Investigations of Thermal Deformation Based on the Monitoring System of Tianma 13.2 m VGOS Telescope

Abstract

The thermal expansion of radio telescopes has been recognized as a significant systematic error in Very Long Baseline Interferometry (VLBI) data analysis. Although the thermal expansion model recommended by International Earth Rotation Service (IERS) Conventions 2010 can achieve millimeter accuracy for the International VLBI Service for Geodesy and Astrometry (IVS) routine telescopes, both the International Terrestrial Reference Frame 2020 (ITRF2020) in preparation and the VLBI2010 project encourage the scientific community to reconsider its modeling. To this end, we developed a monitoring system for the Tianma 13.2 m VLBI Global Observing System (VGOS) telescope. Based on the observed data, we refined the IERS expansion model, with results showing that the accuracy of our modified model was improved by 1.9 times. It suggested that the IERS thermal expansion model can achieve the declared millimeter accuracy, and refining its modeling can meet the requirement of 0.3 mm rms stability of the VGOS antenna reference point for the VLBI2010 project.