Roma-BZCAT Multi-Frequency Catalog of Blazars

Consequently, peculiar sources such as the so called "radio quiet BL Lacs", which are reported in some other catalogs, are not included here because of possible contamination by hot stars and other extragalactic objects. In the 5th edition, the authors use a similar denomination for the blazars to that adopted in the previous editions. Each blazar is identified by a code, with 5BZ for all blazars, a fourth letter that specifies the type (B, G, Q or U), followed by the truncated equatorial coordinates (J2000).

The authors introduced the edition number before the letters BZ to avoid possible confusion due to the fact that several sources changed their old names because of a newly adopted classification. The 5th edition contains 1151 BZB sources (92 of which are reported as candidates because their optical spectra could not be found in the literature), 1909 BZQ sources, 274 BZG sources, and 227 BZU objects. This database table was originally ingested by the HEASARC in September 2013, based on <a href="cdsarc.cds.unistra.fr/ftp/cats/J/A+A/495/691">CDS Catalog J/A+A/495/691</a> file bzcat4.dat.

It was updated in March 2016, and it is now based on <a href="cdsarc.cds.unistra.fr/ftp/cats/VII/274">CDS Catalog VII/274</a> file bzcat5.dat. This is a service provided by NASA HEASARC .