Event #4989: 1P/Halley returns

Text #1497

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Then also in the month of April and May there appeared in the heavens a star which they call a comet.

Text #5866

607 February 28; China.

A tailed star comet that extended across the heavens was seen in eastern Pegasus and went out of sight after 20 days.

Ho (237)

Text #2252

1P/607 H1 (Halley)

Discovered: 607 March 19.9 (Δ=1.16 AU, r=0.59 AU, Elong.=31°)

Last seen: 607

Closest to the Earth: 607 April 19 (0.0893 AU)

Calculated path: PSC (Disc), PEG (Apr. 10), PSC (Apr. 14), AND-PSC (Apr. 16), TRI (Apr. 17), PER (Apr. 18), AUR (Apr. 19), GEM (Apr. 20), CNC (Apr. 21), LEO (Apr. 24), SEX (May 1)

This apparition marks one of the more confusing records of 1P/Halley. The annals of the Sui shu (636) and the Pei shih (670) indicate a comet was seen on 607 February 28 and March 13, while the astronomical treatise of the Sui shu indicates a comet was seen on April 4 and October 21. The Pei shih even goes on to mention a comet seen on June 25. What makes these records so confusing is that ephemerides generated from the orbit below do not match the dates and locations given in these accounts, even though the orbital study that produced this orbit went on to represent closely this comet’s observed apparitions prior to 607. Interestingly, when the Dates are ignored, nearly all of the accounts give details which could represent the path of 1P/Halley, so astronomers have assumed errors were made in recording the dates.

The astronomical treatise of the Chinese text Sui shu says a “long-tailed star” was seen on 607 April 4 [hsin-hai day, 3rd month, 3rd year of the Ta Yeh reign-period]. It “was seen in the west direction. It extended across the sky. It trespassed against and passed Khuei [β, δ, ε, ζ, η, μ, ν, and π Andromedae, and σ, τ, υ, φ, χ, ψ, and 65 Piscium], Lou [(α, β, and γ Arietis], Chio [α and ζ Virginis], and Khang [ι, κ, λ, and φ Virginis] then it disappeared.”

The annals of the Chinese text Sui shu contains details of a “long-tailed star” that appeared on February 28 [ping-tzu day, 1st month, 3rd year of the Ta-Yeh reign-period]. It is said to have extended across the sky, to have appeared at Tung-Pi, and to have disappeared after 20 days. A “broom star” appeared on March 13 [chi-chhou day, 2nd month], which was seen at Khuei and Wên-Chhang [θ, τ, υ, and 18 Ursae Majoris]. It passed Thai-Ling [β, ι, κ, ρ, τ, 9, 12, and 16 Persei], Wu-Chhe [α, β, θ, and ι Aurigae, and β Tauri], and Pei-Ho [α and β Geminorum]. It entered the T’ai-wei Enclosure [Coma Berenices, Leo, and Virgo] and swept Ti-Tso [α Herculis]. It ceased after more than 100 days.

The report in the annals of the Chinese text Pei shih (670) is identical to that in the annals of the Sui shu, except that on March 13 the account substitutes Tung-Ching [γ, ε, ζ, λ, μ, ν, ξ, and 36 Geminorum] for Khuei.

The Pei shih and the annals of the Sui shu appear to have been derived from similar sources although the comet’s location on March 13 is different. They both indicate the comet was situated at Tung-Pi on February 28. Based on the orbit given below, the comet would have been a little south of Pegasus on that date, but only about 6° from the sun! F. Richard Stephenson and Kevin K. C. Yau (1985) have suggested the Pei shih and the annals of the Sui shu contained two errors: the “first month” should have read second month, and the “ping-tzu” day should have read “ping-wu” day. This would mean that the comet was actually first detected on March 20. The comet was in Tung-Pi, and it would have remained visible for about 20 days in the east before conjunction with the sun.

T. Kiang (1972) suggested the Chinese documents contained a misprint and that the date of March 13 should be interpreted as April 18. His argument was based on the assumptions that the record should have been read as the third month instead of the second, while the day should have read “i-chhou”, instead of “chi-chhou”. Stephenson and Yau agreed with these assumptions and noted the respective Chinese characters for these months and days have been frequently confused. Although the computed orbits indicate the comet should not have been in that portion of Gemini until April 20, the results certainly come much closer to representing the predicted path of 1P/Halley than the original text did.

