The High Precision Pointing Model Establishment of Tianma 13 m Radio Telescope

The Tianma 13 m radio Telescope is a new generation of VLBI antennas designed for space geodesy, the so-called VGOS system. VGOS observing will change all aspects of VLBI, from scheduling, correlation, observing strategy, to analysis.Compared to current observing, a typical VGOS session will have 1-2 orders of magnitude more data. Tianma 13 m antenna is equipped with a 3-15 GHz broadband refrigeration receiver. The antenna pointing deviation is generally required to be less than 1/10 of the HPBW. In order to meet the requirement of high precision pointing, in this paper, the method of pointing establishment and antenna control scanning strategy are introduced in detail. The complete expression of the system error correction model is given, and the meaning of the parameters in the model is clarified. Based on the measured data of the antenna pointing scan, the pointing accuracy of the telescope is evaluated. The least square method is used to fit the data samples covering the all-sky region, and the pointing model of the Tianma 13 m radio telescope is obtained. The model is loaded into the antenna servo control system for verification, and the blind finger error of the tianma 13 m radio telescope is better than 10 arc seconds.