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Dithering Strategies and Point-Source Photometry

Description: The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes the spatial sampling of a single exposure, and the observing strategy determines the set of dithered exposures with pointing offsets from which the source flux is inferred. In a wide-field imaging survey, sources of interest are randomly distributed within the … more
Date: February 22, 2011
Creator: Samsing, Johan & Kim, Alex G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Precision Photometry to Study the Nature of Dark Energy

Description: Over the past decade scientists have collected convincing evidence that the expansion of the universe is accelerating, leading to the conclusion that the content of our universe is dominated by a mysterious 'dark energy'. The fact that present theory cannot account for the dark energy has made the determination of the nature of dark energy central to the field of high energy physics. It is expected that nothing short of a revolution in our understanding of the fundamental laws of physics is req… more
Date: January 30, 2011
Creator: Lorenzon, Wolfgang & Schubnell, Michael
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Precision Determination of Atmospheric Extinction at Optical and Near IR Wavelengths

Description: The science goals for future ground-based all-sky surveys, such as the Dark Energy Survey, PanSTARRS, and the Large Synoptic Survey Telescope, require calibration of broadband photometry that is stable in time and uniform over the sky to precisions of a per cent or better, and absolute calibration of color measurements that are similarly accurate. This performance will need to be achieved with measurements made from multiple images taken over the course of many years, and these surveys will obs… more
Date: August 24, 2011
Creator: Burke, David L.; Axelrod, T.; Blondin, Stephane; Claver, Chuck; Ivezic, Zeljko; Jones, Lynne et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

LSST Charge-Coupled Device Calibration

Description: The prototype charge-coupled device created at the Stanford Linear Accelerator Center for the Large Synoptic Survey Telescope must be tested to check its functionality and performance. It was installed into the Calypso telescope in Arizona in November of 2008 for this purpose. Since then it has taken many images of various astronomical objects. By doing photometry on standard stars in these images, we can compare our magnitude results to the known magnitudes of these stars. This comparison allo… more
Date: June 22, 2011
Creator: Stout, Tiarra Johannas & /SLAC, /Idaho State U.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

CALiPER Exploratory Study: Accounting for Uncertainty in Lumen Measurements

Description: With a well-defined and shared understanding of uncertainty in lumen measurements, testing laboratories can better evaluate their processes, contributing to greater consistency and credibility of lighting testing a key component of the U.S. Department of Energy (DOE) Commercially Available LED Product Evaluation and Reporting (CALiPER) program. Reliable lighting testing is a crucial underlying factor contributing toward the success of many energy-efficient lighting efforts, such as the DOE GATE… more
Date: March 2011
Creator: Bergman, Rolf; Paget, Maria L. & Richman, Eric E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

Description: Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near… more
Date: March 21, 2011
Creator: Barman, T. S.; Macintosh, B. A.; Konopacky, Q. M. & Marois, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The SDSS Coadd: A Galaxy Photometric Redshift Catalog

Description: We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for {approx} 13 million objects classified as galaxies in the coadd with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx} 89, 000 galaxies that have SDSS photometry an… more
Date: November 1, 2011
Creator: Reis, Ribamar R. R.; Soares-Santos, Marcelle; Annis, James; Dodelson, Scott; Hao, Jiangang; Johnston, David et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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