Wolf, H. (2021). Satellite Scheduling with VieSched++ [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2021.87526
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Very Long Baseline Interferometry (VLBI) is a space-geodetic technique observing extragalactic radio sources with globally distributed radio telescopes. Over the last years, ideas have been proposed to equip one or more satellites of the second generation of the Galileo constellation with a VLBI transmitter. Observations of satellites with VLBI antennas provide a variety of new possibilities such as the direct determination of the absolute orientation of the satellite orbit with respect to the International Celestial Reference Frame (ICRF) and providing space ties instead of using local ties for connecting reference frames of different space-geodetic techniques. As more VLBI antennas have to observe a source simultaneously, it is necessary to create an observation plan, a so-called schedule. Common scheduling software packages support the scheduling of observations to extragalactic radio sources but only a few are able to schedule observations to satellites. The newly developed scheduling software VieSched++, written in C++, was equipped with a satellite scheduling module which allows the generation of a schedule including both, observations to quasars and satellites. In this work, an overview about the new satellite scheduling module in VieSched++ is given and the different available approaches to schedule satellite observations, the semi-manual and the automatic approach, are described. Moreover, this thesis deals with an evaluation study of possible satellite observations to Galileo satellites from a VLBI network. The time periods during which a satellite is observable from the VLBI network are determined using the satellite scheduling module in VieSched++. The possible satellite observations are evaluated through the number of stations from which the satellite could be observed and by the impact on determining the orientation of the satellite constellation directly with respect to ICRF, caused by the observation geometry. The study shows that Galileo satellites exhibit a high visibility for a VLBI network. There are no differences in terms of visibility between the individual orbital planes of the Galileo constellation and between the different orbital positions within these planes. If one satellite would be equipped with a VLBI transmitter there is therefore no preferable plane or slot within a plane to place this satellite. The investigation of the best combination of two satellites equipped with a VLBI transmitter shows that it has to be distinguished if the satellites are within the same plane or in different orbital planes.