Chandra Legacy Survey: 4,016 X-ray Point Sources in the COSMOS Field

The COSMOS-Legacy survey imaged 2.2 square degrees of the COSMOS field using the Chandra X-ray Observatory. It contains 4,016 point sources, including 2,273 new detections, with limiting depths in multiple energy bands. The data was produced by NASA HEASARC in 2016 based on observations conducted between 2012 and 2014.

Use Cases

• Analyze the properties of obscured and unobscured active galactic nuclei based on hardness ratio classifications.
• Compute source number counts in hard and soft X-ray bands to reduce statistical uncertainties.
• Study the spatial distribution and flux of X-ray point sources in a deep, wide-field survey.
• Investigate the relationship between column density and source characteristics for AGN with column density > 10^22 cm^-2.

Strengths

• Large sample of 4,016 X-ray point sources, with 3,814 in the full band.
• Deep survey with effective exposures of ~160 ks over the central 1.5 deg^2 and limiting depths as faint as 2.2 x 10^-16 erg/cm^2/s.
• Combines 56 new observations with previous C-COSMOS data, creating an area-flux region described as likely unsurpassed.
• Reduces uncertainties in source number counts by 5% - 10% due to the large sample size.

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 17:04:55.115742; freshness should be verified.

Provenance

Source

NASA HEASARC, based on CDS Catalog J/ApJ/819/62.

Collection Method

Combination of 56 new Chandra X-ray Visionary Project observations with the previous C-COSMOS survey.

Time Range

Observations conducted in blocks from 2012 November to 2014 March.

Freshness

Last updated 2026-03-13 17:04:55.115742

Geography

Covers the 2.2 square degree COSMOS (Cosmic Evolution Survey) field.