Roma BZCAT: a Multifrequency Blazar catalogue

We present a new catalog of blazars based on multi-frequency surveys and on an extensive review of the literature data. Blazars are classified as BL Lacertae objects, as Flat spectrum radio Quasars or as Blazars of uncertain/transitional type. Each object is identified by a root name, coded as BZB, BZQ and BZU for these three subclasses respectively, and by its coordinates. This catalogue is being built as a tool useful for the identification of the extragalactic sources that will be detected by present and future experiments for X and gamma-ray astronomy, like Swift, AGILE, GLAST and SIMBOL-X. An electronic version is available from the ASI Science Data Center web site at http://www.asdc.asi.it/bzcat. The on-line list includes more than 2500 objects and is continuously updated.