39

The Hou Han shu (445) is the oldest source describing this "broom star". The object appeared in the Mao [the Pleiades] on 39 March 13. The date and location indicate it was in the evening sky, implying a UT of March 13.5. The object is described as exhibiting "rays measuring 30°." The text adds, "It moved slightly toward the northwest and entered Ying–Shih [α and β Pegasi]. It then trespassed against Li–Kung [η, λ, μ, ο, τ, and υ Pegasi]." The comet was last detected after it had reached Tung–Pi [α Andromedae and γ Pegasi] on April 30. The date and location indicate it was in the morning sky, implying a UT of April 29.8. It "went out of sight after an appearance of 49 days."

Full moon: March 28, April 27

Sources: Hou Han shu (445), pp. 148–9; A. G. Pingré (1783), pp. 284, 581–2; J. Williams (1871), p. 11; Ho Peng Yoke (1962), pp. 148–9; I. Hasegawa (1980), p. 66.

46

The Chronicle of Koguryo contained in the Korean text Samguk Sagi (1145) is the only source of information on this object. It says a "sparkling star" appeared sometime during the month of 46 December 17 and 47 January 15. The object was in the south and remained visible for 20 days. Ho Peng Yoke (1962) noted that ancient Korean records were frequently inaccurate.

Full moon: December 31

Sources: Samguk Sagi (1145), p. 149; Ho Peng Yoke (1962), p. 149; I. Hasegawa (1980), p. 66.

X/54 L1

This is an interesting comet which was apparently observed in Italy, China, and Korea. It became known in Rome as "the Claudius comet," and it was believed to have been an omen that heralded the death of Claudius Caesar on 54 October 13. There are some modern astronomical sources which indicate that the Roman comet was distinct from the Chinese comet, but a look at the following records will show the comets moved very similarly to one another and are probably one and the same.

The Roman text Quaestiones Naturales was written by Lucius Annaeus Seneca just six years after this comet appeared and is the most contemporary record available. Seneca wrote, "The Claudius comet rose from the north into the zenith and moved east, always growing dimmer." In comparing the comet to that seen during Nero's reign in 60, Seneca said Nero's comet was visible for six months, while Claudius' "withdrew in fewer months." Later in his book, Seneca reiterated that the comet "was first seen in the north, and was carried continuously straight up and did not stop until it disappeared."

The Roman scholar Gaius Plinius Secundus, also known as Pliny the Elder, wrote Natural History around 77. His account was not as detailed, but is still interesting. He wrote, "But sometimes there is a comet in the western sky, usually a terrifying star and not easily expiated: for instance ... in our day about the time of the poisoning which secured the bequest of the empire by Claudius Caesar to Domitius Nero ...."

Although the comet is mentioned by other Roman historians, no additional details come to light. The details sadly lacking in all the Roman texts are dates. This is where accounts from China may prove useful.

The oldest existing text reporting this comet in China is the Hou Han shu (445). It says "Mercury" was seen "at the 20th degree of Tung–Ching [γ, ε, ζ, λ, μ, ν, ξ, and 36 Geminorum]" on 54 June 9. The text continues, "It developed a white vapor pointing southeastward and became a broom star with rays measuring 5°. It moved toward the northeast and came to a stop when it reached the western wall of the Tzu–Wei Enclosure [Draco, Ursa Minor, Cepheus, and Camelopardalis]." The comet was still in the Tzu–Wei Enclosure when it went out of sight on July 9.

The curious fact about this Chinese account is that the object is actually referred to as Mercury. Mercury was indeed in Gemini on the date given, but so was the sun. The two were separated by about 5° or 6°, and it is therefore very doubtful that Mercury was actually seen. Another piece of evidence against the identification of this object as Mercury is that it developed a tail 5° long. It is possible that a comet, situated so close to the sun at discovery, showed only its nucleus, or a well–condensed coma in the twilight, and that it had the same appearance as Mercury. As the object moved away from the sun, and out of twilight, the tail became visible, thus identifying it as a comet.

A possible observation of the Chinese comet also came from Korea, although the dates are off by several months. The Chronicle of Silla, contained in the Korean text Samguk Sagi (1145), said a "sparkling star" was seen sometime during the month of 54 February 27 to March 27. The object was observed at the Tzu–Wei Enclosure. Although the date is earlier than given in the Chinese text, it should be noted that Ho Peng Yoke (1962) said the Korean records frequently contained errors during this period.

