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H. Krasna, F. Jaron, J. Gruber, J. Böhm, A. Nothnagel:
"Baseline-dependent clock offsets in VLBI analysis";
Talk: 25th Meeting of the European VLBI Group for Geodesy and Astrometry, Cyberspace; 2021-03-14 - 2021-03-18.

The primary goal of the geodetic Very Long Baseline Interferometry technique is to provide highly accurate terrestrial and celestial reference frames with Earth orientation parameters. In compliance with the concept of VLBI, additional parameters have to be estimated such as relative clock offsets and their variations at the stations with respect to a reference clock in the observing network. Reality shows that in many cases significant offsets appear in the observed group delays for individual baselines which have to be compensated for by estimating the so-called baseline-dependent clock offsets (BCOs). We investigate various aspects of BCOs including their impact on the estimates of geodetically important parameters. We choose a systematic approach for the empirical tests and investigate some of the theory behind BCO estimation. For the case study, we choose both legacy networks of the CONT17 campaign. We conclude that it is essential to estimate BCOs for baselines where an offset in the observed delay appears. Further we show, that estimation of the BCOs at baselines without any significant offset does not harm the geodetic solution under the condition that there are enough observations at the telescopes with good sky coverage which allows for decorrelation of station dependent parameters.

https://publik.tuwien.ac.at/files/publik_295800.pdf