pulsar. We find that regarding its optical-X-ray spectral properties this γ-ray pulsar is not distinct from other pulsars detected in both ranges. However, like the Vela pulsar, it is very inefficient in the optical and X-rays. Among a dozen optical sources overlapping with the pulsar X-ray nebula we find one with V ≈ 26.m9 and R ≈ 26.m3, whose colour is slightly bluer than that of the field stars and is consistent with the peculiar colours typical for pulsar nebula features. It positionally coincides with a relatively bright feature of the pulsar X-ray nebula, resembling the Crab wisp and is located in ~2 from the pulsar. We suggest this source as a counterpart candidate to the feature. Conclusions: Based on the substantial interstellar extinction towards the pulsar and its optical inefficiency, additional optical studies should be carried out at longer wavelengths. Based on observations made

  5. A new method of optical biopsy: demonstration of mechanical contrast in deep tissue using an optical coherence elastography needle probe

    NASA Astrophysics Data System (ADS)

    Kennedy, Kelsey M.; Kennedy, Brendan F.; McLaughlin, Robert A.; Sampson, David D.

    2012-02-01

    We incorporate for the first time optical coherence elastography (OCE) into a needle probe and demonstrate its ability to provide depth-resolved information about the mechanical properties of soft tissues. This allows analysis of tissues located much deeper than has previously been possible with other forms of OCE. OCE exploits the microscopic resolution of optical coherence tomography (OCT) to produce high-resolution maps of tissue mechanical properties. While OCE has potential to delineate diseased and healthy tissues (e.g., stiff tumor in soft tissue), standard techniques are limited by the penetration depth of OCT in tissue (2-3 mm). Our OCE needle probe overcomes this limitation, as it may be inserted deep within the body to perform measurements. We tested needle-based OCE in tissue-mimicking phantoms and ex vivo porcine airway tissue comprising layers of varying stiffness. Results demonstrate mechanical differentiation of tissues and identification of tissue interfaces. The proof-of-principle results presented here pave the way for future measurements in human breast tissue that will aim to establish needle-based OCE as a viable technique for intraoperative guidance of breast cancer surgery.

  6. 100 years of photometry and radiometry

    NASA Astrophysics Data System (ADS)

    Hardis, Jonathan E.

    2001-06-01

    Measurement of light is an old subject, though the past 100 years have seen significant advances. 100 years ago, photometry - the art and science of measuring light as it is perceived by people - had the greater technological importance. Even today SI (the metric system) retains a base unit for photometry, the candela. However, early work at NBS included pivotal projects in the field of radiometry - the measurement of the physical characteristics of light. These included the validation of Planck's newly-minted theory of blackbody radiation, determining the radiation constants with good accuracy, and the definitive analysis of the spectral responsivity of human vision, so as to relate photometry to radiometry. This latter work has only increased in importance over the past 75 years as the definition of the candela has changed and improved. Today, NIST makes radiometric, and hence photometric measurements, with unprecedented precision. Cryogenic radiometers based on the principle of electrical substitution measure optical flux with uncertainties of 0.02%. Additional facilities enable measurement of spectral responsivity, spectral radiance, and spectral irradiance. Novel detectors, such as light-traps, allow the best accuracy to be transferred from the primary standards to routinely-used instruments and to calibration customers. Filtered detectors are used to realize photometric scales, radiation temperature scales, and other specialized measurements. Indeed, the story of the metrology of light is the story of continuous improvement, both driven by and enabled by advances in technology. We touch upon some of these as a prelude to the other talks in this Conference.

  7. Dielectric strength, optical absorption, and deep ultraviolet detectors of hexagonal boron nitride epilayers

    NASA Astrophysics Data System (ADS)

    Li, J.; Majety, S.; Dahal, R.; Zhao, W. P.; Lin, J. Y.; Jiang, H. X.

    2012-10-01

    Hexagonal boron nitride (hBN) epilayers have been synthesized by metal organic chemical vapor deposition and their dielectric strength, optical absorption, and potential as a deep ultraviolet (DUV) detector material have been studied. Based on the graphene optical absorption concept, the estimated band-edge absorption coefficient of hBN is about 7 × 105/cm, which is more than 3 times higher than the value for wurtzite AlN (˜2 × 105 /cm). The dielectric strength of hBN epilayers exceeds that of AlN and is greater than 4.4 MV/cm based on the measured result for an hBN epilayer released from the host sapphire substrate. The hBN epilayer based DUV detectors exhibit a sharp cut-off wavelength around 230 nm, which coincides with the band-edge photoluminescence emission peak and virtually no responses in the long wavelengths. Based on the present study, we have identified several advantageous features of hBN DUV photodetectors: (1) low long wavelength response or high DUV to visible rejection ratio; (2) requiring very thin active layers due to high optical absorption; (3) high dielectric strength and chemical inertness and resistance to oxidation and therefore suitable for applications in extreme conditions; (4) high prospects of achieving flexible devices; and (5) possible integration with graphene optoelectronics due to their similar structures and lattice constants.

  8. Pointing, acquisition, and tracking architecture tools for deep-space optical communications

    NASA Astrophysics Data System (ADS)

    Mohan, Swati; Alvarez-Salazar, Oscar; Birnbaum, Kevin; Biswas, Abhijit; Farr, William; Hemmati, Hamid; Johnson, Shawn; Ortiz, Geraldo; Quirk, Kevin; Rahman, Zahidul; Regher, Martin; Rizvi, Farheen; Shields, Joel; Srinivasan, Meera

    2014-03-01

    Deep-Space Optical Communications is a key emerging technology that is being pursued for high data-rate communications, which may enable rates up to ten times more than current Ka-band technology. Increasing the frequency of communication, from Ka-band to optical, allows for a higher data rate transfers. However, as the frequency of communication increases, the beam divergence decreases. Less beam divergence requires more accurate and precise pointing to make contact with the receiver. This would require a three-order-of-magnitude improvement from Ka-Band (~ 1 mrad) to optical (~ 1 urad) in the required pointing. Finding an architecture that can provide the necessary pointing capability is driven by many factors, such as allocated signal loss due to pointing, range to Earth, spacecraft disturbance profile, spacecraft base pointing capability, isolation scheme, and detector characteristics. We have developed a suite of tools to 1) flow down a set of pointing requirements (Error Budget Tool), 2) determine a set of architectures capable of meeting the requirements (Pointing Architecture Tool), and 3) assess the performance of possible architecture over the mission trajectory (Systems Engineering Tool). This paper describes the three tools and details their use through the case study of the Asteroid Retrieval Mission. Finally, this paper details which aspects of the pointing, acquisition, and tracking subsystem still require technology infusion, and the future steps needed to implement these pointing architectures.

  9. Three-dimensional deep sub-diffraction optical beam lithography with 9 nm feature size.

    PubMed

    Gan, Zongsong; Cao, Yaoyu; Evans, Richard A; Gu, Min

    2013-01-01

    The current nanofabrication techniques including electron beam lithography provide fabrication resolution in the nanometre range. The major limitation of these techniques is their incapability of arbitrary three-dimensional nanofabrication. This has stimulated the rapid development of far-field three-dimensional optical beam lithography where a laser beam is focused for maskless direct writing. However, the diffraction nature of light is a barrier for achieving nanometre feature and resolution in optical beam lithography. Here we report on three-dimensional optical beam lithography with 9 nm feature size and 52 nm two-line resolution in a newly developed two-photon absorption resin with high mechanical strength. The revealed dependence of the feature size and the two-line resolution confirms that they can reach deep sub-diffraction scale but are limited by the mechanical strength of the new resin. Our result has paved the way towards portable three-dimensional maskless laser direct writing with resolution fully comparable to electron beam lithography.

  10. Deep-subwavelength Nanometric Image Reconstruction using Fourier Domain Optical Normalization.

    PubMed

    Qin, Jing; Silver, Richard M; Barnes, Bryan M; Zhou, Hui; Dixson, Ronald G; Henn, Mark-Alexander

    Quantitative optical measurements of deep sub-wavelength, three-dimensional, nanometric structures with sensitivity to sub-nanometer details address an ubiquitous measurement challenge. A Fourier domain normalization approach is used in the Fourier optical imaging code to simulate the full three-dimensional scattered light field of nominally 15 nm sized structures, accurately replicating the light field as a function of the focus position. Using the full three-dimensional light field, nanometer scale details such as a 2 nm thin conformal oxide and nanometer topography are rigorously fitted for features less than 1/30(th) of the wavelength in size. The densely packed structures are positioned nearly an order of magnitude closer than the conventional Rayleigh resolution limit and can be measured with sub-nanometer parametric uncertainties. This approach enables a practical measurement sensitivity to size variations of only a few atoms in size using a high throughput optical configuration with broad application in measuring nanometric structures and nanoelectronic devices.

  11. Deep reactive ion etched anti-reflection coatings for sub-millimeter silicon optics.

    PubMed

    Gallardo, Patricio A; Koopman, Brian J; Cothard, Nicholas F; Bruno, Sarah Marie M; Cortes-Medellin, German; Marchetti, Galen; Miller, Kevin H; Mockler, Brenna; Niemack, Michael D; Stacey, Gordon; Wollack, Edward J

    2017-04-01

    Refractive optical elements are widely used in millimeter and sub-millimeter (sub-mm) astronomical telescopes. High-resistivity silicon is an excellent material for dielectric lenses given its low loss tangent, high thermal conductivity, and high index of refraction. The high index of refraction of silicon causes a large Fresnel reflectance at the vacuum-silicon interface (up to 30%), which can be reduced with an anti-reflection (AR) coating. In this work, we report techniques for efficiently AR coating silicon at sub-mm wavelengths using deep reactive ion etching (DRIE) and bonding the coated silicon to another silicon optic. Silicon wafers of 100 mm diameter (1 mm thick) were coated and bonded using the silicon direct bonding technique at high temperature (1100°C). No glue is used in this process. Optical tests using a Fourier transform spectrometer show sub-percent reflections for a single-layer DRIE AR coating designed for use at 320 μm on a single wafer. Cryogenic (10 K) measurements of a bonded pair of AR-coated wafers also reached sub-percent reflections. A prototype two-layer DRIE AR coating to reduce reflections and increase bandwidth is presented, and plans for extending this approach are discussed.

  12. Smart optical coherence tomography for ultra-deep imaging through highly scattering media

    PubMed Central

    Badon, Amaury; Li, Dayan; Lerosey, Geoffroy; Boccara, A. Claude; Fink, Mathias; Aubry, Alexandre

    2016-01-01

    Multiple scattering of waves in disordered media is a nightmare whether it is for detection or imaging purposes. So far, the best approach to get rid of multiple scattering is optical coherence tomography. This basically combines confocal microscopy and coherence time gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging-depth range remains limited to 1 mm at best in human soft tissues because of aberrations and multiple scattering. We propose a matrix approach of optical imaging to push back this fundamental limit. By combining a matrix discrimination of ballistic waves and iterative time reversal, we show, both theoretically and experimentally, an extension of the imaging-depth limit by at least a factor of 2 compared to optical coherence tomography. In particular, the reported experiment demonstrates imaging through a strongly scattering layer from which only 1 reflected photon out of 1000 billion is ballistic. This approach opens a new route toward ultra-deep tissue imaging. PMID:27847864

  13. Options for daytime monitoring of atmospheric visibility in optical communications

    NASA Technical Reports Server (NTRS)

    Erickson, D.; Cowles, K.

    1989-01-01

    Techniques for daytime detection of atmospheric transmission and cloud cover to determine the capabilities of future deep-space optical communications links are considered. A modification of the planned nighttime photometry program will provide the best data while minimizing the need for further equipment. Greater degrees of modification will provide increased detection capabilities. Future testing of the equipment will better define the improvement offered by each level of modification. Daytime photometry is favored at certain wavelengths because of higher transmission and lower background noise, thus giving an increased signal-to-noise ratio. A literature search has provided a list of stars brighter than second magnitude at these wavelengths.

  14. Deep-Ultraviolet Nonlinear Optics in a Borate Framework with 21-Ring Channels.

    PubMed

    Wei, Qi; Wang, Jia-Jia; He, Chao; Cheng, Jian-Wen; Yang, Guo-Yu

    2016-07-25

    A new borate LiBa3 (OH)[B9 O16 ][B(OH)4 ], which combines the uniform porosity of open-frameworks with the extraordinary NLO properties of borates, has been obtained under hydrothermal conditions by using mixed lithium and barium ions as templates. The framework displays an acs-type net with large 21-ring channels. The second harmonic generation (SHG) measurement shows that it is a type I phase-matchable material with a strong SHG signal intensity about 3.1 times that of KDP (KH2 PO4 ). UV/Vis-NIR diffuse reflectance analysis indicates that the compound has a wide transparency range with the short-wavelength absorption edge below 200 nm. These characteristics reveal that the compound is a promising deep-UV nonlinear optical material.

  15. Needle optical coherence elastography for the measurement of microscale mechanical contrast deep within human breast tissues

    NASA Astrophysics Data System (ADS)

    Kennedy, Kelsey M.; McLaughlin, Robert A.; Kennedy, Brendan F.; Tien, Alan; Latham, Bruce; Saunders, Christobel M.; Sampson, David D.

    2013-12-01

    Optical coherence elastography (OCE) is an emerging imaging technique that probes microscale mechanical contrast in tissues with the potential to differentiate healthy and malignant tissues. However, conventional OCE techniques are limited to imaging the first 1 to 2 mm of tissue in depth. We demonstrate, for the first time, OCE measurements deep within human tissues using needle OCE, extending the potential of OCE as a surgical guidance tool. We use needle OCE to detect tissue interfaces based on mechanical contrast in both normal and malignant breast tissues in freshly excised human mastectomy samples, as validated against histopathology. Further, we demonstrate the feasibility of in situ measurements >4 cm from the tissue surface using ultrasound guidance of the OCE needle probe. With further refinement, our method may potentially aid in accurate detection of the boundary of the tumor to help ensure full removal of all malignant tissues, which is critical to the success of breast-conserving surgery.

  16. Reflected Sunlight Reduction and Characterization for a Deep-Space Optical Receiver Antenna (DSORA)

    NASA Technical Reports Server (NTRS)

    Clymer, B. D.

    1990-01-01

    A baffle system for the elimination of first-order specular and diffuse reflection of sunlight from the sunshade of a deep-space optical receiver telescope is presented. This baffle system consists of rings of 0.5cm blades spaced 2.5 cm apart on the walls of GO hexagonal sunshade tubes that combine to form the telescope sunshade. The shadow cast by the blades, walls, and rims of the tubes prevent all first-order reflections of direct sunlight from reaching the primary mirror of the telescope. A reflection model of the sunshade without baffles is also presented for comparison. Since manufacturers of absorbing surfaces do not measure data near grazing incidence, the reflection properties at anticipated angles of incidence must be characterized. A description of reflection from matte surfaces in term of bidirectional reflection distribution function (BRDF) is presented along with a discussion of measuring BRDF near grazing incidence.

  17. The Ground-based Electro-Optical Deep Space Surveillance /GEODSS/ system

    NASA Astrophysics Data System (ADS)

    Jeas, W. C.; Anctil, R.

    1981-11-01

    After an account of the four-site Baker-Nunn telescope system that was its forerunner, the Ground-based Electro-Optical Deep Space Surveillance (GEODSS) system is described with attention to its function, capabilities, and such system elements as its telescopes and their mounts, TV camera, automatic moving target indicator (AMTI), and software. GEODSS is a passive tracking system operating within the constraints of night skies and atmospheric conditions, and consists of two 40-inch aperture wide-field telescopes equipped with sensitive, low light level television cameras and radiometers that are coupled to signal processors and computerized system management. Satellite signal detection is by means of the sunlight reflected by objects as dim as 16.0 m and site locations are in New Mexico, South Korea, Diego Garcia and the Eastern Atlantic, providing overlapping sky coverage. Detection, observation and object orbit element maintenance extends to altitudes of 40,000 km.

  18. RbMgCO₃F: A New Beryllium-Free Deep-Ultraviolet Nonlinear Optical Material.

    PubMed

    Tran, T Thao; He, Jiangang; Rondinelli, James M; Halasyamani, P Shiv

    2015-08-26

    A new deep-ultraviolet nonlinear optical material, RbMgCO3F, has been synthesized and characterized. The achiral nonpolar acentric material is second harmonic generation (SHG) active at both 1064 and 532 nm, with efficiencies of 160 × α-SiO2 and 0.6 × β-BaB2O4, respectively, and exhibits a short UV cutoff, below 190 nm. RbMgCO3F possesses a three-dimensional structure of corner-shared Mg(CO3)2F2 polyhedra. Unlike other acentric carbonate fluorides, in this example, the inclusion of Mg(2+) creates pentagonal channels where the Rb(+) resides. Our electronic structure calculations reveal that the denticity of the carbonate linkage, monodentate or bidendate, to the divalent cation is a useful parameter for tuning the transparency window and achieving the sizable SHG response.

  19. Fully reflective deep ultraviolet to near infrared spectrometer and entrance optics for resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Schulz, B.; Bäckström, J.; Budelmann, D.; Maeser, R.; Rübhausen, M.; Klein, M. V.; Schoeffel, E.; Mihill, A.; Yoon, S.

    2005-07-01

    We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO3, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4eV.

  20. Effects of aerosol optical properties on deep convective clouds and radiative forcing

    SciTech Connect

    Fan, Jiwen; Zhang, Renyi; Tao, Wei-Kuo; Mohr, Karen I

    2008-04-23

    The aerosol radiative effects (ARE) on the deep convective clouds are investigated by using a spectral-bin cloud-resolving model coupled with a radiation scheme and an explicit land surface model. The sensitivity of cloud properties and the associated radiative forcing to aerosol single-scattering albedo (SSA) are examined. The ARE on cloud properties is pronounced for mid-visible SSA of 0.85. Relative to the case without ARE, the cloud fraction and optical depth decrease by about 18% and 20%, respectively. Ice particle number concentrations, liquid water path, ice water path, and droplet size decrease by more than 15% when the ARE is introduced. The ARE causes a surface cooling of about 0.35 K and significantly high heating rates in the lower troposphere (about 0.6 K day-1 higher at 2 km), both of which lead to a more stable atmosphere and hence weaker convection. The weaker convection explains the less cloudiness, lower cloud optical depth, less LWP and IWP, smaller droplet size, and less precipitation resulting from the ARE. The daytime-mean direct forcing induced by black carbon is about 2.2 W m-2 at the top of atmosphere (TOA) and -17.4 W m-2 at the surface for SSA of 0.85. The semi-direct forcing is positive, about 10 and 11.2 W m-2 at the TOA and surface, respectively. Both the TOA and surface total radiative forcing values are strongly negative for the deep convective clouds, attributed mostly to aerosol indirect forcing. Aerosol direct and semi-direct effects are very sensitive to SSA when aerosol optical depth is high. Because the positive semi-direct forcing compensates the negative direct forcing at the surface, the surface temperature and heat fluxes decrease less significantly with the increase of aerosol absorption (decreasing SSA). The cloud fraction, optical depth, convective strength, and precipitation decrease with the increase of absorption, resulting from a more stable atmosphere due to enhanced

  1. V photometry of Titania, Oberon, and Triton

    SciTech Connect

    Goguen, J.D.; Hammel, H.B.; Brown, R.H.

    1989-02-01

    The phase angle and orbital brightness variations of Titania, Oberon, and Triton are presently obtained through analysis of V filter photometry obtained at Mauna Kea in 1982-1983. While Titania and Oberon exhibit magnitude variations with phase angle comparable to those of low-to-moderate albedo asteroids observed within several deg of opposition, Triton's phase variation is distinctly different from these and has a phase coefficient consistent with either a high-albedo regolith or an optically thick nonparticulate scattering layer (perhaps an atmosphere, or an ocean). A low-albedo regolith cannot on the strength of these data be ruled out, however. 39 references.

  2. V photometry of Titania, Oberon, and Triton

    NASA Technical Reports Server (NTRS)

    Goguen, J. D.; Hammel, H. B.; Brown, R. H.

    1989-01-01

    The phase angle and orbital brightness variations of Titania, Oberon, and Triton are presently obtained through analysis of V filter photometry obtained at Mauna Kea in 1982-1983. While Titania and Oberon exhibit magnitude variations with phase angle comparable to those of low-to-moderate albedo asteroids observed within several deg of opposition, Triton's phase variation is distinctly different from these and has a phase coefficient consistent with either a high-albedo regolith or an optically thick nonparticulate scattering layer (perhaps an atmosphere, or an ocean). A low-albedo regolith cannot on the strength of these data be ruled out, however.

  3. V photometry of Titania, Oberon, and Triton

    NASA Astrophysics Data System (ADS)

    Goguen, J. D.; Hammel, H. B.; Brown, R. H.

    1989-02-01

    The phase angle and orbital brightness variations of Titania, Oberon, and Triton are presently obtained through analysis of V filter photometry obtained at Mauna Kea in 1982-1983. While Titania and Oberon exhibit magnitude variations with phase angle comparable to those of low-to-moderate albedo asteroids observed within several deg of opposition, Triton's phase variation is distinctly different from these and has a phase coefficient consistent with either a high-albedo regolith or an optically thick nonparticulate scattering layer (perhaps an atmosphere, or an ocean). A low-albedo regolith cannot on the strength of these data be ruled out, however.

  4. The Chandra Deep Field South as a test case for Global Multi Conjugate Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Portaluri, E.; Viotto, V.; Ragazzoni, R.; Gullieuszik, M.; Bergomi, M.; Greggio, D.; Biondi, F.; Dima, M.; Magrin, D.; Farinato, J.

    2017-04-01

    The era of the next generation of giant telescopes requires not only the advent of new technologies but also the development of novel methods, in order to exploit fully the extraordinary potential they are built for. Global Multi Conjugate Adaptive Optics (GMCAO) pursues this approach, with the goal of achieving good performance over a field of view of a few arcmin and an increase in sky coverage. In this article, we show the gain offered by this technique to an astrophysical application, such as the photometric survey strategy applied to the Chandra Deep Field South as a case study. We simulated a close-to-real observation of a 500 × 500 arcsec2 extragalactic deep field with a 40-m class telescope that implements GMCAO. We analysed mock K-band images of 6000 high-redshift (up to z = 2.75) galaxies therein as if they were real to recover the initial input parameters. We attained 94.5 per cent completeness for source detection with SEXTRACTOR. We also measured the morphological parameters of all the sources with the two-dimensional fitting tools GALFIT. The agreement we found between recovered and intrinsic parameters demonstrates GMCAO as a reliable approach to assist extremely large telescope (ELT) observations of extragalactic interest.

  5. Increasing Tracking Bandwidth for Deep-Space Optical Communications Using Linear Accelerometers

    NASA Astrophysics Data System (ADS)

    Lee, S.; Ortiz, G. G.; Liu, W.; Garkanian, V.

    2003-11-01

    In deep-space optical communications, acquisition, tracking, and pointing are all challenging because of the stringent -- on the order of submicroradian -- pointing requirement. To achieve this level of pointing accuracy, one must maintain high-bandwidth tracking control. Feasible tracking sources (beacons) include uplink laser beams and celestial objects such as the Earth, Moon, and stars. However, these tracking sources do not all provide the kilohertz tracking rate needed for pointing in deep space. One approach to enable a high tracking rate is to augment the tracking loop with inertial sensors to estimate high-frequency beacon movements. In this article, we discuss the use of linear accelerometers, mounted in a configuration to measure angular displacement, to achieve high-bandwidth tracking with dim beacon sources. The advantages of linear accelerometers (or angular accelerometers) are their low cost, high bandwidth, and small size compared with other inertial sensors such as gyros. Simulation and experimental results show good agreement. A tracking bandwidth increase of 11 times is demonstrated.

  6. New i-line and deep-UV optical wafer stepper

    NASA Astrophysics Data System (ADS)

    Unger, Robert; Disessa, Peter A.

    1991-07-01

    A new line of optical wafer steppers is discussed. These tools, which have been developed in conjunction with Sematech and its member companies, feature new high-numerical aperture, widefield reduction lenses for operation at either i-line (365 nm) or deep-UV (248 nm) wavelengths. The i-line tool achieves practical resolution at the 0.50 micrometers level with usable working focal depth, while the deep-UV tool is capable of practical resolution at the 0.35 micrometers level with usable working focal depth. The design of these tools incorporates and expands upon optical wafer stepper technologies which have been field proven, particularly in the areas of alignment, focusing, INSITUTM metrology, automatic calibration, and diagnostic utilities. New features added to theses tools, to support their application at or below 0.50 micrometers , include a new system structure designed for inherent stability to maintain tight coupling among the imaging and alignment subsystems, and wafer stage advancements to achieve increased positioning accuracy, which supports obtaining overall tool overlay accuracy commensurate with sub-half-micron resolution. Of particular significance is the incorporation of a field-by-field leveling system, which optimizes the usable depth of focus over large image fields on product wafers. The tools also include an entirely new control system, which has been designed based on a new hierarchical control architecture, and incorporates digital servo controls and automated diagnostics. The control interface is designed as an intuitive graphic touch screen display, providing simplicity to the operator and significant job process flexibility, compatible with advanced memory and Application Specific Integrated Circuits (ASIC) fab operations. Design considerations for these tools are described together with performance results obtained in the field.

  7. k2photometry: Read, reduce and detrend K2 photometry

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Nowak, Grzegorz; Albrecht, Simon; Palle, Enric; Ribas, Ignasi; Bruntt, Hans; Perger, Manuel; Gandolfi, Davide; Hirano, Teriyuki; Sanchis-Ojeda, Roberto; Kiilerich, Amanda; Arranz, Jorge P.; Badenas, Mariona; Dai, Fei; Deeg, Hans J.; Guenther, Eike W.; Montanes-Rodriguez, Pilar; Narita, Norio; Rogers, Leslie A.; Bejar, Victor J. S.; Shrotriya, Tushar S.; Winn, Joshua N.; Sebastian, Daniel

    2016-02-01

    k2photometry reads, reduces and detrends K2 photometry and searches for transiting planets. MAST database pixel files are used as input; the output includes raw lightcurves, detrended lightcurves and a transit search can be performed as well. Stellar variability is not typically well-preserved but parameters can be tweaked to change that. The BLS algorithm used to detect periodic events is a Python implementation by Ruth Angus and Dan Foreman-Mackey (https://github.com/dfm/python-bls).

  8. UBV photometry of Cyg X-1 from 1996 to 2003

    NASA Astrophysics Data System (ADS)

    Voloshina, I. B.; Lyuty, V.

    2004-07-01

    The preliminary results of analysis of $UBV$-photometry of the black hole candidate Cyg X-1 in primary minimum are presented. These observations were carried out with the main goal of studying in detail the variability that was detected by Lyuty in 1985 in the optical light curve of this system near orbital phase 0.00.

  9. Optimising deep anterior lamellar keratoplasty (DALK) using intraoperative online optical coherence tomography (iOCT).

    PubMed

    Steven, Philipp; Le Blanc, Carolin; Lankenau, Eva; Krug, Marc; Oelckers, Stefan; Heindl, Ludwig M; Gehlsen, Uta; Huettmann, Gereon; Cursiefen, Claus

    2014-07-01

    To describe the use of intraoperative online optical coherence tomography (iOCT) for improving deep anterior lamellar keratoplasty (DALK) surgery. Retrospective case series of 6 eyes of 6 male patients with keratokonus, corneal dystrophy or herpetic stromal scars undergoing DALK were investigated using intraoperative optical coherence tomography and postsurgical image/video analysis. Main outcome measures were: visibility of surgical steps, especially, assessment of placement depth of injection needle, preparation of bare Descemet's membrane and drainage of interface fluid. iOCT enables real-time visualisation of all surgical steps of DALK procedure in all patients. Placement of air injection needle above Descemet's membrane was reliably monitored as was presence of bare Descemet's membrane and potential interface fluid. iOCT assists with visualisation of injection needle placement and with assessment of bare Descemet's membrane as well as interface fluid during the DALK procedure. Overall iOCT may be a helpful device that supports surgeons in all steps of DALK procedure.

