SIMBAD references

The optical counterparts of 23 extragalactic radio sources, of which 13 are in the southern hemisphere, have been observed by three telescopes equipped with CCDs. By reference to the Astrographic/Tycho (ACT) Reference, Carlsberg Meridian (CMC),Positions and Proper Motions (PPM), Hipparcos (HIP) and Lick Northern Proper Motion (NPM) catalogues, the positions of the 23 objects have been obtained. The mean standard errors in right ascension and declination are better than 0.2arcsec. The differences from the radio positions are given, and a comparison between our results and those of other studies is also made.