《符天历》历元问题再研究

A Re-examination of the Epoch Date of the Futian Li

文章通过考察相关研究和文献资料,提出《符天历》历元的确切日期为显庆五年庚申岁正月壬寅雨水合朔,该雨水为定气而不是一般认为的平气,对应公元日期为660年2月16日,对应的儒略日序为1962169;解决了历来部分学者以为的《符天历》历元"气朔不合"与文献记载《符天历》历元"气朔相合"之间的矛盾;并引用了几则与《符天历》有关的传世星占文献和出土历日资料中的积日数据对结论加以讨论和验证;最后通过对《九执历》积日算法的讨论,指出使用该算法不能支持《符天历》历元为显庆五年正月三日雨水甲辰(660年2月18日)的结论。

After investigating some previous research and related literature, it is concluded that the epoch date of Futian Li （符天历） is the date renyin （壬寅 ）, when the solar term of yushui （Rainwater） combined with the first day of the first month of the 5th year of Reign Xianqing （显庆） This yushui is a kind of ＇true solar term＇ （定气） instead of ＂mean solar term＇ （平气）. Its corresponding Gregorian date is February 16,660, and its Julian date is 1962169. A contradiction is thus resolved between the opinion that the ＇ solar term yushui does not conform to the new moon＇ , which was held by some previous researchers, and the opposite point of view recorded in relevant literature. The conclusion is further examined by means of four records on the sum of days accumulated from the Futian Li＇s epoch date, which are preserved in astrological and calendrical sources. Finally, after a detailed discussion on the Jiuzhi Li＇s method of calculating accumulated days from epoch, it is pointed out that the Jiuzhi Li＇s method does not support the argument of taking the third day of the first month of the 5th year of Reign Xianqing （February 18,660） as the epoch date of the Futian Li.