  10. Optimising deep anterior lamellar keratoplasty (DALK) using intraoperative online optical coherence tomography (iOCT)

    PubMed Central

    Steven, Philipp; Le Blanc, Carolin; Lankenau, Eva; Krug, Marc; Oelckers, Stefan; Heindl, Ludwig M; Gehlsen, Uta; Huettmann, Gereon; Cursiefen, Claus

    2014-01-01

    Background/aims To describe the use of intraoperative online optical coherence tomography (iOCT) for improving deep anterior lamellar keratoplasty (DALK) surgery. Methods Retrospective case series of 6 eyes of 6 male patients with keratokonus, corneal dystrophy or herpetic stromal scars undergoing DALK were investigated using intraoperative optical coherence tomography and postsurgical image/video analysis. Main outcome measures were: visibility of surgical steps, especially, assessment of placement depth of injection needle, preparation of bare Descemet's membrane and drainage of interface fluid. Results iOCT enables real-time visualisation of all surgical steps of DALK procedure in all patients. Placement of air injection needle above Descemet's membrane was reliably monitored as was presence of bare Descemet's membrane and potential interface fluid. Conclusions iOCT assists with visualisation of injection needle placement and with assessment of bare Descemet's membrane as well as interface fluid during the DALK procedure. Overall iOCT may be a helpful device that supports surgeons in all steps of DALK procedure. PMID:24590554

  11. A three-photon microscope with adaptive optics for deep-tissue in vivo structural and functional brain imaging

    NASA Astrophysics Data System (ADS)

    Tao, Xiaodong; Lu, Ju; Lam, Tuwin; Rodriguez, Ramiro; Zuo, Yi; Kubby, Joel

    2017-02-01

    We developed a three-photon adaptive optics add-on to a commercial two-photon laser scanning microscope. We demonstrated its capability for structural and functional imaging of neurons labeled with genetically encoded red fluorescent proteins or calcium indicators deep in the living mouse brain with cellular and subcellular resolution.

  12. Atmospheric aerosol optical parameters, deep convective clouds and hail occurence - a correlation study

    NASA Astrophysics Data System (ADS)

    Talianu, Camelia; Andrei, Simona; Toanca, Florica; Stefan, Sabina

    2016-04-01

    Among the severe weather phenomena, whose frequency has increased during the past two decades, hail represents a major threat not only for agriculture but also for other economical fields. Generally, hail are produced in deep convective clouds, developed in an unstable environment. Recent studies have emphasized that besides the state of the atmosphere, the atmospheric composition is also very important. The presence of fine aerosols in atmosphere could have a high impact on nucleation processes, initiating the occurrence of cloud droplets, ice crystals and possibly the occurrence of graupel and/or hail. The presence of aerosols in the atmosphere, correlated with specific atmospheric conditions, could be predictors of the occurrence of hail events. The atmospheric investigation using multiwavelength Lidar systems can offer relevant information regarding the presence of aerosols, identified using their optical properties, and can distinguish between spherical and non-spherical shape, and liquid and solid phase of these aerosols. The aim of this study is to analyse the correlations between the presence and the properties of aerosols in atmosphere, and the production of hail events in a convective environment, using extensive and intensive optical parameters computed from lidar and ceilometer aerosols measurements. From these correlations, we try to evaluate if these aerosols can be taken into consideration as predictors for hail formation. The study has been carried out in Magurele - Romania (44.35N, 26.03E, 93m ASL) using two collocated remote sensing systems: a Raman Lidar (RALI) placed at the Romanian Atmospheric 3D Observatory and a ceilometer CL31 placed at the nearby Faculty of Physics, University of Bucharest. To evaluate the atmospheric conditions, radio sounding and satellite images were used. The period analysed was May 1st - July 15th, 2015, as the May - July period is climatologically favorable for deep convection events. Two hail events have been

  13. Photometry from space

    NASA Technical Reports Server (NTRS)

    Nelson, M. J.; Bless, R. C.; Percival, J. W.; White, R. L.

    1992-01-01

    A brief description of the High Speed Photometer (HSP) of the Hubble Space Telescope is given, in particular the HSP light path, detectors, entrance apertures, and filters. The status of HSP testing to date is reported, and problems encountered with the bright earth and the telescope pointing system are described. The calibration effort for the HSP is well under way. Results of internal (instrument coordinate) aperture locations good to 0.05 arcsec and external (telescope coordinate) locations good to 0.02 arcsec are shown. The effects of spacecraft pointing and jitter on HSP photometry are detailed, and a preliminary measurement of spacecraft jitter with HSP is shown. The aperture calibration effort is verified by accurate pointing of a star to different HSP 1.0 arcsec entrance apertures, and photometric performance of the instrument is shown to be accurate to the 2 percent photon noise of the observations. Future science verification and guaranteed observing time programs are listed. Suggestions are made for future space-based photometers.

  14. 40-Gbps optical backbone network deep packet inspection based on FPGA

    NASA Astrophysics Data System (ADS)

    Zuo, Yuan; Huang, Zhiping; Su, Shaojing

    2014-11-01

    In the era of information, the big data, which contains huge information, brings about some problems, such as high speed transmission, storage and real-time analysis and process. As the important media for data transmission, the Internet is the significant part for big data processing research. With the large-scale usage of the Internet, the data streaming of network is increasing rapidly. The speed level in the main fiber optic communication of the present has reached 40Gbps, even 100Gbps, therefore data on the optical backbone network shows some features of massive data. Generally, data services are provided via IP packets on the optical backbone network, which is constituted with SDH (Synchronous Digital Hierarchy). Hence this method that IP packets are directly mapped into SDH payload is named POS (Packet over SDH) technology. Aiming at the problems of real time process of high speed massive data, this paper designs a process system platform based on ATCA for 40Gbps POS signal data stream recognition and packet content capture, which employs the FPGA as the CPU. This platform offers pre-processing of clustering algorithms, service traffic identification and data mining for the following big data storage and analysis with high efficiency. Also, the operational procedure is proposed in this paper. Four channels of 10Gbps POS signal decomposed by the analysis module, which chooses FPGA as the kernel, are inputted to the flow classification module and the pattern matching component based on TCAM. Based on the properties of the length of payload and net flows, buffer management is added to the platform to keep the key flow information. According to data stream analysis, DPI (deep packet inspection) and flow balance distribute, the signal is transmitted to the backend machine through the giga Ethernet ports on back board. Practice shows that the proposed platform is superior to the traditional applications based on ASIC and NP.

  15. Deep Optical Observations of Unusual Neutron Star Calvera with the GTC

    NASA Astrophysics Data System (ADS)

    Shibanov, Yury; Danilenko, Andrey; Zharikov, Sergey; Shternin, Peter; Zyuzin, Dima

    2016-11-01

    Calvera is an unusual, isolated neutron star with a pure thermal X-ray spectrum typical of central compact objects in supernova remnants. On the other hand, its rotation period and spin-down rate are typical of ordinary rotation-powered pulsars. It was discovered and studied through X-rays, and has not yet been detected in other spectral domains. We present deep optical imaging of the Calvera field, obtained with the Gran Telescopio Canarias, in the g\\prime and i\\prime bands. Within the vicinity of ≈ 1\\prime\\prime of Calvera, we detected two point-like objects that were invisible at previous shallow observations. However, accurate astrometry showed that neither of them can be identified with the pulsar. We put new upper limits of g\\prime \\gt 27.87 and i\\prime \\gt 26.84 on its optical brightness. We also reanalyzed all available archival X-ray data on Calvera. Comparison of the Calvera thermal emission parameters and upper limits on optical and non-thermal X-ray emission with respective data on rotation-powered pulsars shows that Calvera might belong to the class of ordinary middle-aged pulsars, if we assume that its distance is in the range of 1.5-5 kpc. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, on the island of La Palma, program GTC1-14AMEX.

  16. The Subaru/XMM-Newton Deep Survey (SXDS). V. Optically Faint Variable Object Survey

    NASA Astrophysics Data System (ADS)

    Morokuma, Tomoki; Doi, Mamoru; Yasuda, Naoki; Akiyama, Masayuki; Sekiguchi, Kazuhiro; Furusawa, Hisanori; Ueda, Yoshihiro; Totani, Tomonori; Oda, Takeshi; Nagao, Tohru; Kashikawa, Nobunari; Murayama, Takashi; Ouchi, Masami; Watson, Mike G.; Richmond, Michael W.; Lidman, Christopher; Perlmutter, Saul; Spadafora, Anthony L.; Aldering, Greg; Wang, Lifan; Hook, Isobel M.; Knop, Rob A.

    2008-03-01

    We present our survey for optically faint variable objects using multiepoch (8-10 epochs over 2-4 years) i'-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg2 in the Subaru/XMM-Newton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10 m class telescopes or the Hubble Space Telescope. The detection limit for variable components is i'vari ~ 25.5 mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGNs), based on the optical morphologies, magnitudes, colors, and optical-mid-infrared colors of the host objects, spatial offsets of variable components from the host objects, and light curves. Detection completeness was examined by simulating light curves for periodic and irregular variability. We detected optical variability for 36% +/- 2% (51% +/- 3% for a bright sample with i' < 24.4 mag) of X-ray sources in the field. Number densities of variable objects as functions of time intervals Δ t and variable component magnitudes i'vari are obtained. Number densities of variable stars, SNe, and AGNs are 120, 489, and 579 objects deg-2, respectively. Bimodal distributions of variable stars in the color-magnitude diagrams indicate that the variable star sample consists of bright (V ~ 22 mag) blue variable stars of the halo population and faint (V ~ 23.5 mag) red variable stars of the disk population. There are a few candidates of RR Lyrae providing a possible number density of ~10-2 kpc-3 at a distance of >150 kpc from the Galactic center. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations (program GN-2002B-Q-30) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a

  17. Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5

    SciTech Connect

    Pallanca, C.; Ferraro, F. R.; Dalessandro, E.; Lanzoni, B.; Hessels, J. W. T.; Stairs, I.; Freire, P. C. C.

    2014-11-01

    We report on the determination of astrometric, spin, and orbital parameters for PSR J1518+0204C, a 'black widow' binary millisecond pulsar in the globular cluster (GC) M5. The accurate position and orbital parameters obtained from radio timing allowed us to search for the optical companion. By using WFC3/Hubble Space Telescope images, we identified a very faint variable star (m{sub F390W} ≳ 24.8, m{sub F606W} ≳ 24.3, m{sub F814W} ≳ 23.1) located at only 0.''25 from the pulsar's timing position. Due to its strong variability, this star is visible only in a subsample of images. However, the light curve obtained folding the available data with the orbital parameters of the pulsar shows a maximum at the pulsar inferior conjunction and a possible minimum at the pulsar superior conjunction. Furthermore, the shape of the optical modulation indicates a heating process possibly due to the pulsar wind. This is the first identification of an optical companion to a black widow pulsar in the dense stellar environment of a GC.

  18. How the extinction of extragalactic background light affects surface photometry of galaxies, groups and clusters

    NASA Astrophysics Data System (ADS)

    Zackrisson, E.; Micheva, G.; Östlin, G.

    2009-08-01

    The faint regions of galaxies, groups and clusters hold important clues about how these objects formed, and surface photometry at optical and near-infrared wavelengths represents a powerful tool for studying such structures. Here, we identify a hitherto unrecognized problem with this technique, related to how the night sky flux is typically measured and subtracted from astronomical images. While most of the sky flux comes from regions between the observer and the target object, a small fraction - the extragalactic background light (EBL) - comes from behind. We argue that since this part of the sky flux can be subjected to extinction by dust present in the galaxy/group/cluster studied, standard reduction procedures may lead to a systematic oversubtraction of the EBL. Even very small amounts of extinction can lead to spurious features in radial surface brightness profiles and colour maps of extended objects. We assess the likely impact of this effect on a number of topics in extragalactic astronomy where very deep surface photometry is currently attempted, including studies of stellar haloes, starburst host galaxies, disc truncations and diffuse intragroup/intracluster light. We argue that EBL extinction may provide at least a partial explanation for the anomalously red colours reported for the haloes of disc galaxies and for the hosts of local starburst galaxies. EBL extinction effects also mimic truncations in discs with unusually high dust opacities, but are unlikely to be the cause of such features in general. Failure to account for EBL extinction can also give rise to a non-negligible underestimate of intragroup and intracluster light at the faintest surface brightness levels currently probed. Finally, we discuss how EBL extinction effects may be exploited to provide an independent constraint on the surface brightness of the EBL, using a combination of surface photometry and direct star counts.

  19. Photometry Of The Semi-regular Variable Tx Tau

    NASA Astrophysics Data System (ADS)

    Wyman, Katherine; Spear, G.; McLin, K.; Cominsky, L.; Mankiewicz, L.; Reichart, D.; Ivarsen, K.

    2009-12-01

    We report V-band and I-band photometry for the SRA type variable TX Tau. Photometry was obtained using the robotic telescope GORT at the Hume Observatory (NASA funded through Sonoma State University) and the PROMPT robotic telescopes at Cerro Tololo Inter-American Observatory (NSF and NASA funded through the University of North Carolina). Photometry was also obtained using the PI of the Sky optical transient search system at Las Campanas Observatory developed by a consortium of institutions in Poland. Modern periods are determined, the V-band and I-band light curves are compared, and V-I colors are derived. It is possible that the classification for this variable should be reconsidered.

  20. Division B Commission 25: Astronomical Photometry and Polarimetry

    NASA Astrophysics Data System (ADS)

    Walker, Alistair; Adelman, Saul; Milone, Eugene; Anthony-Twarog, Barbara; Bastien, Pierre; Chen, Wen Ping; Howell, Steve; Knude, Jens; Kurtz, Donald; Magalhães, Antonio Mario; Menzies, John; Smith, Allyn; Volk, Kevin

    2016-04-01

    Commission 25 (C25) deals with the techniques and issues involved with the measurement of optical and infrared radiation intensities and polarization from astronomical sources. As such, in recent years attention has focused on photometric standard stars, atmospheric extinction, photometric passbands, transformation between systems, nomenclature, and observing and reduction techniques. At the start of the trimester C25 changed its name from Stellar Photometry and Polarization to Astronomical Photometry and Polarization so as to explicitly include in its mandate particular issues arising from the measurement of resolved sources, given the importance of photometric redshifts of distant galaxies for many of the large photometric surveys now underway. We begin by summarizing commission activities over the 2012-2014 period, follow with a report on Polarimetry, continue with Photometry topics that have been of interest to C25 members, and conclude with a Vision for the Future.

  1. Correlations between optical/near-infrared and UV extinction parameters and the prediction of UV extinction from ground-based photometry

    NASA Technical Reports Server (NTRS)

    Cardelli, Jason A.; Clayton, Goeffrey C.; Mathis, John S.

    1988-01-01

    An analysis of the variability of absolute UV extinction, A lambda derived through the ratio total-to-selective extinction, R Av/E(B-V), for 31 lines of sight for which UV extinction parameters were derived, is presented. For these data, which sample a wide range of environments and which are characterized by R = 2.5 to 6.0, differences in the shapes of UV extinction curves are largely due to variations in optical/near-UV extinction through changes in R. From this, it is found that UV extinction curves can be reproduced with reasonable accuracy by simply knowing R. Detection of an A2175/E(B-V) = 10 + or - 1 mag implies that the total extinction at 2175 A can be estimated from E(B-V) alone.

  2. Probability of the Physical Association of 104 Blended Companions to Kepler Objects of Interest Using Visible and Near-infrared Adaptive Optics Photometry

    NASA Astrophysics Data System (ADS)

    Atkinson, Dani; Baranec, Christoph; Ziegler, Carl; Law, Nicholas; Riddle, Reed; Morton, Tim

    2017-01-01

    We determine probabilities of physical association for stars in blended Kepler Objects of Interest (KOIs), and find that 14.5{ % }-3.4 % +3.8 % of companions within ∼4″ are consistent with being physically unassociated with their primary. This produces a better understanding of potential false positives in the Kepler catalog and will guide models of planet formation in binary systems. Physical association is determined through two methods of calculating multi-band photometric parallax using visible and near-infrared adaptive optics observations of 84 KOI systems with 104 contaminating companions within ∼4″. We find no evidence that KOI companions with separations of less than 1″ are more likely to be physically associated than KOI companions generally. We also reinterpret transit depths for 94 planet candidates, and calculate that 2.6% ± 0.4% of transits have R> 15{R}\\oplus , which is consistent with prior modeling work.

  3. Correlations between optical/near-infrared and UV extinction parameters and the prediction of UV extinction from ground-based photometry

    NASA Technical Reports Server (NTRS)

    Cardelli, Jason A.; Clayton, Goeffrey C.; Mathis, John S.

    1988-01-01

    An analysis of the variability of absolute UV extinction, A lambda derived through the ratio total-to-selective extinction, R Av/E(B-V), for 31 lines of sight for which UV extinction parameters were derived, is presented. For these data, which sample a wide range of environments and which are characterized by R = 2.5 to 6.0, differences in the shapes of UV extinction curves are largely due to variations in optical/near-UV extinction through changes in R. From this, it is found that UV extinction curves can be reproduced with reasonable accuracy by simply knowing R. Detection of an A2175/E(B-V) = 10 + or - 1 mag implies that the total extinction at 2175 A can be estimated from E(B-V) alone.

  4. Deep optical survey of the stellar content of Sh2-311 region

    NASA Astrophysics Data System (ADS)

    Yadav, Ram Kesh; Pandey, A. K.; Sharma, Saurabh; Jose, J.; Ogura, K.; Kobayashi, N.; Samal, M. R.; Eswaraiah, C.; Chandola, H. C.

    2015-01-01

    The stellar content in and around Sh2-311 region have been studied using the deep optical observations as well as near-infrared (NIR) data from 2MASS. The region contains three clusters, viz. NGC 2467, Haffner 18 and Haffner 19. We have made an attempt to distinguish the stellar content of these individual regions as well as to re-determine their fundamental parameters such as distance, reddening, age, onto the basis of a new and more extended optical and infrared photometric data set. NGC 2467 and Haffner 19 are found to be located in the Perseus arm at the distances of 5.0 ± 0.4 kpc and 5.7 ± 0.4 kpc, respectively, whereas Haffner 18 is located at the distance of 11.2 ± 1.0 kpc. The clusters NGC 2467 and Haffner 19 might have formed from the same molecular cloud, whereas the cluster Haffner 18 is located in the outer galactic arm, i.e. the Norma-Cygnus arm. We identify 8 class II young stellar objects (YSOs) using the NIR (J-H)/(H-K) two colour diagram. We have estimated the age and mass of the YSOs identified in the present work and those by Snider et al. (2009) using the V/(V-I) colour-magnitude diagram. The estimated ages and mass range of the majority of the YSOs are ≲1 Myr and ∼0.4-3.5 M⊙, respectively, indicating that these sources could be T-Tauri stars or their siblings. Spatial distribution of the YSOs shows that some of the YSOs are distributed around the HII region Sh2-311, suggesting a triggered star formation at its periphery.

  5. Visible to deep ultraviolet range optical absorption of electron irradiated borosilicate glass

    NASA Astrophysics Data System (ADS)

    Wang, Tie-Shan; Duan, Bing-Huang; Tian, Feng; Peng, Hai-Bo; Chen, Liang; Zhang, Li-Min; Yuan, Wei

    2015-07-01

    To study the room-temperature stable defects induced by electron irradiation, commercial borosilicate glasses were irradiated by 1.2 MeV electrons and then ultraviolet (UV) optical absorption (OA) spectra were measured. Two characteristic bands were revealed before irradiation, and they were attributed to silicon dangling bond (E’-center) and Fe3+ species, respectively. The existence of Fe3+ was confirmed by electron paramagnetic resonance (EPR) measurements. After irradiation, the absorption spectra revealed irradiation-induced changes, while the content of E’-center did not change in the deep ultraviolet (DUV) region. The slightly reduced OA spectra at 4.9 eV was supposed to transform Fe3+ species to Fe2+ species and this transformation leads to the appearance of 4.3 eV OA band. By calculating intensity variation, the transformation of Fe was estimated to be about 5% and the optical absorption cross section of Fe2+ species is calculated to be 2.2 times larger than that of Fe3+ species. Peroxy linkage (POL, ≡Si-O-O-Si≡), which results in a 3.7 eV OA band, is speculated not to be from Si-O bond break but from Si-O-B bond, Si-O-Al bond, or Si-O-Na bond break. The co-presence defect with POL is probably responsible for 2.9-eV OA band. Project supported by the Fundamental Research Funds for the Central Universities of China (Grant No. lzujbky-2014-16).

  6. Interpreting Flux from Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.; Breeveld, Alice; Roming, Peter W. A.; Siegel, Michael

    2016-10-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.

  7. Five years of photometry of Sigma Geminorum

    NASA Technical Reports Server (NTRS)

    Fried, R. E.; Vaucher, C. A.; Hopkins, J. L.; Sabia, J. D.; Krisciunas, K.; Chambliss, C. R.; Landis, H. J.; Eaton, J. A.; Hall, D. S.; Henry, G. W.

    1983-01-01

    Thirteen observatories have collaborated in obtaining five years of photoelectric photometry for the bright, K1 III RS CVn binary Sigma Geminorum. Except for one year, the light curve has exhibited two minima which are separated by approximately half a cycle. At the 1977.2 epoch of discovery one minimum was shallower, but as of 1982.2 they have become comparable in depth. During the 1979-80 season, the light curve changed shape rapidly, with the shallower minimum becoming as deep as the other within a period of no more than 80 days. The overall brightness range during the five years in V has been 4.13-4.29 mag, and it is found that the times of both minima can be fit with a photometric period of 19.423 days.

  8. Optimizations of a Hardware Decoder for Deep-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Cheng, Michael K.; Nakashima, Michael A.; Moision, Bruce E.; Hamkins, Jon

    2007-01-01

    The National Aeronautics and Space Administration has developed a capacity approaching modulation and coding scheme that comprises a serial concatenation of an inner accumulate pulse-position modulation (PPM) and an outer convolutional code [or serially concatenated PPM (SCPPM)] for deep-space optical communications. Decoding of this code uses the turbo principle. However, due to the nonbinary property of SCPPM, a straightforward application of classical turbo decoding is very inefficient. Here, we present various optimizations applicable in hardware implementation of the SCPPM decoder. More specifically, we feature a Super Gamma computation to efficiently handle parallel trellis edges, a pipeline-friendly 'maxstar top-2' circuit that reduces the max-only approximation penalty, a low-latency cyclic redundancy check circuit for window-based decoders, and a high-speed algorithmic polynomial interleaver that leads to memory savings. Using the featured optimizations, we implement a 6.72 megabits-per-second (Mbps) SCPPM decoder on a single field-programmable gate array (FPGA). Compared to the current data rate of 256 kilobits per second from Mars, the SCPPM coded scheme represents a throughput increase of more than twenty-six fold. Extension to a 50-Mbps decoder on a board with multiple FPGAs follows naturally. We show through hardware simulations that the SCPPM coded system can operate within 1 dB of the Shannon capacity at nominal operating conditions.

  9. Deep learning as a tool to distinguish between high orbital angular momentum optical modes

    NASA Astrophysics Data System (ADS)

    Knutson, E. M.; Lohani, Sanjaya; Danaci, Onur; Huver, Sean D.; Glasser, Ryan T.

    2016-09-01

    The generation of light containing large degrees of orbital angular momentum (OAM) has recently been demon- strated in both the classical and quantum regimes. Since there is no fundamental limit to how many quanta of OAM a single photon can carry, optical states with an arbitrarily high difference in this quantum number may, in principle, be entangled. This opens the door to investigations into high-dimensional entanglement shared between states in superpositions of nonzero OAM. Additionally, making use of non-zero OAM states can allow for a dramatic increase in the amount of information carried by a single photon, thus increasing the information capacity of a communication channel. In practice, however, it is difficult to differentiate between states with high OAM numbers with high precision. Here we investigate the ability of deep neural networks to differentiate between states that contain large values of OAM. We show that such networks may be used to differentiate be- tween nearby OAM states that contain realistic amounts of noise, with OAM values of up to 100. Additionally, we examine how the classification accuracy scales with the signal-to-noise ratio of images that are used to train the network, as well as those being tested. Finally, we demonstrate the simultaneous classification of < 100 OAM states with greater than 70 % accuracy. We intend to verify our system with experimentally-produced classi- cal OAM states, as well as investigate possibilities that would allow this technique to work in the few-photon quantum regime.

  10. Investigating the Merger Origin of Early-type Galaxies using Ultra-deep Optical Images

    NASA Astrophysics Data System (ADS)

    Duc, P.-A.; Cuillandre, J.-C.; Alatalo, K.; Blitz, L.; Bois, M.; Bournaud, F.; Bureau, M.; Cappellari, M.; Côté, P.; Davies, R. L.; Davis, T. A.; de Zeeuw, P. T.; Emsellem, E.; Ferrarese, L.; Ferriere, E.; Gwyn, S.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; Lablanche, P.-Y.; MacArthur, L.; McDermid, R. M.; Michel-Dansac, L.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.; Young, L. M.

    2011-12-01

    The mass assembly of galaxies leaves various imprints on their surroundings, such as shells, streams and tidal tails. The frequency and properties of these fine structures depend on the mechanism driving the mass assembly: e.g. a monolithic collapse, rapid cold-gas accretion followed by violent disk instabilities, minor mergers or major dry/wet mergers. Therefore, by studying the outskirts of galaxies, one can learn about their main formation mechanism. I present here our on-going work to characterize the outskirts of Early-Type Galaxies (ETGs), which are powerful probes at low redshift of the hierarchical mass assembly of galaxies. This work relies on ultra-deep optical images obtained at CFHT with the wide-field of view MegaCam camera of field and cluster ETGs obtained as part of the ATLAS3D and NGVS projects. State of the art numerical simulations are used to interpret the data. The images reveal a wealth of unknown faint structures at levels as faint as 29 mag arcsec-2 in the g-band. Initial results for two galaxies are presented here.

  11. Fluorooxoborates: Beryllium-Free Deep-Ultraviolet Nonlinear Optical Materials without Layered Growth.

    PubMed

    Zhang, Bingbing; Shi, Guoqiang; Yang, Zhihua; Zhang, Fangfang; Pan, Shilie

    2017-03-27

    Deep-ultraviolet nonlinear optical (DUV NLO) crystals are the key materials to extend the output range of solid-state lasers to below 200 nm. The only practical material KBe2 BO3 F2 suffers high toxicity through beryllium and strong layered growth. Herein, we propose a beryllium-free material design and synthesis strategy for DUV NLO materials. Introducing the (BO3 F)(4-) , (BO2 F2 )(3-) , and (BOF3 )(2-) groups in borates could break through the fixed 3D B-O network that would produce a larger birefringence without layering and simultaneously keep a short cutoff edge down to DUV. The theoretical and experimental studies on a series of fluorooxoborates confirm this strategy. Li2 B6 O9 F2 is identified as a DUV NLO material with a large second harmonic generation efficiency (0.9×KDP) and a large predicted birefringence (0.07) without layering. This study provides a feasible way to break down the DUV wall for NLO materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  13. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  14. An Application of Multi-band Forced Photometry to One Square Degree of SERVS: Accurate Photometric Redshifts and Implications for Future Science

    NASA Astrophysics Data System (ADS)

    Nyland, Kristina; Lacy, Mark; Sajina, Anna; Pforr, Janine; Farrah, Duncan; Wilson, Gillian; Surace, Jason; Häußler, Boris; Vaccari, Mattia; Jarvis, Matt

    2017-05-01

    We apply The Tractor image modeling code to improve upon existing multi-band photometry for the Spitzer Extragalactic Representative Volume Survey (SERVS). SERVS consists of post-cryogenic Spitzer observations at 3.6 and 4.5 μm over five well-studied deep fields spanning 18 deg2. In concert with data from ground-based near-infrared (NIR) and optical surveys, SERVS aims to provide a census of the properties of massive galaxies out to z ≈ 5. To accomplish this, we are using The Tractor to perform “forced photometry.” This technique employs prior measurements of source positions and surface brightness profiles from a high-resolution fiducial band from the VISTA Deep Extragalactic Observations survey to model and fit the fluxes at lower-resolution bands. We discuss our implementation of The Tractor over a square-degree test region within the XMM Large Scale Structure field with deep imaging in 12 NIR/optical bands. Our new multi-band source catalogs offer a number of advantages over traditional position-matched catalogs, including (1) consistent source cross-identification between bands, (2) de-blending of sources that are clearly resolved in the fiducial band but blended in the lower resolution SERVS data, (3) a higher source detection fraction in each band, (4) a larger number of candidate galaxies in the redshift range 5 < z < 6, and (5) a statistically significant improvement in the photometric redshift accuracy as evidenced by the significant decrease in the fraction of outliers compared to spectroscopic redshifts. Thus, forced photometry using The Tractor offers a means of improving the accuracy of multi-band extragalactic surveys designed for galaxy evolution studies. We will extend our application of this technique to the full SERVS footprint in the future.

