Precision Estimates of Universal Time from Radio-Interferometric Observations

Abstract

Considerable improvement in the determination of the motion of the Earth is possible by the potentially high accuracy inherent in very-long-baseline interferometry. Precisions of UT1 are estimated from time delay and fringe frequency measurements of extragalactic radio sources with positional uncertainties at the level. Case studies resulted in standard deviations about one order of magnitude smaller than those obtained by classical astrometric methods. The dependence of estimates on baseline orientations and source declinations is discussed.