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Pseudo-Dionysius of Tell-Mahre, Theophanes, and the Comet of 760 CE

Pseudo-Dionysius of Tell-Mahre drew a picture of a comet in 760 CE which suggests that Harrak (1999) is correct that Pseudo-Dionysius of Tell-Mahre is a contemporaneous source. This also assists in deciphering the chronology of the By No Means Mild Quake. In Pseudo-Dionysius' entry for A.G. 1071, we can read in Harrak (1999:198)'s translation:
759-760 The year one thousand and seventy-one: In the month of Adar (March), a shining sign was seen in the sky1 before dawn on the northeast side which is called Ram in the Zodiac, to the north of the three most shining stars. Its shape resembled a broom. On the twenty-second day of the month, it was still in the Ram at its head, in the first degree (of the Zodiac circle), the second after the wandering stars Kronos and Ares,2 somehow slightly to the south. The sign remained for fifteen nights, to the eve of the Pentecost feast. At one of its ends, which was narrow and more shining*3 a star was seen and was turning toward the North. The other side, which was large and darker, was turning toward the South. The sign was moving little by little toward the Northeast. This was its form (Vat.sir.162 137r-136v):

Drawing of Comet in 760 CE by Pseudo Dionysius of Tell-Mahre Drawing of Comet in 760 CE by Pseudo Dionysius of Tell-Mahre - redrawn by Harrak Left - original drawing of a comet in 760 CE by Pseudo-Dionysius of Tell-Mahre (Vat.sir.162 137r-136v)

Right - redrawn comet by Harrak (1999:198)


On the eve of the third day after Pentecost*, the sign was seen again in the evening in the Northwest, and it remained for twenty five evenings. It moved little by little to the South and then it disappeared. Then it reappeared in the southwest, where it remained in this way for many days.

During this time, many schisms took place in the church because of leadership. The eastern monasteries made John Patriarch, while neither the cities of the Jazira nor all the monasteries approved him. The people of the West and Mosul approved George. Because of this the entire Church became troubled.4
Footnotes

1 A brief mention in Theophanes 431: A.M. 6252 (760-761).

2 Following Ptolemy, the ancients believed that there were seven "wandering stars", Syriac | | (i.e. planets): The Moon, Mercury, Venus, the Sun, Mars (=Ares), Jupiter and Saturn (= Kronos), all revolving around the earth.

3 | | : See Manna, Dalil, 54, for its meaning.

4 See above pp. 193ff and 216ff.

Hayakawa et al (2017:11-12) suggests that this was a description of Halley's comet.
This should be the record of Halley’s Comet, which has an orbital period of about 75 years. According to Yeomans and Kiang (1981), Halley’s Comet was at perihelion on day 20.671 (UT) of May 760 CE. The comet was also observed by Chinese astronomers. There is a record in JiùTángshū (旧唐书), one of the official histories of the Táng Dynasty, stating that the comet was first observed on May 16, 760 CE within Aries and continued to be visible for about 50 days (JiùTángshū (旧唐书), Astronomy II: p. 1324). The observed period and the association with Aries are consistent between the Chinese and the Syriac records.
The discrepancy in months was discussed by Hayakawa et al (2017:11)
Firstly, we discuss its date and time. According to the text, the event was in the month ādār (March), so it should be March of 760 CE. The event was first seen on the 22nd of the month, remained 15 nights until the dawn of the Pentecost feast, appeared again on the third day after Pentecost, and remained another 25 days. From the text, it is also clear that the event was seen during the night. The time and the duration of the event as well as its shape, which we discuss below, are consistent with the interpretation that it was a large comet. The date of the event, on the other hand, is rather confusing. It is written that this event was seen on March 22 and lasted 15 nights up to the eve of Pentecost, but the date of the Pentecost of that year is May 25 (Grumel, 1958), so it cannot be 15 nights after March 22. A probable explanation for this inconsistency is a miswriting of May
ܐܝܪ(eyar)
as March
‫ܐܕܪ(adar)
in the manuscript as there only one letter difference between them in the Syriac letter system. After a short break, this event reappeared on the eve of the third day after Pentecost and lasted another 25 nights. Thus, we conclude that this event started around 22 May 760 CE and lasted until early July of 760 CE.
If we accept that Pseudo-Dionysius dates this to May, the Macedonian reckoning gives the correct year consistent with what Sebastian Brock (personal communication - 2021) relates - that Macedonian reckoning with a New Year starting on 1 October would be the standard for Syriac sources of the time.
Year Reference Corrections Notes
760 CE A.G. 1071 none Macedonian Reckoning dates A.G. 1071 to 1 October 759 - 30 September 760 CE
761 CE A.G. 1071 none Babylonian Reckoning dates A.G. 1071 to 2 April 760 - 1 April 761 CE
Pseudo-Dionysius dates the By No Means Mild Quake to 3 Adar A.G. 1067 which is 4 years earlier than A.G. 1071 (760 CE). This dates the earthquake to the 3rd of Adar in 756 CE - according to Pseudo-Dionysius. Theophanes also mentions the comet in his A.M.a 6252 entry which is also 4 years after his earthquake account in A.M.a 6248. In Mango and Scott (1997:596-597)'s translation (Turtledove's translation is available here), we can read Theophanes' description of the comet
[A.M. 6252, AD 759/60] ...
II In the same year a very bright comet appeared for ten days in the east and another twenty-one days in the west. II
Theophanes' regnal years and his A.M.a dates are all consistently 4 years apart from the comet of 760 CE. Thus, it would appear that Halley's comet of 760 CE also fixes Theophanes earthquake date to 756 CE. By extension, this also indicates that Theophanes' date for the Talking Mule Quake (one of the Sabbatical Year Quakes) in A.M.a 6241 places that earthquake in 749 CE.

