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Johannes Böhm
Type of contribution: poster

The contribution of the Twin Telescopes at Onsala and Wettzell to the VGOS System

Caroline Sch"onberger, TU Wien Paul Gnilsen, TU Wien Johannes B"ohm, TU Wien R"udiger Haas, Chalmers University of Technology, Onsala Space Observatory

During the last years the International VLBI Service for Geodesy and Astrometry (IVS) spent efforts to improve the accuracy of the geodetic Very Long Baseline Interferometry (VLBI) system to 1 mm for station positions and 0.1 mm/yr for station velocity. To achieve these ambitious goals the VLBI2010 concept was developed, which includes broadband observations with fast-slewing antennas and suggests twin telescopes to reduce the source switching interval and increase the number of observations. Wettzell in Germany has already installed a Twin Telescope and more Twin Telescopes will be installed in the coming years at Onsala (Sweden), Ny-Alesund (Spitsbergen, Norway) and probably Kazan (Russia). In this study, the Vienna VLBI Software (VieVS) was used to schedule and simulate a global VLBI network using the sites that participated in the CONT11 campaign, with and without the Twin Telescopes in Onsala and Wettzell. Different scheduling approaches (Onsala60 telescope or Twin Telescope, continuous or multidirectional mode, etc.) were compared by evaluating the numbers of observations and scans as well as baseline length repeatability, station positions, Earth orientation parameters, atmospheric parameters and clock estimates. In general an improvement in the estimated parameters is visible with the Twin Telescopes especially with the Onsala Twin Telescope operated in a continuous observing mode and the scheduling strategy with four sources observed in the network simultaneously.