The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8Ms, Chandra program that has imaged the central 0.9deg^2^ of the COSMOS field down to limiting depths of 1.9x10^-16^erg/cm^2^/s in the soft (0.5-2keV) band, 7.3x10^-16^erg/cm^2^/s in the hard (2-10keV) band, and 5.7x10^-16^erg/cm^2^/s in the full (0.5-10keV) band. In this paper we report the i, K, and 3.6um identifications of the 1761 X-ray point sources. We use the likelihood ratio technique to derive the association of optical/infrared counterparts for 97% of the X-ray sources. For most of the remaining 3%, the presence of multiple counterparts or the faintness of the possible counterpart prevented a unique association. For only 10 X-ray sources we were not able to associate a counterpart, mostly due to the presence of a very bright field source close by. Only two sources are truly empty fields. The full catalog, including spectroscopic and photometric redshifts and classification described here in detail, is available online.

Cone search capability for table J/ApJS/201/30/catalog (Chandra-COSMOS identification catalog)