ASTROMETRIC CCD POSITIONS FOR EXTRAGALACTIC RADIOSOURCES

We present results from CCD observations made at the 1.60 m Telescope of the Laboratorio Nacional de Astrofisica, Itajuba, Brazil, for 85 ex tragalactic radiosources uniformly distributed over -80 degrees less t han or equal to delta less than or equal to+20 degrees declination, fr om the IAU list of objects scheduled to define the International Celes tial Reference System (ICRS). The positions are referred to the Carlsb erg Series (CAMC), PPM and ACRS catalogues. They were derived by using a method which allows obtaining precise positions based on corrected positions from the Guide Star Catalogue. A set of 60 fiducial sources was selected by means of their positional are length differences, to l ink and compare the optical results and the VLBI radiosource positions . Relative orientation angles between the optical and radio frames wer e found within 0.'' 02 precision. Comparison of positions on both fram es for all radiosources has shown a dispersion of 0.'' 2, consistent w ith the errors in the reference catalogues used. (C) 1997 American Ast ronomical Society.