An experiment to observe GNSS signals with the Australian VGOS array

TL;DR

This paper demonstrates the feasibility of using Australian VGOS radio telescopes to observe GNSS satellites, enabling direct VLBI-GNSS measurements that improve terrestrial reference frame accuracy.

Contribution

It introduces the novel use of VGOS telescopes for GNSS observations, bridging a gap between radio astronomy and satellite geodesy techniques.

Findings

Successful VLBI observations of GPS satellites with VGOS telescopes

First demonstration of inter-technique ties between VLBI and GNSS in Australia

Potential for critical geodetic measurements for space missions

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. Inter-technique biases are a major error source in the terrestrial reference frame. Combining two major space-geodetic techniques, GNSS and 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 VGOS telescopes is shown here, invalidating this prevailing opinion. A series of test observations demonstrates geodetic VLBI observations to GPS 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 towards the Genesis mission, geodesy's flagship project in the area of space ties set for launch in 2028.