EVALUATION OF CATALOGS OF EXTRAGALACTIC RADIO-SOURCES

A combined catalogue is constructed from the observations of extragalactic radio sources compiled in independent catalogues providing precise positions determined by radio interferometric techniques. Positions and catalogue differences are derived and discussed. The average precision of the combined catalogue is at the level of 0.7 mas in right ascension and 1.3 mas in declination. For the more recent catalogues the systematic differences amount to a fraction of a millisecond of arc.