OPTICAL POSITIONS OF RADIO EMITTING STARS

In order to contribute to the alignment of the radio and optical refer ence frames, 50 stars with confirmed radio emission and published radi o positions were observed by astrographical means. Additionally, two c onfirmed radio-stars of fainter magnitude were observed using a CCD di rect camera with a long focus, large aperture telescope. The reduction s are made relative to four catalogues: the Carlsberg Meridian Catalog ue #4, the International Reference Stars Catalogue, the Positions and Proper Motion Catalogue and the Astrographical Catalogue of Reference Stars. The best results were obtained with the CAMC catalogue. The pla te error of a radio star position is 0 ''.07 for both right ascension and declination, rising to 0 ''.10 - 0 ''.20 for bright stars. Ten of the program stars are not in the HIPPARCOS Input Catalogue and 12 do n ot belong td any of the major reference catalogues used. As soon as th e HIPPARCOS results become available, its reference stars already meas ured in the plates will enable us to get positions for those 10 radio stars in the HIPPARCOS system.