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APPENDIX III

ECLIPSES IN THE REIGN OF EMPEROR HSÜAN

i. HS 8: 7a, b, reads, "In the [period] Ti-chieh, I (the first year), . . . xii
(in the twelfth month), on [the day] kuei-hai, the last day of the month,
there was an eclipse of the sun." (Han-chi 17: 7a reads the same.)
HS 27 Cb: 14b repeats the foregoing and adds, "It was 15 degrees in [the
constellation] Ying-shih." This date was, according to P. Hoang, Feb.
13, 68 B.C.

Oppolzer calculates his eclipse no. 2712 on that date and charts the
path of annular totality as passing through Sumatra and Borneo and ending
at sunset near the island of Mindanao. Calculation shows that at
Ch'ang-an this eclipse reached a magnitude of only 0.10 at 4:20 p.m.,
local time. The eclipse began at 4:19 and ended at 5:03 p.m., which
was 42 minutes before sunset, according to the U. S. Nautical Almanac.
This eclipse must have been observed by watching the sun's reflection
in water or in a mirror, for there was no perceptible diminution of sunlight
at Ch'ang-an. To the east and south, the eclipse was more conspicuous.
If an eclipse that is so barely visible was recorded, why were the many
more conspicuous eclipses that preceded and followed this eclipse not
recorded?

The sun was in long. 322° = 324° R.A. According to Neugebauer,
Sterntafeln, the two stars of Ying-shih, α, β Pegasi, were then in 321°
and 322° R.A. respectively.

In the 12 years between this and the preceding recorded eclipse, three
eclipses were visible in China: on Jan. 3, 75 B.C. (at sunrise), on May 8,
73 B.C. and on Feb. 25, 69 B.C. The eclipse of Jan. 3, 75 B.C. was
invisible in the Yangtze valley and north, but at Canton, at sunrise, it
reached a magnitude of 0.18, according to calculation.

ii. HS 8: 18b, 19a says, "In Wu-feng I, xii, . . . on yi-yu, the first
day of the month, there was an eclipse of the sun." Han-chi 20: 1a
reads the same. HS 27 Cb: 14b adds, "It was 10 degrees in [the constellation]
Wu-nü."

P. Hoang equates this date with Jan. 3, 56 B.C., for which Oppolzer
calculates his solar eclipse no. 2742.

Calculation, according to the method in P. Neugebauer, Astronomische
Chronologie, shows that this eclipse was invisible in Ch'ang-an, so that
it must have been reported from outside the capital. At sunrise in the
present Peiping, it had reached a magnitude of 0.18. At the present

Shan-hai-kuan, at sunrise, it had reached a magnitude of 0.40. At lat.
40° N. it was invisible west of long. 113.5° E. (pres. Ta-t'ung, Shansi)
and at lat. 35° N. it was invisible west of long. 111.3° E. (pres. Shan-hsien,
western Honan), so that, although it was not visible in Ch'ang-an,
yet it was barely visible at sunrise in Lo-yang, whence reports might
easily have been brought to the capital.

The sun was in long. 281° = 280° R.A. The principal star of Wu-nü,
ε Aquarii, was then in 284° R.A.

In the twelve years between this and the preceding recorded eclipse,
four eclipses were visible in China: on Aug. 9, 68 B.C., Sept. 20, 61 B.C.,
July 20, 58 B.C., and July 9, 57 B.C.

iii. HS 8: 20b says, In Wu-feng IV, "iv, on hsin-ch'ou, the last day
of the month [27 Cb: 14b and Han-chi 20: 8b read correctly, "the first day
of the month," cf. n. 20.8], there was an eclipse of the sun." HS 27 Cb:
15a adds, "It was 19 degrees in [the constellation] Pi."

P. Hoang equates that date with May 9, 54 B.C., for which Oppolzer
calculates his solar eclipse no. 2747. He charts the path of the eclipse
as passing thru central China and calculates the sun in long. 45° = 42°
R.A. The first star of Pi, λ Tauri, was then in 33° R.A.

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