High precision pointing error detection method for large radio telescope
Abstract
In the paper, the main factors influencing pointing precision of large radio telescopes are discussed. Then the TianMa radio telescope (TM65 m) is selected for demonstration. The methods of detecting and separating the pointing errors which produce in all the segments from the subreflector to the track rail of the telescope are introduced. They includes: (1) half power point tracking to evaluate the overall antenna pointing error; (2) detecting the pointing error due to position changing of the subreflector support; (3) detecting the deviation of the antenna mount due to temperature changing; (4) detecting the asynchronization of the mechanical axis and the encode axis; (5) high precision pointing modeling based on the uneveness of track rail. A few measurement methods and their respective results are discussed.