  15. Water Optical Properties and Water Color Remote Sensing in Optically Deep and Shallow Waters of Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Xi, Hongyan

    In this study, Lake Taihu in Jiangsu Province of China, a typical large freshwater lake, is selected as the study area. Based on the field spectral measurements and laboratory analyses performed in October 2008, water optical properties and water color/quality remote sensing retrieval models in Lake Taihu were investigated. It was recognized that water quality varied a lot in different areas. Waters in Lake Taihu were classified as optically deep waters (ODWs) and optically shallow waters (OSWs). ODWs are the waters where the water depth is more than three times the measured Secchi Disk Depth (SDD), otherwise they are OSWs. Cyanobacteria blooms happen frequently in ODWs and the water is eutrophicated heavily. Whereas water is very clear with rare cyanobacteria blooms but many aquatic plants in OSWs. Focused on the two types of water areas respectively, the inherent optical properties (lOPs), apparent optical properties (lOPs) and reflectance spectra were analyzed, as well as their relationships to water quality parameters. Local optical parameters f and Q, which play significant roles in water quality parameters retrieval models, were also determined. Measured remote sensing reflectance data were used to establish two-band and three-band models for chlorophyll-a (Chl-a) concentration estimation, results showed both models were suitable in ODWs. However, aquatic plants in OSWs had great influence on spectra, resulting in the inapplicability of the established models at these sites. Absorption and backscattering coefficients were used to remove those influences and simulate new set of remote sensing reflectance based on radiative transfer theory, which were proved reliable to establish Chl-a retrieval algorithms. Three-band model established by simulated spectra showed more satisfactory performance in whole ODWs, and performance of two-band model in OSWs was also enhanced much. Several models were established to estimate total suspended solids (TSS) concentrations

  16. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    NASA Technical Reports Server (NTRS)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  17. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    NASA Technical Reports Server (NTRS)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  18. VizieR Online Data Catalog: Photometry and redshifts of galaxies in the UDF (Rafelski+, 2015)

    NASA Astrophysics Data System (ADS)

    Rafelski, M.; Teplitz, H. I.; Gardner, J. P.; Coe, D.; Bond, N. A.; Koekemoer, A. M.; Grogin, N.; Kurczynski, P.; McGrath, E. J.; Bourque, M.; Atek, H.; Brown, T. M.; Colbert, J. W.; Codoreanu, A.; Ferguson, H. C.; Finkelstein, S. L.; Gawiser, E.; Giavalisco, M.; Gronwall, C.; Hanish, D. J.; Lee, K.-S.; Mehta, V.; de Mello, D. F.; Ravindranath, S.; Ryan, R. E.; Scarlata, C.; Siana, B.; Soto, E.; Voyer, E. N.

    2016-02-01

    We present photometry and derived redshifts from up to eleven bandpasses for 9927 galaxies in the Hubble Ultra Deep field (UDF), covering an observed wavelength range from the near-ultraviolet (NUV) to the near-infrared (NIR) with Hubble Space Telescope (HST) observations. The NUV coverage of the UDF (UVUDF) is comprised of three WFC3-UVIS filters: F225W, F275W, and F336W. The UVUDF observations were obtained in 2012. The optical data are covered by the four original Advanced Camera for Surveys (ACS) optical filters: F435W, F606W, F775W, and F850LP. The deep NIR coverage includes four WFC3-IR filters: F105W, F125W, F140W, and F160W obtained in the UDF09 and UDF12 programs (Oesch et al. 2010ApJ...709L..21O, 2010ApJ...709L..16O; Bouwens et al. 2011ApJ...737...90B; Ellis et al. 2013ApJ...763L...7E; Koekemoer et al. 2013ApJS..209....3K). The entire field is also covered by three of the four WFC3-IR filters (F105W, F125W, and F160W) in the CANDELS GOODS-S observations (Grogin et al. 2011ApJS..197...35G; Koekemoer et al. 2011ApJS..197...36K). (2 data files).

  19. Strong [Fe X] Emission and Deep Optical Eclipses of the Classical Nova V5593 Sgr 2012 No. 5

    NASA Astrophysics Data System (ADS)

    Starrfield, Sumner; Wagner, R. Mark; Walter, Frederick M.; Woodward, Charles E.; Schwarz, Greg; Krautter, Joachim

    2016-01-01

    V5593 Sgr was discovered by T. Kojima on 2012 July 16.512 UT at a magnitude of ~12.6. A low-resolution spectrum obtained by M. Fujii on 2012 July 18.572 UT confirmed that the object was indeed a Classical Nova. The AAVSO V-band light curve showed that the nova peaked near 11th mag on July 23-24 UT and subsequently declined in brightness with a t_2 of about 27 days making it a moderately fast nova. We obtained optical spectroscopy of V5593 Sgr between 2012 July 26 and 2013 February 19 UT with the SMARTS/CTIO 1.5 m telescope (+RC spectrograph) and then between 2014 August 25 and 2015 June 17 UT using the MDM Observatory 2.4 m Hiltner telescope (+CCDS), the 8.4 m Large Binocular Telescope (+MODS1), and the 6.5 m MMT (+BlueChannel). The SMARTS spectra confirmed the Fe II classification but showed that by 2013 February 19 UT the Fe II lines became much weaker and strong He II 468.5 nm and [Fe VII] 608.7 nm became prominent. A spectrum obtained on 2014 August 25 UT exhibited Balmer, He II, and [Fe VII] emission lines, but also for the first time, the presence of strong [Fe X] 637.4 nm emission with an observed intensity ratio with respect to Halpha of about 1.5. Other identified emission lines in our spectra included O VI, [Ca V], [Ca VI], [Ca VII], [Fe VI], [Fe XI], and [Fe XIV]. Surprisingly, [O III] emission was weak or absent. By 2015 June, a spectrum showed that the observed [Fe X]/Halpha intensity ratio had decreased to about 0.74. Contemporaneous optical photometry was obtained with the SMARTS/CTIO 1 m telescope (+ANDICAM) between 2014 March 19 and 2015 September 28 UT in the BVRIJHK bands. In agreement with our spectra in quiescence, V5593 Sgr is very red with (B-V) ~ 1 mag and (V-K) ~ 5 mag. The photometry shows ellipsoidal-like modulations with a peak-to-peak amplitude exceeding 2 mag in R and I. The modulation is seen in B through K; however, the amplitude is lower in JHK. Brief eclipses occur at the minimum of the ellipsoidal variation with a depth of at

  20. Radio-optical reference frame link using the U.S. Naval observatory astrograph and deep CCD imaging

    SciTech Connect

    Zacharias, N.; Zacharias, M. I.

    2014-05-01

    Between 1997 and 2004 several observing runs were conducted, mainly with the CTIO 0.9 m, to image International Celestial Reference Frame (ICRF) counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images, the same fields were observed with the U.S. Naval Observatory astrograph in the same bandpass. They provide accurate positions on the Hipparcos/Tycho-2 system for stars in the 10-16 mag range used as reference stars for the deep CCD imaging data. Here we present final optical position results of 413 sources based on reference stars obtained by dedicated astrograph observations that were reduced following two different procedures. These optical positions are compared to radio very long baseline interferometry positions. The current optical system is not perfectly aligned to the ICRF radio system with rigid body rotation angles of 3-5 mas (= 3σ level) found between them for all three axes. Furthermore, statistically, the optical-radio position differences are found to exceed the total, combined, known errors in the observations. Systematic errors in the optical reference star positions and physical offsets between the centers of optical and radio emissions are both identified as likely causes. A detrimental, astrophysical, random noise component is postulated to be on about the 10 mas level. If confirmed by future observations, this could severely limit the Gaia to ICRF reference frame alignment accuracy to an error of about 0.5 mas per coordinate axis with the current number of sources envisioned to provide the link. A list of 36 ICRF sources without the detection of an optical counterpart to a limiting magnitude of about R = 22 is provided as well.

  1. Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2012-01-01

    The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

  2. Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2012-01-01

    The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

  3. Beryllium-free Li4Sr(BO3)2 for deep-ultraviolet nonlinear optical applications.

    PubMed

    Zhao, Sangen; Gong, Pifu; Bai, Lei; Xu, Xiang; Zhang, Shuquan; Sun, Zhihua; Lin, Zheshuai; Hong, Maochun; Chen, Chuangtian; Luo, Junhua

    2014-05-29

    Nonlinear optical (NLO) materials are of great importance in laser science and technology, as they can expand the wavelength range provided by common laser sources. Few NLO materials, except KBe2BO3F2 (KBBF), can practically generate deep-ultraviolet coherent light by direct second-harmonic generation process, limited by the fundamental requirements on the structure-directing optical properties. However, KBBF suffers a strong layering tendency and high toxicity of the containing beryllium, which hinder the commercial availability of KBBF. Here we report a new beryllium-free borate, Li4Sr(BO3)2, which preserves the structural merits of KBBF, resulting in the desirable optical properties. Furthermore, Li4Sr(BO3)2 mitigates the layering tendency greatly and enhances the efficiency of second-harmonic generation by more than half that of KBBF. These results suggest that Li4Sr(BO3)2 is an attractive candidate for the next generation of deep-ultraviolet NLO materials. This beryllium-free borate represents a new research direction in the development of deep-ultraviolet NLO materials.

  4. Beryllium-free Li4Sr(BO3)2 for deep-ultraviolet nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Zhao, Sangen; Gong, Pifu; Bai, Lei; Xu, Xiang; Zhang, Shuquan; Sun, Zhihua; Lin, Zheshuai; Hong, Maochun; Chen, Chuangtian; Luo, Junhua

    2014-05-01

    Nonlinear optical (NLO) materials are of great importance in laser science and technology, as they can expand the wavelength range provided by common laser sources. Few NLO materials, except KBe2BO3F2 (KBBF), can practically generate deep-ultraviolet coherent light by direct second-harmonic generation process, limited by the fundamental requirements on the structure-directing optical properties. However, KBBF suffers a strong layering tendency and high toxicity of the containing beryllium, which hinder the commercial availability of KBBF. Here we report a new beryllium-free borate, Li4Sr(BO3)2, which preserves the structural merits of KBBF, resulting in the desirable optical properties. Furthermore, Li4Sr(BO3)2 mitigates the layering tendency greatly and enhances the efficiency of second-harmonic generation by more than half that of KBBF. These results suggest that Li4Sr(BO3)2 is an attractive candidate for the next generation of deep-ultraviolet NLO materials. This beryllium-free borate represents a new research direction in the development of deep-ultraviolet NLO materials.

  5. Fixing the U-band Photometry of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Krisciunas, Kevin; Bastola, Deepak; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Hamuy, Mario; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M.; Suntzeff, Nicholas B.

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift ~0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted. Based in part on observations taken at the Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  6. Optimizations of a Turbo-Like Decoder for Deep-Space Optical Communications

    NASA Astrophysics Data System (ADS)

    Cheng, M. K.; Nakashima, M. A.; Moision, B. E.; Hamkins, J.

    2007-02-01

    The National Aeronautics and Space Administration has developed a capacity-approaching modulation and coding scheme that comprises a serial concatenation of an inner accumulate pulse-position modulation and an outer convolutional code for deep-space optical communications. Decoding of this serially concatenated pulse-position modulation (SCPPM) code uses a turbo-like algorithm. However, the inner code trellis contains many parallel edges that are not typical in standard turbo codes and, therefore, a straightforward application of classical turbo decoding is very inefficient. Here, we present various optimizations applicable in hardware implementation of the SCPPM decoder. More specifically, we feature a Super Gamma computation to efficiently handle parallel trellis edges, a "maxstar top 2" circuit fit for pipelining, a modified two's complement subtraction circuit with a shorter path delay, and a cyclic redundancy check circuit for window-based turbo decoders. We also present a polynomial interleaver where current interleaver positions can be calculated from previous positions. This recursive interleaver property enables an algorithmic realization in which no memory is needed to store the interleaver mappings. Using the featured optimizations, we implement a 6.72 megabits-per-second (Mbps) SCPPM decoder on a single field-programmable gate array (FPGA). Compared to the current data rate of 256 kbps from Mars, the SCPPM-coded scheme represents a throughput increase of more than twenty-six fold. Extension to a 50-Mbps decoder on a board with multiple FPGAs follows naturally. We show through hardware simulations that the SCPPM-coded system can operate within 1 dB of the Shannon capacity at nominal operating conditions.

  7. Tunable spin-orbit-coupled Bose-Einstein condensates in deep optical lattices

    NASA Astrophysics Data System (ADS)

    Salerno, M.; Abdullaev, F. Kh.; Gammal, A.; Tomio, Lauro

    2016-10-01

    Binary mixtures of Bose-Einstein condensates (BECs) trapped in deep optical lattices and subjected to equal contributions of Rashba and Dresselhaus spin-orbit coupling (SOC) are investigated in the presence of a periodic time modulation of the Zeeman field. SOC tunability is explicitly demonstrated by adopting a mean-field tight-binding model for the BEC mixture and by performing an averaging approach in the strong modulation limit. In this case, the system can be reduced to an unmodulated vector discrete nonlinear Schrödinger equation with a rescaled SOC tuning parameter α , which depends only on the ratio between amplitude and frequency of the applied Zeeman field. We consider the attractive interaction case and focus on the effect of the SOC tuning on the localized ground states. The dependence of the spectrum of the linear system on α has been analytically characterized. In particular, we show that extremal curves (ground and highest excited states) of the linear spectrum are continuous piecewise functions (together with their derivatives) of α , which consist of a finite number of decreasing band lobes joined by constant lines. This structure also remains in the presence of inter- and intra-species interactions, the nonlinearity mainly introducing a number of localized states in the band gaps. The stability of ground states in the presence of the modulating field has been demonstrated by real-time evolutions of the original (unaveraged) system. Localization properties of the ground state induced by the SOC tuning, and a parameter design for possible experimental observation, have also been discussed.

  8. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

    NASA Astrophysics Data System (ADS)

    Chen, Wei; You, Jiang; Gu, Xiaochun; Du, Congwu; Pan, Yingtian

    2016-12-01

    Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF) networks in mouse brain over a large field-of-view (FOV: 8.5 × 5 × 3.2 mm3) was scanned through thinned skull. Results showed that fast flows up to 3 cm/s in pial vessels and minute flows down to 0.3 mm/s in arterioles or venules were readily detectable at depths down to 3.2 mm. Moreover, the dynamic changes of the CBF networks elicited by acute cocaine such as heterogeneous responses in various vessel compartments and at different cortical layers as well as transient ischemic events were tracked, suggesting the potential of SS-ODT for brain functional imaging that requires high flow sensitivity and dynamic range, fast frame rate and a large FOV to cover different brain regions.

  9. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

    PubMed Central

    Chen, Wei; You, Jiang; Gu, Xiaochun; Du, Congwu; Pan, Yingtian

    2016-01-01

    Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF) networks in mouse brain over a large field-of-view (FOV: 8.5 × 5 × 3.2 mm3) was scanned through thinned skull. Results showed that fast flows up to 3 cm/s in pial vessels and minute flows down to 0.3 mm/s in arterioles or venules were readily detectable at depths down to 3.2 mm. Moreover, the dynamic changes of the CBF networks elicited by acute cocaine such as heterogeneous responses in various vessel compartments and at different cortical layers as well as transient ischemic events were tracked, suggesting the potential of SS-ODT for brain functional imaging that requires high flow sensitivity and dynamic range, fast frame rate and a large FOV to cover different brain regions. PMID:27934907

  10. Post-Test Analysis of the Deep Space One Spare Flight Thruster Ion Optics

    NASA Technical Reports Server (NTRS)

    Anderson, John R.; Sengupta, Anita; Brophy, John R.

    2004-01-01

    The Deep Space 1 (DSl) spare flight thruster (FT2) was operated for 30,352 hours during the extended life test (ELT). The test was performed to validate the service life of the thruster, study known and identify unknown life limiting modes. Several of the known life limiting modes involve the ion optics system. These include loss of structural integrity for either the screen grid or accelerator grid due to sputter erosion from energetic ions striking the grid, sputter erosion enlargement of the accelerator grid apertures to the point where the accelerator grid power supply can no longer prevent electron backstreaming, unclearable shorting between the grids causes by flakes of sputtered material, and rouge hole formation due to flakes of material defocusing the ion beam. Grid gap decrease, which increases the probability of electron backstreaming and of arcing between the grids, was identified as an additional life limiting mechanism after the test. A combination of accelerator grid aperture enlargement and grid gap decrease resulted in the inability to prevent electron backstreaming at full power at 26,000 hours of the ELT. Through pits had eroded through the accelerator grid webbing and grooves had penetrated through 45% of the grid thickness in the center of the grid. The upstream surface of the screen grid eroded in a chamfered pattern around the holes in the central portion of the grid. Sputter deposited material, from the accelerator grid, adhered to the downstream surface of the screen grid and did not spall to form flakes. Although a small amount of sputter deposited material protruded into the screen grid apertures, no rouge holes were found after the ELT.

  11. Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials.

    PubMed

    Tran, T Thao; Young, Joshua; Rondinelli, James M; Halasyamani, P Shiv

    2017-01-25

    Noncentrosymmetric mixed-metal carbonate fluorides are promising materials for deep-ultraviolet (DUV) nonlinear optical (NLO) applications. We report on the synthesis, characterization, structure-property relationships, and electronic structure calculations on two new DUV NLO materials: KMgCO3F and Cs9Mg6(CO3)8F5. Both materials are noncentrosymmetric (NCS). KMgCO3F crystallizes in the achiral and nonpolar NCS space group P6̅2m, whereas Cs9Mg6(CO3)8F5 is found in the polar space group Pmn21. The compounds have three-dimensional structures built up from corner-shared magnesium oxyfluoride and magnesium oxide octahedra. KMgCO3F (Cs9Mg6(CO3)8F5) exhibits second-order harmonic generation (SHG) at both 1064 and 532 nm incident radiation with efficiencies of 120 (20) × α-SiO2 and 0.33 (0.10) × β-BaB2O4, respectively. In addition, short absorption edges of <200 and 208 nm for KMgCO3F and Cs9Mg6(CO3)8F5, respectively, are observed. We compute the electron localization function and density of states of these two compounds using first-principles density functional theory, and show that the different NLO responses arise from differences in the denticity and alignment of the anionic carbonate units. Finally, an examination of the known SHG active AMCO3F (A = alkali metal, M = alkaline earth metal, Zn, Cd, or Pb) materials indicates that, on average, smaller A cations and larger M cations result in increased SHG efficiencies.

  12. Post-Test Analysis of the Deep Space One Spare Flight Thruster Ion Optics

    NASA Technical Reports Server (NTRS)

    Anderson, John R.; Sengupta, Anita; Brophy, John R.

    2004-01-01

    The Deep Space 1 (DSl) spare flight thruster (FT2) was operated for 30,352 hours during the extended life test (ELT). The test was performed to validate the service life of the thruster, study known and identify unknown life limiting modes. Several of the known life limiting modes involve the ion optics system. These include loss of structural integrity for either the screen grid or accelerator grid due to sputter erosion from energetic ions striking the grid, sputter erosion enlargement of the accelerator grid apertures to the point where the accelerator grid power supply can no longer prevent electron backstreaming, unclearable shorting between the grids causes by flakes of sputtered material, and rouge hole formation due to flakes of material defocusing the ion beam. Grid gap decrease, which increases the probability of electron backstreaming and of arcing between the grids, was identified as an additional life limiting mechanism after the test. A combination of accelerator grid aperture enlargement and grid gap decrease resulted in the inability to prevent electron backstreaming at full power at 26,000 hours of the ELT. Through pits had eroded through the accelerator grid webbing and grooves had penetrated through 45% of the grid thickness in the center of the grid. The upstream surface of the screen grid eroded in a chamfered pattern around the holes in the central portion of the grid. Sputter deposited material, from the accelerator grid, adhered to the downstream surface of the screen grid and did not spall to form flakes. Although a small amount of sputter deposited material protruded into the screen grid apertures, no rouge holes were found after the ELT.

  13. Image-guided modified deep anterior lamellar keratoplasty (DALK) corneal transplant using intraoperative optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tao, Yuankai K.; LaBarbera, Michael; Ehlers, Justis P.; Srivastava, Sunil K.; Dupps, William J.

    2015-03-01

    Deep anterior lamellar keratoplasty (DALK) is an alternative to full-thickness corneal transplant and has advantages including the absence of allograft rejection; shortened duration of topical corticosteroid treatment and reduced associated risk of glaucoma, cataract, or infection; and enables use of grafts with poor endothelial quality. DALK begins by performing a trephination of approximately 80% stromal thickness, as measured by pachymetry. After removal of the anterior stoma, a needle is inserted into the residual stroma to inject air or viscoelastic to dissect Descemet's membrane. These procedures are inherently difficult and intraoperative rates of Descemet's membrane perforation between 4-39% have been reported. Optical coherence tomography (OCT) provides high-resolution images of tissue microstructures in the cornea, including Descemet's membrane, and allows quantitation of corneal layer thicknesses. Here, we use crosssectional intraoperative OCT (iOCT) measurements of corneal thickness during surgery and a novel micrometeradjustable biopsy punch to precision-cut the stroma down to Descemet's membrane. Our prototype cutting tool allows us to establish a dissection plane at the corneal endothelium interface, mitigates variability in cut-depths as a result of tremor, reduces procedure complexity, and reduces complication rates. iOCT-guided modified DALK procedures were performed on 47 cadaveric porcine eyes by non-experts and achieved a perforation rate of ~5% with a mean corneal dissection time <18 minutes. The procedure was also successful performed on a human donor eye without perforation. Our data shows the potential for iOCT-guided precision anterior segment surgery without variability as a result of tremor and improvements to standard clinical care.

  14. RF and Optical Communications: A Comparison of High Data Rate Returns From Deep Space in the 2020 Timeframe

    NASA Technical Reports Server (NTRS)

    Williams, W. Dan; Collins, Michael; Boroson, Don M.; Lesh, James; Biswas, Abihijit; Orr, Richard; Schuchman, Leonard; Sands, O. Scott

    2007-01-01

    As NASA proceeds with plans for increased science data return and higher data transfer capacity for science missions, both RF and optical communications are viable candidates for significantly higher-rate communications from deep space to Earth. With the inherent advantages, smaller apertures and larger bandwidths, of optical communications, it is reasonable to expect that at some point in time and combination of increasing distance and data rate, the rapidly emerging optical capabilities would become more advantageous than the more mature and evolving RF techniques. This paper presents a comparison of the burden to a spacecraft by both RF and optical communications systems for data rates of 10, 100, and 1000 Mbps and large distances. Advanced technology for RF and optical communication systems have been considered for projecting capabilities in the 2020 timeframe. For the comparisons drawn, the optical and RF ground terminals were selected to be similar in cost. The RF system selected is composed of forty-five 12-meter antennas, whereas the selected optical system is equivalent to a 10-meter optical telescope. Potential differences in availability are disregarded since the focus of this study is on spacecraft mass and power burden for high-rate mission data, under the assumption that essential communications will be provided by low-rate, high availability RF. For both the RF and optical systems, the required EIRP, for a given data rate and a given distance, was achieved by a design that realized the lowest possible communications subsystem mass (power + aperture) consistent with achieving the lowest technology risk. A key conclusion of this paper is that optical communications has great potential for high data rates and distances of 2.67 AU and beyond, but requires R&D and flight demonstrations to prove out technologies.

  15. Surface Photometry of Local Volume Galaxies

    NASA Astrophysics Data System (ADS)

    Sakai, Shoko; van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Funes, Jose G.

    2009-08-01

    We propose to obtain UBVR images of a statistically complete sample of spiral and irregular galaxies in the Local Volume Legacy (LVL) survey to investigate the correlation between past star formation activity and other physical properties such as SFR, dust content, and metallicity. The proposed optical imaging observations of 34 galaxies (27 southern, 7 northern) will be combined with existing UV, H(alpha), and IR observations, and will serve to nearly complete the optical imaging coverage of the full LVL sample of 258 galaxies. As expected for a volume limited sample, the majority of galaxies targeted here are low luminosity dwarf galaxies. The observed optical colors, in addition to optical-IR colors, will be compared with stellar population models to estimate the past history of star formation in these low mass galaxies and to provide constraints on the stellar mass-to-light ratios. The observed surface photometry will also allow us to study the photometric properties, the morphology, and spatial distributions of the different stellar populations in these low mass systems.

  16. Detection Performance of Upgraded "Polished Panel" Optical Receiver Concept on the Deep-Space Network's 34 Meter Research Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2012-01-01

    The development and demonstration of a "polished panel" optical receiver concept on the 34 meter research antenna of the Deep Space Network (DSN) has been the subject of recent papers. This concept would enable simultaneous reception of optical and microwave signals by retaining the original shape of the main reflector for microwave reception, but with the aluminum panels polished to high reflectivity to enable focusing of optical signal energy as well. A test setup has been installed on the DSN's 34 meter research antenna at Deep Space Station 13 (DSS-13) of NASA's Goldstone Communications Complex in California, and preliminary experimental results have been obtained. This paper describes the results of our latest efforts to improve the point-spread function (PSF) generated by a custom polished panel, in an attempt to reduce the dimensions of the PSF, thus enabling more precise tracking and improved detection performance. The design of the new mechanical support structure and its operation are described, and the results quantified in terms of improvements in collected signal energy and optical communications performance, based on data obtained while tracking the planet Jupiter with the 34 meter research antenna at DSS-13.

  17. Detection Performance of Upgraded "Polished Panel" Optical Receiver Concept on the Deep-Space Network's 34 Meter Research Antenna

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2012-01-01

    The development and demonstration of a "polished panel" optical receiver concept on the 34 meter research antenna of the Deep Space Network (DSN) has been the subject of recent papers. This concept would enable simultaneous reception of optical and microwave signals by retaining the original shape of the main reflector for microwave reception, but with the aluminum panels polished to high reflectivity to enable focusing of optical signal energy as well. A test setup has been installed on the DSN's 34 meter research antenna at Deep Space Station 13 (DSS-13) of NASA's Goldstone Communications Complex in California, and preliminary experimental results have been obtained. This paper describes the results of our latest efforts to improve the point-spread function (PSF) generated by a custom polished panel, in an attempt to reduce the dimensions of the PSF, thus enabling more precise tracking and improved detection performance. The design of the new mechanical support structure and its operation are described, and the results quantified in terms of improvements in collected signal energy and optical communications performance, based on data obtained while tracking the planet Jupiter with the 34 meter research antenna at DSS-13.

  18. Supernova Classification Using Swift UVOT Photometry

    NASA Astrophysics Data System (ADS)

    Smith, Madison; Brown, Peter J.

    2017-01-01

    With the great influx of supernova discoveries over the past few years, the observation time needed to acquire the spectroscopic data needed to classify supernova by type has become unobtainable. Instead, using the photometry of supernovae could greatly reduce the amount of time between discovery and classification. For this project we looked at the relationship between colors and supernova types through machine learning packages in Python. Using data from the Swift Ultraviolet/Optical Telescope (UVOT), each photometric point was assigned values corresponding to colors, absolute magnitudes, and the relative times from the peak brightness in several filters. These values were fed into three classifying methods, the nearest neighbors, decision tree, and random forest methods. We will discuss the success of these classification systems, the optimal filters for photometric classification, and ways to improve the classification.

  19. Spectroscopy and Photometry of MWC 137

    NASA Astrophysics Data System (ADS)

    Alimardanova, F.; Miroshnichenko, A. S.; Zharikov, S. V.; Rudy, R. J.; Manset, N.; Kusakin, A. V.; Kuratov, K. S.; Khokhlov, S.

