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Search Publications by: Steven W. Brown (Fed)

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Displaying 26 - 50 of 325

Tunable Laser Techniques for Improving the Precision of Optical Astronomy

September 13, 2012
Author(s)
Keith R. Lykke, Claire E. Cramer, John T. Woodward IV, Steven W. Brown, Ping-Shine Shaw
Improving the precision of optical astronomy requires not only new telescopes and instrumentation, but also advances in observing protocols, calibrations and data analysis. The Laser Applications Group at the National Institute of Standards and Technology

Stray light correction algorithm for multi-spectral hyperspectral spectrographs

June 1, 2012
Author(s)
Michael Feinholz, Stephanie J. Flora, Steven W. Brown, Yuqin Zong, Keith R. Lykke, Mark A. Yarbrough, B. Carol Johnson, D. K. Clark
An algorithm is developed to correct a multi-channel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral

Hyperspectral Image Projector Applications

February 15, 2012
Author(s)
Joseph P. Rice, Steven W. Brown, David W. Allen, Howard W. Yoon, Maritoni A. Litorja, Jeeseong Hwang
For the past several years NIST has been developing, along with several collaborators, a Hyperspectral Image Projector (HIP). This scene projector produces high-resolution programmable spectra and projects them into dynamic two-dimensional images. The

Results from Solar Reflective Band End-to-End Testing for VIIRS F1 Sensor Using T-SIRCUS

October 24, 2011
Author(s)
Jeff McIntire, David Moyer, James K. McCarthy, Steven W. Brown, Keith R. Lykke, Frank De Luccia, Xiaoxiong Xiong, James J. Butler, Bruce Guenther
Verification of the Visible Infrared Imager Radiometer Suite (VIIRS) End-to-End (E2E) sensor calibration is highly recommended before launch, to identify any anomalies and to improve our understanding of the sensor on-orbit calibration performance. E2E

Ground-based observatory operations optimized and enhanced by direct atmospheric measurements

July 22, 2010
Author(s)
John T. McGraw, Peter C. Zimmer, Azzam Mansour, Dean C. Hines, Anthony B. Hull, Lisa Rossmann, Daniel C. Zirzow, Steven W. Brown, Gerald T. Fraser, Keith R. Lykke, Allan W. Smith, John T. Woodward IV, Christopher W. Stubbs
Earth's atmosphere represents a turbulent, turbid refractive element for every ground-based telescope. We describe the significantly enhanced and optimized operation of observatories supported by the combination of a lidar and spectrophotometer that allows

Spectroradiometric Calibration of Telescopes using Laser Illumination of Flat Field Screens

July 15, 2010
Author(s)
Steven W. Brown, Claire E. Cramer, Keith R. Lykke, Allan W. Smith, John T. Woodward IV, Peter Doherty, Emilio Falco, Christopher W. Stubbs
It is standard practice at many telescopes to take a series of flat field images prior to an observation run. Typically the flat field consists of a screen mounted inside the telescope dome that is uniformly illuminated with a broadband light source. These

Space-based photometric precision from ground-based telescopes

July 1, 2010
Author(s)
Peter C. Zimmer, John T. McGraw, Anthony B. Hull, Daniel C. Zirzow, Steven W. Brown, Claire E. Cramer, Gerald T. Fraser, Keith R. Lykke, Allan W. Smith, John T. Woodward IV, Christopher W. Stubbs, Mark R. Ackermann, Dean C. Hines
Ground-based telescopes supported by lidar and spectrophotometric auxiliary instrumentation can attain space-based precision for all-sky photometry, with uncertainties dominated by fundamental photon counting statistics. Earth‟s atmosphere is a wavelength-

Internal quantum efficiency modeling of silicon photodiodes

April 1, 2010
Author(s)
Thomas R. Gentile, Steven W. Brown, Keith R. Lykke, Ping-Shine Shaw, John T. Woodward IV
Results are presented for modeling of the internal quantum efficiency (IQE) of silicon photodiodes in the 400 nm to 900 nm wavelength range. The IQE data are based on measurements of the external quantum efficiencies of three transmission trap detectors

Hyperspectral Imager Characterization and Calibration

December 1, 2009
Author(s)
John T. Woodward IV, Steven W. Brown, Allan W. Smith, Keith R. Lykke
Current radiometric calibration standards, specifically blackbody and lamp-based optical radiation sources, produce spatially, spectrally, and temporally simple scenes. Hyperspectral imaging instruments, which in-practice view spatially, spectrally, and

A proposed global atmospheric monitoring networkbased on standard stars

November 2, 2009
Author(s)
Gerald T. Fraser, Steven W. Brown, Keith R. Lykke, John T. McGraw, Allan W. Smith, John T. Woodward IV, Peter C. Zimmer, Christopher W. Stubbs
The feasibility of developing a network of telescopes to monitor the composition of the nighttime atmosphere using stellar spectrophotometry is explored. Spectral measurements of the extinction of starlight by the atmosphere would allow, for instance

Report on the Key Comparison CCPR K2.a-2003

October 30, 2009
Author(s)
Yoshihiro Ohno, Steven W. Brown, Thomas C. Larason
Under the framework of Mutual Recognition Arrangement (MRA) for national measurements standards and for calibration and measurement certificates issued by National Metrology Institutes (NMIs) signed in 1999, an international comparison of spectral

Absolute Flux Calibration of Stars; Calibration of the Reference Telescope

June 2, 2009
Author(s)
Allan W. Smith, John T. Woodward IV, Colleen A. Jenkins, Steven W. Brown, Keith R. Lykke
Absolute stellar photometry is based on 1970s terrestrial measurements of the star Vega with instruments calibrated using the Planckian radiance from a Cu fixed-point blackbody. Significant advances in absolute radiometry have been made in the last 30
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