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Proceedings Paper

A Spitzer IRAC measure of the zodiacal light
Author(s): Jessica E. Krick; William J. Glaccum; Sean J. Carey; Patrick J. Lowrance; Jason A. Surace; James G. Ingalls; Joseph L. Hora; William T. Reach
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Paper Abstract

The dominant non-instrumental background source for space-based infrared observatories is the zodiacal light (ZL). We present Spitzer Infrared Array Camera (IRAC) measurements of the ZL at 3.6, 4.5, 5.8, and 8.0 μm, taken as part of the instrument calibrations. We measure the changing surface brightness levels in approximately weekly IRAC observations near the north ecliptic pole over the period of roughly 8.5 years. This long time baseline is crucial for measuring the annual sinusoidal variation in the signal levels due to the tilt of the dust disk with respect to the ecliptic, which is the true signal of the ZL. This is compared to both Cosmic Background Explorer Diffuse Infrared Background Experiment data and a ZL model based thereon. Our data show a few percent discrepancy from the Kelsall et al.(1998)1 model including a potential warping of the interplanetary dust disk and a previously detected overdensity in the dust cloud directly behind the Earth in its orbit. Accurate knowledge of the ZL is important for both extragalactic and Galactic astronomy including measurements of the cosmic infrared background, absolute measures of extended sources, and comparison to extrasolar interplanetary dust models. IRAC data can be used to further inform and test future ZL models.

Paper Details

Date Published: 21 September 2012
PDF: 9 pages
Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84421X (21 September 2012); doi: 10.1117/12.926664
Show Author Affiliations
Jessica E. Krick, Spitzer Science Ctr., California Institute of Technology (United States)
William J. Glaccum, Spitzer Science Ctr., California Institute of Technology (United States)
Sean J. Carey, Spitzer Science Ctr., California Institute of Technology (United States)
Patrick J. Lowrance, Spitzer Science Ctr., California Institute of Technology (United States)
Jason A. Surace, Spitzer Science Ctr., California Institute of Technology (United States)
James G. Ingalls, Spitzer Science Ctr., California Institute of Technology (United States)
Joseph L. Hora, Harvard-Smithsonian Ctr. for Astrophysics (United States)
William T. Reach, SOFIA, NASA Ames Research Ctr. (United States)


Published in SPIE Proceedings Vol. 8442:
Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave
Mark C. Clampin; Giovanni G. Fazio; Howard A. MacEwen; Jacobus M. Oschmann, Editor(s)

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