|
Description
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that has imaged the central 0.5 deg<sup>2</sup> of the COSMOS field (centered at RA, Dec of 10 hours , +02 degrees) with an effective exposure of ~ 160 ks, and an outer 0.4 deg<sup>2</sup> area with an effective exposure of ~ 80 ks. The limiting source detection depths are 1.9 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the soft (0.5 - 2 keV) band, 7.3 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the hard (2 - 10 keV) band, and 5.7 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> in the full (0.5 - 10 keV) band. In this paper, the authors describe the strategy, design, and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of < 2 x 10<sup>-5</sup> (1655 in the full, 1340 in the soft, and 1017 in the hard bands). By using a grid of 36 heavily (~ 50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (+/-12%) exposure across the inner 0.5 deg<sup>2</sup> field was obtained, leading to a sharply defined lower flux limit. The widely different point-spread functions obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. This method produced reliable sources down to a 7-12 counts, as verified by the resulting log N-log S curve, with sub-arcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper. Supporting data products for this table (including images, event files, and exposure maps) are available at the <a href="https://cosmos.astro.caltech.edu/page/xray/">COSMOS Survey website</a> and at <a href="https://irsa.ipac.caltech.edu/data/COSMOS/">IRSA</a>. At the IRSA website, it is also possible to search a database that includes "postage stamps" of the X-ray data for each source, along with the multi-wavelength optical and infrared data, including the I-band, K-band, and Spitzer 3.6-micron (Band 1) images used in the Part III paper (Civano et al. 2012) to identify the sources. See also the related table <a href="ccosmosoid.html">CCOSMOSOID</a> for the optical and infrared identifications of the surveyed X-ray point sources. This table was created by the HEASARC in November 2009 based on an electronic version of the C-COSMOS Catalog which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
|
