Cross-identifications and astro-photometric comparisons of the ICRF with recent catalogs of quasars

Observatoire de Paris, SYRTE, 61 avenue de l'observatoire, 75014 Paris, France e-mail: jean.souchay@obspm.fr

Received: 19 October 2005
Accepted: 10 January 2006

Abstract

The ICRF represents the most accurate astrometric catalog that is the primary reference frame adopted by the IAU General Assembly at Kyoto in 1997. Despite its importance, an exhaustive study of both the sky coverage and the physical properties of the extragalactic sources representing the ICRF is lacking. The object of the present paper is to extract some information concerning these sources and cross-identify them with the data gathered by Véron-Cetty & Véron (2003, A&A, 412, 399), which is the largest compilation of various catalogs of quasars. After this cross-identification of the sources, we carry out a study of some general features of the ICRF concerning the visual magnitudes, the redshifts, and the flux at radio wavelengths