A radio optical reference frame. 7: Additional source positions from a Southern hemisphere short baseline survey

Abstract

We report accurate radio positions for 107 VLBI sources using Very Long Baseline Inteferometry (VLBI), as part of a continuing program to establish a global reference frame of about 400 extragalactic radio positions. The observations were made with Australian radio telescopes at Tidbinbilla and Hobart during 1990 using Mark III VLBI recording systems. The positions reported here add 50 new sources to the global reference frame catalog, bringing the total number to 403, of which 208 are in the Northern hemisphere and 195 in the Southern. The new positions have median errors of about 5 milliarseconds, limited by the relatively short baseline of 832 km.