Improvement and extension of the International Celestial Reference Frame in the Southern Hemisphere

Abstract

The U.S. Naval Observatory (USNO) and the Australia Telescope National Facility (ATNF) are collaborating in a continuing VLBI research program in Southern Hemisphere ICRF source imaging and astrometry using USNO, ATNF and ATNF-accessible facilities. These observations are aimed specifically toward improvement of the International Celestial Reference Frame (ICRF) in the Southern Hemisphere. We present the contributions of this program to the densification of the ICRF in the Southern Hemisphere and the imaging of all southern hemisphere ICRF sources for calculation of a "structure index". The impact of both these contributions to the improvement of the ICRF in the Southern Hemisphere will be discussed. © Springer-Verlag Berlin Heidelberg 2007.