Precise determination of the reference point coordinates of Shanghai Tianma 65-m radio telescope

Abstract

A local survey was implemented at the newly constructed Shanghai Tianma 65-m radio telescope. In this article, the survey implementation and data analysis are described. Particularly, by application of coordinate transformation, dimensionality reduction and step fitting of parameters, as well as adoption of reliability test measures of parameters, the mathematical model of data analysis is simplified, the detrimental effects of observation noises and unevenly spatial coverage of sample points are effectively compressed, the stability and precision of parameter solutions are improved, and so the geocentric three-dimensional coordinates of the reference point of this telescope in the precision of millimeters were determined, and the axis-offset was shown not significant on the precision level of 3 mm. The outcome provides important reference to the subsequent activities of antenna maintenance and scientific application, including the establishment of precise antenna orientation model, orientation guidance, fringe searching in data cross-correlation, analysis and application studies of VLBI observations. It is also important archive data for monitoring possible subsidence and lateral displacement of antenna foundation as well as deformation of antenna tracking-rail and structure.