Automatic Observation of Astronomical Coordinates Using the Shandong University of Science and Technology/National Astronomical Observatories Digital Zenith Tube

Abstract

Abstract The digital zenith tube (DZT) is developed based on the astrogeodetic and photogrammetric theory. One prototype of DZT integrating techniques of global positioning system (GPS) and charge-coupled device (CCD) photogrammetry has been developed jointly by Shandong University of Science and Technology and National Astronomical Observatories of Chinese Science Academy, China. It can automatically estimate astronomical coordinates in real time by CCD star image processing and GPS data processing. The DZT’s errors are analyzed in three aspects, namely, the instrument error, observation error, and data processing error. Reliability and accuracy of DZT integrating GPS and CCD are verified by the practical field operations. Observing results on many unknown points by the repeated observations of each point show the internal precision of the astronomical latitude and longitude. Observing results on several known points and the comparison with the EGM2008-derived results verify the external accuracy of the DZT, and the differences of these points in astronomical latitude and longitude are within ±0.15″ and greater than 1″, respectively.