There is one more record which may refer to this comet. The obscure Latin poet Calpurnius Siculus wrote Eclogue I around 60. He stated, "Do ye mark how already for a twentieth time the night is agleam in an unclouded sky, displaying a comet radiant in tranquil light? and how brightly, with no presage of bloodshed, twinkles its undiminished luster? Is it with any trace of blood–hued flame that, as is a comet's way, it besprinkles either pole? Does its torch flash with gory fire? But aforetime it was not such, when, at Caesar's taking off, it pronounced upon luckless citizens the destined wars." This statement was surrounded by references made to "Caesar's death" and most commentators of this work have said it refers to the comet of 54 and the death of Claudius Caesar. On the other hand, A. A. Barrett (1978) and a few others have suggested the account refers to the comet of 60, and that the very last sentence is actually a reference to the death of Julius Caesar and the comet of -43.

The first item that needs clarifying is that some sources have claimed the Roman comet was seen at the time of Claudius' death in October, and is therefore not the same as the Chinese comet; however, the earliest Roman sources do not make such a claim. Seneca does not even mention Claudius' death while talking of the comet, and Pliny, writing 23 years after the event, said the comet appeared "about the time of the poisoning" of Claudius. Suetonius, writing nearly 70 years after the event, calls the comet one of the omens of Claudius' death. The Romans believed strongly in omens or portents. The Roman historian Titus Livy finished The History of Rome from its Foundation around -8. He frequently went to great trouble to list the portents preceding notable events, some of which occurred nearly a year before the event they supposedly portended.

If it is at least accepted that the Roman comet could have appeared during the same time period as the Chinese comet, the next step is to prove that their movements were the same. Seneca wrote that the comet first appeared in the north, rose toward the zenith, and then moved eastward and faded from sight. Pliny, on the other hand, specifically noted that this comet first appeared in the west. The Chinese did not specify the direction in which the comet was first seen, but they did say that it was in Gemini and that as it moved a tail developed that pointed southeastward. With the sun in Gemini on June 9, Gemini was partially visible at sunrise in the east and at sunset in the west. It is also apparent from the Chinese and Korean descriptions that the comet was not showing a tail when first seen and was probably enveloped in strong twilight. But the key here is the comet's southeastward pointing tail. Since a comet's tail always points away from the sun a southeastward–pointing tail indicates the sun was northwest of the comet. Thus, the comet was observed by the Chinese in the western sky. If the comet's head was physically within Gemini, then the solar elongation was probably near 15°.

In summary, the Chinese and Pliny both noted the comet in the west. The Chinese said the comet moved toward the northern sky, the tail growing longer as it exited twilight and reached a length of 5°. Seneca also reported the comet was seen in the northern sky. Both Seneca and the Chinese said the comet then moved eastward, with the Chinese adding that the comet's motion seemed to slow and it faded from sight.

An additional detail can be derived. Since the comet was found in the western sky, the probable date of discovery by the Chinese is June 9.5 UT. The June full moon would not have affected observations since the comet was found in twilight, and as the moon's light waned during the days that followed, the comet could have been observed without any interference except from clouds. The July full moon could have contributed to the fading comet being lost to the naked eye a few days earlier than if the moon had not been present.

J. Williams (1871) said the comet was seen from 55 June 4 to July 4.

Full moon: June 8, July 8

Sources: Quaestiones Naturales (63), book 7, pp. 262–3, 270–1, 288–9; Eclogue I (60), p. 225; Natural History (77), book 2, pp. 234–5; The Lives of the Caesars (120), book 5, section 46; Roman History (229), book 61, pp. 32–3; Hou Han shu (445), p. 149; Samguk Sagi (1145), p. 149; A. G. Pingré (1783), p. 284; J. Williams (1871), p. 11; Ho Peng Yoke (1962), p. 149; A. A. Barrett (1978), pp. 98–100.

55

The Hou Han shu (445) is the oldest text to report this object. It says a "guest star" was seen by the Chinese on 55 December 12. The object measured about 2° in length and moved in a southwest direction. The object went out of sight on 56 March 27 "when it came within about 6° to the northeast of Yü–Kuei [γ, δ, η, and θ Cancri] after appearing for 113 days." A. G. Pingré (1783) dated this object as 56, and did not mention the 55 December observation. Although it apparently showed a tail and motion, Édouard C. Biot listed this in his catalog of "extraordinary stars."

