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Proceedings Paper

IRACproc: a software suite for processing and analyzing Spitzer/IRAC data
Author(s): Michael T. Schuster; Massimo Marengo; Brian M. Patten
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Paper Abstract

We have developed a post-Basic Calibrated Data pipeline processing software suite called "IRACproc". This package facilitates the co-addition of dithered or mapped Spitzer/IRAC data to make them ready for further analysis with application to a wide variety of IRAC observing programs. In acting as a wrapper for the Spitzer Science Center's MOPEX software, IRACproc improves the rejection of cosmic rays and other transients in the co-added data. In addition, IRACproc performs (optional) Point Spread Function (PSF) fitting, subtraction, and masking of saturated stars. The under/critically sampled IRAC PSFs are subject to large variations in shape between successive frames as a result of sub-pixel shifts from dithering or telescope jitter. IRACproc improves cosmic ray and other transient rejection by using spatial derivative images to map the locations and structure of astronomical sources. By protecting sources with a metric that accounts for these large variations in the PSFs, our technique maintains the structure and photometric reliability of the PSF, while at the same time removing transients at the lowest level. High Dynamic Range PSFs for each IRAC band were obtained by combining an unsaturated core, derived from stars in the IRAC PSF calibration project, with the wings of a number of bright stars. These PSFs have dynamic ranges of ~107 and cover the entire IRAC field of view. PSF subtraction can drastically reduce the light from a bright star outside the saturated region. For a bright star near the array center it is possible to detect faint sources as close as ~15-20" that would otherwise be lost in the glare. In addition, PSF fitting has been shown to provide photometry accurate to 1-2% for over-exposed stars.

Paper Details

Date Published: 30 June 2006
PDF: 11 pages
Proc. SPIE 6270, Observatory Operations: Strategies, Processes, and Systems, 627020 (30 June 2006); doi: 10.1117/12.673134
Show Author Affiliations
Michael T. Schuster, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Univ. of Minnesota (United States)
Massimo Marengo, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Brian M. Patten, Harvard-Smithsonian Ctr. for Astrophysics (United States)

Published in SPIE Proceedings Vol. 6270:
Observatory Operations: Strategies, Processes, and Systems
David R. Silva; Rodger E. Doxsey, Editor(s)

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