An Experiment to Observe GNSS Signals with the Australian VGOS Array

Abstract This paper introduces a new instrument enabling a novel combination of Earth measuring techniques: direct observations with the radio astronomical instruments to satellites of the global navigation satellite systems (GNSS). Inter-technique biases are a major error source in the terrestrial reference frame. Combining two major space-geodetic techniques, GNSS and Very Long Baseline Interferometry (VLBI), through observations to identical sensors has been considered infeasible due to their seemingly incompatible operating frequencies. The newly accessible L -band capability of the Australian VLBI Global Observing System telescopes is shown here, invalidating this prevailing opinion. A series of test observations demonstrate geodetic VLBI observations to Global Positioning System satellites for a continental-wide IVS telescope array, with the potential for observations at a critical scale. We anticipate immediate impact for the geodetic community, through first-ever inter-technique ties between VLBI and GNSS in the Australian region and via the opportunity for critical test observations toward the Genesis mission, geodesy’s flagship project in the area of space ties set for launch in 2028.