Chioniades, George (or Gregory)

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(b. Constantinople, c. 1240–1250;

d. Trebizond, c. 1320), astronomy.

Byzantine scholar, physician (iatrosophist), and astronomer, George Chioniades was born probably at Constantinople between 1240 and 1250 and died at Trebizond around 1320. His life is not well known. According to his correspondence, it is known that he traveled between Constantinople, Trebizond, and Tabriz during 1295 to 1310. Monk and priest, he was named bishop of Tabriz, probably around 1304 or 1305, to defend Christians living in the Mongol Empire. The change of name from George to Gregory may have occurred at that time. It may have been on the occasion of this nomination that he wrote a profession of Christian faith, preserved in Vaticanus gr. 2226. In this document, he refuted accusations of having adopted foreign beliefs from having stayed so long among the Persians, the Chaldeans, and Arabs. He also defended himself against having accepted astrological fatalism contrary to the Christian religion. Around 1310 or 1314, he spoke of himself as an old man. On his death some of his classical books passed into the hands of Constantine Loukites, Protonotarius of Trebizond, with whom Chioniades maintained friendly relations.

His name is associated with the introduction of the Persian astronomical tables to Constantinople. According to the preface of the Persian Syntaxis of George Chrysococces (written around 1347), Chioniades, desiring to learn astronomy in order to better practice medicine (or iatromathematics), went to Trebizond where he obtained financial support from Alexis II Comnenus (1297–1330) to travel to Persia, then under Mongol domination. Going to the court, he learned the language of the country and obtained authorization to learn astronomy in return for his services. He then returned to Trebizond with astronomical books he translated into Greek. His books passed into the hands of the priest Manual of Trebizond, with whom George Chrysococces was learning astronomy.

It is difficult to know exactly what the astronomical work of Chioniades was, and his exact role in the introduction of Persian astronomy to Constantinople, for few texts under his name have come down to the present. A manuscript in New York (Smith West. Add. 10, Columbia University) contains autograph notes of George Chioniades: some commentaries on John of Damascus, and elementary astronomical and astrological diagrams containing Arabic terms mentioning the Persians. The Persian Syntaxis of George Chrysococces was based, according to its author, on a “Persian Syntaxis, better than the others,” which Chioniades had Hellenized, without adding commentaries to it (Usener, 1914 p. 357). The principal source has been identified by Raymond Mercier. It consists of the Zīj ī- Īlkhānī of Naṣīr ad-Dīn aṭ - Ṭūsī. (c. 1270). Chioniades therefore must have put into Greek the tables of the Zīj ī- Īlkhānī, without explanation, but this version has not come down to us.

Besides, an important corpus of Byzantine astronomical texts, adapted from Arabic and Persian, was preserved in manuscripts of the thirteenth and fourteenth centuries, and David Pingree has seen in these adaptations of the work of George Chioniades. These manuscripts are principally the Vaticanus gr. 211 (end thirteenth century), the Vaticanus gr. 191 (c. 1302), Laurentianus28/17 (copied after 1346 by Theodore Meliteniotes), the Vaticanus gr. 185 (c. 1345), the Vaticanus gr. 1058 (c. 1345–1360), and some others of later date.

The oldest, the Vaticanus gr. 211, contains a Byzantine version of the Zīj al-‘Alā'ī of the Arabic astronomer alFahhād (c. 1176), executed according to the teaching of Shams Bukhārī (c. 1295–1296), a Byzantine version of the Zīj as-Sanjārī of the Arabic astronomer al-Khazīnī (c. 1115), tables of these two treatises, and several other texts and diagrams, notably the pre-Copernican figures deriving from the Tadhkhira of Naṣīr ad-Dīn aṭ - Ṭūsī. This manuscript, contemporary with Chioniades, preserves several titles in Arabic. The Vaticanus gr. 191 contains notes and calculations dated 1302, as well as unidentified tables starting in 1093.

The Laurentianus 28/17 contains the teaching of Shams Bukhārī on the Zīj al-‘Alā'ī, as well as the Zīj as Sanjārī, but without any table. The copy was partly made from the Vaticanus gr. 211, partly from an original of the thirteenth century, now lost. The Vaticanus gr. 185 also has the tables of 1093, and the Vaticanus gr. 1058 repeats the texts of the Vaticanus gr. 211. Finally, a treatise on the astrolabe of Siamps the Persian (Shams Bukhari), dedicated to the emperor Andronicus II, appears in a number of manuscripts of the fourteenth and fifteenth centuries (for example, Marcianus gr. 309 and Vaticanus gr. 210).

What was Chioniades’s part in these adaptations? The question is difficult to decide. His name was mentioned only in the account by Chrysococces and his handwriting, known from the autograph noted above, nowhere appears in the manuscripts of the thirteenth century that contained adaptations of the Persian treatises. Chioniades may be the author of the translations preserved in Vaticanus gr. 211 and in Laurentianus 28/17, but the astronomical notes of Vaticanus gr. 191 are certainly due to another Byzantine scholar.

The various hands that one encounters in the manuscripts, the variations in the adaptations of the Persian names allow one to think that more than one person had worked on this material. Chioniades certainly had collaborators, secretaries, and students. His successors included the priest Manuel of Trebizond, the teacher of Chrysococces, who is perhaps the author of the Ephemerides compiled at Trebizond for the year 1336, preserved in the manuscript Monacensis gr. 525; George Chrysococces, principal source of information about Chioniades; Theodore Meliteniotes, copyist of the Laurentianus28/17, and author of an Astronomical Tribiblos, of which Book Three is devoted to the Persian tables.

Whoever was the author of these Byzantine adaptations of Persian astronomical treatises, they were written in a rather unelegant style, with technical words simply transcribed in Greek. Difficult to understand for a Byzantine reader, they would meet only a limited diffusion and were replaced from 1347 by the Persian Syntaxis of George Chrysococces.

Chioniades was also a physician (his Profession of Faith designates him as iatrosophist). A list of antidotes translated from Persian is preserved under his name in Ambrosianus Q 94 sup. (fourteenth century).


Mercier, Raymond. “The Greek ‘Persian Syntaxis’ and the Zīj ī- Īlkhānī.” Archives Internationales d’Histoire des Sciences34, no. 112:3 (1984): 35–60.

———. An Almanac for Trebizond for the Year 1336, Corpus des Astronomes Byzantins VII. Louvain-la-Neuve, Belgium: Academia-Bruylant, 1994.

Neugebauer, Otto. “Studies in Byzantine Astronomical Terminology.” Transactions of the American Philosophical Society, n.s., 50, pt. 2. (1960): 3–45.

Paschos, Emmanuel A., and Panagiotis Sotiroudis. The Schemata of the Stars. Byzantine Astronomy from 1300 A.D. Singapore: World Scientific, 1998.

Pingree, David. “Gregory Chioniades and Palaeologan Astronomy.” Dumbarton Oaks Papers18 (1964): 135–160.

———. The Astronomical Works of Gregory Chioniades, Vol. I: The Zīj al-‘Alā'ī, part 1: Text, Translation, Commentary; part 2: Tables, Corpus des Astronomes Byzantins II, 2 vols. Amsterdam: Gieben, 1985–1986.

Tihon, Anne. “Les tables astronomiques persanes à Constantinople dans la première moitié du XIVe siècle.” Byzantion57 (1987): 471–487.

Usener, Hermann. “Ad historiam astronomiae symbola.” In Kleine Schriften III, Leipzig- Berlin: Teubner, 1914.

Westerink, L. G. “La profession de foi de Grégoire Chioniadès.” Revue des Études Byzantines 38 (1980): 233–245.

Anne Tihon