ROSAT/SDSS AGN Catalog: 7,000 X-Ray Emitting Active Galactic Nuclei

NASA HEASARC provides a catalog of approximately 7,000 confirmed quasars and other active galactic nuclei (AGN) identified as X-ray sources. The data results from a cross-correlation of X-ray data from the ROSAT All Sky Survey with optical imaging and spectroscopic data from the Sloan Digital Sky Survey Data Release 5, covering 5,740 square degrees of sky. This table was created in February 2007, replacing a previous version based on earlier SDSS data releases.

Use Cases

• Identify rare AGN subpopulations like X-ray-emitting BL Lac objects based on the description mentioning 'several hundreds' of such candidates.
• Study correlations between X-ray and optical properties of AGN using the large sample size described.
• Select the 'best' objects for follow-up X-ray spectral studies based on criteria like X-ray brightness, subclass, or redshift mentioned in the description.

Strengths

• Contains approximately 7,000 confirmed quasars and AGN with statistically secure X-ray identifications.
• Covers a wide range of optical magnitudes (15 < m < 21) and redshifts (0.01 < z < 4).
• Includes substantial numbers of rare AGN types, such as several hundred candidate BL Lac objects and narrow-line Seyfert 1 galaxies.

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 18:33:43.645082; freshness should be verified.

Provenance

Source

NASA HEASARC, based on data from the ROSAT All Sky Survey and Sloan Digital Sky Survey Data Release 5.

Collection Method

Cross-correlation of RASS X-ray sources with SDSS optical imaging and spectroscopic data.

Time Range

Observational data from the ROSAT All Sky Survey and SDSS DR5; catalog table created February 2007.

Freshness

Last updated 2026-03-13 18:33:43.645082; the underlying data is from SDSS Data Release 5 and a 2007 table creation.

Geography

Covers 5,740 square degrees of sky spectroscopically observed by SDSS DR5.