Roma-BZCAT: Multi-Frequency Catalog of 3,561 Blazars

A catalog of 3,561 blazars and candidate blazars, providing coordinates and multi-frequency data. The 5th edition, maintained by NASA HEASARC, includes 1,151 BZB, 1,909 BZQ, 274 BZG, and 227 BZU sources, with updates based on CDS archives. All sources have a confirmed radio band detection and, with noted exceptions, published spectroscopic information.

Use Cases

• Classifying blazar types (BZB, BZQ, BZG, BZU) based on the catalog's updated classification scheme.
• Cross-matching radio sources with optical and other frequency data using the provided coordinates.
• Studying the spectral properties of confirmed blazars using the referenced spectroscopic information.
• Filtering catalogs to exclude 'radio quiet BL Lacs' for studies requiring confirmed radio detections.

Strengths

• Contains data on 3,561 sources, about 30% more than the 1st edition.
• All sources have a confirmed detection in the radio band, reducing contamination from other object types.
• Provides a detailed breakdown of 1,151 BZB, 1,909 BZQ, 274 BZG, and 227 BZU sources.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Excludes 'radio quiet BL Lacs' and some BL Lac candidates where optical spectra are unavailable, which may limit certain comparisons.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

NASA HEASARC, based on CDS Catalog VII/274.

Collection Method

Catalog compilation from astronomical observations and literature.

Time Range

Catalog edition reflects data available up to its publication and updates.

Freshness

Last updated 2026-03-13 19:19:47.184848; freshness should be verified.

Geography

Celestial coordinates (J2000) for extragalactic sources.