This comet was widely observed for nearly three months, which accounts ultimately appearing in texts written in Japan, China, Korea, Italy, England, Scotland, Ireland, and Syria.
The oldest account of this comet comes from Japan. The Nihongi (720) says, “A star appeared in the East” during the autumn in the month of 676 July 16 to August 14. It was about 7° or 8° in length. During the month of September 13 to October 10 “it at length disappeared from the sky.” This account is listed after an event that was dated July 31, so the comet was probably discovered between August 1 and 14.
The next oldest account was Ecclesiastical History, written by the English historian Bede around 734. It says, “In the year of the incarnation of the Lord 678, which is the eighth year of the rule of King Ecgfrith, there appeared in the month of August the star which is called a comet; and continuing for three months, it rose in the morning, sending out, as it were, a tall pillar of shining flame.” Bertram Colgrave and R. A. B. Mynors (1969) said Bede borrowed his account “from the Life of Pope Donus (676-8) in the Liber Pontificalis.” They added that his attribution of the observation to the year 678 was incorrect, and should have been 676.
Several Chinese texts, the oldest being Chiu T’ang shu (945) and T’ang hui yao (961), give details of this “broom star.” It was first seen on 676 September 4, when it appeared at the Tung-Ching [γ, ε, ζ, λ, μ, ν, ξ, and 36 Geminorum], pointing toward Nan-Ho [a, β, and γ Canis Minoris] and Chi-Hsin [κ Geminorum]. The comet was over 3° long and gradually turned to point toward the northeast. The “rays” eventually grew to a length of about 30° and swept Chung-Thai [λ and μ Ursae Majoris], pointing toward Wên-Chhang [θ, τ, υ, and 18 Ursae Majoris]. The comet remained visible for 58 days or until about November 1. The Chinese accounts indicate the comet was originally found in the morning sky, implying a UT of September 3.8.
The comet is mentioned in numerous monastic histories, usually under dates ranging from 676 to 678. The Italian text Historia Gentis Langobardorum (787) says, “in the month of August, a comet appeared in the east with very brilliant rays, which again turned back upon itself and disappeared.” The Peterborough edition of the English text Anglo-Saxon Chronicle (1154) says, “Here the star comet appeared in August, and every morning for 3 months shone like a sunbeam.” The Irish text Annals of Tigernach (1178) says that in 677, “A bright comet was seen in the months of September and October.” The Italian text Chronica Andreae Danduli (1280) says a comet appeared in the east for three months.
The Chronicle of Silla, contained in the Korean text Samguk Sagi (1145), says this “broom star” was seen sometime during the month of 676 August 15 to September 12. It appeared between Pei-Ho [α and β Geminorum] and Chi-Shui [λ Persei], and measured 6-7 paces.
Andrew Palmer (1993) described a comet seen in Syria by Agapius of Manbij during 677, which is probably the comet seen in 676. He said, “An awesome comet appeared every morning from 28 August to 26 October, sixty days in all.”
J. Williams (1871) dated the Chinese observations as July 7 and September 3. Ho Peng Yoke (1962) suggested Williams derived the first date by overlooking the intercalary third month in the Chinese calendar.
Full Moon: July 30, August 29
Sources: Nihongi (720), book 2, p. 333; Bede, Ecclesiastical History (734), pp. 370-1; Historia Gentis Langobardorum (787), p. 235; Chiu T’ang shu (945), p. 169, T’ang hui yao (961), p. 169; Chronica (1111), p. 326; Chronicon ex Chronica (1118), p. 26; Samguk Sagi (1145), p. 169; Anglo-Saxon Chronicle (1154), p. 38; Annals of Tigernach (1178), folio 11a1; Chronicle of Holyrood (1189), p. 95; Chronica Majora (1247), part 1, p. 299; Chronica Andreae Danduli (1280), p. 100; Annals of Ulster (1498), p. 129; Chronicum Scotorum (1650), p. 105; A. G. Pingré (1783), pp. 331-3, 609; J. Williams (1871), p. 41; G. F. Chambers (1889), p. 567; Nihon Temmon Shiryo (1935), p. 476; EHD1 (1955), pp. 154, 654; Ho Peng Yoke (1962), p. 169; Bede’s Ecclesiastical History of the English people, edited and translated by Bertram Colgrave and R. A. B. Mynors, Great Britain: Oxford University Press (1969), pp. 370-1; Palmer (1993), p. 194; personal correspondence from David Cook (1998).