The VLBI celestial reference frame of the NASA Crustal Dynamics Project

Abstract

A celestial reference frame can be defined by precise positions of extragalactic radio sources using Mark III VLBI data available to the NASA Crustal Dynamics Project for geodynamic research. Seven years of such data have been analyzed to generate a catalogue of 101 sources with formal statistical errors between 0.01 and 0.77 ms in right ascension and between 0.2 and 9.3 mas in declination. In order to achieve such precision it is necessary to adjust the standard IAU nutation model. The rotations and scatter of the positions from year to year are generally less than 1 mas. A comparison of this catalogue with a completely independent catalogue derived from Mark II data shows a weighted average position difference, after a rotation, of 1.9 mas.