Analysis of ancient Chinese records of occultations between planets and stars

Abstract

Abstract : One hundred seventy-three historical Chinese records of occultations and appulses (conjunctions with small least separations) of planets with stars, other planets, and extended objects were examined. The observations were made by the Chinese imperial astronomers from 12 December 146 B.C. to 3 February 1761 A.D. and preserved in the Chinese dynastic histories. Sixty-six of the records were of occultations, 83 records were of appulses, and 24 records were questionable as to the objects involved. These observations were compared to both ephemerides derived from the Bretagnon (1982) planetary theory and the JPL planetary ephemeris DE1O2. Both of the ephemerides verified that all of the well-recorded events occurred, and usually on the recorded day. This constitutes the first comparison of planetary theories and integration with ancient Chinese observations giving a weak check of the theories over moderately long periods of time. The results of this check show no evidence within the accuracy of these observations, inferred to be about 300, for secular discrepancies in the present theories on the timescale of two thousand years. When the deceleration of the Earth's rotation was taken into account, it was also found that the events usually took place at the time of night recorded by the Chinese observers, approx. 1/10 of the night. This constitutes a check on the DELTA TAU determinations independent of solar eclipse observations. Therefore, these records reveal that to the accuracy of these observations there are no serious flaws in the presently accepted planetary theories or determinations of the rotational deceleration of the Earth (DELTA TAU). Also, this study gives some insight into how the Chinese imperial astronomers charted the motions of the planets in the heavens. (3 tables, 19 refs.)