NASA GSFC global geodetic VLBI quarterly solutions

NASA Goddard Space Flight Center global geodetic Very Long Baseline
Interferometry (VLBI) quarterly solutions provide estimates of
stations positions, station velocities, harmonic variations in
site positions, parameters of non-linear station motions, positions
of extragalactic radio sources, and the estimates of an expansion
of the Earth orientation parameters into harmonic and B-spline bases.
These parameters were adjusted in a single least square analysis
by analyzing group delays derived from processing all publicly
available geodetic VLBI experiments accumulated since the 1980s till
present.