The date of April 4. certainly could represent an observation of 1P/Halley, but the Chinese text says that the comet was seen in the west at a time when the comet should have been a prominent object in the east. Since the comet should certainly have been noticeable an April 4 and situated 45° from the sun, the Author believes it probable that an error was made in the direction and that the date was correct. On the other hand, Stephenson and Yau said the description of “long star” for that date does not fit since 1P/Halley was still over 0.6 AU from Earth and unlikely to be displaying a long tail.

What about the dates of June 25 and October 21? Both occurred long after the comet’s perihelion and actual observations of 1P/Halley seem unlikely. The date of June 25 fell on the kuei-yu day of the fifth month and the object was in Wên-Chhang. Although the comet could not have passed this asterism, its tail should have, and the easiest error to assume is that the “kuei-yu” day was placed in the wrong month. The previous occurrence of “kuei-yu” was April 26 - a time when the comet and tail were certainly far from the Ursa Major region, so if this observation was 1P/Halley, a simple dating error is out of the question. There are many details given for the October 21 comet and they indicate a link to 1P/Halley is unlikely. The most important is that the comet almost circled the sky during about three months of visibility, passing through all but two of the Chinese lunar mansions. This implies the comet passed through over 22 hours of right ascension, but 1P/Halley only passed through about 10 hours of right ascension, one hour of which was through Orion - one of the two lunar mansions the October comet did not pass through. Because of the difficulties in assuming errors in the dates of the June and October comets, they seem to represent comets other than 1P/Halley and are therefore listed separately below (see comets 607 and X/607 U1).

The Italian text Historia Gentis Langobardorum (787) notes, “in the months of April and May there appeared in the heavens a star which they call a comet.”

J. Williams (1871) listed two comets: one discovered on March 13, and the other discovered on April 4.

An investigation into the past orbital motion of 1P/Halley was conducted during 1907-8 by P. H. Cowell and A. C. D. Crommelin. For this particular apparition of Halley’s Comet, they computed the planetary perturbations from Venus to Uranus upon the comet and obtained a perihelion date of 607 March 26.

Additional orbital investigations were conducted by Kiang (1972), Yu-Che Chang (1979), Yeomans and Kiang (1981), J. L. Brady (1982), Werner Landgraf (1986), and G. Sitarski (1988). Calculations using the Yeomans-Kiang orbit below indicate the comet reached a minimum solar elongation of 5° on February 24. On April 8, the comet reached a maximum solar elongation of 47°. By April 17 the comet should have been low in the east in the morning sky and was probably in twilight. On April 18, the comet reached a minimum solar elongation of 17°. (The comet could have been situated low in in the northwest in the evening and low in the northeast in the morning.) On April 19, the comet reached its most northerly declination of +33° (apparent) and was in the evening sky. On April 30, the comet reached a maximum solar elongation of 90°, while it reached a minimum solar elongation of 9° on August 30.

T 607 Mar. 15.476 (UT)

ω 098.799

Ω (2000.0) 43.261

i 163.476

q 0.58083

e 0.96804

ABSOLUTE MAGNITUDE: H₁₀ = 2.5 (Kronk)

Full Moon: March 19, April 17, May 17.

Sources: Sui shu (636), p. 167; Pei shih (670), p. 167; Historia Gentis Langobardorum (787), p. 175; A. G. Pingré (1783), pp. 327, 606-7; J. Williams (1871), pp. 38-9; MNRAS, 68 (Supp. 1908), pp. 665-70; PA, 42 (1934 Apr.), pp. 195-6; Ho Peng Yoke (1962), p. 167; MRAS, 76 (1972), pp. 35, 53; CAA, 3 (1979), p. 122; D. K. Yeomans and T. Kiang (1981), p. 643; J. L. Brady (1982), p. 210; JBIS, 38 (1985), pp. 204-5; W. Landgraf (1986), p. 258; G. Sitarski (1988), p. 263.

Text #6498

607 April 4; China.

A tailed star comet was seen in the west extending across the heavens. It traveled through Pisces, Aries, and Virgo (?). The Chinese account states that this comet was again seen on October 21 in the south. It was seen in Virgo, Hercules, and nearly circled the sky before going out of sight in late January 608. This was certainly a separate comet altogether.

Ho (237)

Text #2253

607 March-April; (P = March 15.5, d= 0.09 on April 19) China.

Comet Halley. Three or four separate apparitions of cometlike objects result in a confusing set of observations in 607. Stephenson and Yau (1985) suggest that Halley was first recorded on April 18 in Gemini and Ursa Major. It passed Perseus, Auriga, and Gemini. It may also have been seen on March 30 in eastern Pegasus and followed for 20 days before being lost in the eastern morning twilight.

Ho (237)