Characterizing the Completeness of Spitzer IRAC Imaging and the GLIMPSE Point Source Catalog in High-background Regions

Type Conference Paper
Names Henry A. Kobulnicky, M. Alexander, B. Brian, M. Meade, B. Whitney, E. Churchwell
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astrnomical Society, AAS Meeting #219, #428.07
Volume 219
Date January 1, 2012
Library Catalog NASA ADS
Abstract The Spitzer Space Telescope Galactic Legacy MidPlane Survey Extraordinaire (GLIMPSE) programs (GLIMPSE I, II, 3D, 360) have surveyed hundreds of square degrees of the Galactic Plane in four (two for GLIMPSE 360) mid-infrared bandpasses with the Infrared Array Camera (IRAC). The resulting GLIMPSE Point Source Catalog contains over 100 million objects and has become a widely used resource. Other large and Legacy Spitzer programs have used IRAC to survey additional regions totaling over 100 square degrees. The utility of the data and of the point source catalogs from ANY IRAC observations is limited, however, by the fact that the completeness of the photometric catalogs vary inversely with background surface brightness. This is especially significant in the 5.8 and 8.0 micron (IRAC1 and IRAC2) bands where diffuse interstellar PAH features are strong. In this contribution we use fake star tests to characterize the completeness and reliability of single-frame, single-band data from the commonly used short-exposure IRAC observing modes as a function of background surface brightness and stellar magnitude. We also explore empirically the completeness of the GLIMPSE Point Source Catalog as a function of background brightness and magnitude. We provide plots and analytical prescriptions to allow an end user to asses the completeness over specified magnitude and background brightness ranges.
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