Appendix II. Eclipses During the Reign of Emperor Ai

i. In Yüan-shou I, i (the first month), on the day hsin-ch'ou, the first day of the month, an eclipse of the sun is recorded (11: 7a). HS 27 Cb: 16a adds, "It was not total, [but] like a hook, and was 10 degrees in [the constellation] Ying-shih, in the same month and day as that in the seventh year of Emperor Hui."

Huang, Concordance des chronologies néoméniques, gives this date as Feb. 5, 2 B.C., for which day Oppolzer, Canon der Finsternisse, calculates his solar eclipse no. 2879. He charts the path of totality as passing along the Yangtze River. Calculation of this eclipse according to Neugebauer, Astronomische Chronologie, shows that at Ch'ang-an it reached a magnitude (totality = 1.00) of 0.85 a, Southern Szechuan, southern Hunan and Foochow. The sun was in longitude 314° = 317° R.A. The first and principal star in Ying-shih, α, Pegasi was then in 319° R.A. It is interesting that a total eclipse was not reported when it went so far south.

In the 10 years between this and the preceding recorded eclipse, no solar eclipses were visible in China.

ii. HS 11: 8a states, in Yüan-shou II, "the summer, fourth month, on [the day] jen-ch'en, the last day of the month, there was an eclipse of the sun." Han-chi 29: 12b merely states, "In the summer, the fourth month, there was an eclipse of the sun." HS 27 Cb: 16a however states, "In [Yüan-shou] II, the third month, on [the day] jen-ch'en, the last day of the month, there was an eclipse of the sun." Huang gives no jen-ch'en day in the fourth month, but makes that day the last day of the third month, May 21, 1 B.C. He gives the last day of the fourth month as a jen-hsü day, June 20, 1 B.C., for which day Oppolzer calculates his solar eclipse no. 2882. He gives none for the other date. Calculation of this partial eclipse by Neugebauer's tables shows that it reached a magnitude of 0.06 at sunset, 5:08 p.m. local time at Ch'ang-an.

It is then evident that jen-ch'en 辰 is a mistaken reading for jen-hsü 戌 (a natural error), and that someone who knew that jen-ch'en could not have been the last day of the fourth month corrected the record in ch. 27. Astronomers must have been looking for this eclipse, else they would not have perceived it. In the 16 months between this and the preceding recorded eclipses, no solar eclipses were visible in China.