Astrometry of 25 Southern Hemisphere Radio Sources from a VLBI Short-Baseline Survey

Milliarcsecond-accurate radio positions for 25 southern hemisphere extragalactic sources are reported. These positions are derived from Mark III Very Long Baseline Interferometry observations made between 2003 September and 2004 May on the intra-Australia baseline connecting Hobart, Tasmania and Parkes, New South Wales. The results presented here represent an ongoing program intended to increase the number of phase-reference sources with accurate positions in the southern hemisphere for use in astrophysical observations. The positions for all but 1 of the 25 sources are south of δ = -45° and have average formal uncertainties of 3 mas in α cos δ and 2 mas in δ. As the reported positions are in the frame of the International Celestial Reference Frame (ICRF), the results reported here can also be used to increase the sky density of southern hemisphere ICRF sources, although with reduced accuracy.