Online Versions and Further Reading
References

Cook, D. (1999). "A Survey of Muslim Material on Comets and Meteors." Journal for the History of Astronomy 30(2): 131-160. - open access

Hayakawa, H., et al. (2016). "The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Zuqnin." Publications of the Astronomical Society of Japan 69. - open access

Neuhäuser, D. L., et al. (2021). "Orbit determination just from historical observations? Test case: The comet of AD 760 is identified as 1P/Halley." Icarus 364: 114278. - open access

Notes
Easter and Pentecost in 760 CE

Grumel (1958:310) lists the Easter date as Sunday 6 April in 760 CE. Since the Pentecost is exactly 7 weeks after Easter, this would indicate that the Pentecost was on Sunday 25 May in 760 CE.

Julian Calendar in 760 CE

Neuhauser et al (2021:7) report that the text of Pseudo-Dionysius reports that "the white sign" (i.e. the comet) was seen for "15 nights until dawn of the feast of Pentecost". Pentecost takes place on a Sunday and in AG 1071, most Christian churches (including churches under the Byzantine Patriarchate) celebrated Pentecost on 760 May 25, but some eastern churches celebrated Pentecost one week later on June 1 (Neuhauser et al, 2021:7). This, according to Neuhauser et al (2021:7), is further evidence that Iyyar (May) was the correct month for the comet not Adar (March).

Neuhauser et al (2021:7) further noted that:

The reason for the two different Pentecost (and Easter) dates in AD 760 is the difference between two ecclesiastical Easter calendars: in AD 760, the first computed (cyclic) full moon after the start of spring (defined for March 21 at the AD 325 Council of Nicaea) was on Saturday Apr 5 according to the 532-year cycle constructed by Irion in AD 562 for the Byzantine Patriarchate (based on a previous 200-year cycle by Andreas of Byzantium for AD 353-552), so that the Byzantines celebrated Easter on Apr 6 (like also the Roman church following the 532-year Easter calendar by Dionysius Exiguus starting in AD 532), while the Armenian, Jacobite, and Nestorian churches followed a different 532-year Easter table, namely the Armenian scholar Anania Siralcaci's (AD 610-685) reform (early AD 660ies) of Andreas' Easter table, according to which the paschal full moon in AD 760 would be on Sunday Apr 6, so that Easter has to be dated Apr 13 (see Sanjian, 1966, Mosshammer, 2008, pp. 257-277). This dispute is also reflected in the Chronicle of Zuqnin (Harrak, 1999):
The year (SE) 1070: Lent was confused. Some of the Easterners introduced Lent on the 18th of: Sebat (Feb) and ended it on the 6th of Islisdn (Apr). Others introduced Lent on the 25th of Sebat (Feb) and ended it on the 13th of Nisan (Apr). All of the Christians were confused, when in one place they celebrated Easter, in another place Palm Sunday; in one place it was Passion week, in another place Easter.
(With the above expression "some of the Easterners" for the other churches, our author probably refereed to the Byzantine Patriarchate or other churches west of the Euphrates.)

