Modeling Azimuthal Steel-Track Deformation to Determine the Reference Point of Wheel-Track VLBI Antenna

To determine a more precise reference point (RP) coordinate of Very Long Baseline Interfero-metry (VLBI) antenna in a local surveying, the effects of azimuthal track deformations in four-wheels and pedestal-based radio telescopes are analyzed, and an azimuthal steel-track residual deformation correction model is firstly proposed and derived to correct the coordinates of target points (TPs), which are used to determine the RP position. Using the real measurements of TPs and the leveling data of the steel track, systematic effects in residual of TP coordinates are explained and theoretical TP coordinates are corrected so that the corresponding RP precision is significantly improved. The results show that applying azimuthal steel-track residual deformation correction and estimation models can improve the standard error of post-fit TP residuals by 50% and 65%, respectively. The RP precision can improve about 30%. Moreover, the proposed steel-track residual deformation estimation model can be well applied to monitor the azimuth steel-track deformation of four-wheels and pedestal-based antenna.