MILLIQUAS: Million Quasars Catalog with 1,021,800 Objects (Version 8)

MILLIQUAS Version 8 is a catalog of 1,021,800 type-I quasars, AGN, blazars, and candidates, largely complete from the literature to 30 June 2023. It includes 907,144 confirmed objects and 66,026 high-confidence candidates, with 60.7% featuring Gaia-EDR3 astrometry. The HEASARC updated this table in July 2023 based on data from the author's website.

Use Cases

• Training classification models for quasar identification based on spectral line and photometric redshift data.
• Analyzing spatial distributions of quasars based on provided sky coordinates.
• Studying correlations between optical magnitudes and redshift for cosmological research.
• Validating candidate quasars via the catalog's radio/X-ray association methodology.

Strengths

• Contains 1,021,800 total objects, including 907,144 confirmed type-I QSOs and AGN.
• 60.7% of objects include Gaia-EDR3 astrometry for positional accuracy.
• Applies quality cuts and de-duplication to present one unique reliable object per row.
• Provides reliable spectroscopic redshifts derived from spectral line classification.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Low-confidence or questionable objects identified by original researchers are excluded.

Provenance

Source

Compiled from literature and source catalogs by Eric Flesch, updated by HEASARC/NASA.

Collection Method

Compendium from literature, with classifications via spectral lines and radio/X-ray associations.

Time Range

Largely complete from literature to 30 June 2023.

Freshness

Last updated 2026-03-13 18:15:11.077019; freshness should be verified.

Geography

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