Impact of the VLBA on reference frames and earth orientation studies

The geodetic vlbi community began using vlba antennas in 1989 for geodesy and astrometry. we examine how usage of the vlba has improved the celestial reference frame, the terrestrial reference frame, and earth orientation parameters. without the vlba, icrf2 would have had only 1011 sources instead of 3414. icrf3 will contain at least 4121 sources, with approximately 70 % or more coming exclusively from vlba astrometry and geodesy sessions. the terrestrial reference frame is also more stable and precise due to vlba geodesy sessions. approximately two dozen geodesy stations that have participated in vlba sessions show average position formal errors that are $$sim $$ 13–14 % better in the horizontal components and $$sim $$ 5 % better in the vertical component than would be expected solely from the increased number of observations. also the earth orientation parameters obtained from the rdv sessions represent the most accurate eop series of any of the long-term vlbi session types.