SEXSI: Optical Counterparts for 1,000 Hard X-Ray Sources from Chandra

Nearly 1,000 hard X-ray sources from over 2 square degrees of Chandra images have optical counterparts or flux limits derived from R-band imaging. Optical spectra for 477 counterparts provide identifications and redshifts for 438 sources, with redshifts ranging from 0.1 to 4.33. This table combines data from the SEXSI program's optical follow-up studies published in 2005 and 2006 by NASA HEASARC.

Use Cases

• Correlating optical and X-ray flux for extragalactic sources based on the described imaging data.
• Investigating the properties of optically faint, hard X-ray sources as mentioned in the description.
• Studying the density of optical sources surrounding X-ray counterparts using the provided positional data.
• Analyzing the relationship between optical flux and X-ray hardness ratio as referenced in the program's findings.
• Building catalogs of identified AGNs using the provided redshifts and source classifications.

Strengths

• Covers a large area of more than 2 square degrees of Chandra images, complementing deeper but smaller field studies.
• Provides optical data for nearly 1,000 hard X-ray sources, including redshifts for 438 sources.
• Combines data from multiple telescopes (Palomar, MDM, Keck) and two key publications (2005, 2006).

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Typical completeness levels are stated as 40-70%, indicating partial coverage.

Provenance

Source

NASA HEASARC, based on data from the SEXSI Program optical follow-up studies (Eckart et al. 2005, 2006).

Collection Method

Optical R-band imaging and spectroscopy from ground-based telescopes to identify counterparts for Chandra X-ray sources.

Time Range

Observational data likely from the early 2000s, corresponding to the cited publications.

Freshness

Last updated 2026-03-13 19:15:18.620075; freshness should be verified.

Geography

Extragalactic; celestial coordinates are implied but not specified in the description.