Radio Reference Frame Stability from VLBI Data [chapter]

O. J. Sovers, R. N. Treuhaft
1988 The Impact of VLBI on Astrophysics and Geophysics  
Intercontinental radio interferometric measurements between NASA's Deep Space Network stations yield a catalog of positions of 106 extragalactic radio sources, uniformly distributed between -45° and +85° declination. Almost all of the source positions have formal uncertainties between 0.5 and 3 milliarcseconds. Estimates of three independent sets of 32 source coordinates at average epochs 1980.0, 1983.2, and 1984.5 assess the level of stability of the reference frame over a five-year period.
more » ... ive-year period. Comparisons of the three sets of source coordinates show a number of cases of > 2σ differences, particularly betwen the 1984-85 and 1981-83 periods. No sources, however, show 2σ shifts among both pairs of epochs. Upper limits of the order of 1 mas/yr can be placed on the time rates of change of the 32 source coordinates.
doi:10.1007/978-94-009-2949-4_113 fatcat:wgannw2orffvrnhggfx2wenyre