Calendar Differences Between the Northern and Southern Dynasties in 384 – 589

According to Index to Comprehensive Mirror to Aid in Governmance, the month 11 conjunction in 447 in the Northern Wei dynasty occurred on a jiǎ xū day (Dec. 23). However, in Compilation of Historical Calendars by Wāng Yuēzhēn, the month 12 conjunction was listed on a jiǎ xū day and is at odds with its statement that the winter solstice occurred on a jiǎ xū day in month 11. The month 12 conjunction on a jiǎ xū day is certainly a typo because a jiǎ xū day was 29 days (or 89 days) after a yǐ sì day, which was the leap month 10 conjunction date. So jiǎ xū day could only be the month 11 conjunction date. In 3500 Years of Calendars and Astronomical Phenomena by Zhāng Péiyú and Tables of Historical Lunar Conjunctions and Leap Months by Chén Yuán, the month 11 conjunction is mistakenly listed on Dec. 24. They were probably misled by Wāng's typo. The book A Sino-Western Calendar For Two Thousand Years (1-2000) by Hsueh Chung-San and Ouyang Yi correctly places the month 11 conjunction on Dec. 23. Surprisingly, the Chinese-Western calendar conversion website created by Academia Sinica in Taiwan, whose ancient calendar data are based on A Sino-Western Calendar For Two Thousand Years (1-2000), does not follow the book and mistakenly places the month 11 conjunction on Dec. 24.

There is a discrepancy between the main text and Appendix 3 in the book 3500 Years of Calendars and Astronomical Phenomena. The leap month in 502 is listed as after month 5 in the main text but after month 4 in Appendix 3.