Point sources from a Spitzer IRAC survey of the Galactic Center

Creators: Ramírez, Solange V.; Arendt, Richard G.; Sellgren, Kris; Stolovy, Susan R.; Cotera, Angela; Smith, Howard A.; Yusef-Zadeh, Farhad

Abstract

We have obtained Spitzer IRAC observations of the central 2.0° × 1.4° (~280 × 200 pc) of the Galaxy at 3.6-8.0 μm. A point-source catalog of 1,065,565 objects is presented. The catalog includes magnitudes for the point sources at 3.6, 4.5, 5.8, and 8.0 μm, as well as JHK_s photometry from Two Micron All Sky Survey (2MASS). The point-source catalog is confusion limited with average limits of 12.4, 12.1, 11.7, and 11.2 mag for [3.6], [4.5], [5.8], and [8.0], respectively. We find that the confusion limits are spatially variable because of stellar surface density, background surface brightness level, and extinction variations across the survey region. The overall distribution of point-source density with Galactic latitude and longitude is essentially constant, but structure does appear when sources of different magnitude ranges are selected. Bright stars show a steep decreasing gradient with Galactic latitude and a slow decreasing gradient with Galactic longitude, with a peak at the position of the Galactic center. From IRAC color-magnitude and color-color diagrams, we conclude that most of the point sources in our catalog have IRAC magnitudes and colors characteristic of red giant and asymptotic giant branch (AGB) stars.

Additional Information

© 2008 The American Astronomical Society. Print publication: Issue 1 (2008 March). Received 2007 August 4, accepted for publication 2007 September 18. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The research described in this paper was partially carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. K. S. thanks the NASA Faculty Fellowship Program for financial support and the hospitality of the JPL Long Wavelength Center and the Spitzer Science Center. We thank S. Carey, P. Lowrance, R. Blum, C. Koresko, D. Shupe, M. Meade, and B. Babler for enlightening discussions.

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