AAS 207th Meeting, 8-12 January 2006
Session 23 Future Space Missions
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[23.03] Mitigating the Impact of Large Intrapixel Quantum Efficiency Variations on Precision Stellar Photometry and Astrometry

K. J. Mighell (NOAO)

Current infrared detector technology can produce imagers with non-uniform intrapixel response functions. This can cause significant stellar flux loss (depending on where a star is centered within the central pixel) which is an observational fact in some existing space-based astronomical cameras. Large intrapixel quantum efficiency (QE) variations can also cause the observed (apparent) positions of stars to be significantly corrupted. With such ugly detectors, the observed stellar brightnesses and positions are neither precise or accurate. Excellent stellar photometry and astrometry is, fortunately, still achievable even in the presence of large intrapixel QE variations --- as long as the image formation process inside the detector is accurately modeled within the photometric reduction code. Detailed analysis of simulated space-based stellar observations are presented which demonstrate how the impact of large intrapixel QE variations can be mitigated using the MATPHOT algorithm with accurate discrete Point Spread functions and accurate Detector Response Functions. Source code and documentation for MATPHOT and support software is freely available at the following web site: http://www.noao.edu/staff/mighell/matphot K.J.M was supported by a grant from the National Aeronautics and Space Administration (NASA), Interagency Order No. NNG05EB61I, which was awarded by the Applied Information Systems Research (AISR) Program of NASA's Science Mission Directorate.

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