The Improvement of Determination of the Instantaneous Azimuth Error of Lower Latitude Meridian Circle(LLMC)

By using the zenith distances of a pair of stars which have the almost same declinatons and are observed at the almost same moment in the east and west of the prime vertical, the instantaneous azimuth error of the instrument can be determined absolutely. In comparison with the original method, there is no superposition of the variation of the azimuth error in the present method and the original design of the instrument is not needed to be changed. Therefore, the observational system of LLMC is expected to be improved.