FAHHĀD, FARĪD-AL-DĪN ABU’L-ḤASAN ʿALĪ, b. ʿAbd-al-Karīm Šarvānī (fl. 6th/12th cent.; he is sometimes called by his father’s name ʿAbd-al-Karīm), the most prolific producer of astronomical tables (zīj) in the Islamic world. He is credited with a total of six tables, all of which are lost. There are three lists of these tables, given by Moḥammad b. Abū Bakr Fāresī in his al-Zīj al-momtaḥan al-moẓaffarī (Lee, p. 255), by Šams Monajjem Wābeknavī in his al-Zīj al-moḥaqqaq (Krause, 519), and by Ḥājī Ḵalīfa (Kašf al-ẓonūn, ed. Flügel, III, pp. 567-68), which is clearly based on Fāresī’s list (Table 1).
Šams Monajjem states that Fahhād (whom he names ʿAlī b. ʿAbd-al-Bākūʾī) based the Zīj al-ʿalāʾī on observations, and used it as the basis for tables nos. 1 to 4. Fāresī also (Lee, pp. 255-59) gives a lengthy and complimentary account of Fahhād’s observations, which extended, he claims, over thirty years. The dates which Fāresī explicitly mentions with regard to these observation are 10 December 1166 (a conjunction of Jupiter and Saturn, used as an example in chapter 59 of Gregory Chioniades’ Persian Composition) and the ʿAlāʾī’s epoch at the beginning of Yazdegerdi 541/2 February 1172. Fāresī adds his own al-Zīj al-momtaḥan al-moẓaffarī (Kennedy, no. 54) to the list of those based on al-Zīj al-ʿalāʾī; its epoch is the beginning of Yazdegerdi 631/10 January 1262.
During 1295 and 1296 Šams-al-Dīn Boḵārī lectured in Persian on the ʿAlāʾī to Gregory Chioniades at Tabrīz. Gregory produced Greek versions of these lectures, the Persian Composition of Astronomy (the examples in chapters 38 to 60 come from Fahhād’s work, and were composed at Šarvān between 1166 and 1176) and a set of Revised Canons together with the ʿAlāʾī’s tables. In about 720/1320 Šams Monajjem based his al-Zīj al-moḥaqqaq (Kennedy, no. 35) on the Zījal-ʿalāʾī.
While Fahhād’s chief zīj enjoyed this international popularity in the late 13th and early 14th centuries, it must be mentioned that the unknown author of al-Zīj al-šāmel (Kennedy, no. 29) states that the author of al-Zīj al-ʿalāʾī falsely claims to have derived his mean motions from observations since they had been given already by Abu’l-Wafāʾ Būzjānī in al-Zīj al-wāżehá (Kennedy, no. 73), written the late 10th century. This is lost, but its parameters are claimed to have been used in a number of other zījes (see above I 393b). In any case, it is not clear whether the Zījal-ʿalāʾī referred to in the Šāmel is Fahhād’s or one of several others whose existence is known (Kennedy, no. 42).
Bibliography (for cited works not given in detail, see “Short References”):
Gregory Chioniades, Persian Composition of Astronomy, in Pingree, ed., pp. 36-259.
Idem, Revised Canons, in Pingree, ed., pp. 260-333.
E. S. Kennedy, “A Survey of Islamic Astronomical Tables,” Transactions of the American Philosophical Society, N.S. 46, 1956, pp. 123-77.
M. Krause, “Stambuler Handschriften islamischer Mathematiker,” Quellen und Studien zur Geschichte der Mathematik III, 1936, pp. 437-532.
S. Lee, “Notes of the Astronomical Tables of Mohammed Abibakr Al Farsi, Two Copies of which Are Preserved in the Public Library of the University of Cambridge,” Transactions of the Cambridge Philosophical Society 1, 1822, pp. 249-65.
D. Pingree, ed., The Astronomical Works of Gregory Chioniades I: Corpus des astronomes byzantins, Amsterdam, 1985.
Originally Published: December 15, 1999
Last Updated: January 20, 2012
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Vol. IX, Fasc. 2, pp. 157-158