THE SPITZER-WISE SURVEY OF THE ECLIPTIC POLES

Journal Article · Sun Jul 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/735/2/112· OSTI ID:21578383

Jarrett, T H; Masci, F; Cutri, R M; Marsh, K; Padgett, D; Tsai, C W ^[1]; Cohen, M ^[2]; Wright, E; Petty, S ^[3]; Stern, D; Eisenhardt, P; Mainzer, A; Ressler, M ^[4]; Benford, D ^[5]; Blain, A ^[6]; Carey, S; Surace, J ^[7]; Lonsdale, C ^[8]; Skrutskie, M ^[9]; Stanford, S ^[10]

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1. IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)
2. Monterey Institute for Research in Astronomy, 200 8th Street, Marina CA 93933 (United States)
3. UCLA, Physics and Astronomy Building, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 (United States)
4. Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)
5. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
6. University of Leicester, Department of Physics and Astronomy, University Road, Leicester, LE1 7RH (United Kingdom)
7. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
8. NRAO, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)
9. University of Virginia, Department of Astronomy, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
10. UC Davis, Department of Physics, One Shields Avenue, Davis, CA 95616-8677 (United States)

We have carried out a survey of the north and south ecliptic poles, EP-N and EP-S, respectively, with the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE). The primary objective was to cross-calibrate WISE with the Spitzer and Midcourse Space Experiment (MSX) photometric systems by developing a set of calibration stars that are common to these infrared missions. The ecliptic poles were continuous viewing zones for WISE due to its polar-crossing orbit, making these areas ideal for both absolute and internal calibrations. The Spitzer IRAC and MIPS imaging survey covers a complete area of 0.40 deg{sup 2} for the EP-N and 1.28 deg{sup 2} for the EP-S. WISE observed the whole sky in four mid-infrared bands, 3.4, 4.6, 12, and 22 {mu}m, during its eight-month cryogenic mission, including several hundred ecliptic polar passages; here we report on the highest coverage depths achieved by WISE, an area of {approx}1.5 deg{sup 2} for both poles. Located close to the center of the EP-N, the Sy-2 galaxy NGC 6552 conveniently functions as a standard calibrator to measure the red response of the 22 {mu}m channel of WISE. Observations from Spitzer-IRAC/MIPS/IRS-LL and WISE show that the galaxy has a strong red color in the mid-infrared due to star-formation and the presence of an active galactic nucleus (AGN), while over a baseline >1 year the mid-IR photometry of NGC 6552 is shown to vary at a level less than 2%. Combining NGC 6552 with the standard calibrator stars, the achieved photometric accuracy of the WISE calibration, relative to the Spitzer and MSX systems, is 2.4%, 2.8%, 4.5%, and 5.7% for W1 (3.4 {mu}m), W2 (4.6 {mu}m), W3 (12 {mu}m), and W4 (22 {mu}m), respectively. The WISE photometry is internally stable to better than 0.1% over the cryogenic lifetime of the mission. The secondary objective of the Spitzer-WISE Survey was to explore the poles at greater flux-level depths, exploiting the higher angular resolution Spitzer observations and the exceptionally deep (in total coverage) WISE observations that potentially reach down to the confusion limit of the survey. The rich Spitzer and WISE data sets were used to study the Galactic and extragalactic populations through source counts, color-magnitude and color-color diagrams. As an example of what the data sets facilitate, we have separated stars from galaxies, delineated normal galaxies from power-law-dominated AGNs, and reported on the different fractions of extragalactic populations. In the EP-N, we find an AGN source density of {approx}260 deg{sup -2} to a 12 {mu}m depth of 115 {mu}Jy, representing 15% of the total extragalactic population to this depth, similar to what has been observed for low-luminosity AGNs in other fields.

• OSTI ID: 21578383
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 735; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

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