Abstract
Abstract. The International VLBI Service for Geodesy and Astrometry (IVS) is currently setting up a network of smaller and thus faster radio telescopes observing at broader bandwidths for improved determination of geodetic parameters. However, this new VLBI Global Observing System (VGOS) network is not yet strongly linked to the legacy S/X network and the International Terrestrial Reference Frame (ITRF) as only station WESTFORD has ITRF2014 coordinates. In this work, we calculated VGOS station coordinates based on publicly available VGOS sessions until the end of 2019 while defining the geodetic datum by fixing the Earth orientation parameters and the coordinates of the WESTFORD station in an unconstrained adjustment. This set of new coordinates allows the determination of geodetic parameters from the analysis of VGOS sessions, which would otherwise not be possible. As it is the concept of VGOS to use smaller, faster slewing antennas in order to increase the number of observations, shorter estimation intervals for the zenith wet delays and the tropospheric gradients along with different relative constraints were tested and the best performing parametrization, judged by the baseline length repeatability, was used for the estimation of the VGOS station coordinates.
Highlights
In order to improve the accuracies of geodetic parameters determined with Very Long Baseline Interferometry (VLBI) observations, the International VLBI Service for Geodesy and Astrometry (IVS) (Nothnagel et al, 2017) has developed the VLBI Global Observing System (VGOS) (Petrachenko et al, 2009)
In this study we demonstrated how an unconstrained adjustment can be used for the definition of the geodetic datum of VLBI sessions to connect the VGOS network with the International Terrestrial Reference Frame (ITRF)
The station coordinates of WESTFORD and the five Earth Orientation Parameters (EOP) were fixed to their a priori values
Summary
In order to improve the accuracies of geodetic parameters determined with Very Long Baseline Interferometry (VLBI) observations, the International VLBI Service for Geodesy and Astrometry (IVS) (Nothnagel et al, 2017) has developed the VLBI Global Observing System (VGOS) (Petrachenko et al, 2009). This new system is based on smaller and faster VLBI radio telescopes, allowing for a significantly increased number of observations, thereby enabling an improved estimation of tropospheric parameters which are considered one of the major error sources in geodetic VLBI (Schuh and Böhm, 2013). The main challenge is caused by the fact that the datum has to be defined without accurate a priori coordinates of most stations
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