Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination

Abstract

The difference of universal time to atomic time UT1-UTC (dUT1) is a key parameter for precise positioning and navigation using space geodetic techniques. Measurements of dUT1 can only be provided by the geodetic Very Long Baseline Interferometry (VLBI). The parameter is routinely estimated twice per week from VLBI 24-hour sessions and with a lower latency from so-called intensive sessions. Routine intensives are observed daily for one hour, on one or sometimes two baselines. All of the current IVS (International VLBI Service for Geodesy and Astrometry) intensive sessions are operated on baselines involving northern hemisphere telescopes only. In 2019 we started the Southern Hemisphere Intensive observing program (SI) as a joint initiative of TU Wien, the University of Tasmania and the Hartebeesthoek Radio Astronomy Observatory. The SI sessions are observed with three VLBI stations located south of the equator: HART15M (South Africa), HOBART12 (Tasmania) and YARRA12M (Western Australia). Observations including HOBART12 are observed in mixed-mode configuration, using the VGOS receiver in Hobart and the legacy systems at the other stations.For the year 2020, we scheduled 38 SI sessions recorded with a high data rate of 1 Gbps to compensate for the reduced sensitivity of the smaller antennas. Starting from April the program is continued with 36 sessions scheduled for 2021. In this contribution, we will primarily focus on the dUT1 results of the sessions from the year 2020, which could be successfully observed, correlated and analyzed.