Contribution to the global VGOS network by potential sites in South America

Abstract

Very-long-baseline interferometry (VLBI) networks have historically lacked enough antennas to densify the southern hemi-sphere adequately. This situation not only impacts directly the realization of the Celestial Reference System but also thedetermination of the Earth Orientation Parameters (EOP). In the last years, a significant step in the modernization of the VLBIinfrastructure has been taken with the VLBI Global Observing System (VGOS). However, the distribution of VGOS antennasis still far from being homogeneous. In this work, we used the software VieSched++ for VLBI scheduling to simulate ninenew VGOS arrays. These networks, which are more dense in the southern hemisphere and focus on South America, wereplanned considering existing geodetic sites where a VGOS antenna could be added and new sites where the installation isfeasible. We compared the statistical performance of the proposed networks with that of a simulated standard VGOS networkand the actual VGOS performance for the last 2 years. A more uniform station distribution does not seem to be associatedwith better repeatabilities for station coordinates, but the results for EOP and source coordinates improve as expected.