    2017-02-01

    MWC 137 is an object with a strong emission-line spectrum associated with an 1'-size H Imall> region Sharpless 266. It was included in a catalog of planetary nebulae in 1967, in the first list of objects with the B[e] phenomenon in 1976, and in a list of Herbig Ae/Be stars in 1984. A recent analysis of the stellar and nebular spectra of MWC 137 by several authors suggested that it is most likely a B[e] supergiant located at a distance 4-6 kpc away from the Sun. No high-resolution spectra of the object have been published so far. We present the results of our analysis of high-resolution optical spectra of MWC 137 obtained in 2004-2016 and UBVRI photometry.

  20. PSF reconstruction for AO photometry and astrometry

    NASA Astrophysics Data System (ADS)

    Ascenso, J.; Neichel, B.; Silva, M.; Fusco, T.; Garcia, P.

    2015-12-01

    Extracting accurate photometry (and astrometry) from images taken with adaptive optics assisted instruments is particularly challenging. Current post-processing tools are not prepared to achieve high accuracy from AO data, especially in limiting cases of crowded fields and marginally resolved sources. We quantify the limitations of these tools with synthetic images, and present a proof-of-concept study showing the potential of using reconstructed PSFs from the (GL)AO system telemetry to increase the measured photometric accuracy. We show that the photometric accuracy is significantly improved with a good PSF reconstruction in considerably crowded regions. We demonstrate the need for a dedicated post-processing tool that incorporates available information about the PSF, as well as the ability to adjust to the spatial variations of the PSF characteristic of AO data.

  1. First autonomous bio-optical profiling float in the Gulf of Mexico reveals dynamic biogeochemistry in deep waters.

    PubMed

    Green, Rebecca E; Bower, Amy S; Lugo-Fernández, Alexis

    2014-01-01

    Profiling floats equipped with bio-optical sensors well complement ship-based and satellite ocean color measurements by providing highly-resolved time-series data on the vertical structure of biogeochemical processes in oceanic waters. This is the first study to employ an autonomous profiling (APEX) float in the Gulf of Mexico for measuring spatiotemporal variability in bio-optics and hydrography. During the 17-month deployment (July 2011 to December 2012), the float mission collected profiles of temperature, salinity, chlorophyll fluorescence, particulate backscattering (bbp), and colored dissolved organic matter (CDOM) fluorescence from the ocean surface to a depth of 1,500 m. Biogeochemical variability was characterized by distinct depth trends and local "hot spots", including impacts from mesoscale processes associated with each of the water masses sampled, from ambient deep waters over the Florida Plain, into the Loop Current, up the Florida Canyon, and eventually into the Florida Straits. A deep chlorophyll maximum (DCM) occurred between 30 and 120 m, with the DCM depth significantly related to the unique density layer ρ = 1023.6 (R2 = 0.62). Particulate backscattering, bbp, demonstrated multiple peaks throughout the water column, including from phytoplankton, deep scattering layers, and resuspension. The bio-optical relationship developed between bbp and chlorophyll (R2 = 0.49) was compared to a global relationship and could significantly improve regional ocean-color algorithms. Photooxidation and autochthonous production contributed to CDOM distributions in the upper water column, whereas in deep water, CDOM behaved as a semi-conservative tracer of water masses, demonstrating a tight relationship with density (R2 = 0.87). In the wake of the Deepwater Horizon oil spill, this research lends support to the use of autonomous drifting profilers as a powerful tool for consideration in the design of an expanded and integrated observing network for

  2. First Autonomous Bio-Optical Profiling Float in the Gulf of Mexico Reveals Dynamic Biogeochemistry in Deep Waters

    PubMed Central

    Green, Rebecca E.; Bower, Amy S.; Lugo-Fernández, Alexis

    2014-01-01

    Profiling floats equipped with bio-optical sensors well complement ship-based and satellite ocean color measurements by providing highly-resolved time-series data on the vertical structure of biogeochemical processes in oceanic waters. This is the first study to employ an autonomous profiling (APEX) float in the Gulf of Mexico for measuring spatiotemporal variability in bio-optics and hydrography. During the 17-month deployment (July 2011 to December 2012), the float mission collected profiles of temperature, salinity, chlorophyll fluorescence, particulate backscattering (bbp), and colored dissolved organic matter (CDOM) fluorescence from the ocean surface to a depth of 1,500 m. Biogeochemical variability was characterized by distinct depth trends and local “hot spots”, including impacts from mesoscale processes associated with each of the water masses sampled, from ambient deep waters over the Florida Plain, into the Loop Current, up the Florida Canyon, and eventually into the Florida Straits. A deep chlorophyll maximum (DCM) occurred between 30 and 120 m, with the DCM depth significantly related to the unique density layer ρ = 1023.6 (R2 = 0.62). Particulate backscattering, bbp, demonstrated multiple peaks throughout the water column, including from phytoplankton, deep scattering layers, and resuspension. The bio-optical relationship developed between bbp and chlorophyll (R2 = 0.49) was compared to a global relationship and could significantly improve regional ocean-color algorithms. Photooxidation and autochthonous production contributed to CDOM distributions in the upper water column, whereas in deep water, CDOM behaved as a semi-conservative tracer of water masses, demonstrating a tight relationship with density (R2 = 0.87). In the wake of the Deepwater Horizon oil spill, this research lends support to the use of autonomous drifting profilers as a powerful tool for consideration in the design of an expanded and integrated observing network

  3. THE ARAUCARIA PROJECT. A DISTANCE DETERMINATION TO THE LOCAL GROUP SPIRAL M33 FROM NEAR-INFRARED PHOTOMETRY OF CEPHEID VARIABLES

    SciTech Connect

    Gieren, Wolfgang; Pietrzynski, Grzegorz; Graczyk, Dariusz E-mail: pietrzyn@hubble.cfm.udec.cl; and others

    2013-08-10

    Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO Very Large Telescope. From the data, we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of {+-}0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B - V) = 0.19 {+-} 0.02, in agreement with the value used by the Hubble Space Telescope Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1%-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.

  4. Adaptive optics microscopy enhances image quality in deep layers of CLARITY processed brains of YFP-H mice

    NASA Astrophysics Data System (ADS)

    Reinig, Marc R.; Novack, Samuel W.; Tao, Xiaodong; Ermini, Florian; Bentolila, Laurent A.; Roberts, Dustin G.; MacKenzie-Graham, Allan; Godshalk, S. E.; Raven, M. A.; Kubby, Joel

    2016-03-01

    Optical sectioning of biological tissues has become the method of choice for three-dimensional histological analyses. This is particularly important in the brain were neurons can extend processes over large distances and often whole brain tracing of neuronal processes is desirable. To allow deeper optical penetration, which in fixed tissue is limited by scattering and refractive index mismatching, tissue-clearing procedures such as CLARITY have been developed. CLARITY processed brains have a nearly uniform refractive index and three-dimensional reconstructions at cellular resolution have been published. However, when imaging in deep layers at submicron resolution some limitations caused by residual refractive index mismatching become apparent, as the resulting wavefront aberrations distort the microscopic image. The wavefront can be corrected with adaptive optics. Here, we investigate the wavefront aberrations at different depths in CLARITY processed mouse brains and demonstrate the potential of adaptive optics to enable higher resolution and a better signal-to-noise ratio. Our adaptive optics system achieves high-speed measurement and correction of the wavefront with an open-loop control using a wave front sensor and a deformable mirror. Using adaptive optics enhanced microscopy, we demonstrate improved image quality wavefront, point spread function, and signal to noise in the cortex of YFP-H mice.

  5. Rapid Optical Photometry of V404 Cyg

    NASA Astrophysics Data System (ADS)

    Hynes, R. I.; Robinson, E. L.; Morales, J.

    2015-06-01

    We observed the outbursting black hole X-ray transient V404 Cyg (GCN #17929, #17931, #17933, #17938, #17940, #17944, #17945, #17946, #17948; ATel #7646, #7647, #7650, #7655, #7658, #7659, #7661, #7662, #7663, #7665, #7666, #7667, #7669, #7671, #7674) for about four hours on 2015 June 18.26-18.44 UT using the Argos photometer on the 2.1m Otto Struve Telescope at McDonald Observatory.

  6. Optical Multicolor Photometry of Spectrophotometric Standard Stars

    NASA Astrophysics Data System (ADS)

    Landolt, Arlo U.; Uomoto, Alan K.

    2007-03-01

    Photoelectric data on the Johnson-Kron-Cousins UBVRI broadband photometric system are provided for a set of stars that have been used as spectrophotometric standard stars for the Hubble Space Telescope.

  7. In-situ formation compaction monitoring in deep reservoirs by use of fiber optics

    NASA Astrophysics Data System (ADS)

    Murai, Daisuke; Kunisue, Shoji; Higuchi, Tomoyuki; Kokubo, Tatsuo

    2013-04-01

    1. Background The Southern Kanto gas field, the largest field of natural gas dissolved in water in Japan, is located primarily under the Chiba Prefecture. In this field 8 companies produce 460*10^6m3/y of natural gas. In addition, the concentration of the iodine in the brine is almost 2000 times that in seawater and the iodine as well as natural gas is collected from the brine. Iodine is industrially useful and essential for the human body. About 30% of world production is produced in this area in recent years. On the other hand, the land subsidence has become the big problem since 1965 and more than 10cm/mm of land subsidence was observed by leveling in 1972. The natural gas and iodine producers in this area have made a land subsidence prevention agreement with the local government and made effort to prevent and control land subsidence. Although their pumping brine for the gas and the iodine production is inferred to be the main cause of land subsidence from that time, the ratio of the formation compaction caused by pumping brine in the total land subsidence hasn't been well known. Therefore, the measurement of the actual formation compaction has become an important technological issue for the companies and they jointly have developed a new monitoring system for the formation compaction. 2. Contents (1) By using fiber optics technology, we have developed a world's first monitoring system which measures each of the in-situ formation compactions continuously without running tools into the well. (2) In order to check a reliability of this system and the problems when construction, we carried out the preliminary test. We installed the prototype system in the shallow observation well with a depth of 80 m and measured the actual formation compaction. The water well was drilled at the 10m away from the observation well and the formation was artificially compacted by pumping groundwater from it. (3) We installed the monitoring system in the deep observation well with a

  8. Thermally-assisted optically stimulated luminescence from deep electron traps in α-Al2O3:C,Mg

    NASA Astrophysics Data System (ADS)

    Kalita, J. M.; Chithambo, M. L.; Polymeris, G. S.

    2017-07-01

    We report thermally-assisted optically stimulated luminescence (TA-OSL) in α-Al2O3:C,Mg. The OSL was measured at elevated temperatures between 50 and 240 °C from a sample preheated to 500 °C after irradiation to 100 Gy. That OSL could be measured even after the preheating is direct evidence of the existence of deep electron traps in α-Al2O3:C,Mg. The TA-OSL intensity goes through a peak with measurement temperature. The initial increase is ascribed to thermal assistance to optical stimulation whereas the subsequent decrease in intensity is deduced to reflect increasing incidences of non-radiative recombination, that is, thermal quenching. The activation energy for thermal assistance corresponding to a deep electron trap was estimated as 0.667 ± 0.006 eV whereas the activation energy for thermal quenching was calculated as 0.90 ± 0.04 eV. The intensity of the TA-OSL was also found to increase with irradiation dose. The dose response is sublinear from 25 to 150 Gy but saturates with further increase of dose. The TA-OSL dose response has been discussed by considering the competition for charges at the deep traps. This study incidentally shows that TA-OSL can be effectively used in dosimetry involving large doses.

  9. Physical Properties of White Dwarfs from Multi-Band Photometry

    NASA Astrophysics Data System (ADS)

    Raddi, R.

    2017-03-01

    We describe a hierarchical Bayesian model to measure the physical parameters (mass, cooling age, distance, interstellar extinction) of single white dwarfs using only multi-band UV to IR photometry. We test our model on a set of known white dwarfs with well-assessed atmospheric parameters, determined via optical spectroscopy. Looking forward to the results of the ESA Gaia mission, we derive the posterior distributions of white dwarf parameters in two different scenarios with known or unknown parallaxes.

  10. BVRI Surface Photometry of Isolated Galaxies in the Local Universe

    NASA Astrophysics Data System (ADS)

    Zendejas-Domínguez, J.; Ortega-Esbrí, S.; Salazar-Contreras, J. R.; Hernández-Toledo, H. M.

    2008-04-01

    We present preliminary results of multicolor broadband CCD (BVRI) photometry for a sample of 230 isolated (elliptical and spiral) galaxies drawn from the Catalog of Isolated Galaxies (CIG) by Karachentseva (1973). Images were acquired at the San Pedro Mártir (OAN-SPM) National Optical Observatory in Baja California, Mexico. We estimated total magnitudes and colors at various circular apertures, as well as global structural/morphological parameters: Concentration, Asymmetry and Clumpiness (CAS).

  11. Simulations of deep galaxy fields. 1: Monte Carlo simulations of optical and near-infrared counts

    NASA Technical Reports Server (NTRS)

    Chokshi, Arati; Lonsdale, Carol J.; Mazzei, Paola; De Zotti, Gianfranco

    1994-01-01

    Monte Carlo simulations of three-dimensional galaxy distributions are performed, following the 1988 prescription of Chokshi & Wright, to study the photometric properties of evolving galaxy populations in the optical and near-infrared bands to high redshifts. In this paper, the first of a series, we present our baseline model in which galaxy numbers are conserved, and in which no explicit 'starburst' population is included. We use the model in an attempt to simultaneously fit published blue and near-infrared photometric and spectroscopic observations of deep fields. We find that our baseline models, with a formation redshift, z(sub f), of 1000, and H(sub 0) = 50, are able to reproduce the blue counts to b(sub j) = 22, independent of the value of Omega(sub 0), and also to provide a satisfactory fit to the observed blue-band redshift distributions, but for no value of Omega(sub 0) do we achieve an acceptable fit to the fainter blue counts. In the K band, we fit the number counts to the limit of the present-day surveys only for an Omega(sub 0) = 0 cosmology. We investigate the effect on the model fits of varying the cosmological parameters H(sub 0), the formation red-shift z(sub f), and the local luminosity function. Changing H(sub 0) does not improve the fits to the observations. However, reducing the epoch of a galaxy formation used in our simulations has a substantial effect. In particular, a model with z(sub f) approximately equal to 5 in a low Omega(sub 0) universe improves the fit to the faintest photometric blue data without any need to invoke a new population of galaxies, substantial merging, or a significant starburst galaxy population. For an Omega(sub 0) = 1 universe, however, reducing z(sub f) is less successful at fitting the blue-band counts and has little effect at all at K. Varying the parameters of the local luminosity function can also have a significant effect. In particular the steep low end slope of the local luminosity function of Franceschini et

  12. Improving satellite quantitative precipitation estimates by incorporating deep convective cloud optical depth

    NASA Astrophysics Data System (ADS)

    Stenz, Ronald D.

    As Deep Convective Systems (DCSs) are responsible for most severe weather events, increased understanding of these systems along with more accurate satellite precipitation estimates will improve NWS (National Weather Service) warnings and monitoring of hazardous weather conditions. A DCS can be classified into convective core (CC) regions (heavy rain), stratiform (SR) regions (moderate-light rain), and anvil (AC) regions (no rain). These regions share similar infrared (IR) brightness temperatures (BT), which can create large errors for many existing rain detection algorithms. This study assesses the performance of the National Mosaic and Multi-sensor Quantitative Precipitation Estimation System (NMQ) Q2, and a simplified version of the GOES-R Rainfall Rate algorithm (also known as the Self-Calibrating Multivariate Precipitation Retrieval, or SCaMPR), over the state of Oklahoma (OK) using OK MESONET observations as ground truth. While the average annual Q2 precipitation estimates were about 35% higher than MESONET observations, there were very strong correlations between these two data sets for multiple temporal and spatial scales. Additionally, the Q2 estimated precipitation distributions over the CC, SR, and AC regions of DCSs strongly resembled the MESONET observed ones, indicating that Q2 can accurately capture the precipitation characteristics of DCSs although it has a wet bias . SCaMPR retrievals were typically three to four times higher than the collocated MESONET observations, with relatively weak correlations during a year of comparisons in 2012. Overestimates from SCaMPR retrievals that produced a high false alarm rate were primarily caused by precipitation retrievals from the anvil regions of DCSs when collocated MESONET stations recorded no precipitation. A modified SCaMPR retrieval algorithm, employing both cloud optical depth and IR temperature, has the potential to make significant improvements to reduce the SCaMPR false alarm rate of retrieved

  13. A Comprehensive Study of Detectability and Contamination in Deep Rapid Optical Searches for Gravitational Wave Counterparts

    NASA Astrophysics Data System (ADS)

    Cowperthwaite, P. S.; Berger, E.

    2015-11-01

    The first direct detection of gravitational waves (GWs) by the ground-based Advanced LIGO/Virgo interferometers is expected to occur within the next few years. These interferometers are designed to detect the mergers of compact object binaries composed of neutron stars and/or black holes to a fiducial distance of ˜200 Mpc and a localization region of ˜100 deg2. To maximize the science gains from such GW detections it is essential to identify electromagnetic counterparts. Among the wide range of proposed counterparts, the most promising is optical/IR emission powered by the radioactive decay of r-process elements synthesized in the neutron-rich merger ejecta—a “kilonova.” Here we present detailed simulated observations that encompass a range of strategies for kilonova searches during GW follow-up. We utilize these simulations to assess both the detectability of kilonovae and our ability to distinguish them from a wide range of contaminating transients in the large GW localization regions. We find that if pre-existing deep template images for the GW localization region are available, then nightly observations to a depth of i ≈ 24 mag and z ≈ 23 mag are required to achieve a 95% detection rate; observations that commence within ˜12 hr of trigger will also capture the kilonova peak and provide stronger constraints on the ejecta properties. We also find that kilonovae can be robustly separated from other known and hypothetical types of transients utilizing cuts on color (i - z ≳ 0.3 mag) and rise time (trise ≲ 4 days). In the absence of a pre-existing template the observations must reach ˜1 mag deeper to achieve the same kilonova detection rate, but robust rejection of contaminants can still be achieved. Motivated by the results of our simulations we discuss the expected performance of current and future wide-field telescopes in achieving these observational goals, and find that prior to LSST the Dark Energy Camera on the Blanco 4 m telescope and Hyper

  14. A COMPREHENSIVE STUDY OF DETECTABILITY AND CONTAMINATION IN DEEP RAPID OPTICAL SEARCHES FOR GRAVITATIONAL WAVE COUNTERPARTS

    SciTech Connect

    Cowperthwaite, P. S.; Berger, E.

    2015-11-20

    The first direct detection of gravitational waves (GWs) by the ground-based Advanced LIGO/Virgo interferometers is expected to occur within the next few years. These interferometers are designed to detect the mergers of compact object binaries composed of neutron stars and/or black holes to a fiducial distance of ∼200 Mpc and a localization region of ∼100 deg{sup 2}. To maximize the science gains from such GW detections it is essential to identify electromagnetic counterparts. Among the wide range of proposed counterparts, the most promising is optical/IR emission powered by the radioactive decay of r-process elements synthesized in the neutron-rich merger ejecta—a “kilonova.” Here we present detailed simulated observations that encompass a range of strategies for kilonova searches during GW follow-up. We utilize these simulations to assess both the detectability of kilonovae and our ability to distinguish them from a wide range of contaminating transients in the large GW localization regions. We find that if pre-existing deep template images for the GW localization region are available, then nightly observations to a depth of i ≈ 24 mag and z ≈ 23 mag are required to achieve a 95% detection rate; observations that commence within ∼12 hr of trigger will also capture the kilonova peak and provide stronger constraints on the ejecta properties. We also find that kilonovae can be robustly separated from other known and hypothetical types of transients utilizing cuts on color (i − z ≳ 0.3 mag) and rise time (t{sub rise} ≲ 4 days). In the absence of a pre-existing template the observations must reach ∼1 mag deeper to achieve the same kilonova detection rate, but robust rejection of contaminants can still be achieved. Motivated by the results of our simulations we discuss the expected performance of current and future wide-field telescopes in achieving these observational goals, and find that prior to LSST the Dark Energy Camera on the Blanco 4 m

  15. Heavy Element Abundances in Planetary Nebulae from Deep Optical Echelle Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mashburn, Amanda; Sterling, Nicholas C.; Dinerstein, Harriet L.; Garofali, Kristen; Jensema, Rachael; Turbyfill, Amanda; Wieser, Hannah-Marie N.; Reed, Evan C.; Redfield, Seth

    2016-01-01

    We present the abundances of neutron(n)-capture elements (atomic number Z > 30) and iron determined from deep optical echelle spectroscopy of 14 Galactic planetary nebulae (PNe). The spectra were obtained with the 2D-coudé spectrograph on the 2.7-m Harlan J. Smith telescope at McDonald Observatory. The abundances of n-capture elements can be enhanced in PNe due to slow n-capture nucleosynthesis in the progenitor asymptotic giant branch (AGB) stars. The high spectral resolution of these data (R = 36,700) allow most n-capture element emission lines to be resolved from other nebular and telluric features. We detect Kr in all of the observed PNe (with multiple ions detected in several objects), while Br, Rb, and Xe were each detected in 4--5 objects. Using the new Kr ionization correction factors (ICFs) of Sterling et al. (2015, ApJS, 218, 25), we find [Kr/O] abundances ranging from 0.05 to 1.1 dex. We utilize approximate ICFs for the other n-capture elements, and find slightly lower enrichments for Br and Rb (-0.1 to 0.7 dex), while Xe is enhanced relative to solar by factors of two to 30. The [Xe/Kr] ratios range from -0.3 to 1.4 dex, indicating a significant range in neutron exposures in PN progenitor stars. Interestingly, the largest [Xe/Kr] ratio is found in the thick-disk PN NGC 6644, which has a lower metallicity than the other observed PNe. We detect iron emission lines in all but one target. Fe can be depleted into dust grains in ionized nebulae, and its abundance thus provides key information regarding dust-to-gas ratios and grain destruction processes. We find that [Fe/O] ranges from -1.3 to -0.7 dex in the observed PNe, a smaller spread of depletion factors than found in recent studies (Delgado-Inglada & Rodriguez 2014, ApJ, 784, 173) though this may be due in part to our smaller sample. These data are part of a larger study of heavy elements in PNe, which will provide more accurate determinations of n-capture element abundances than previous estimates in

  16. High speed low noise multiplexed three color absorbance photometry.

    PubMed

    Dadesh, Khaled M; Kurup, G K; Basu, Amar S

    2011-01-01

    Multispectral photometry is often required to distinguish samples in flow injection analysis and flow cytometry; however, the cost of multiple light detectors, filters, and optical paths contribute to the high cost of multicolor and spectral detection systems. This paper describes frequency division multiplexing (FDM), a simple approach for performing multi-wavelength absorbance photometry with a single light detector and a single interrogation window. In previous efforts, modulation frequencies were <10 KHz, resulting in a detector bandwidth of <20 Hz. This paper presents a high frequency FDM circuit which can increase the oscillation frequencies to several 100 KHz, improving the detection bandwidth by a factor of 10 while still maintaining low cost. Light from 3 different LED sources are encoded into unique frequency channels, passed through the detection cell, and later demodulated using phase-sensitive electronics. Electronic multiplexing couples all light sources into a single optical train without spectral filters. Theory and high frequency considerations are demonstrated. Simultaneous three color absorbance detection is demonstrated in solutions and in flowing droplet microreactors. This technique can potentially reduce the cost of multicolor photometry by replacing expensive optical components with low-cost electronics.

  17. Comparing Aperture Photometry Software Packages

    NASA Astrophysics Data System (ADS)

    Bajaj, V.; Khandrika, H.

    2017-04-01

    Multiple software packages exist to perform aperture photometry on HST data. Three of the most used softwares are the Python package PhotUtils, the IDL function APER, and the IRAF/PyRAF package DAOPHOT. The results produced by DAOPHOT are slightly incorrect, at approximately 0.1% too large for WFC3/IR images measured with a 3-pixel aperture (PhotUtils and APER produce the correct results). The magnitude of the DAOPHOT discrepancy is dependent on the type of source and filter used (as this impacts the PSF) due to DAOPHOT's approximation of a circle as a slightly larger irregular polygon. We present a quantification of this error for WFC3/IR data, though the analysis is applicable for any small-aperture photometry.

  18. Classical photometry of prefractal surfaces.

    PubMed

    Shkuratov, Yuriy; Petrov, Dmitriy; Videen, Gorden

    2003-11-01

    Using the scale invariance of classical photometry, we develop an approach to finding the photometric function of prefractal structures that form a random topography. The photometric function of the prefractal surfaces is found as the general solution of the resulting differential equation in partial derivatives. The function depends on two parameters: the number of hierarchical levels of the prefractal structures and the roughness parameter of the single-level generation. As a limiting case, the approach includes our previous theory that considered fractoids.

  19. Imaging deep skeletal muscle structure using a high-sensitivity ultrathin side-viewing optical coherence tomography needle probe

    PubMed Central

    Yang, Xiaojie; Lorenser, Dirk; McLaughlin, Robert A.; Kirk, Rodney W.; Edmond, Matthew; Simpson, M. Cather; Grounds, Miranda D.; Sampson, David D.

    2013-01-01

    We have developed an extremely miniaturized optical coherence tomography (OCT) needle probe (outer diameter 310 µm) with high sensitivity (108 dB) to enable minimally invasive imaging of cellular structure deep within skeletal muscle. Three-dimensional volumetric images were acquired from ex vivo mouse tissue, examining both healthy and pathological dystrophic muscle. Individual myofibers were visualized as striations in the images. Degradation of cellular structure in necrotic regions was seen as a loss of these striations. Tendon and connective tissue were also visualized. The observed structures were validated against co-registered hematoxylin and eosin (H&E) histology sections. These images of internal cellular structure of skeletal muscle acquired with an OCT needle probe demonstrate the potential of this technique to visualize structure at the microscopic level deep in biological tissue in situ. PMID:24466482

  20. Characterisation of the Gaia photometry

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Jordi, C.; Fabricius, C.; Voss, H.; Weiler, M.

    2014-07-01

    Our team at the University of Barcelona has contributed since the early phases of the mission to the definition, evaluation and calibration modelling of the Gaia photometry. To maximise the Gaia scientific exploitation, we have frequently shared many different tools and data with the astronomical community. Among this information we have defined several relationships among colours involving Gaia magnitudes and colours from other commonly used photometric systems (Johnson-Cousins, SDSS, Hipparcos, Tycho and 2MASS) for several types of stars (including white dwarfs). These relationships can be used for planning scientific exploitation of Gaia data, performing simulations of the Gaia-like sky, planning ground-based complementary observations and for building catalogues with auxiliary validation data. During the commissioning phase our team (as part of the Payload Experts group) has been intensively checking the first photometric data to analyse the health and properties of the real instrument. These preliminary analyses allowed us to monitor the throughput variations with time, assess the spectral resolution and re-evaluate the performances of the end-of-mission photometry. The Payload Experts group activities continue beyond the commissioning phase aiming to optimize the operations onboard for maximizing the scientific return. Some example of first spectra and photometry are shown.

  1. Deep Proton Writing for the rapid prototyping of polymer micro-components for optical interconnects and optofluidics

    NASA Astrophysics Data System (ADS)

    Van Erps, Jürgen; Vervaeke, Michael; Ottevaere, Heidi; Hermanne, Alex; Thienpont, Hugo

    2013-07-01

    The use of photonics in data communication and numerous other industrial applications brought plenty of prospects for innovation and opened up different unexplored market opportunities. This is a major driving force for the fabrication of micro-optical and micro-mechanical structures and their accurate alignment and integration into opto-mechanical modules and systems. To this end, we present Deep Proton Writing (DPW) as a powerful rapid prototyping technology for such micro-components. The DPW process consists of bombarding polymer samples (PMMA or SU-8) with swift protons, which results after chemical processing steps in high-quality micro-optical components. One of the strengths of the DPW micro-fabrication technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we comment on how we shifted from using 8.3 to 16.5 MeV protons for DPW and give some examples of micro-optical and micro-mechanical components recently fabricated through DPW, targeting applications in optical interconnections and in optofluidics.

