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 the1980s till present.
The quarterly global VLBI geodetic solutions:
Methods of data analysis are described in full detail in Petrov & Kovalev, "The Radio Fundamental Catalog", 2025, The Astrophysical Journal Supplement Series, 276:38 (51pp), doi: 10.3847/1538-4365/ad8c36.
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