C-COSMOS: Chandra X-ray Source Optical/IR Counterparts Catalog

1761 X-ray point sources from the 1.8-Ms Chandra COSMOS Survey are identified with optical and infrared counterparts. The catalog includes i, K, and 3.6-um identifications, with unique associations for 97% of the sources, plus spectroscopic and photometric redshifts. This table was created by NASA's HEASARC in December 2012 based on data from the CDS catalog.

Use Cases

• Cross-matching X-ray sources with optical and infrared counterparts based on the likelihood ratio technique described.
• Analyzing the properties of X-ray sources with spectroscopic and photometric redshifts provided in the catalog.
• Studying source populations in the COSMOS field using the deep, multi-band X-ray flux limits (e.g., 1.9e-16 erg/cm2/s in soft band).
• Investigating the small fraction (3%) of sources with ambiguous or no counterpart association mentioned in the description.

Strengths

• High counterpart association rate of 97% for the 1761 X-ray sources.
• Provides deep X-ray flux limits across three energy bands (soft, hard, full).
• Includes spectroscopic and photometric redshifts for source classification.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Last updated 2026-03-13 19:28:58.893697; freshness should be verified.

Provenance

Source

NASA HEASARC, based on CDS Catalog J/ApJS/201/30.

Collection Method

Data from the Chandra COSMOS Survey (C-COSMOS), with optical/IR counterpart identification using the likelihood ratio technique.

Freshness

Last updated 2026-03-13 19:28:58.893697

Geography

Covers the central 0.9 square degrees of the COSMOS field.