  2. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. X. ULTRAVIOLET TO INFRARED PHOTOMETRY OF 117 MILLION EQUIDISTANT STARS

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Weisz, Daniel R.; Byler, Nell; Johnson, L. C. E-mail: jd@astro.washington.edu E-mail: lcjohnso@astro.washington.edu; and others

    2014-11-01

    We have measured stellar photometry with the Hubble Space Telescope Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys in near ultraviolet (F275W, F336W), optical (F475W, F814W), and near infrared (F110W, F160W) bands for 117 million resolved stars in M31. As part of the Panchromatic Hubble Andromeda Treasury survey, we measured photometry with simultaneous point-spread function (PSF) fitting across all bands and at all source positions after precise astrometric image alignment (<5-10 mas accuracy). In the outer disk, the photometry reaches a completeness-limited depth of F475W ∼ 28, while in the crowded, high surface brightness bulge, the photometry reaches F475W ∼ 25. We find that simultaneous photometry and optimized measurement parameters significantly increase the detection limit of the lowest-resolution filters (WFC3/IR) providing color-magnitude diagrams (CMDs) that are up to 2.5 mag deeper when compared with CMDs from WFC3/IR photometry alone. We present extensive analysis of the data quality including comparisons of luminosity functions and repeat measurements, and we use artificial star tests to quantify photometric completeness, uncertainties and biases. We find that the largest sources of systematic error in the photometry are due to spatial variations in the PSF models and charge transfer efficiency corrections. This stellar catalog is the largest ever produced for equidistant sources, and is publicly available for download by the community.

  3. Hot-embossing replication of self-centering optical fiber alignment structures prototyped by deep proton writing

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Wissmann, Markus; Guttmann, Markus; Kolew, Alexander; Worgull, Matthias; Barié, Nicole; Schneider, Marc; Hofmann, Andreas; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-07-01

    This paper presents the hot-embossing replication of self-centering fiber alignment structures for high-precision, single-mode optical fiber connectors. To this end, a metal mold insert was fabricated by electroforming a polymer prototype patterned by means of deep proton writing (DPW). To achieve through-hole structures, we developed a postembossing process step to remove the residual layer inherently present in hot-embossed structures. The geometrical characteristics of the hot-embossed replicas are compared, before and after removal of the residual layer, with the DPW prototypes. Initial measurements on the optical performance of the replicas are performed. The successful replication of these components paves the way toward low-cost mass replication of DPW-fabricated prototypes in a variety of high-tech plastics.

  4. Low-loss nanowire and nanotube plasmonic waveguide with deep subwavelength light confinement and enhanced optical trapping forces

    NASA Astrophysics Data System (ADS)

    Chen, Xiaogang; Lu, Qijing; Wu, Xiang; Yang, Hongqin; Xie, Shusen

    2017-06-01

    With the rapid development of the micro/nano fabrication technology, the semiconductor nanowires and nanotubes with size and dimensions controllable realize wide applications in nanophotonics. In this talk, we propose two kinds of hybrid plasmonics waveguides, one is consisting of nanowires, another is consisting of nanotubes. By employing the simulating with different geometric parameters, the basic waveguiding properties, including the effective mode area, the propagation length, the mode character and the optical trapping forces can be achieved. Compared with previous plasmonic waveguide with plane metal substrate, current plasmonics waveguides with ease of fabrication have the advantage of long propagation length and effectively optical trapping of nanoparticles with deep subwavelength light confinement, which may be very useful for nanophotonic integrated circuits, nanolasers and biosensing.

  5. Molecular imaging needles: dual-modality optical coherence tomography and fluorescence imaging of labeled antibodies deep in tissue

    PubMed Central

    Scolaro, Loretta; Lorenser, Dirk; Madore, Wendy-Julie; Kirk, Rodney W.; Kramer, Anne S.; Yeoh, George C.; Godbout, Nicolas; Sampson, David D.; Boudoux, Caroline; McLaughlin, Robert A.

    2015-01-01

    Molecular imaging using optical techniques provides insight into disease at the cellular level. In this paper, we report on a novel dual-modality probe capable of performing molecular imaging by combining simultaneous three-dimensional optical coherence tomography (OCT) and two-dimensional fluorescence imaging in a hypodermic needle. The probe, referred to as a molecular imaging (MI) needle, may be inserted tens of millimeters into tissue. The MI needle utilizes double-clad fiber to carry both imaging modalities, and is interfaced to a 1310-nm OCT system and a fluorescence imaging subsystem using an asymmetrical double-clad fiber coupler customized to achieve high fluorescence collection efficiency. We present, to the best of our knowledge, the first dual-modality OCT and fluorescence needle probe with sufficient sensitivity to image fluorescently labeled antibodies. Such probes enable high-resolution molecular imaging deep within tissue. PMID:26137379

  6. In-vivo monitoring of tissue oxygen saturation in deep brain structures using a single fiber optical system

    PubMed Central

    Yu, Linhui; Wu, Ying; Dunn, Jeff F.; Murari, Kartikeya

    2016-01-01

    We propose a single fiber optical system for monitoring tissue oxygen saturation (sO2) based on continuous-wave reflectance spectroscopy in the visible wavelengths. The system is designed for measurements in deep brain structures by stereotaxically implanting the 200 μm-core fiber probe into the tissue of interest. Monte Carlo (MC) simulations were used to estimate the measurement tissue volume between 0.02–0.03 mm3. Experiments in an optical phantom indicated the system had a root mean squared error (RMSE) of 4.21% compared with a commercial fluorescence-based tissue oxygen partial pressure measuring system. Finally, we used the system for continuously monitoring tissue sO2 from a highly-localized volume in anesthetized mice. PMID:27896007

  7. Transmitters and receivers in free space optical communications for Deep Space links

    NASA Technical Reports Server (NTRS)

    Beebe, J.

    2003-01-01

    Two of the many research areas integral making a Mars-Earth optical communication link a reality are optical antenna design and laser transmitter design. This paper addresses areas of both of these by exploring a mode-matched design for a cavity-dumped communications laser, and by reporting on the initial stages of the analysis of an existing 100 inch telescope for use as an optical communications receiver.

  8. The regime of aerosol optical depth over Central Asia based on MODIS Aqua Deep Blue data

    NASA Astrophysics Data System (ADS)

    Floutsi, Athina; KorrasCarraca, Marios; Matsoukas, Christos; Biskos, George

    2015-04-01

    Atmospheric aerosols, both natural and anthropogenic, can affect the regional and global climate through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. To quantify these effects it is therefore important to determine the aerosol load, and an effective way to do that is by measuring the aerosol optical depth (AOD). In this study we investigate the spatial and temporal variability of the AOD over the climatically sensitive region of Central Asia (36° N - 50° N, 46° E - 75° E), which has significant sources of both natural and anthropogenic particles. The primary source of anthropogenic particles is fossil fuel combustion occurring mainly at oil refineries in the Caspian Sea basin. Natural particles originate mostly from the two deserts in the region (namely Kara-Kum and Kyzyl-Kum), where persistent dust activity is observed. Another source is the Aral Sea region, which due to its phenomenal desertification also drives an intense salt and dust transport from the exposed sea-bed to the surrounding regions. This transport is of particular interest because of health-hazardous materials contained in the Aral Sea sea-bed. For our analysis we use Level-3 daily MODIS - Aqua Dark Target - Deep Blue combined product, from the latest MODIS collection (006), available in 1° x 1° resolution (about 100 km x 100 km) over the period 2002-2014.Our first results indicate a significant spatial variability of the aerosol load over the study region. The data also show a clear seasonal cycle, with large aerosol load being associated with strong dust activity during spring and summer (AOD up to 0.5), and low during autumn and winter (AOD up to 0.4). In spring and summer significant aerosol load is observed in the Garabogazköl basin, Northeast and South-southeast Caspian Sea (offshore North Iran and Azerbaijan), as well as southwest of the Aral Sea. In the later region, the high AOD values can be explained by export of

  9. Multi-channel fiber photometry for population neuronal activity recording.

    PubMed

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-10-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals.

  10. Multi-channel fiber photometry for population neuronal activity recording

    PubMed Central

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-01-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals. PMID:26504642

  11. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

    PubMed Central

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-01-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4. PMID:27126353

  12. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal.

    PubMed

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-04-29

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4.

  13. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-04-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4.

  14. Ti:sapphire-pumped deep-infrared femtosecond optical parametric oscillator based on CdSiP2.

    PubMed

    Ramaiah-Badarla, V; Chaitanya Kumar, S; Esteban-Martin, A; Devi, K; Zawilski, K T; Schunemann, P G; Ebrahim-Zadeh, M

    2016-04-15

    We report on a femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on the Kerr-lens-mode-locked Ti:sapphire laser as the pump source. By deploying a novel cascaded intracavity arrangement, comprising a femtosecond OPO based on the nonlinear crystal, CdSiP2, synchronously pumped internal to a MgO:PPLN femtosecond OPO, we have generated broadly tunable radiation across 5958-8117 nm using rapid static cavity delay tuning, with a maximum power of 64 μW at 6791 nm, limited by the absorption in mirror substrates as well as polarization-dependent intracavity losses. The deep-IR idler power exhibits excellent passive stability of better than 1.1% rms over 2 h, with a spectral bandwidth as large as ∼650 nm at ∼6800 nm. The demonstrated concept is generic and can be similarly deployed in other operating time scales and wavelength regions, also using different laser pump sources and nonlinear materials.

  15. Deep optical observations of the γ-ray pulsar PSR J0007+7303 in the CTA 1 supernova remnant

    NASA Astrophysics Data System (ADS)

    Mignani, R. P.; de Luca, A.; Rea, N.; Shearer, A.; Collins, S.; Torres, D. F.; Hadasch, D.; Caliandro, A.

    2013-04-01

    The Fermi Large Area Telescope discovered the time signature of a radio-silent pulsar coincident with RX J0007.0+7302, a plerion-like X-ray source at the centre of the CTA 1 supernova remnant. The inferred timing parameters of the γ-ray pulsar PSR J0007+7303 (P = 315.8 ms; dot{P} ˜ 3.6× 10^{-13} s s-1) point to a Vela-like neutron star, with an age comparable to that of CTA 1. The PSR J0007+7303 low distance (˜1.4 kpc), interstellar absorption (AV ˜ 1.6), and relatively high energy loss rate (dot{E} ˜ 4.5× 10^{35} erg s-1), make it a suitable candidate for an optical follow-up. Here, we present deep optical observations of PSR J0007+7303. The pulsar is not detected in the Gran Telescopio Canarias images down to a limit of r' ˜ 27.6 (3σ), the deepest ever obtained for this pulsar, while William Herschel Telescope images yield a limit of V ˜ 26.9. Our r'-band limit corresponds to an optical emission efficiency η _opt equiv L_opt/dot{E} lesssim 9.4 × 10^{-8}. This limit is more constraining than those derived for other Vela-like pulsars, but is still above the measured optical efficiency of the Vela pulsar. We compared the optical upper limits with the extrapolation of the XMM-Newton X-ray spectrum and found that the optical emission is compatible with the extrapolation of the X-ray power-law component, at variance with what is observed, e.g. in the Vela pulsar.

  16. Sensitive Spitzer Photometry of Supermassive Black Holes at the Final Stage of Adolescence

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad; Netzer, Hagai; Mor, Rivay; Trakhtenbrot, Benny

    2011-05-01

    We propose to obtain sensitive Spitzer snapshot observations of a unique sample of 35 Sloan Digital Sky Survey quasars at redshift 4.8 for which we obtained reliable, Mg II-based determinations of the supermassive black hole (SMBH) mass and normalized accretion rate (L/L_Edd). These quasars appear to mark the final stage of SMBH `adolescence' in the history of the Universe as their SMBHs are significantly less massive and their L/L_Edd values are significantly higher with respect to their counterparts at lower redshifts. Our observations will provide both 1) deep coverage of the fields around these quasars which will be utilized as crucial priors for our approved Herschel/SPIRE observations of these sources, and 2) coverage of the rest-frame optical SEDs of these fast accreting quasars. The results will maximize our ability to measure the star-formation rate in the host galaxies of these quasars using Herschel. We will thus be able to investigate correlations between SMBH growth and star-forming activity in the early Universe. The Spitzer photometry will also provide invaluable information about the shape of the rest-frame optical continuum in these quasars which will be used to search for extreme disk properties that may be signatures of the remarkably high accretion rates in these sources.

  17. Multicolor surface photometry of powerful radio galaxies

    SciTech Connect

    Smith, E.P.

    1988-01-01

    CCD images of 72 powerful radio galaxies have been obtained with the KPNO 2.1m, 4m and CTIO 4m telescopes utilizing B, V, and R filters to study the colors and other photometric properties of these large systems. The GASP software package was used for the data reduction and detailed 2-d surface photometry. In addition, image modeling techniques were employed to investigate the contributions to galaxy properties by point-like nuclear sources seen in some of these galaxies. It was found that powerful radio galaxies show a much higher frequency than normal bright ellipticals of having optical morphologies which deviate from elliptical symmetry. Approximately 50% of the sample exhibit non-elliptically symmetric isophotes. These prominent distortions are present at surface brightness levels of {le} 25 V mag/(arc sec){sup 2}. In addition, a large fraction ({approximately}50%) of the remaining radio galaxies without the aforementioned morphological peculiarities have large isophotal twists ({Delta}P.A. {ge} 10{degree}) or ellipticity gradients. Significantly {approximately}50% of the galaxies with strong optical emission lines in their spectra display optically peculiar structures very similar to those found by Toomre and Toomre (1972) in their simulations of interacting disk galaxies. The galaxies with weak emission lines in their spectra are less frequently ({approximately}10%) distorted from elliptical shape. Those that are exhibit features like isophote twists, double nuclei and close companion galaxies embedded in the radio galaxy optical isophotes. The (B-V) colors of many of the powerful radio galaxies with strong emission lines are blue relative to normal giant ellipticals at the same redshift.

  18. Photometry of astrometric reference stars

    NASA Technical Reports Server (NTRS)

    Castelaz, Michael W.; Persinger, Tim; Stein, John W.; Prosser, James; Powell, Harry D.

    1991-01-01

    UBVRI, DDO, and uvby, H-beta photometry of astrometric reference stars is presented. Spectral types and luminosity classifications made from the colors are used to determine their spectroscopic parallaxes. In this paper, colors for 309 stars in 25 regions are given, and classifications for 210 stars have been made. These stars form reference frames in the Allegheny Observatory Multichannel Astrometric Photometer astrometric program, and in the Praesepe cluster reduced by Russell (1976). It is found that the present photometric spectral types are reliable to within 2.5 spectral subclasses.

  19. Surface photometry of comet P/Encke

    NASA Astrophysics Data System (ADS)

    Djorgovski, S.; Spinrad, H.

    1985-05-01

    A scheme to clean cometary digital images from offending background-star trails, and this technique has been applied to a pair of deep Kitt Peak 4-m plates of comet P/Encke, taken in October 1980. Simultaneous and subsequent digital spectra have been obtained at Lick Observatory. The non-polluted coma images show a strong asymmetric sunward-oriented fan/jet, and an extended and rounder (mostly gaseous) main coma, out to approximately 100,000 km radius. The stellar-trail point-spread function has a narrow width (sigma approximately 0.6 arcsec), so that spatial resolution better than approximately 300 km is achieved at the comet. The photometric gradient near the nucleus is very steep, strongly suggesting an icy-grain component which evaporates quickly (at radii equal to or less than 500 km) in the sunlight. Further from the nucleus, the profile becomes shallower, bluer, and more gas dominated. The effect of solar radiation pressure on C2, CN, and other molecules is probably responsible for the rounding of the outer, fainter isophotes. The source of the molecules is likely to be larger than the nucleus itself, and a substantial fraction may originate in the jet. The technique described here may also be applicable in surface photometry of galaxies, in cases where the heavy image pollution by foreground stars is present.

  20. Surface photometry of comet P/Encke

    NASA Technical Reports Server (NTRS)

    Djorgovski, S.; Spinrad, H.

    1985-01-01

    A scheme to clean cometary digital images from offending background-star trails, and this technique has been applied to a pair of deep Kitt Peak 4-m plates of comet P/Encke, taken in October 1980. Simultaneous and subsequent digital spectra have been obtained at Lick Observatory. The non-polluted coma images show a strong asymmetric sunward-oriented fan/jet, and an extended and rounder (mostly gaseous) main coma, out to approximately 100,000 km radius. The stellar-trail point-spread function has a narrow width (sigma approximately 0.6 arcsec), so that spatial resolution better than approximately 300 km is achieved at the comet. The photometric gradient near the nucleus is very steep, strongly suggesting an icy-grain component which evaporates quickly (at radii equal to or less than 500 km) in the sunlight. Further from the nucleus, the profile becomes shallower, bluer, and more gas dominated. The effect of solar radiation pressure on C2, CN, and other molecules is probably responsible for the rounding of the outer, fainter isophotes. The source of the molecules is likely to be larger than the nucleus itself, and a substantial fraction may originate in the jet. The technique described here may also be applicable in surface photometry of galaxies, in cases where the heavy image pollution by foreground stars is present.

  1. Feasibility of infrared Earth tracking for deep-space optical communications.

    PubMed

    Chen, Yijiang; Hemmati, Hamid; Ortiz, Gerry G

    2012-01-01

    Infrared (IR) Earth thermal tracking is a viable option for optical communications to distant planet and outer-planetary missions. However, blurring due to finite receiver aperture size distorts IR Earth images in the presence of Earth's nonuniform thermal emission and limits its applicability. We demonstrate a deconvolution algorithm that can overcome this limitation and reduce the error from blurring to a negligible level. The algorithm is applied successfully to Earth thermal images taken by the Mars Odyssey spacecraft. With the solution to this critical issue, IR Earth tracking is established as a viable means for distant planet and outer-planetary optical communications. © 2012 Optical Society of America

  2. Relationships between laser flare photometry values and complications of uveitis.

    PubMed

    Gonzales, C A; Ladas, J G; Davis, J L; Feuer, W J; Holland, G N

    2001-12-01

    To determine whether relationships exist between elevated laser flare photometry values and common abnormalities and complications associated with uveitis. We retrospectively studied all patients with uveitis on whom laser flare photometry measurements ("flare") were obtained (N = 111) at 2 academic medical centers. The first laser flare photometry values obtained for each patient were compared with the presence or absence of the following abnormalities or complications associated with uveitis: keratic precipitates, posterior synechiae, cataract, macular edema, optic disc edema, and glaucoma. In bilateral cases, the eye with the higher flare was used in primary analyses. Flare was significantly higher in patients with posterior synechiae (P<.001) and in those with macular edema (P =.02) than in patients with uveitis who did not have these complications. Flare was significantly higher in patients with prior cataract surgery or cataract at the study visit than in those without cataracts (P =.001). There was no significant difference in flare between patients with and without keratic precipitates, optic disc edema, or glaucoma. No relationships were found between abnormalities or complications and the level of inflammatory cells or flare as determined by clinical assessment. We also identified an inverse relationship between flare and visual acuity that was not completely explained by the presence of complications in a stepwise regression model. Although causal relationships were not established, associations between flare and some complications of uveitis suggest that aqueous humor protein may be an important factor in the development of these problems. Consequently, laser flare photometry could play a role in predicting outcomes or monitoring therapy for patients with uveitis.

  3. Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale

    NASA Astrophysics Data System (ADS)

    Miville-Deschênes, M.-A.; Duc, P.-A.; Marleau, F.; Cuillandre, J.-C.; Didelon, P.; Gwyn, S.; Karabal, E.

    2016-08-01

    Diffuse Galactic light has been observed in the optical since the 1930s. We propose that, when observed in the optical with deep imaging surveys, it can be used as a tracer of the turbulent cascade in the diffuse interstellar medium (ISM), down to scales of about 1 arcsec. Here we present a power spectrum analysis of the dust column density of a diffuse cirrus at high Galactic latitude (l ≈ 198°, b ≈ 32°) as derived from the combination of a MegaCam g-band image, obtained as part of the MATLAS large programme at the CFHT, with Planck radiance and WISE 12 μm data. The combination of these three datasets have allowed us to compute the density power spectrum of the H i over scales of more than three orders of magnitude. We found that the density field is well described by a single power law over scales ranging from 0.01 to 50 pc. The exponent of the power spectrum, γ = -2.9 ± 0.1, is compatible with what is expected for thermally bi-stable and turbulent H i. We did not find any steepening of the power spectrum at small scales indicating that the typical scale at which turbulent energy is dissipated in this medium is smaller than 0.01 pc. The ambipolar diffusion scenario that is usually proposed as the main dissipative agent, is consistent with our data only if the density of the cloud observed is higher than the typical values assumed for the cold neutral medium gas. We discuss the new avenue offered by deep optical imaging surveys for the study of the low density ISM structure and turbulence.

  4. Infrared Photometry of 487 Sources in the Inner Regions of NGC 5128 (Centaurus A)

    NASA Astrophysics Data System (ADS)

    Alonso, M. Victoria; Minniti, Dante

    1997-04-01

    We study the sources present in the inner 3 kpc region of NGC 5128 (Cen A), most of which are star clusters of different ages. Photometry of archival Hubble Space Telescope WFPC images (F675W filter) is complemented with IR photometry (JHK' filters) obtained with the IRAC2B infrared array camera at the ESO/MPI 2.2 m telescope. From IR color maps we divide the field into two regions: a clear region outside the dust lane, and an obscured region well inside the dust lane of NGC 5128. In the unreddened region there is a great variety of sources such as globular clusters, star associations, and H II regions. These sources are not individual stars, which would be too faint to be resolved from ground-based telescopes. The vast majority of IR sources in the reddened region, where the dust lane dominates, are not seen at all in the deep HST images. The presence of large amounts of differential extinction makes it difficult to evaluate them. In total, there are 372 objects detected in the inner region of NGC 5128. From them, 125 objects are detected both in IR and HST frames. There are 247 IR sources without optical counterparts (47 in the clear region and 200 in the dust lane). Accounting for the small volume sampled, there must be a total of ~500 sources with K < 18 in the dust lane region. The distribution of these sources is rather uniform and not particularly centrally concentrated. This fact suggests that the majority of them are located in a disk, as would be expected if they are young associations or clusters. The degree of background and foreground contamination is evaluated using observations of a nearby field. We found 115 IR sources in this field. The nucleus itself is invisible in deep optical images, but it is clearly identified in the IR. In the region just south of the nucleus the extinction must be larger than AK = 3. In the clear region, where the effect of the dust lane is negligible, we have identified some objects as intermediate-age clusters containing

  5. Picocyanobacteria and deep-ocean fluorescent dissolved organic matter share similar optical properties

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Gonsior, Michael; Luek, Jenna; Timko, Stephen; Ianiri, Hope; Hertkorn, Norbert; Schmitt-Kopplin, Philippe; Fang, Xiaoting; Zeng, Qinglu; Jiao, Nianzhi; Chen, Feng

    2017-05-01

    Marine chromophoric dissolved organic matter (CDOM) and its related fluorescent components (FDOM), which are widely distributed but highly photobleached in the surface ocean, are critical in regulating light attenuation in the ocean. However, the origins of marine FDOM are still under investigation. Here we show that cultured picocyanobacteria, Synechococcus and Prochlorococcus, release FDOM that closely match the typical fluorescent signals found in oceanic environments. Picocyanobacterial FDOM also shows comparable apparent fluorescent quantum yields and undergoes similar photo-degradation behaviour when compared with deep-ocean FDOM, further strengthening the similarity between them. Ultrahigh-resolution mass spectrometry (MS) and nuclear magnetic resonance spectroscopy reveal abundant nitrogen-containing compounds in Synechococcus DOM, which may originate from degradation products of the fluorescent phycobilin pigments. Given the importance of picocyanobacteria in the global carbon cycle, our results indicate that picocyanobacteria are likely to be important sources of marine autochthonous FDOM, which may accumulate in the deep ocean.

  6. Picocyanobacteria and deep-ocean fluorescent dissolved organic matter share similar optical properties

    PubMed Central

    Zhao, Zhao; Gonsior, Michael; Luek, Jenna; Timko, Stephen; Ianiri, Hope; Hertkorn, Norbert; Schmitt-Kopplin, Philippe; Fang, Xiaoting; Zeng, Qinglu; Jiao, Nianzhi; Chen, Feng

    2017-01-01

    Marine chromophoric dissolved organic matter (CDOM) and its related fluorescent components (FDOM), which are widely distributed but highly photobleached in the surface ocean, are critical in regulating light attenuation in the ocean. However, the origins of marine FDOM are still under investigation. Here we show that cultured picocyanobacteria, Synechococcus and Prochlorococcus, release FDOM that closely match the typical fluorescent signals found in oceanic environments. Picocyanobacterial FDOM also shows comparable apparent fluorescent quantum yields and undergoes similar photo-degradation behaviour when compared with deep-ocean FDOM, further strengthening the similarity between them. Ultrahigh-resolution mass spectrometry (MS) and nuclear magnetic resonance spectroscopy reveal abundant nitrogen-containing compounds in Synechococcus DOM, which may originate from degradation products of the fluorescent phycobilin pigments. Given the importance of picocyanobacteria in the global carbon cycle, our results indicate that picocyanobacteria are likely to be important sources of marine autochthonous FDOM, which may accumulate in the deep ocean. PMID:28513605

  7. CHEOPS: a space telescope for ultra-high precision photometry of exoplanet transits

    NASA Astrophysics Data System (ADS)

    Fortier, Andrea; Beck, Thomas; Benz, Willy; Broeg, Christopher; Cessa, Virginie; Ehrenreich, David; Thomas, Nicolas

    2014-08-01

    The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission (expected to launch in 2017) dedicated to search for exoplanet transits by means of ultra-high precision photometry. CHEOPS will provide accurate radii for planets down to Earth size. Targets will mainly come from radial velocity surveys. The CHEOPS instrument is an optical space telescope of 30 cm clear aperture with a single focal plane CCD detector. The tube assembly is passively cooled and thermally controlled to support high precision, low noise photometry. The telescope feeds a re-imaging optic, which supports the straylight suppression concept to achieve the required Signal to Noise.

  8. REPEATABILITY OF AUTOMATED VESSEL DENSITY AND SUPERFICIAL AND DEEP FOVEAL AVASCULAR ZONE AREA MEASUREMENTS USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Diurnal Findings.

    PubMed

    Yanik Odabaş, Özge; Demirel, Sibel; Özmert, Emin; Batıoğlu, Figen

    2017-05-02

    To evaluate the repeatability of vessel density and superficial and deep foveal avascular zone measurements using optical coherence tomography angiography, and to specify a diurnal change range. Forty-six eyes of 25 healthy individuals were included. Optical coherence tomography angiography measurements were planned for three consecutive sessions, with 3 hours in between them. AngioVue software of the RTVue XR Avanti was used. Superficial and deep retinal layer vessel density values, including the whole retina, fovea, and each parafoveal zone, were obtained from the software. The intraclass correlation, coefficient of variation, and coefficient of repeatability were calculated for each parameter. The whole image intraclass correlation value was 0.81 for the superficial and 0.86 for the deep layer among the three consecutive sessions. The smallest real difference (coefficient of repeatability) value of whole image measurements was 7.72% for the superficial and 9.84% for the deep retinal layer. Foveal avascular zone area intraclass correlation value was 0.97 for the superficial and 0.83 for the deep retinal layer. The optical coherence tomography angiography analysis provides quantitative data about the retinal microvasculature, which could be used to distinguish between normal and pathology. Changes in superficial vessel density >8% and deep vessel density >10% may be considered as real clinical change rather than variation.

  9. Conceptual design and algorithm evaluation for a very accurate imaging star tracker for deep- space optical communications

    NASA Astrophysics Data System (ADS)

    Maurer, Donald E.; Boone, Bradley G.

