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H. Wolf, J. Böhm, M. Schartner, U. Hugentobler, B. Soja, A. Nothnagel:
"Observations to Galileo satellites with VLBI: an evaluation study";
Talk: Frontiers of Geodetic Science 2021, Online; 2021-09-21 - 2021-09-23.

The mounting of a Very Long Baseline Interferometry (VLBI) transmitter on one or more future Galileo satellites would enable VLBI antennas to observe satellites in parallel to natural extra-galactic radio sources (quasars). These observations would provide various new possibilities such as the determination of the absolute orientation of the satellite constellation with respect to the International Celestial Reference Frame (ICRF). Further, it is possible to compare the position of the satellite obtained from VLBI observations with positions obtained from other space geodetic techniques, which allows a high-precision tying of the different space geodetic techniques and leads to an improvement of the Terrestrial Reference Frame (TRF).

This presentation provides an evaluation of satellite observations by assessing the visibility of the satellites and the sensitivity of the observations with respect to different parameters. For the latter, so-called Dilution of Precision (DOP) factors are introduced which indicate the change of the observable by a change of a certain parameter and therefore represent the sensitivity of the satellite observation towards this parameter.
In our study, possible observation periods to Galileo satellites from a VLBI network are determined using the satellite scheduling module in VieSched++ and are assessed through the number of stations from which a satellite is visible simultaneously. Moreover, these potential satellite observations are evaluated by using DOP factors, which depict the sensitivity of an observation towards UT1-UTC and towards the components of the satellite position in the orbit-fixed RSW-frame with radial, along-track and cross-track directions.

https://publik.tuwien.ac.at/files/publik_299006.pdf