Geodetic Determination of Radio Telescope Antenna Reference Point and Rotation Axis Parameters

Large parabola dish antennae are in use for station-to-satellite communications, satellite tracking for precise orbit determination, very long baseline interferometry , and others. In this paper a procedure for the precise determination of the satellite tracking antenna reference point (ARP) position in the International Terrestrial Reference Frame is outlined. It is based on measurements made directly to the rotatable elevation housing of the antenna in various azimuth and elevation positions. The three-dimensional position of both rotation axes are obtained from the calculation of best-fitting circles. The resulting ARP is tied into a local geodetic network around the antenna to be observed by global positioning system (GPS) in combination with terrestrial measurements using a 3D data integration model including geoidal heights. ITRF coordinates are determined by static GPS observations using the products of the International Global Navigation Satellite Systems Service . Results are shown exemplarily for two European Space Agency antennae. The ARP was determined in both cases with a coordinate accuracy of approximately 5 mm . A description of the procedures, including terrestrial measurements, data evaluation models, and quality assessment is given.