    2002-12-01

    The National Aeronautics and Space Administration is planning high data rate optical communications for future deep space missions. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is responding by developing concepts for implementing optical communications terminals that are more compact and lightweight than heretofore. An essential requirement for these long-range optical links is a high-precision pointing and tracking system. Focal plane array (FPA)-based star trackers that enable open-loop pointing and tracking are necessary. Spacecraft attitude instabilities, emphemeris errors, tracking sensor noise, clock errors, and mechanical misalignments are among the error sources that must be minimized and compensated for. To achieve this JHU/APL has developed an imaging star tracker concept using redundant multi-aperture FPA's symmetrically disposed about the laser downlink. Centroid estimation and pattern matching techniques account for aberration and motion errors. Robustness, sensitivity to detection thresholds, field-of-view sizing, number of stars per frame, missed detections, false alarms, and position biases, as well as stellar catalog size and star selection, will be described. Finally the conceptual design of a frame-to-frame integration method and sensor fusion algorithm (such as a Kalman filter) will be considered. The goal is to achieve a system pointing and tracking error significantly less than 1 μrad.

  10. Deep learning for evaluating difficult-to-detect incomplete repairs of high fluence laser optics at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Mundhenk, T. Nathan; Kegelmeyer, Laura M.; Trummer, Scott K.

    2017-03-01

    Two machine-learning methods were evaluated to help automate the quality control process for mitigating damage sites on laser optics. The mitigation is a cone-like structure etched into locations on large optics that have been chipped by the high fluence (energy per unit area) laser light. Sometimes the repair leaves a difficult to detect remnant of the damage that needs to be addressed before the optic can be placed back on the beam line. We would like to be able to automatically detect these remnants. We try Deep Learning (convolutional neural networks using features autogenerated from large stores of labeled data, like ImageNet) and find it outperforms ensembles of decision trees (using custom-built features) in finding these subtle, rare, incomplete repairs of damage. We also implemented an unsupervised method for helping operators visualize where the network has spotted problems. This is done by projecting the credit for the result backwards onto the input image. This shows regions in an image most responsible for the networks decision. This can also be used to help understand the black box decisions the network is making and potentially improve the training process.

  11. VAPHOT: Precision differential aperture photometry package

    NASA Astrophysics Data System (ADS)

    Deeg, Hans J.; Doyle, Laurance R.

    2013-09-01

    VAPHOT is an aperture photometry package for precise time-series photometry of uncrowded fields, geared towards the extraction of target lightcurves of eclipsing or transiting systems. Its photometric main routine works within the IRAF (ascl:9911.002) environment and is built upon the standard aperture photometry task 'phot' from IRAF, using optimized aperture sizes. The associated analysis program 'VANALIZ' works in the IDL environment. It performs differential photometry with graphical and numerical output. VANALIZ produces plots indicative of photometric stability and permits the interactive evaluation and weighting of comparison stars. Also possible is the automatic or manual suppression of data-points and the output of statistical analyses. Several methods for the calculation of the reference brightness are offered. Specific routines for the analysis of transit 'on'-'off' photometry, comparing the target brightness inside against outside a transit are also available.

  12. Comparative Study of Optical and Radio-Frequency Communication Systems for a Deep-Space Mission

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Wilson, K.; Sue, M. K.; Harcke, L. J.; Wilhelm, M.; Chen, C.-C.; Lesh, J.; Feria, Y.; Rascoe, D.; Lansing, F.

    1997-01-01

    We have performed a study on telecommunication systems for a hypothetical mission to Mars. The objective of the study was to evaluate and compare the benefits that microwave-X-band (8.4 GHz) and Ka-band (32 GHz) - and optical communications technologies a afford to future missions. The telecommunication systems were required to return data after launch and in orbit at 2.7 AU with daily data volumes of 0.1, 1.0, or 10.0 Gbits (Gb). Spacecraft terminals capable of delivering each of the three data volumes were proposed and characterized in terms of mass, power consumption, size, and cost. The estimated parameters for X-band, Ka-band, and optical frequencies are compared and presented here. For all cases, the optical light terminal exhibits about 60 percent of the mass of the corresponding radio frequency (RF) subsystem. Power consumption is comparable for all three technologies at a 0.1 Gb/day data volume, but the power required at either Ka-band or optical is less than half of the X-band requirement at 10 Gb/day. These benefits can be obtained only with a suitable investment in reception facilities for Ka-band or optical frequencies.

  13. Non-interferometric deep optical resolution photoacoustic remote sensing microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    HajiReza, Parsin H.; Bell, Kevan L.; Shi, Wei; Zemp, Roger J.

    2017-03-01

    A novel all-optical non-contact photoacoustic microscopy system is introduced. The confocal configuration is used to ensure detection of initial pressure shock wave-induced intensity reflections at the subsurface origin where pressures are largest. Phantom studies confirm signal dependence on optical absorption, index-contrast, and excitation fluence. Taking advantage of a focused1310 nm interrogation beam, the penetration depth of the system is improved to 2mm for an optical resolution system. High signal-to-noise ratios (>60dB) with 2.5 cm working distance from the objective lens to the sample is achieved. Real-time in-vivo imaging of microvasculature and melanoma tumors are demonstrated.

  14. Deep-space navigation applications of improved ground-based optical astrometry

    NASA Technical Reports Server (NTRS)

    Null, G. W.; Owen, W. M., Jr.; Synnott, S. P.

    1992-01-01

    Improvements in ground-based optical astrometry will eventually be required for navigation of interplanetary spacecraft when these spacecraft communicate at optical wavelengths. Although such spacecraft may be some years off, preliminary versions of the astrometric technology can also be used to obtain navigational improvements for the Galileo and Cassini missions. This article describes a technology-development and observational program to accomplish this, including a cooperative effort with U.S. Naval Observatory Flagstaff Station. For Galileo, Earth-based astrometry of Jupiter's Galilean satellites may improve their ephemeris accuracy by a factor of 3 to 6. This would reduce the requirements for onboard optical navigation pictures, so that more of the data transmission capability (currently limited by high-gain antenna deployment problems) can be used for science data. Also, observations of European Space Agency (ESA) Hipparcos stars with asteroid 243 Ida may provide significantly improved navigation accuracy for a planned August 1993 Galileo spacecraft encounter.

  15. VizieR Online Data Catalog: gr photometry of Sextans A and Sextans B (Bellazzini+, 2014)

    NASA Astrophysics Data System (ADS)

    Bellazzini, M.; Beccari, G.; Fraternali, F.; Oosterloo, T. A.; Sollima, A.; Testa, V.; Galleti, S.; Perina, S.; Faccini, M.; Cusano, F.

    2014-04-01

    The tables present deep LBT/LBC g and r photometry of the stars having image quality parameters (provided by DAOPHOTII) CHI<=2 and SHARP within magnitude-dependent contours traced to include the bulk of stellar objects. The observations were achieved on the night og 2012-02-21 with the Large Binocular Camera at the Large Binocular Telescope in binocular mode; g images were acquired with the blue arm and r images with the red arm of the telescope/camera. The astrometry and the photometry were calibrated with stars in common with SDSS-DR9 (V/139). (2 data files).

  16. Vortex formation of a Bose-Einstein condensate in a rotating deep optical lattice

    SciTech Connect

    Kato, Akira; Nakano, Yuki; Kasamatsu, Kenichi; Matsui, Tetsuo

    2011-11-15

    We study the dynamics of vortex nucleation and lattice formation in a Bose-Einstein condensate in a rotating square optical lattice by numerical simulations of the Gross-Pitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical lattice. We make an extensive comparison with the experiments by R. A. Williams et al.[Phys. Rev. Lett. 104, 050404 (2010)], especially focusing on the issues of the critical rotation frequency for the first vortex nucleation and the vortex number as a function of rotation frequency.

  17. A Deep Space Optical Communications Demonstration with the Galileo Spacecraft on its Way to Jupiter (abstract)

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Lesh, J. R.; Yan, T-Y.

    1993-01-01

    The GOPEX (Galileo Optical communications from an Earth-based transmitter) demonstration was performed from transmitter sites at Table Mountain Observatory, CA and Starfire Optical Range, NM. The experiment was done over an eight day period, December 9 through December 16 as Galileo receded from Earth on its way to Jupiter. At a range of 6 million kilometers (15 times the Earth-Moon distance), the transmission from Table Mountain Observatory eight days after Earth-flyby represents the longest range for laser transmission and detection.

  18. An optical clearing technique for plant tissues allowing deep imaging and compatible with fluorescence microscopy.

    PubMed

    Warner, Cherish A; Biedrzycki, Meredith L; Jacobs, Samuel S; Wisser, Randall J; Caplan, Jeffrey L; Sherrier, D Janine

    2014-12-01

    We report on a nondestructive clearing technique that enhances transmission of light through specimens from diverse plant species, opening unique opportunities for microscope-enabled plant research. After clearing, plant organs and thick tissue sections are amenable to deep imaging. The clearing method is compatible with immunocytochemistry techniques and can be used in concert with common fluorescent probes, including widely adopted protein tags such as GFP, which has fluorescence that is preserved during the clearing process. © 2014 American Society of Plant Biologists. All Rights Reserved.

  19. New optical and radio frequency angular tropospheric refraction models for deep space applications

    NASA Technical Reports Server (NTRS)

    Berman, A. L.; Rockwell, S. T.

    1976-01-01

    The development of angular tropospheric refraction models for optical and radio frequency usage is presented. The models are compact analytic functions, finite over the entire domain of elevation angle, and accurate over large ranges of pressure, temperature, and relative humidity. Additionally, FORTRAN subroutines for each of the models are included.

  20. Optical coherence microscopy for deep tissue imaging of the cerebral cortex with intrinsic contrast

    PubMed Central

    Srinivasan, Vivek J.; Radhakrishnan, Harsha; Jiang, James Y.; Barry, Scott; Cable, Alex E.

    2012-01-01

    In vivo optical microscopic imaging techniques have recently emerged as important tools for the study of neurobiological development and pathophysiology. In particular, two-photon microscopy has proved to be a robust and highly flexible method for in vivo imaging in highly scattering tissue. However, two-photon imaging typically requires extrinsic dyes or contrast agents, and imaging depths are limited to a few hundred microns. Here we demonstrate Optical Coherence Microscopy (OCM) for in vivo imaging of neuronal cell bodies and cortical myelination up to depths of ~1.3 mm in the rat neocortex. Imaging does not require the administration of exogenous dyes or contrast agents, and is achieved through intrinsic scattering contrast and image processing alone. Furthermore, using OCM we demonstrate in vivo, quantitative measurements of optical properties (index of refraction and attenuation coefficient) in the cortex, and correlate these properties with laminar cellular architecture determined from the images. Lastly, we show that OCM enables direct visualization of cellular changes during cell depolarization and may therefore provide novel optical markers of cell viability. PMID:22330462

  1. The optical identification content of the Einstein Observatory deep X-ray survey of a region in Pavo

    NASA Technical Reports Server (NTRS)

    Griffiths, R. E.; Murray, S. S.; Giacconi, R.; Bechtold, J.; Murdin, P.; Smith, M.; Macgillivray, H. T.; Ward, M.; Danziger, J.; Lub, J.

    1983-01-01

    Results are presented from the Einstein deep X-ray survey in Pavo, with correlated optical and radio observations of a complete sample of candidate identifications. There are 16 X-ray sources detected with positional accuracy better than 10 arcsec, of which five are identified, with a further seven (and a maximum nine) probable identifications. Of the identified sources, four are QSOs with J-magnitude about 20 (one is an inverted spectrum radio source) and one is associated with extended emission from a pair or cluster of galaxies. Of the probable identifications, one is a galaxy and the rest are a subset of a yellow stellar object population which may also be QSOs. Identifications with QSOs and QSO candidates with J less than 24 account for 60-80 percent of the detected sources.

  2. Toward More Precise Photometric Redshifts: Calibration Via CCD Photometry

    NASA Astrophysics Data System (ADS)

    Brunner, Robert J.; Connolly, Andrew J.; Szalay, Alexander S.; Bershady, Matthew A.

    1997-06-01

    We present the initial results from a deep, multiband photometric survey of selected high Galactic latitude redshift fields. Previous work using the photographic data of Koo and Kron demonstrated that the distribution of galaxies in the multidimensional flux space U, B, R, and I is nearly planar. The position of a galaxy within this plane is determined by its redshift, luminosity, and spectral type (Connolly et al. 1995). Using recently acquired deep CCD photometry in existing, published redshift fields, we have redetermined the distribution of galaxies in this four-dimensional magnitude space. Furthermore, from our CCD photometry and the published redshifts, we have quantified the photometric-redshift relation within the standard AB magnitude system. This empirical relation has a measured dispersion of σz ~ 0.02 for z < 0.4. With this work we are reaching the asymptotic intrinsic dispersions (σz ~ 0.016 for z < 0.4) that were predicted from simulated distributions of galaxy colors. This result will prove useful in providing estimated redshifts for large photometric surveys, as well as improve the sampling of specific redshift regions for spectroscopic surveys through the use of an estimated redshift selection criteria.

  3. Photometry of late type stars

    NASA Technical Reports Server (NTRS)

    Doherty, L. R.

    1972-01-01

    Broad band filter photometry for 57 bright stars of spectral type A2 discussed with peak instrument responses at 3320, 2980, 2460 and 1910 A. The data include nearly all usable filter observations of G, K and M types. Sampling is nearly complete for A and F giants and supergiants, with the exception of Cepheid variables. The basic results presented are relative digital counting rates obtained with a field-stop aperture of 10 minutes of arc. Characteristics of the four filter-photometer combinations and errors are discussed. Some observations require substantial correction if they are to represent the visually brightest star in the field. These corrections and the effects of interstellar reddening are discussed. The adjusted counts are then used to construct color-color diagrams and are compared to the recent SAO grid of model atmospheres.

  4. High Speed Photometry for BUSCA

    NASA Astrophysics Data System (ADS)

    Cordes, O.; Reif, K.

    The camera BUSCA (Bonn University Simultaneous CAmera) is a standard instrument at the 2.2m telescope at Calar Alto Observatory (Spain) since 2001. At the moment some modifications of BUSCA are planned and partially realised. One major goal is the replacement of the old thick CCDs in the blue, yellow-green, and near-infrared channels. The newer CCDs have better cosmetics and performance in sensitivity. The other goal is to replace the old "Heidelberg"-style controller with a newly designed controller with the main focus on high-speed readout and on an advanced windowing mechanism. We present a theoretical analysis of the new controller design and its advantage in high speed photometry of rapidly pulsating stars. As an example PG1605+072 was chosen which was observed with BUSCA before in 2001 and 2002.

  5. The 2060 Chiron: CCD photometry

    NASA Technical Reports Server (NTRS)

    Bus, Schelte J.; Bowell, Edward; Harris, Alan W.

    1987-01-01

    R-band CCD photometry of 2060 was carried out on nine nights in Nov. and Dec. 1986. The rotation period is 5.9181 + or - 0.0003 hr and the peak to peak lightcurve amplitude is 0.088 + or - 0.0003 mag. Photometric parameters are H sub R = 6.24 + or - 0.02 mag and G sub R = + or - 0.15, though formal errors may not be realistic. The lightcurve has two pairs of extrema, but its asymmetry, as evidenced by the presence of significant odd Fourier harmonics, suggests macroscopic surface irregularities and/or the presence of some large scale albedo variegation. The observational rms residual is + or - 0.015 mag. On time scales from minutes to days there is no evidence for nonperiodic (cometary) brightness changes at the level of a few millimagnitudes.

  6. Macular pigment assessment by motion photometry.

    PubMed

    Moreland, J D

    2004-10-15

    A Moreland anomaloscope was modified to measure macular pigment optical density (MPOD) profiles by motion photometry. A grating (spatial frequency 0.38 c deg(-1)), whose alternate bars were filled, respectively, with 460 nm (maximum MP absorption) and 580 nm (zero MP absorption) lights, drifted steadily at 37 degrees s(-1). The subject adjusted the 580 nm radiance to minimise perceived motion (equiluminance between 460 and 580 nm). Five or more settings were made for two foveal fields (0.9 degrees and 2.2 degrees diameter) and 11 extrafoveal annular fields (0.8 degrees -7.5 degrees eccentricity). Twenty subjects made measurements for both eyes: some with replications. MPOD profiles varied in scale (0.18-0.75 for the 0.9 degrees foveal field) and in shape. A mean profile was derived. Foveal data were optimally aligned with annular data in that profile when plotted at 0.71 of the foveal field radius. Factors that limit precision were identified, such as fixation errors foveally and Troxler's effect parafoveally.

  7. Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    van Haren, H.; Taupier-Letage, I.; Aguilar, J. A.; Albert, A.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J.-J.; Auer, R.; Baret, B.; Basa, S.; Bazzotti, M.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bou-Cabo, M.; Bouwhuis, M. C.; Brown, A.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Carminati, G.; Carr, J.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Charvis, Ph.; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Cottini, N.; Coyle, P.; Curtil, C.; de Bonis, G.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; Emanuele, U.; Ernenwein, J.-P.; Escoffier, S.; Fehr, F.; Flaminio, V.; Fratini, K.; Fritsch, U.; Fuda, J.-L.; Giacomelli, G.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; de Jong, M.; Kalantar-Nayestanaki, N.; Kalekin, O.; Kappes, A.; Katz, U.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kretschmer, W.; Lahmann, R.; Lamare, P.; Lambard, G.; Larosa, G.; Laschinsky, H.; Lefèvre, D.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Lucarelli, F.; Lyons, K.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J. A.; Maurin, G.; Mazure, A.; Melissas, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Motz, H.; Naumann, C.; Neff, M.; Ostasch, R.; Palioselitis, G.; Păvălaş, G. E.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Picq, C.; Pillet, R.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Radu, A.; Reed, C.; Riccobene, G.; Richardt, C.; Rujoiu, M.; Russo, G. V.; Salesa, F.; Schoeck, F.; Schuller, J.-P.; Shanidze, R.; Simeone, F.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Tamburini, C.; Tasca, L.; Toscano, S.; Vallage, B.; van Elewyck, V.; Vecchi, M.; Vernin, P.; Wijnker, G.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

    2011-08-01

    An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutrino telescope near Toulon, France, thus providing a unique opportunity to compare high-resolution acoustic and optical observations between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward vertical currents of magnitudes up to 0.03 m s-1 in late winter and early spring 2006. In the same period, observations were made of enhanced levels of acoustic reflection, interpreted as suspended particles including zooplankton, by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These observations coincided with high light levels detected by the telescope, interpreted as increased bioluminescence. During winter 2006 deep dense-water formation occurred in the Ligurian subbasin, thus providing a possible explanation for these observations. However, the 10-20 days quasi-periodic episodes of high levels of acoustic reflection, light and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for suspended material to be moved vertically later in the year is local advection, linked with topographic boundary current instabilities along the rim of the 'Northern Current'.

  8. In vivo imaging of cortical vitreous using 1050-nm swept-source deep range imaging optical coherence tomography.

    PubMed

    Stanga, Paulo E; Sala-Puigdollers, Anna; Caputo, Silvestro; Jaberansari, Hojr; Cien, Monica; Gray, Jane; D'Souza, Yvonne; Charles, Stephen J; Biswas, Susmito; Henson, David B; McLeod, David

    2014-02-01

    To image the cortical vitreous, determine the prevalence of the bursa premacularis and space of Martegiani, and measure the dimensions of the bursa using the new 1050-nm swept-source deep range imaging optical coherence tomography (DRI OCT-1 Atlantis). Retrospective cross-sectional study. One hundred and nineteen consecutive patients (5-100 years) underwent an OCT scan using 1050-nm swept-source deep range imaging optical coherence tomography. Prevalence of the bursa premacularis and space of Martegiani and the stage of posterior vitreous detachment (PVD) were determined. The horizontal (width) and anteroposterior (depth) dimensions of the bursa were recorded along with the patient's age. A bursa was detected in 57.1% (136/238) of eyes. The bursa and space of Martegiani coexisted in 97.8% of eyes. Prevalence of detected bursa was 84.5% in eyes with either no PVD or perifoveal PVD only; the prevalence fell with further increases in the extent of PVD. Prevalence of detected bursa was 75.4% in patient group aged 0-60 years and 38% in the group aged 60-100 years. Mean width was 7001 μm (range: 3354-10 316 μm, SD: 1412 μm). Mean depth was 416 μm (range: 31-1189 μm, SD: 187 μm). Width and depth of the bursa did not correlate with age (R(2) width = 0.0316; R(2) depth = 0.0108). Bilateral bursa tended to be symmetrical in width but less so in depth (R(2) width = 0.63, P < .001; R(2) depth = 0.33, P < .001). Swept-source OCT has allowed us to demonstrate the almost invariable coexistence of the bursa premacularis and space of Martegiani. Swept-source OCT can image both in patients from as early as the first to as late as the tenth decade of life. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Effects of Pressure on Optically Active Deep Levels in Phosphorus Doped ZnSe

    NASA Astrophysics Data System (ADS)

    Weinstein, B. A.; Iota, V.

    1998-03-01

    We report high pressure photoluminescence (PL) and PL-excitation (PLE) studies at 8K of the 'midgap' emission in P-doped ZnSe using a diamond-cell with He medium. The dominant emission at low pressure is due to donor-acceptor-pair (DAP) transitions between shallow donors and deep trigonally relaxed P_Se acceptors.(J. Davies, et al., J. Luminescence 18/19, 322 (1979)) Its PL and PLE peaks shift by 8.2meV/kbar and 5.9meV/kbar, respectively -- Stokes shift decreasing with pressure. At 35kbar a new PL band, shifting to lower energy (-5.4meV/kbar), emerges from above the absorption edge, and concurrently the original DAP PL quenches. This shows that a resonant level, a deep donor or possibly a P_Se antibonding state,(R. Watts, et al., Phys. Rev. B3), 404 (1971) crosses the conduction edge into the gap. A third PL band is seen only with internse UV excitation. It occurs initially as a high energy shoulder of the original DAP peak, but shifts more rapidly upward (9.4meV/kbar) until it crosses the edge and quenches at 40kbar. We discuss candidates for this band, including donor-P_Se complexes, and we compare our results to similar work on the Zn vacancy in ZnSe. (figures)

  10. Optical dimensional metrology at Physikalisch-Technische Bundesanstalt (PTB) on deep sub-wavelength nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Bodermann, B.; Ehret, G.; Endres, J.; Wurm, M.

    2016-06-01

    The dark-field microscopy method with alternating grazing incidence UV illumination (UV-AGID) developed at Physikalisch-Technische Bundesanstalt offers the possibility of measuring individual isolated line structures with linewidths down to the sub-wavelength regime. In contrast, scatterometry is able and already widely used to measure average dimensional parameters of periodic structures down to the deep sub-wavelength regime. Both methods can be used for dimensional measurements of micro- and nanostructures, in particular the critical dimensions (CDs) on wafers or photomasks in the semiconductor industry, complementing each other favourably. Based on numerical simulations, we have investigated the ultimate limits of these two methods in the deep sub-wavelength regime. It has been shown that AGID microscopy in the DUV spectral range is in principle capable of measuring line structures with CDs down to a few 10 nm, depending on the structure material. For scatterometry, no fundamental limit has been observed. In practice, a technical limit due to the limited signal-to-noise ratio is expected for CDs of a few nm in width.

  11. 10 Gbps Colorless Optical Source in Wavelength-Division Multiplexed Passive Optical Networks for Monolithic Integration of Deep-Ridge Waveguide Electroabsorption Modulator with Planar Buried-Heterostructure Semiconductor Optical Amplifier

    NASA Astrophysics Data System (ADS)

    Kim, Dong Churl; Kim, Ki Soo; Kim, Hyun-Soo; Choi, Byung-Seok; Kwon, O.-Kyun

    2012-05-01

    For the 10 Gbps colorless optical source in wavelength-division multiplexed passive optical networks (WDM-PONs), we have fabricated a semiconductor optical amplifier-reflective electorabsorption modulator (SOA-REAM) by monolithic integration of deep-ridge waveguide REAM (DRW-REAM) with planar buried-heterostructure (PBH) SOA using a PNP-current blocking layer. The SOA-REAM has a spot-size convertor for easy fiber coupling. Using a butterfly module with an SMA connector, we have packaged the SOA-REAM. At a -10 dBm input power of 1550 nm, the saturation output power is about 6 dBm. At 10.7 Gbps, we can obtain clear eye diagrams, and the power penalty at 10-9 bit-error rate (BER) after 20 km transmission is less than 1 dB over 35 nm.

  12. A high performance fiber optic pressure penetrator for use in the deep ocean

    NASA Astrophysics Data System (ADS)

    Cowen, S. J.

    1981-02-01

    This report describes results obtained in an FY 80 developmental program carried out at the Naval Ocean System Center, San Diego, under Independent Exploratory Development funding. The objective was to develop a robust, fully-demountable, high pressure penetrator design suitable for coupling light signals transmitted by optical fiber elements in an undersea cable operated at high ambient hydrostatic pressure into an electronics package or manned space. The feasibility of constructing such penetrators utilizing Graded Refractive Index (GRIN) rod lenses as combination pressure barriers and imaging devices has been demonstrated. Prototype realizations have exhibited excellent optical throughput performance and readily survive in excess of 10,000 psi pressure differential as well as tolerating a wide temperature range. The design lends itself to hermetic construction for applications requiring no vapor diffusion over long mission durations. Such devices exhibit excellent potential for satisfying SUBSAFE requirements for manned submarine applications.

  13. Design and evaluation of an ultra-slim objective for in-vivo deep optical biopsy

    PubMed Central

    Landau, Sara M.; Liang, Chen; Kester, Robert T.; Tkaczyk, Tomasz S.; Descour, Michael R.

    2010-01-01

    An estimated 1.6 million breast biopsies are performed in the US each year. In order to provide real-time, in-vivo imaging with sub-cellular resolution for optical biopsies, we have designed an ultra-slim objective to fit inside the 1-mm-diameter hypodermic needles currently used for breast biopsies to image tissue stained by the fluorescent probe proflavine. To ensure high-quality imaging performance, experimental tests were performed to characterize fiber bundle’s light-coupling efficiency and simulations were performed to evaluate the impact of candidate lens materials’ autofluorescence. A prototype of NA = 0.4, 250-µm field of view, ultra-slim objective optics was built and tested, yielding diffraction-limited performance and estimated resolution of 0.9 µm. When used in conjunction with a commercial coherent fiber bundle to relay the image formed by the objective, the measured resolution was 2.5 µm. PMID:20389489

  14. Deep optically thin cirrus clouds in the polar regions. I - Infrared extinction characteristics

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Yoo, Jung-Moon; Dalu, Giuseppe; Fraser, R. S.

    1990-01-01

    The spectral data obtained by the infrared interferometer Spectrometer (IRIS) flown on Nimbus 4 satellite in 1970 indicated the existence of optically thin ice clouds in the upper troposphere that probably extended into lower stratosphere, in the polar regions, during winter and early spring. The spectral features of these clouds differ somewhat from that of the optically thin cirrus clouds in the tropics. From theoretical simulation of the infrared spectra in the 8-25 micron region, it is inferred that these polar clouds have a vertical stratification in particle size, with larger particles (about 12 microns) in the bottom of the cloud and smaller ones (less than 1 micron) aloft. Radiative transfer calculations also suggest that the equivalent ice-water content of these polar clouds is of the order of 1 mg/sq cm.

  15. Deep optically thin cirrus clouds in the polar regions. I - Infrared extinction characteristics

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Yoo, Jung-Moon; Dalu, Giuseppe; Fraser, R. S.

    1990-01-01

    The spectral data obtained by the infrared interferometer Spectrometer (IRIS) flown on Nimbus 4 satellite in 1970 indicated the existence of optically thin ice clouds in the upper troposphere that probably extended into lower stratosphere, in the polar regions, during winter and early spring. The spectral features of these clouds differ somewhat from that of the optically thin cirrus clouds in the tropics. From theoretical simulation of the infrared spectra in the 8-25 micron region, it is inferred that these polar clouds have a vertical stratification in particle size, with larger particles (about 12 microns) in the bottom of the cloud and smaller ones (less than 1 micron) aloft. Radiative transfer calculations also suggest that the equivalent ice-water content of these polar clouds is of the order of 1 mg/sq cm.

