GALEX/SDSS: 19,812 Candidate Quasi-Stellar Objects at Redshift 0.5-1.5

NASA HEASARC provides a catalog of 19,812 point-source candidates for Quasi-Stellar Objects (QSOs) in the redshift range 0.5 to 1.5. The sample was created from a combined Sloan Digital Sky Survey and Galaxy Evolution Explorer database, with contaminants removed using a subsample of ~4,500 SDSS spectra. This table, created in March 2011 and updated in April 2018, is based on archival data from the GALEX and SDSS missions.

Use Cases

• Training classification models to identify QSOs based on the 7-band UV-optical photometry described.
• Analyzing the distributions of redshift, luminosity, and reddening for QSOs in the specified redshift range.
• Validating photometric selection techniques for QSOs against a spectroscopically confirmed subsample.
• Studying the properties of point sources in combined SDSS-GALEX survey data.

Strengths

• Contains a final sample of 19,812 point-source candidates, with an estimated ~19,100 (~96%) true QSOs.
• Contaminants were removed using a subsample of ~4,500 SDSS spectra, suggesting a high-purity catalog.
• Based on combined data from two major astronomical surveys, SDSS and GALEX.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown for the initial ~60,000 object sample; only the final catalog size is provided.
• Last updated 2026-03-13 19:41:48.404215; freshness should be verified.

Provenance

Source

National Aeronautics and Space Administration (NASA HEASARC), based on data from the Sloan Digital Sky Survey (SDSS) and the Galaxy Evolution Explorer (GALEX).

Collection Method

Created from the electronic version of Table 2 from the reference paper, based on archival survey data.

Freshness

Last updated 2026-03-13 19:41:48.404215