The Establishment of Pointing Model for the Shanghai VGOS Radio Telescope

Abstract

Using a pointing model is a common practice among radio telescopes devoted to astronomy to correct for mechanical misalignments. Pointing accuracy is one of the most important indicators for the performance of radio telescopes, especially radio telescopes with a large diameter or which operate at high frequencies. The general requirement for deviation in pointing is less than 10% of the antenna’s half-power beamwidth. The method to establish the pointing model for the Shanghai VGOS radio telescope is described. Obtaining a large amount of test data by scanning the strong power source in the whole sky zone. Fitting these data by Gaussian to find the pointing deviation. We believe that a physical model is more desirable since it allows to identify the source of the pointing errors and may help in removing or minimizing the causes. Finally, an eight-parameter pointing model is built after fitting all the collected single-point errors. It is verified that the model works well in the broadband feed systems