  16. Design and implementation of optical imaging and sensor systems for characterization of deep-sea biological camouflage

    NASA Astrophysics Data System (ADS)

    Haag, Justin Mathew

    The visual ecology of deep-sea animals has long been of scientific interest. In the open ocean, where there is no physical structure to hide within or behind, diverse strategies have evolved to solve the problem of camouflage from a potential predator. Simulations of specific predator-prey scenarios have yielded estimates of the range of possible appearances that an animal may exhibit. However, there is a limited amount of quantitative information available related to both animal appearance and the light field at mesopelagic depths (200 m to 1000 m). To mitigate this problem, novel optical instrumentation, taking advantage of recent technological advances, was developed and is described in this dissertation. In the first half of this dissertation, the appearance of mirrored marine animals is quantitatively evaluated. A portable optical imaging scatterometer was developed to measure angular reflectance, described by the bidirectional reflectance distribution function (BRDF), of biological specimens. The instrument allows for BRDF capture from samples of arbitrary size, over a significant fraction of the reflectance hemisphere. Multiple specimens representing two species of marine animals, collected at mesopelagic depths, were characterized using the scatterometer. Low-dimensional parametric models were developed to simplify use of the data sets, and to validate the BRDF method. Results from principal component analysis confirm that BRDF measurements can be used to study intra- and interspecific variability of mirrored marine animal appearance. Collaborative efforts utilizing the BRDF data sets to develop physically-based scattering models are underway. In the second half of this dissertation, another key part of the deep-sea biological camouflage problem is examined. Two underwater radiometers, capable of low-light measurements, were developed to address the lack of available information related to the deep-sea light field. Quantitative comparison of spectral

  17. Modulated-alignment dual-axis (MAD) confocal microscopy for deep optical sectioning in tissues

    PubMed Central

    Leigh, Steven Y.; Chen, Ye; Liu, Jonathan T.C.

    2014-01-01

    A strategy is presented to enable optical-sectioning microscopy with improved contrast and imaging depth using low-power (0.5 - 1 mW) diode laser illumination. This technology combines the inherent strengths of focal-modulation microscopy and dual-axis confocal (DAC) microscopy for rejecting out-of-focus and multiply scattered background light in tissues. The DAC architecture is unique in that it utilizes an intersecting pair of illumination and collection beams to improve the spatial-filtering and optical-sectioning performance of confocal microscopy while focal modulation selectively ‘labels’ in-focus signals via amplitude modulation. Simulations indicate that modulating the spatial alignment of dual-axis beams at a frequency f generates signals from the focal volume of the microscope that are modulated at 2f with minimal modulation of background signals, thus providing nearly an order-of-magnitude improvement in optical-sectioning contrast compared to DAC microscopy alone. Experiments show that 2f lock-in detection enhances contrast and imaging depth within scattering phantoms and fresh tissues. PMID:24940534

  18. Reflecting optics in the diverticular eye of a deep-sea barreleye fish (Rhynchohyalus natalensis).

    PubMed

    Partridge, J C; Douglas, R H; Marshall, N J; Chung, W-S; Jordan, T M; Wagner, H-J

    2014-05-07

    We describe the bi-directed eyes of a mesopelagic teleost fish, Rhynchohyalus natalensis, that possesses an extensive lateral diverticulum to each tubular eye. Each diverticulum contains a mirror that focuses light from the ventro-lateral visual field. This species can thereby visualize both downwelling sunlight and bioluminescence over a wide field of view. Modelling shows that the mirror is very likely to be capable of producing a bright, well focused image. After Dolichopteryx longipes, this is only the second description of an eye in a vertebrate having both reflective and refractive optics. Although superficially similar, the optics of the diverticular eyes of these two species of fish differ in some important respects. Firstly, the reflective crystals in the D. longipes mirror are derived from a tapetum within the retinal pigment epithelium, whereas in R. natalensis they develop from the choroidal argentea. Secondly, in D. longipes the angle of the reflective crystals varies depending on their position within the mirror, forming a Fresnel-type reflector, but in R. natalensis the crystals are orientated almost parallel to the mirror's surface and image formation is dependent on the gross morphology of the diverticular mirror. Two remarkably different developmental solutions have thus evolved in these two closely related species of opisthoproctid teleosts to extend the restricted visual field of a tubular eye and provide a well-focused image with reflective optics.

  19. Photometry of the cometary atmosphere: A review

    NASA Technical Reports Server (NTRS)

    Vanysek, V.

    1976-01-01

    Photometry and polarimetry of the cometary heads one of the most important sources of information about the physical processes in comets is reviewed. Methods of inspection discussed include: narrow band photometry, wide band photometry, color photography, tilting filter techniques, and photoelectric spectrum scanning. Results of photoelectric observations of comets are described including photoelectric and infrared measurements of comet Kohoutek. Photometric profiles of the coma in monochromatic light are used to determine the lifetime of the parent molecules for the observed radicals, CN and C2.

  20. Spectroscopy and photometry for low-mass stars in Praesepe

    NASA Technical Reports Server (NTRS)

    Williams, Scott D.; Stauffer, John R.; Prosser, Charles F.; Herter, Terry

    1994-01-01

    We have obtained spectral types, H alpha equivalent widths, and optical photometry for a small sample of late K and M dwarf candidate members of the Praesepe open cluster. At least for the small sample of stars we have observed, all of the Paesepe members later than M2 have H alpha in emission. The chromospheric activity of the Praesepe satrs is essentially the same as that for Hyades members of the same mass, as expected since the two clusters are thought to be the same age.

  1. Long term monitoring of the optical background in the Capo Passero deep-sea site with the NEMO tower prototype

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Aiello, S.; Ameli, F.; Anghinolfi, M.; Ardid, M.; Barbarino, G.; Barbarito, E.; Barbato, F. C. T.; Beverini, N.; Biagi, S.; Biagioni, A.; Bouhadef, B.; Bozza, C.; Cacopardo, G.; Calamai, M.; Calì, C.; Calvo, D.; Capone, A.; Caruso, F.; Ceres, A.; Chiarusi, T.; Circella, M.; Cocimano, R.; Coniglione, R.; Costa, M.; Cuttone, G.; D'Amato, C.; D'Amico, A.; De Bonis, G.; De Luca, V.; Deniskina, N.; De Rosa, G.; di Capua, F.; Distefano, C.; Enzenhöfer, A.; Fermani, P.; Ferrara, G.; Flaminio, V.; Fusco, L. A.; Garufi, F.; Giordano, V.; Gmerk, A.; Grasso, R.; Grella, G.; Hugon, C.; Imbesi, M.; Kulikovskiy, V.; Lahmann, R.; Larosa, G.; Lattuada, D.; Leismüller, K. P.; Leonora, E.; Litrico, P.; Llorens Alvarez, C. D.; Lonardo, A.; Longhitano, F.; Lo Presti, D.; Maccioni, E.; Margiotta, A.; Marinelli, A.; Martini, A.; Masullo, R.; Migliozzi, P.; Migneco, E.; Miraglia, A.; Mollo, C. M.; Mongelli, M.; Morganti, M.; Musico, P.; Musumeci, M.; Nicolau, C. A.; Orlando, A.; Orzelli, A.; Papaleo, R.; Pellegrino, C.; Pellegriti, M. G.; Perrina, C.; Piattelli, P.; Pugliatti, C.; Pulvirenti, S.; Raffaelli, F.; Randazzo, N.; Real, D.; Riccobene, G.; Rovelli, A.; Saldaña, M.; Sanguineti, M.; Sapienza, P.; Sciacca, V.; Sgura, I.; Simeone, F.; Sipala, V.; Speziale, F.; Spitaleri, A.; Spurio, M.; Stellacci, S. M.; Taiuti, M.; Terreni, G.; Trasatti, L.; Trovato, A.; Ventura, C.; Vicini, P.; Viola, S.; Vivolo, D.

    2016-02-01

    The NEMO Phase-2 tower is the first detector which was operated underwater for more than 1 year at the "record" depth of 3500 m. It was designed and built within the framework of the NEMO (NEutrino Mediterranean Observatory) project. The 380 m high tower was successfully installed in March 2013 80 km offshore Capo Passero (Italy). This is the first prototype operated on the site where the Italian node of the KM3NeT neutrino telescope will be built. The installation and operation of the NEMO Phase-2 tower has proven the functionality of the infrastructure and the operability at 3500 m depth. A more than 1 year long monitoring of the deep water characteristics of the site has been also provided. In this paper the infrastructure and the tower structure and instrumentation are described. The results of long term optical background measurements are presented. The rates show stable and low baseline values, compatible with the contribution of ^{40}K light emission, with a small percentage of light bursts due to bioluminescence. All these features confirm the stability and good optical properties of the site.

  2. Optical coherence microscopy in 1700-nm spectral band for high-resolution deep-tissue imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masahito; Teranishi, Tatsuhiro; Kawagoe, Hiroyuki; Nishizawa, Norihiko

    2017-02-01

    Optical coherence microscopy (OCM) is a high-resolution imaging technique based on optical coherence tomography and confocal microscopy. The recent studies on OCM operating at 800-1300 nm spectral region have shown that OCM enables to visualize micrometer- or sub-micrometer-scale structures of animal tissues. Although OCMs offers such high-resolution label-free imaging capability of animal tissues, the imaging depth was restricted by multiple light scattering and light absorption of water in samples. Here, for high-resolution deep-tissue imaging, we developed an OCM in the 1700-nm spectral band by using a supercontinuum (SC) source with a Gaussian-like spectral shape in the wavelength region. Recently, it has been reported that the 1700-nm spectral band is a promising choice for enhancing the imaging depth in the observation of turbid scattering tissues because of the low attenuation coefficient of light. In this study, to clarify that the 1700-nm OCM has a potential to realize the enhanced imaging depth, we compared the attenuation of the signal-to-noise ratio between the 1700-nm and 1300-nm OCM imaging of a mouse brain under the same signal detection sensitivity condition. The result shows that the 1700-nm OCM enables us to achieve the enhanced imaging depth. In this 1700-nm OCM, we also confirmed that the lateral resolution of 1.3 µm and axial resolution of 2.8 µm in tissue were achieved.

  3. An optical MEMS accelerometer fabricated using double-sided deep reactive ion etching on silicon-on-insulator wafer

    NASA Astrophysics Data System (ADS)

    Teo, Adrian J. T.; Li, Holden; Tan, Say Hwa; Yoon, Yong-Jin

    2017-06-01

    Optical MEMS devices provide fast detection, electromagnetic resilience and high sensitivity. Using this technology, an optical gratings based accelerometer design concept was developed for seismic motion detection purposes that provides miniaturization, high manufacturability, low costs and high sensitivity. Detailed in-house fabrication procedures of a double-sided deep reactive ion etching (DRIE) on a silicon-on-insulator (SOI) wafer for a micro opto electro mechanical system (MOEMS) device are presented and discussed. Experimental results obtained show that the conceptual device successfully captured motion similar to a commercial accelerometer with an average sensitivity of 13.6 mV G-1, and a highest recorded sensitivity of 44.1 mV G-1. A noise level of 13.5 mV was detected due to experimental setup limitations. This is the first MOEMS accelerometer developed using double-sided DRIE on SOI wafer for the application of seismic motion detection, and is a breakthrough technology platform to open up options for lower cost MOEMS devices.

  4. DEEP-South: Preliminary Lightcurves of Potentially Hazardous Asteroids from the First Year Operation

    NASA Astrophysics Data System (ADS)

    Moon, Hong-Kyu; Kim, Myung-Jin; Choi, Young-Jun; Yim, Hong-Suh; Park, Jintae; Roh, Dong-Goo; Lee, Hee-Jae; Oh, Young-Seok; Bae, Young-Ho

    2016-10-01

    Deep Ecliptic Patrol of the Southern Sky (DEEP-South) observation is being made during the off-season for exoplanet search. It started in October 2015, using Korea Microlensing Telescope Network (KMTNet), a network of three identical telescopes with 1.6 m aperture equipped with 18K × 18K CCDs located in Chile (CTIO), South Africa (SAAO), and Australia (SSO). The combination of KMTNet's prime focus optics and the 340 million pixel CCD provides four square degree field of view with 0.4 arcsec/pixel plate scale.Most of the allocated time for DEEP-South is devoted to targeted photometry of PHAs and NEAs to increase the number of those objects with known physical properties. It is efficiently achieved by multiband, time series photometry. This Opposition Census (OC) mode targets objects near their opposition, with km-sized PHAs in early stage and goes down to sub-km objects. Continuous monitoring of the sky with KMTNEt is optimized for spin characterization of various kinds of asteroids, including binaries, slow/fast- and non-principal axis- rotators, and hence expected to facilitate the debiasing of previously reported lightcurve observations. We present the preliminary lightcurves of PHAs from year one of the DEEP-South Project.

  5. A deep search for the host galaxies of gamma-ray bursts with no detected optical afterglow

    NASA Astrophysics Data System (ADS)

    Rossi, A.; Klose, S.; Ferrero, P.; Greiner, J.; Arnold, L. A.; Gonsalves, E.; Hartmann, D. H.; Updike, A. C.; Kann, D. A.; Krühler, T.; Palazzi, E.; Savaglio, S.; Schulze, S.; Afonso, P. M. J.; Amati, L.; Castro-Tirado, A. J.; Clemens, C.; Filgas, R.; Gorosabel, J.; Hunt, L. K.; Küpcü Yoldaş, A.; Masetti, N.; Nardini, M.; Nicuesa Guelbenzu, A.; Olivares, F. E.; Pian, E.; Rau, A.; Schady, P.; Schmidl, S.; Yoldaş, A.; de Ugarte Postigo, A.

    2012-09-01

    Context. Gamma-ray bursts (GRBs) can provide information about star formation at high redshifts. Even in the absence of a bright optical/near-infrared/radio afterglow, the high detection rate of X-ray afterglows by Swift/XRT and its localization precision of 2-3 arcsec facilitates the identification and the study of GRB host galaxies. Aims: We focus on the search for the host galaxies of 17 bursts with arcsec-sized XRT error circles but no detected long-wavelength afterglow, in spite of their deep and rapid follow-up observations. Three of these events can also be classified as truly dark bursts, i.e., the observed upper limit on the optical flux of the afterglow was less than expected based on the measured X-ray flux. Our goals are to identify the GRB host galaxy candidates and characterize their phenomenological parameters. Methods: Our study is based on deep RC and Ks-band observations performed with FORS1, FORS2, VIMOS, ISAAC, and HAWK-I at the ESO/VLT, partly supported by observations with the seven-channel imager GROND at the 2.2-m telescope on La Silla, and supplemented by observations with NEWFIRM at the 4-m telescope on Kitt Peak. To be conservative, we searched for host galaxy candidates within an area of twice the radius of each associated 90% c.l. Swift/XRT error circle. Results: For 15 of the 17 bursts, we find at least one galaxy within the searching area, and in the remaining two cases only a deep upper limit to RC and Ks can be provided. In seven cases, we discover extremely red objects in the error circles, at least four of which might be dust-enshrouded galaxies. The most remarkable case is the host of GRB 080207, which has a color of (RC - Ks)AB ~ 4.7 mag, and is one of the reddest galaxies ever associated with a GRB. As a by-product of our study we identify the optical afterglow of GRB 070517. Conclusions: Only a minority of optically dim afterglows are due to Lyman dropout (≲ 1/3). Extinction by dust in the host galaxies might explain all

  6. Long-term photometry of WX Arietis: evidence for eclipses and dips

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gil, P.; Casares, J.; Dhillon, V. S.; Martínez-Pais, I. G.

    2000-03-01

    We present R-band photometry of the SW Sex-type cataclysmic variable WX Arietis made in October 1995 and August 1998-February 1999. Contrary to previous results, we find that WX Ari is an eclipsing system with an orbital inclination of i =~ 72o. The R-band light curves display highly variable, shallow eclipses ~ 0.15-mag deep and =~ 40 min long. The observed eclipse depth suggests a partial eclipse of the accretion disc. The light curves also show a wide dip in brightness centred at orbital phase varphi ~ 0.75 and a hump close to the opposite phase at varphi ~ 0.2. The observed dip may be explained by the probable vertical thickening of the outer rim of the accretion disc downstream from the bright spot. We also demonstrate that the disc brightness in all SW Sex systems is nearly the same. This implies that the orbital inclination of these systems is only a function of eclipse depth. Based on observations made with the Optical Ground Station (OGS) and the IAC--80 telescopes, operated on the island of Tenerife by the European Space Agency (ESA) and the Ins\\-ti\\-tu\\-to de Astrof\\'\\i sica de Canarias (IAC), respectively, at the Spanish Observatorio del Teide and with the Jacobus Kapteyn Telescope (JKT), operated on the island of La Palma by PPARC at the Spanish Observatorio del Roque de los Muchachos.

  7. Deep-ultraviolet antireflective coating with improved conformality, optical density, and etch rate

    NASA Astrophysics Data System (ADS)

    Guerrero, Douglas J.; Meador, James D.; Xu, Gu; Suzuki, Hitoshi; Sone, Yasuhisa; Krishnamurthy, Vandana N.; Claypool, James B.; Lamb, James E., III

    1998-06-01

    A new bottom antireflective coating (BARC) for 248 nm lithography is described. The new coating has an optical density of approximately 10/micrometers (k equals 0.41 and n equals 1.482) and plasma etches at rates higher than that of DUV resists depending on the etch conditions. Coating conformality is superior to older generation BARCs, also contributing to improved etch dynamics. Excellent 0.25 micrometers features have been obtained with ESCAP, Acetal and t-BOC type photoresists. The new BARC is spin coated from safe solvents and is spin bowl compatible with EBR and photoresist solvents.

  8. A Phosphorus Phthalocyanine Formulation with Intense Absorbance at 1000 nm for Deep Optical Imaging.

    PubMed

    Zhou, Yang; Wang, Depeng; Zhang, Yumiao; Chitgupi, Upendra; Geng, Jumin; Wang, Yuehang; Zhang, Yuzhen; Cook, Timothy R; Xia, Jun; Lovell, Jonathan F

    2016-01-01

    Although photoacoustic computed tomography (PACT) operates with high spatial resolution in biological tissues deeper than other optical modalities, light scattering is a limiting factor. The use of longer near infrared wavelengths reduces scattering. Recently, the rational design of a stable phosphorus phthalocyanine (P-Pc) with a long wavelength absorption band beyond 1000 nm has been reported. Here, we show that when dissolved in liquid surfactants, P-Pc can give rise to formulations with absorbance of greater than 1000 (calculated for a 1 cm path length) at wavelengths beyond 1000 nm. Using the broadly accessible Nd:YAG pulse laser emission output of 1064 nm, P-Pc could be imaged through 11.6 cm of chicken breast with PACT. P-Pc accumulated passively in tumors following intravenous injection in mice as observed by PACT. Following oral administration, P-Pc passed through the intestine harmlessly, and PACT could be used to non-invasively observe intestine function. When the contrast agent placed under the arm of a healthy adult human, a PACT transducer on the top of the arm could readily detect P-Pc through the entire 5 cm limb. Thus, the approach of using contrast media with extreme absorption at 1064 nm readily enables high quality optical imaging in vitro and in vivo in humans at exceptional depths.

  9. A Phosphorus Phthalocyanine Formulation with Intense Absorbance at 1000 nm for Deep Optical Imaging

    PubMed Central

    Zhou, Yang; Wang, Depeng; Zhang, Yumiao; Chitgupi, Upendra; Geng, Jumin; Wang, Yuehang; Zhang, Yuzhen; Cook, Timothy R.; Xia, Jun; Lovell, Jonathan F.

    2016-01-01

    Although photoacoustic computed tomography (PACT) operates with high spatial resolution in biological tissues deeper than other optical modalities, light scattering is a limiting factor. The use of longer near infrared wavelengths reduces scattering. Recently, the rational design of a stable phosphorus phthalocyanine (P-Pc) with a long wavelength absorption band beyond 1000 nm has been reported. Here, we show that when dissolved in liquid surfactants, P-Pc can give rise to formulations with absorbance of greater than 1000 (calculated for a 1 cm path length) at wavelengths beyond 1000 nm. Using the broadly accessible Nd:YAG pulse laser emission output of 1064 nm, P-Pc could be imaged through 11.6 cm of chicken breast with PACT. P-Pc accumulated passively in tumors following intravenous injection in mice as observed by PACT. Following oral administration, P-Pc passed through the intestine harmlessly, and PACT could be used to non-invasively observe intestine function. When the contrast agent placed under the arm of a healthy adult human, a PACT transducer on the top of the arm could readily detect P-Pc through the entire 5 cm limb. Thus, the approach of using contrast media with extreme absorption at 1064 nm readily enables high quality optical imaging in vitro and in vivo in humans at exceptional depths. PMID:27022416

  10. The VVDS-VLA deep field. II. Optical and near infrared identifications of VLA S1.4 GHz > 80 μ Jy sources in the VIMOS VLT deep survey VVDS-02h field

    NASA Astrophysics Data System (ADS)

    Ciliegi, P.; Zamorani, G.; Bondi, M.; Pozzetti, L.; Bolzonella, M.; Gregorini, L.; Garilli, B.; Iovino, A.; McCracken, H. J.; Mellier, Y.; Radovich, M.; de Ruiter, H. R.; Parma, P.; Bottini, D.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Picat, J. P.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Arnouts, S.; Bardelli, S.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; Meneux, B.; Merighi, R.; Merluzzi, P.; Paltani, S.; Pollo, A.; Zucca, E.; Bongiorno, A.; Busarello, G.; Gavignaud, I.; Pellò, R.; Ripepi, V.; Rizzo, D.

    2005-10-01

    In this paper we present the optical and near-infrared identifications of the 1054 radio sources detected in the 20 cm deep radio survey down to a 5σ flux limit of ~80 μJy obtained with the VLA in the VIMOS VLT Deep Survey VVDS-02h deep field. Using U,B,V,R,I and K data, with limiting magnitudes of UAB˜25.4, BAB˜26.5, VAB˜26.2, RAB˜25.9 IAB˜25.0, JAB˜24.2, KAB˜23.9 (50% completeness) we identified 718 radio sources (~74% of the whole sample). The photometric redshift analysis shows that, in each magnitude bin, the radio sample has a higher median photometric redshift than the whole optical sample, while the median (V-I)AB color of the radio sources is redder than the median color of the whole optical sample. These results suggest that radio detection is preferentially selecting galaxies with higher intrinsic optical luminosity. From the analysis of the optical properties of the radio sources as function of the radio flux, we found that while about 35% of the radio sources are optically unidentified in the higher radio flux bin (S> 1.0 mJy), the percentage of unidentified sources decreases to about 25% in the faintest bins (S< 0.5 mJy). The median IAB magnitude for the total sample of radio sources, i.e. including also the unidentified ones, is brighter in the faintest radio bins than in the bin with higher radio flux. This suggests that most of the faintest radio sources are likely to be associated to relatively lower radio luminosity objects at relatively modest redshift, rather than radio-powerful, AGN type objects at high redshift. Using a classification in early-type and late-type galaxies based on the (B-I)AB color and the photometric redshift, we found that the majority of the radio sources below ~0.15 mJy are indeed late-type star forming galaxies. Finally, the radio sources without optical counterpart in our deep imaging have a median radio flux of 0.15 mJy, equal to that of identified sources. Given the very faint optical limits, these

  11. UBV photometry of V934 Her in the X-ray outburst

    NASA Astrophysics Data System (ADS)

    Metlova, N. V.; Goranskij, V. P.

    2014-09-01

    After Swift detection of the X-ray outburst in the system of M2 III giant with a neutron star V934 Her (4U 1700+24, HD 154791) on 18 Sep 2014 (ATel #6482), we perform its optical photometry at the Sternberg Astronomical Institute Crimean Station using 60 cm telescope and Lyuty's photoelectric UBV photometer.

  12. WFPC2 Stellar Photometry with HSTphot

    NASA Technical Reports Server (NTRS)

    Dolphin, Andrew E.

    2000-01-01

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data. Subject headz'ngs: techniques: photometric

  13. Permanent optical doping of amorphous metal oxide semiconductors by deep ultraviolet irradiation at room temperature

    SciTech Connect

    Seo, Hyungtak; Cho, Young-Je; Bobade, Santosh M.; Park, Kyoung-Youn; Choi, Duck-Kyun; Kim, Jinwoo; Lee, Jaegab

    2010-05-31

    We report an investigation of two photon ultraviolet (UV) irradiation induced permanent n-type doping of amorphous InGaZnO (a-IGZO) at room temperature. The photoinduced excess electrons were donated to change the Fermi-level to a conduction band edge under the UV irradiation, owing to the hole scavenging process at the oxide interface. The use of optically n-doped a-IGZO channel increased the carrier density to approx10{sup 18} cm{sup -3} from the background level of 10{sup 16} cm{sup -3}, as well as the comprehensive enhancement upon UV irradiation of a-IGZO thin film transistor parameters, such as an on-off current ratio at approx10{sup 8} and field-effect mobility at 22.7 cm{sup 2}/V s.

  14. First photometry results from Gaia

    NASA Astrophysics Data System (ADS)

    Brown, Anthony

    2015-08-01

    An overview of the Gaia Photometric Processing is presented. The Gaia photometry consists of the white light (330-1050 nm) G-band, and low resolution spectrophotometry realized by two prisms dispersing all the light entering the field of view. One disperser - called BP for Blue Photometer- operates in the wavelength range 330-680 nm; the other - called RP for Red Photometer - covers the wavelength range 640-1050 nm. The light collected by BP and RP can also be integrated into two broad bands, G_BP and G_RP.This photometric data reduction is based on the overall principle of a self-calibrating system improved by iteration. The input data includes flux (G, G_BP, G_RP) and the low-resolution spectral data. The calibration models and algorithms used are described. Initial validation results are shown which indicate the photometric quality of the preliminary calibrated data. Expectations for the quality of the photometric data to be included in the first public data release (mid-2016) are discussed.

  15. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  16. Multicolor Photometry for Mode Identification

    NASA Astrophysics Data System (ADS)

    Reed, M. D.

    The goal of asteroseismology is to discern the physical conditions of stars by comparing observed pulsations with models. To obtain this goal, the observed pulsation periods and the spherical harmonics (n, l, and m) need to match the theoretical model. Typically the most difficult part in this process is the identification of the pulsation modes in the observations. Multicolour photometry is one method that has proven useful for identifying pulsation modes. By observing stars through various wavebands, and comparing the amplitudes and phases, it is possible to determine the spherical harmonics. This contribution will emphasize the work of Watson (1988), which has since been applied to many different types of variable stars including δ Scuti (Garrido et al., 1990), γ Doradus (Breger et al., 1997), β Cepheid (Cugier et al., 1994), and EC 14026 (Koen, 1998) stars. I will also discuss the technique of summing spectra (especially UV) into various wavebands which are then used to identify modes as pioneered by Robinson, Kepler, and Nather (1982) and applied to white dwarf stars (Kepler et al., 2000).

  17. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  18. Improving Kepler Pipeline Sensitivity with Pixel Response Function Photometry.

    NASA Astrophysics Data System (ADS)

    Morris, Robert L.; Bryson, Steve; Jenkins, Jon Michael; Smith, Jeffrey C

    2014-06-01

    We present the results of our investigation into the feasibility and expected benefits of implementing PRF-fitting photometry in the Kepler Science Processing Pipeline. The Kepler Pixel Response Function (PRF) describes the expected system response to a point source at infinity and includes the effects of the optical point spread function, the CCD detector responsivity function, and spacecraft pointing jitter. Planet detection in the Kepler pipeline is currently based on simple aperture photometry (SAP), which is most effective when applied to uncrowded bright stars. Its effectiveness diminishes rapidly as target brightness decreases relative to the effects of noise sources such as detector electronics, background stars, and image motion. In contrast, PRF photometry is based on fitting an explicit model of image formation to the data and naturally accounts for image motion and contributions of background stars. The key to obtaining high-quality photometry from PRF fitting is a high-quality model of the system's PRF, while the key to efficiently processing the large number of Kepler targets is an accurate catalog and accurate mapping of celestial coordinates onto the focal plane. If the CCD coordinates of stellar centroids are known a priori then the problem of PRF fitting becomes linear. A model of the Kepler PRF was constructed at the time of spacecraft commissioning by fitting piecewise polynomial surfaces to data from dithered full frame images. While this model accurately captured the initial state of the system, the PRF has evolved dynamically since then and has been seen to deviate significantly from the initial (static) model. We construct a dynamic PRF model which is then used to recover photometry for all targets of interest. Both simulation tests and results from Kepler flight data demonstrate the effectiveness of our approach. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science

  19. Deep optical imaging and spectroscopy of the lens system SDSS J1339+1310

    NASA Astrophysics Data System (ADS)

    Shalyapin, V. N.; Goicoechea, L. J.

