Unsuccessful attempt for dating the Ulugbeige’s catalogue by the method of Dambis and Efremov

Abstract. In the paper "Dating Ptolemy’s star catalogue on the basis of proper motions: a thousand-year problem is solved " [1] A.K. Dambis ’ and Yu.N. Efremov applied so called “bulk method ” in an attempt for dating the “Almagest ” star catalogue. They obtained T=89±112 B.C. and concluded that this catalogue was created in Hipparchan epoch (about 130 B.C.), rejecting Ptolemy’s (about 130 A.D.) authorship. In order to check the reliability of “the bulk method”, we applied this method for dating the Ulugbeig’s catalogue, selecting from it different samples of fast stars. The main variant of the check points out a time interval of the catalogue’s completion between 1149÷1275 A.D. Correspondence to the traditionally accepted epoch of this catalogue, about 1437 A.D., is only achieved upon exclusion the seven fastest stars. We explain the obtained significant discrepancy as a result of numerous assumptions in the method of Dambis and Efremov which lead to underestimating of the errors and to displacement the epoch of dating. Key words: history of astronomy; problems of dating of the Almagest star catalogue Неуспешен опит за датировка на каталога на Улугбек по метода на Дамбис и Ефремо