Full moon: December 22, January 21, February 19, March 20

Sources: Hou Han shu (445), p. 149; A. G. Pingré (1783), p. 285; CDT (1846), p. 62; G. F. Chambers (1889), p. 557; Ho Peng Yoke (1962), p. 149.

X/60 P1

This is yet another Roman comet which is not precisely dated by any historian. However, once again, there are reports of a comet in Asia which seem to match the few details given by the Roman writers.

The Roman philosopher and statesman Lucius Annaeus Seneca wrote Quaestiones Naturales no more than three years after this comet's appearance. Seneca said, "this last comet ran across half the sky in only six months." He added, "this recent comet started its motion in the north and passing through the west it arrived in the southern region and its orbit passed out of sight as it was rising." Later, Seneca said, "The comet which appeared in the consulship of Paterculus and Vopiscus did what was predicted by Aristotle and Theophrastus: for there were very violent and continuous storms everywhere, and in Achaia and Macedonia cities were destroyed by earthquake." The consulship of Paterculus and Vopiscus was in 60.

Around 64, Seneca wrote the Roman tragedy Octavia. Covering events that occurred in 62, it states in scene II, lines 230–4, "we have seen a comet, a blazing radiance in the sky, spread out its hostile torch where slow Boötes guides his wagon in the endless turning of the night."

The Roman historian Cornelius Tacitus wrote Annales around 116 and noted for the year 60, "A comet having appeared, in this juncture, that phenomenon, according to the popular opinion, announced that governments were to be changed, and kings dethroned."

The astronomical chapter of the Chinese text Hou Han shu (445) said a "broom star" appeared on 60 August 9. The comet "was seen at the north of T'ien–Chhuan [α, γ, δ, η, and μ Persei], measuring about 2°." The date and location indicate the comet could have been visible throughout the night. Its altitude would have been only 10–30° following sunset, but would have steadily increased to 65–80° by sunrise. Being best situated in the morning sky, the actual date of this comet sighting may have been August 8.8 UT. The comet's solar elongation was probably near 100°.

The Hou Han shu added that the comet "moved slightly to the north and arrived south of Khang [ι, κ, λ, and φVirginis]. After 135 days it went out of sight." This period of visibility, when added to the date of discovery, implies a final observation of December 21. Considering the date and constellation, the comet was probably in the morning sky, implying a UT of December 20.9.

The Chronicle of Silla, contained in the Korean text Samguk Sagi (1145), reported that a "sparkling star" appeared sometime within the month of 59 June 30 to July 28. It was seen at T'ien–Chhuan. Ho Peng Yoke (1962) suggested this comet was the same as that seen in China in 60, and added that Korean accounts were inaccurate during this period.

Seneca's account in Quaestiones Naturales bears some resemblance to that of the Chinese. Seneca stated this comet was first seen in the north and passed through the western sky as it headed for the southern regions. It was visible for six months. The Hou Han shu states the comet was discovered in Perseus, moved slightly northward, and then moved to a position south of Virgo. It was visible for 4.5 months. Perseus is situated in the northern part of the sky, while Virgo is in the southern part. Virgo was in the western sky during August and most of September. Interestingly, the sun passed through Khang during late September and early October, and from that point through December 21, this Chinese constellation was in the morning sky. Thus, the comet was in the morning sky when last seen.

The comment in the Octavia about the comet spreading its tail "where slow Boötes guides his wagon" is an interesting one. If the comet's path from Perseus to Virgo was a fairly direct one it would have passed quite close to Boötes. According to one of the legends, Boötes "guides his wagon" in the endless pursuit of the Great Bear, or Ursa Major. If it is assumed that this reference means the comet was in or near Boötes with a tail directed toward Ursa Major, it is possible that the observation was made sometime in October or November.

A. G. Pingré (1783) gave the year of Seneca's comet as 62. He also gave the date of the Nero comet as 64. J. Williams (1871) gave the duration of visibility as 185 days. George F. Chambers (1889) placed Seneca's comet in 64.

Full moon: July 31, August 30

Sources: Quaestiones Naturales (63), book 7, pp. 262–3, 270–1, 286–9; Octavia (64), scene II, lines 231–4, p. 48; Annales (116), book 14, section 22; Hou Han shu (445), p. 149; Samguk Sagi (1145), p. 149; A. G. Pingré (1783), pp. 285, 582; J. Williams (1871), pp. 11–12; G. F. Chambers (1889), p. 557; Ho Peng Yoke (1962), p. 149; A. A. Barrett (1978), pp. 99–100.