Our Chronicle reported the Easter dating problem for SE 1070, i.e. AD 758/9; in AD 759, Easter Sunday was on April 22, in AD 760 on April 6 or 13 (see above); hence, the above given end date of lent (Apr 6 or 13) points to AD 760; the given introduction of lent on Feb 18 or 25 would be a Monday in 760, i.e. the correct weekday for the start of lent in the Syriac churches (where there is no Ash Wednesday). There is also a brief mention of this problem by Theophanes, who dates it to AD 760. Hence, all the evidence points to AD 760 for the report on the Easter dating problem misdated to AD 759 in the Chronicle of Zuqnin. The same problem also happened in AD 570 and 665 (Mosshammer, 2008, pp. 276-277).14

The monastery of Zuqnin belonged to the Syriac Orthodox church, informally known as the Jacobite Church; this is known, because our chronicler listed bishops and patriarchs, which were also listed by the 12th century Michael the Syrian (e.g. Chabot, 1899-1910), who clearly identified them as to belong to the Syriac Orthodox patriarchate (Jacobite). Hence, it is clear that Easter was on Apr 13 and Pentecost on June 1 at the monastery of Zuqnin: since it is reported that the comet was seen "for fifteen nights, until dawn of the feast of Pentecost", it was first detected on May 18 "before early twilight". This is well consistent with the fact that the Chinese sources give May 17 for the first detection (Section 3.1).
Footnotes

14 The Chronicle of Zuqnin does not report any Easter dating problems for AD 570 nor 665; this problem, called "crazatik" or "Erroneous Easter", was resolved only in AD 1824 (Mosshammer, 2008, p. 277). Our Chronicle narrates one other Easter confusion for SE 857 (i.e. Easter AD 546, but correct year is AD 547, see Mosshammer, 200E, p. 256), when three different dates for lent and Easter are mentioned to have been followed by different parts of the population. For a discussion of the Easter problem and Easter tables, see McCluskey (1998, pp. 84-87) and for the Eastern churches also Sanjian (1966) and Mosshammer (2008).

Description of the Comet as a "white sign" or "broom"

The comet described by Pseudo-Dionysius of Tell-Mahre is not explicitly described as a comet in the text. Rather, it is referred to variously as "the white sign" or "broom". Neuhauser et al (2021:7-8) provided the following for why they viewed as a description of a comet:

2.4. The "white sign" as comet Criteria

In transmitted texts on celestial transients, using a pheno-typical description, it is often uncertain which kind of celestial phenomenon is meant: in our text the phenomenon is not called "comet", and even if it would be called that way, it may still be uncertain whether a comet in today's sense is meant. Five criteria are developed (timing, position/di-rection, colour/form, motion/dynamics, and duration/repetition) for various kinds of celestial phenomena, see, e.g., Neuhauser and Neuhauser (2015a) and D.L. Neuhauser et al. (2018a) for criteria for aurora borealis and D.L. Neuhauser et al. (2018b) for meteor showers (and aurorae).

The "white sign" or "broom" reported in the Chronicle of Zurinin fulfils all five criteria for comets:
  1. timing, observed at night-time or twilight: "before early twilight", "fifteen nights", "at evening time", "twenty-five evenings", and stars and planets are mentioned (and shown in the drawing)
  2. Position of first and/or last sighting: often close to Sun, in or near the ecliptic: "before early twilight, in the north-east" "seen again at evening time, from the north-west", and "in the Zodiac [sign] which is called Aries (emro)"; also tail direction away from the Sun: "[at] its one end/tip, the narrow one, a very bright star (kawkbo) was seen at its head/end/tip. And it was tilting to the north side, but the other wide and very dark one was tilting to the south side"
  3. colour and form (extension): "white sign", "resembled in its shape a broom", the white broom points to the comet dust tail appearing white due to reflection of sunlight (while the plasma tail would appear bluish and much fainter)
  4. dynamics, i.e. moving on sky relative to the stars: first "north from these three stars", "it was going bit by bit to the North-East", seen until Pentecost (June 1 morning), then again soon later after conjunction with the Sun, "it was seen again from the north-west", "it was going bit by bit to the south", etc.
  5. duration: "remained for fifteen nights", "remained for twenty-five evenings", etc.
Furthermore, our Chronicler connects the sighting of this transient object as negative portent with unfortunate events (e.g. "many schisms"), as was not unusual at this time.

Celestial nomenclature in the Chronicle of Zuqnin

Halley's Comet (Wikipedia)