    2014-08-01

    We present deep I-band imaging (NOT-ALFOSC) and spectroscopic (GTC-OSIRIS) observations of the gravitational lens system SDSS J1339+1310. This consists of two images of a lensed quasar, A and B, and a lensing galaxy G between the two quasar images. Our observations led to the following main results: (1) We obtained new accurate positions for B and G (relative to A), as well as structure parameters for the light distribution of G. The new position angle for G is separated by ~50° from the previously determined value. (2) The spectrum of G is typical for early-type galaxies, and we measured its redshift (0.609 ± 0.001) for the first time. (3) We determined the flux ratio B/A for the cores of the emission lines in the two quasar spectra. They were used to constrain the macrolens flux ratio MBA and dust extinction parameters. (4) The continuum flux ratio was appropriately corrected to obtain the microlensing magnification ratio of the continuum μBA. This μBA indicates that B is amplified (relative to A) by a factor of about 3-5, with larger amplifications at shorter wavelengths. The observed microlensing chromaticity coincides with a sharp drop in the r-band flux of B. (5) We reconstructed the lensing mass from the new observational constraints on the relative astrometry, MBA and the luminous structure of G. We also used the redshift of G to predict the time delay between quasar images (43 ± 5 d, A is leading).

  20. Deep feature learning for automatic tissue classification of coronary artery using optical coherence tomography

    PubMed Central

    Abdolmanafi, Atefeh; Duong, Luc; Dahdah, Nagib; Cheriet, Farida

    2017-01-01

    Kawasaki disease (KD) is an acute childhood disease complicated by coronary artery aneurysms, intima thickening, thrombi, stenosis, lamellar calcifications, and disappearance of the media border. Automatic classification of the coronary artery layers (intima, media, and scar features) is important for analyzing optical coherence tomography (OCT) images recorded in pediatric patients. OCT has been known as an intracoronary imaging modality using near-infrared light which has recently been used to image the inner coronary artery tissues of pediatric patients, providing high spatial resolution (ranging from 10 to 20 μm). This study aims to develop a robust and fully automated tissue classification method by using the convolutional neural networks (CNNs) as feature extractor and comparing the predictions of three state-of-the-art classifiers, CNN, random forest (RF), and support vector machine (SVM). The results show the robustness of CNN as the feature extractor and random forest as the classifier with classification rate up to 96%, especially to characterize the second layer of coronary arteries (media), which is a very thin layer and it is challenging to be recognized and specified from other tissues. PMID:28271012

  1. Deep feature learning for automatic tissue classification of coronary artery using optical coherence tomography.

    PubMed

    Abdolmanafi, Atefeh; Duong, Luc; Dahdah, Nagib; Cheriet, Farida

    2017-02-01

    Kawasaki disease (KD) is an acute childhood disease complicated by coronary artery aneurysms, intima thickening, thrombi, stenosis, lamellar calcifications, and disappearance of the media border. Automatic classification of the coronary artery layers (intima, media, and scar features) is important for analyzing optical coherence tomography (OCT) images recorded in pediatric patients. OCT has been known as an intracoronary imaging modality using near-infrared light which has recently been used to image the inner coronary artery tissues of pediatric patients, providing high spatial resolution (ranging from 10 to 20 μm). This study aims to develop a robust and fully automated tissue classification method by using the convolutional neural networks (CNNs) as feature extractor and comparing the predictions of three state-of-the-art classifiers, CNN, random forest (RF), and support vector machine (SVM). The results show the robustness of CNN as the feature extractor and random forest as the classifier with classification rate up to 96%, especially to characterize the second layer of coronary arteries (media), which is a very thin layer and it is challenging to be recognized and specified from other tissues.

  2. Daytime Use of Astronomical Telescopes for Deep-Space Optical Links

    NASA Technical Reports Server (NTRS)

    Roberts, W. Thomas; Ortiz, Gerard G.; Boyd, Tim A.

    2006-01-01

    Tests at the 200-inch Hale Telescope on Palomar Mountain have demonstrated this telescope's ability to withstand considerable thermal stress, and subsequently produce remarkably unaffected results. During the day of June 29,2005, the Hale telescope dome was left open, and the telescope was exposed to outside air and direct sunlight for 8 hours. During this time, portions of the telescope structure in the telescope's optical path experienced temperature elevations of 30 C, while the primary mirror experienced unprecedented heating of over 3 C. The telescope's measured blind pointing accuracy after this exposure was not noticeably degraded from the measurements taken before exposure. More remarkably, the telescope consistently produced stellar images which were significantly better after exposure of the telescope (1.2 arcsec) than before (1.6 arcsec), even though the conditions of observation were similar. This data is the first step in co-opting astronomical telescopes for daytime use as astronomical receivers, and supports the contention that deleterious effects from daytime exposure of the telescope can be held to an acceptable level for interleaved communications and astronomy.

  3. Deep dry-etch of silica in a helicon plasma etcher for optical waveguide fabrication

    NASA Astrophysics Data System (ADS)

    Li, W. T.; Bulla, D. A. P.; Love, J.; Luther-Davies, B.; Charles, C.; Boswell, R.

    2005-01-01

    Dry-etch of SiO2 layers using a CF4 plasma in a helicon plasma etcher for optical waveguide fabrication has been studied. Al2O3 thin films, instead of the conventional materials, such as Cr or photoresist, were employed as the masking materials. The Al2O3 mask layer was obtained by periodically oxidizing the surface of an Al mask in an oxygen plasma during the breaks of the SiO2 etching process. A relatively high SiO2/Al2O3 etching selectivity of ~100:1, compared with a SiO2/Al selectivity of ~15:1, was achieved under certain plasma condition. Such a high etching selectivity greatly reduced the required Al mask thickness from over 500 nm down to ~100 nm for etching over 5-μm-thick silica, which make it very easy to obtain the mask patterns with near vertical and very smooth sidewalls. Accordingly, silica wavegudies with vertical sidewalls whose roughness was as low as 10 nm were achieved. In addition, the mechanism of the profile transformation from a mask to the etched waveguide was analyzed numerically; and it was found that the slope angle of the sidewalls of the mask patterns only needed to be larger than 50° for achieving vertical sidewalls of the waveguides, if the etching selectivity was increased to 100.

  4. Daytime Use of Astronomical Telescopes for Deep-Space Optical Links

    NASA Technical Reports Server (NTRS)

    Roberts, W. Thomas; Ortiz, Gerard G.; Boyd, Tim A.

    2006-01-01

    Tests at the 200-inch Hale Telescope on Palomar Mountain have demonstrated this telescope's ability to withstand considerable thermal stress, and subsequently produce remarkably unaffected results. During the day of June 29,2005, the Hale telescope dome was left open, and the telescope was exposed to outside air and direct sunlight for 8 hours. During this time, portions of the telescope structure in the telescope's optical path experienced temperature elevations of 30 C, while the primary mirror experienced unprecedented heating of over 3 C. The telescope's measured blind pointing accuracy after this exposure was not noticeably degraded from the measurements taken before exposure. More remarkably, the telescope consistently produced stellar images which were significantly better after exposure of the telescope (1.2 arcsec) than before (1.6 arcsec), even though the conditions of observation were similar. This data is the first step in co-opting astronomical telescopes for daytime use as astronomical receivers, and supports the contention that deleterious effects from daytime exposure of the telescope can be held to an acceptable level for interleaved communications and astronomy.

  5. Distant Comets Photometry and Dust Modeling

    NASA Astrophysics Data System (ADS)

    Pittichova, Jana; Meech, K. J.; Bar-Nun, A.; Notesco, G.

    2008-09-01

    Several comets have been observed to develop coma on their in-bound leg at heliocentric distances from 5.84 to 11.49 AU. We will present the observational evidence for their activity and propose an explanation based on experiments carried out on amorphous, gas-laden ice samples that are 0.1 to 100 microns thick and formed by flowing water vapor and CO onto a cold surface. The considerable gas emission occurs when the amorphous ice anneals before 135K, where it transforms into a crystalline structure. This activity was found experimentally to be associated with gas release during annealing of the gas-laden amorphous ice. We observed and measured optical CCD photometry for two short-period and five long-period, dynamically new comets, that have enter the inner solar system directly from the Oort cloud for the first time. All of these comets have been observed pre-perihelion. Observations were done with the University of Hawaii 2.2-m telescope on Mauna Kea with the Tektronix 2x2K CCD camera through the Kron-Cousins B, V, R, I filter system. In order to observationally distinguish the physical causes of activity, not only is it important to observe comets at large heliocentric distances, but also those that are dynamically new and on the in-bound leg of their orbits at distances beyond where the amorphous to crystalline ice phase transition can occur. This research includes observations of the level of nucleus activity as a function of distance. We also would like to present Finson-Probstein (FP) dust modeling investigation on select comets. From the FP dust modeling of a cometary tail we can determine three basic parameters: the dust production rate, the particle distribution, and the emission velocity of the grains.

  6. Hybrid quantum dot-fatty ester stealth nanoparticles: toward clinically relevant in vivo optical imaging of deep tissue.

    PubMed

    Shuhendler, Adam J; Prasad, Preethy; Chan, Ho-Ka Carol; Gordijo, Claudia R; Soroushian, Behrouz; Kolios, Michael; Yu, Kui; O'Brien, Peter J; Rauth, Andrew Michael; Wu, Xiao Yu

    2011-03-22

    Despite broad applications of quantum dots (QDs) in vitro, severe toxicity and dominant liver uptake have limited their clinical application. QDs that excite and emit in the ultraviolet and visible regions have limited in vivo applicability due to significant optical interference exerted by biological fluids and tissues. Hence we devised a new biocompatible hybrid fluorophore composed of near-infrared-emitting PbSe quantum dots encapsulated in solid fatty ester nanoparticles (QD-FEN) for in vivo imaging. The quantum yield and tissue penetration depth of the QD-FEN were characterized, and their biological fate was examined in a breast tumor-bearing animal model. It was found for the first time that chemical modification of the headgroup of QD-encapsulating organic fatty acids was a must as these groups quenched the photoluminescence of PbSe nanocrystals. The use of fatty esters enhanced aqueous quantum yields of PbSe QDs up to ∼45%, which was 50% higher than that of water-soluble PbSe nanocrystals in an aqueous medium. As a result, a greater than previously reported tissue penetration depth of fluorescence was recorded at 710 nm/840 nm excitation/emission wavelengths. The QD-FEN had much lower short-term cytotoxicity compared to nonencapsulated water-soluble QDs. More importantly, reduced liver uptake, increased tumor retention, lack of toxic response, and nearly complete clearance of QD-FEN from the tested animals was demonstrated. With a combination of near-infrared spectral properties, enhanced optical properties,and significantly improved biosafety profile, this novel hybrid nanoparticulate fluorophore system demonstrably provides real-time, deep-tissue fluorescent imaging of live animals, laying a foundation for further development toward clinical application.

  7. Optical Line Emission from z ˜ 6.8 Sources with Deep Constraints on Lyα Visibility

    NASA Astrophysics Data System (ADS)

    Castellano, M.; Pentericci, L.; Fontana, A.; Vanzella, E.; Merlin, E.; De Barros, S.; Amorin, R.; Caputi, K. I.; Cristiani, S.; Finkelstein, S. L.; Giallongo, E.; Grazian, A.; Koekemoer, A.; Maiolino, R.; Paris, D.; Pilo, S.; Santini, P.; Yan, H.

    2017-04-01

    We analyze a sample of z-dropout galaxies in the CANDELS GOODS South and UDS fields that have been targeted by a dedicated spectroscopic campaign aimed at detecting their Lyα line. Deep IRAC observations at 3.6 and 4.5 μm are used to determine the strength of optical emission lines affecting these bands at z ˜ 6.5-6.9 in order to (1) investigate possible physical differences between Lyα emitting and non-emitting sources; (2) constrain the escape fraction of ionizing photons; and (3) provide an estimate of the specific star formation rate at high redshifts. We find evidence of strong [O iii]+Hβ emission in the average (stacked) SEDs of galaxies both with and without Lyα emission. The blue IRAC [3.6]-[4.5] color of the stack with detected Lyα line can be converted into a rest-frame equivalent width EW([O iii]+Hβ) = {1500}-440+530 Å assuming a flat intrinsic stellar continuum. This strong optical line emission enables a first estimate of {f}{esc}≲ 20 % on the escape fraction of ionizing photons from Lyα detected objects. The objects with no Lyα line show less extreme EW([O iii]+Hβ) = {520}-150+170 Å, suggesting different physical conditions of the H ii regions with respect to Lyα-emitting ones, or a larger {f}{esc}. The latter case is consistent with a combined evolution of {f}{esc} and the neutral hydrogen fraction as an explanation of the lack of bright Lyα emission at z > 6. A lower limit on the specific star formation rate, SSFR > 9.1 Gyr-1 for {M}{star}=2× {10}9 {M}⊙ galaxies at these redshifts can be derived from the spectroscopically confirmed sample.

  8. The Araucaria Project. A Distance Determination to the Local Group Spiral M33 from Near-infrared Photometry of Cepheid Variables

    NASA Astrophysics Data System (ADS)

    Gieren, Wolfgang; Górski, Marek; Pietrzyński, Grzegorz; Konorski, Piotr; Suchomska, Ksenia; Graczyk, Dariusz; Pilecki, Bogumil; Bresolin, Fabio; Kudritzki, Rolf-Peter; Storm, Jesper; Karczmarek, Paulina; Gallenne, Alexandre; Calderón, Paula; Geisler, Doug

    2013-08-01

    Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO Very Large Telescope. From the data, we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of ±0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B - V) = 0.19 ± 0.02, in agreement with the value used by the Hubble Space Telescope Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1%-2% level and therefore minor contributors to the total uncertainty of our distance result for M33. Based on observations obtained with the ESO VLT for program 382.D-0469(A).

  9. Changes on Pluto's Surface Revealed with Long Timebase Photometry

    NASA Astrophysics Data System (ADS)

    George, Erin; Buie, M.

    2013-10-01

    We are continuing to monitor the long-term photometric behavior of Pluto in order to constrain volatile surface migration. As Pluto passes near the center of the galaxy, the fields are too crowded for normal aperture photometric techniques. We approached this problem with a combination of point-spread function (PSF) photometry and optimal image subtraction (OIS). Our data are from the 0.8-m robotic telescope at Lowell Observatory, the 1-m robotic telescope at New Mexico State Observatory, and the Faulkes 2-m robotic telescope at Siding Spring, part of Las Cumbres Observatory. Our latest results add photometric data up through 2012 to the data collected since discovery. Our new reduction scheme consists of background catalogs, image subtraction using deep templates, and Pluto photometry extraction. We also use the known photometric properties of Charon determined with HST to remove Charon's contribution from old and new data and compare these results with the HST data where Pluto is measured by itself. Data since 2002 show marked departures from the behavior prior to that time. These results provide clear evidence for time evolution of Pluto's surface albedo. We will present these results along with implications for present-day processes that are altering the surface of Pluto. This work also provides crucial insight into the effort required to provide ground-based support observations for the upcoming New Horizons flyby of Pluto in 2015. Support for this work was provided by NASA Planetary Astronomy Program, grant number NNX09AB43G.

  10. Adaptive Optics Views of the Hubble Deep Fields Final report on LLNL LDRD Project 03-ERD-002

    SciTech Connect

    Max, C E; Gavel, D; Pennington, D; Gibbard, S; van Dam, M; Larkin, J; Koo, D; Raschke, L; Melbourne, J

    2007-02-17

    We used laser guide star adaptive optics at the Lick and Keck Observatories to study active galactic nuclei and galaxies, with emphasis on those in the early Universe. The goals were to observe large galaxies like our own Milky Way in the process of their initial assembly from sub-components, to identify central active galactic nuclei due to accreting black holes in galaxy cores, and to measure rates of star formation and evolution in galaxies. In the distant universe our focus was on the GOODS and GEMS fields (regions in the Northern and Southern sky that include the Hubble Deep Fields) as well as the Extended Groth Strip and COSMOS fields. Each of these parts of the sky has been intensively studied at multiple wavelengths by the Hubble Space Telescope, the Chandra X-Ray Observatory, the XMM Space Telescope, the Spitzer Space Telescope, and several ground-based telescopes including the Very Large Array radio interferometer, in order to gain an unbiased view of a significant statistical sample of galaxies in the early universe.

  11. The Long-Wave Infrared Earth Image as a Pointing Reference for Deep-Space Optical Communications

    NASA Astrophysics Data System (ADS)

    Biswas, A.; Piazzolla, S.; Peterson, G.; Ortiz, G. G.; Hemmati, H.

    2006-11-01

    Optical communications from space require an absolute pointing reference. Whereas at near-Earth and even planetary distances out to Mars and Jupiter a laser beacon transmitted from Earth can serve as such a pointing reference, for farther distances extending to the outer reaches of the solar system, the means for meeting this requirement remains an open issue. We discuss in this article the prospects and consequences of utilizing the Earth image sensed in the long-wave infrared (LWIR) spectral band as a beacon to satisfy the absolute pointing requirements. We have used data from satellite-based thermal measurements of Earth to synthesize images at various ranges and have shown the centroiding accuracies that can be achieved with prospective LWIR image sensing arrays. The nonuniform emissivity of Earth causes a mispointing bias error term that exceeds a provisional pointing budget allocation when using simple centroiding algorithms. Other issues related to implementing thermal imaging of Earth from deep space for the purposes of providing a pointing reference are also reported.

  12. U-band photometry of 17 WINGS clusters

    NASA Astrophysics Data System (ADS)

    Omizzolo, A.; Fasano, G.; Reverte Paya, D.; De Santis, C.; Grado, A.; Bettoni, D.; Poggianti, B.; D'Onofrio, M.; Moretti, A.; Varela, J.; Fritz, J.; Gullieuszik, M.; Cava, A.; Grazian, A.; Moles, M.

    2014-01-01

    Context. This paper belongs to a series presenting the WIde Field Nearby Galaxy-cluster Survey (WINGS). The WINGS project has collected wide-field, optical (B, V), and near-infrared (J, K) imaging as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04 photometry of galaxies and stars in the fields of 17 clusters of the WINGS sample. We also extend the original B- and V-band photometry (WINGS-OPT) for 9 and 6 WINGS clusters to a larger field of view. Methods: We used both the new and already existing B-band photometry to obtain reliable (U - B) colors of galaxies within three fixed apertures in kpc. To this aim, we took particular care with the astrometric precision in the reduction procedure. Since not all the observations were taken in good transparency conditions, the photometric calibration was partly obtained by relying on the SDSS and WINGS-OPT photometry for the U- and optical bands, respectively. Results: We provide U-band (also B- and V-band, where possible) total magnitudes of stars and galaxies in the fields of clusters. For galaxies only, the catalogs also provide geometrical parameters and carefully centered aperture magnitudes. The internal consistency of magnitudes was checked for clusters imaged with different cameras, while the external photometric consistency was obtained by comparison with the WINGS-OPT and SDSS surveys. Conclusions: The photometric catalogs presented here add the U-band information to the WINGS database for extending the spectral energy distribution of the galaxies, in particular in the ultraviolet wavelengths which are fundamental for deriving the star formation rate properties. Photometric catalogs are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  13. Towards photometry pipeline of the Indonesian space surveillance system

    NASA Astrophysics Data System (ADS)

    Priyatikanto, Rhorom; Religia, Bahar; Rachman, Abdul; Dani, Tiar

    2015-09-01

    Optical observation through sub-meter telescope equipped with CCD camera becomes alternative method for increasing orbital debris detection and surveillance. This observational mode is expected to eye medium-sized objects in higher orbits (e.g. MEO, GTO, GSO & GEO), beyond the reach of usual radar system. However, such observation of fast moving objects demands special treatment and analysis technique. In this study, we performed photometric analysis of the satellite track images photographed using rehabilitated Schmidt Bima Sakti telescope in Bosscha Observatory. The Hough transformation was implemented to automatically detect linear streak from the images. From this analysis and comparison to USSPACECOM catalog, two satellites were identified and associated with inactive Thuraya-3 satellite and Satcom-3 debris which are located at geostationary orbit. Further aperture photometry analysis revealed the periodicity of tumbling Satcom-3 debris. In the near future, it is not impossible to apply similar scheme to establish an analysis pipeline for optical space surveillance system hosted in Indonesia.

  14. Deep SDSS optical spectroscopy of distant halo stars. II. Iron, calcium, and magnesium abundances

    NASA Astrophysics Data System (ADS)

    Fernández-Alvar, E.; Allende Prieto, C.; Schlesinger, K. J.; Beers, T. C.; Robin, A. C.; Schneider, D. P.; Lee, Y. S.; Bizyaev, D.; Ebelke, G.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan, K.; Simmons, A.

    2015-05-01

    Aims: We analyze a sample of 3944 low-resolution (R ~ 2000) optical spectra from the Sloan Digital Sky Survey (SDSS), focusing on stars with effective temperatures 5800 ≤ Teff ≤ 6300 K, and distances from the Milky Way plane in excess of 5 kpc, and determine their abundances of Fe, Ca, and Mg. Methods: We followed the same methodology as in the previous paper in this series, deriving atmospheric parameters by χ2 minimization, but this time we obtained the abundances of individual elements by fitting their associated spectral lines. Distances were calculated from absolute magnitudes obtained by a statistical comparison of our stellar parameters with stellar-evolution models. Results: The observations reveal a decrease in the abundances of iron, calcium, and magnesium at large distances from the Galactic center. The median abundances for the halo stars analyzed are fairly constant up to a Galactocentric distance r ~ 20 kpc, rapidly decrease between r ~ 20 and r ~ 40 kpc, and flatten out to significantly lower values at larger distances, consistent with previous studies. In addition, we examine [Ca/Fe] and [Mg/Fe] as a function of [Fe/H] and Galactocentric distance. Our results show that the most distant parts of the halo show a steeper variation of [Ca/Fe] and [Mg/Fe] with iron. We found that at the range -1.6 < [Fe/H] < -0.4, [Ca/Fe] decreases with distance, in agreement with earlier results based on local stars. However, the opposite trend is apparent for [Mg/Fe]. Our conclusion that the outer regions of the halo are more metal-poor than the inner regions, based on in situ observations of distant stars, agrees with recent results based on inferences from the kinematics of more local stars, and with predictions of recent galaxy formation simulations for galaxies similar to the Milky Way. Table 1 and beginning of Tables 2 and 3 are available in electronic form at http://www.aanda.orgFull Tables 2 and 3 are only available at the CDS via anonymous ftp to http

  15. FR Cnc revisited: photometry, polarimetry and spectroscopy

    NASA Astrophysics Data System (ADS)

    Golovin, A.; Gálvez-Ortiz, M. C.; Hernán-Obispo, M.; Andreev, M.; Barnes, J. R.; Montes, D.; Pavlenko, E.; Pandey, J. C.; Martínez-Arnáiz, R.; Medhi, B. J.; Parihar, P. S.; Henden, A.; Sergeev, A.; Zaitsev, S. V.; Karpov, N.

    2012-03-01

    This paper is part of a multiwavelength study aimed at using complementary photometric, polarimetric and spectroscopic data to achieve an understanding of the activity process in late-type stars. Here, we present the study of FR Cnc, a young, active and spotted star. We performed analysis of All Sky Automated Survey 3 (ASAS-3) data for the years 2002-08 and amended the value of the rotational period to be 0.826518 d. The amplitude of photometric variations decreased abruptly in the year 2005, while the mean brightness remained the same, which was interpreted as a quick redistribution of spots. BVRC and IC broad-band photometric calibration was performed for 166 stars in FR Cnc vicinity. The photometry at Terskol Observatory shows two brightening episodes, one of which occurred at the same phase as the flare of 2006 November 23. Polarimetric BVR observations indicate the probable presence of a supplementary source of polarization. We monitored FR Cnc spectroscopically during the years 2004-08. We concluded that the radial velocity changes cannot be explained by the binary nature of FR Cnc. We determined the spectral type of FR Cnc as K7V. Calculated galactic space-velocity components (U, V, W) indicate that FR Cnc belongs to the young disc population and might also belong to the IC 2391 moving group. Based on Li Iλ6707.8 measurement, we estimated the age of FR Cnc to be between 10 and 120 Myr. Doppler tomography was applied to create a starspot image of FR Cnc. We optimized the goodness of fit to the deconvolved profiles for axial inclination, equivalent width and v sin i, finding v sin i=46.2 km s-1 and i= 55°. We also generated a synthetic V-band light curve based on Doppler imaging that makes simultaneous use of spectroscopic and photometric data. This synthetic light curve displays the same morphology and amplitude as the observed one. The starspot distribution of FR Cnc is also of interest since it is one of the latest spectral types to have been imaged. No

  16. Flaring on RS CVn systems: Results from EUVE Photometry

    NASA Astrophysics Data System (ADS)

    Osten, R. A.; Brown, A.; Ayres, T. R.

    We present broadband EUV photometry for a sample of RS CVn systems observed with the Deep Survey Spectrometer and Right Angle Program (RAP) Scanners on the Extreme Ultraviolet Explorer (EUVE). We have developed robust data analysis and light curve software for the interpretation of these data. Large-scale flaring activity is seen on 15 of the 18 systems studied. These binaries cover a range in orbital period of 0.7 days to 21 days and include a mixture of giant, subgiant, and dwarf luminosity classes. For many systems the photometric coverage extends over several orbital periods and flaring is unambiguously characterized. We present statistics on the distribution of variability in the survey. Correlations of flaring with binary properties are examined.

  17. Gaia photometry for white dwarfs

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Catalán, S.; Jordi, C.; Tremblay, P.-E.; Napiwotzki, R.; Luri, X.; Robin, A. C.; Kowalski, P. M.

    2014-05-01

    Context. White dwarfs can be used to study the structure and evolution of the Galaxy by analysing their luminosity function and initial mass function. Among them, the very cool white dwarfs provide the information for the early ages of each population. Because white dwarfs are intrinsically faint only the nearby (~ 20 pc) sample is reasonably complete. The Gaia space mission will drastically increase the sample of known white dwarfs through its 5-6 years survey of the whole sky up to magnitude V = 20-25. Aims: We provide a characterisation of Gaia photometry for white dwarfs to better prepare for the analysis of the scientific output of the mission. Transformations between some of the most common photometric systems and Gaia passbands are derived. We also give estimates of the number of white dwarfs of the different galactic populations that will be observed. Methods: Using synthetic spectral energy distributions and the most recent Gaia transmission curves, we computed colours of three different types of white dwarfs (pure hydrogen, pure helium, and mixed composition with H/He = 0.1). With these colours we derived transformations to other common photometric systems (Johnson-Cousins, Sloan Digital Sky Survey, and 2MASS). We also present numbers of white dwarfs predicted to be observed by Gaia. Results: We provide relationships and colour-colour diagrams among different photometric systems to allow the prediction and/or study of the Gaia white dwarf colours. We also include estimates of the number of sources expected in every galactic population and with a maximum parallax error. Gaia will increase the sample of known white dwarfs tenfold to about 200 000. Gaia will be able to observe thousands of very cool white dwarfs for the first time, which will greatly improve our understanding of these stars and early phases of star formation in our Galaxy. Tables 6 and 7 are available in electronic form at http://www.aanda.orgFull Tables 3-5 are available at the CDS via

  18. Deep-ultraviolet nonlinear optical materials: Na2Be4B4O11 and LiNa5Be12B12O33.

    PubMed

    Huang, Hongwei; Liu, Lijuan; Jin, Shifeng; Yao, Wenjiao; Zhang, Yihe; Chen, Chuangtian

    2013-12-11

    Deep-UV coherent light generated by nonlinear optical (NLO) materials possesses highly important applications in photonic technologies. Beryllium borates comprising anionic planar layers have been shown to be the most promising deep UV NLO materials. Here, two novel NLO beryllium borates Na2Be4B4O11 and LiNa5Be12B12O33 have been developed through cationic structural engineering. The most closely arranged [Be2BO5]∞ planar layers, connected by the flexible [B2O5] groups, have been found in their structure