Potential of VLBI VGOS telescope in Tahiti for geodesy and astrometry

Abstract

In the framework of this thesis, the goal is to examine the planned VGOS network, which is currently being developed by the International VLBI Service for Geodesy and Astrometry (IVS). In Very Long Baseline Interferometry (VLBI), groups of radio telescopes are used to observe distant radio galaxies such as quasars to derive important geodetic parameters for scientific purposes. The newly proposed VLBI Global Observing System (VGOS) is expected to lead to a higher accuracy and more reliability in the estimation of the above-mentioned parameters as a result of incorporating smaller telescopes with faster slewing speeds and a larger bandwidth for collecting the data. However, the main problem with the envisioned VGOS network lies within the uneven distribution of telescopes between the northern and the southern hemisphere. However, to reach an increase in the precision of the estimated parameters, having stations in the southern hemisphere is particularly important. Within the context of this work, the task is to evaluate the impact of such a station in Tahiti on the accuracy of the estimated parameters. Currently, the assumption is that a telescope on the island of Tahiti is ought to lead to an increase in the sensitivity of VLBI in regards to variations in the Earth’s rotation. To test this hypothesis, certain sim-ulations are carried out with a state-of-the-art VLBI software. The station Tahiti is added to a VGOS network of choice and subsequently gets compared to all the other stations within the network regarding its impact on the precision of the estimated parameters. The aim is thus to identify possible weaknesses of the used VGOS network and determine the importance of a station in Tahiti in eliminating these weaknesses. Adding a new station in Tahiti certainly supported the initial assumption as significant improvements could be observed for almost all of the estimated geodetic parameters. Furthermore, Tahiti has proven to be of more value than the majority of the other stations of the intended VGOS network, as it often demonstrated to be one of the most important stations to have the greatest impact on precision. Thus, the construction of a telescope in Tahiti is indispensable.