AḤMAD B. ABĪ SAʿD (or SAʿĪD) HERAVĪ, ABU’L-FAŻL, one of the many eminent astronomers employed by the Buyids in the 4th/10th century. He observed the summer and winter solstices on 24 June and 15 December 959 in the presence of Abū Jaʿfar al-Ḵāzen (Bīrūnī, Taḥdīd al-amāken, ed. P. Bulgakov, Cairo, 1964, pp. 98-99; tr. J. Ali, Beirut, 1967, pp. 67-68; commentary, E. S. Kennedy, Beirut, 1973, p. 41), and he determined the latitude of Jorǰān by observing the altitude of the sun at that location at the vernal equinoxes of 982 and 983 (ibid., pp. 244-45, tr. p. 210, commentary, p. 158). Moreover, he determined the latitude of Ray in the days of Rokn-al-dawla (335-66/947-77; ibid., p. 238, tr. p. 203, commentary, p. 152; Bīrūnī, al-Qānūn al-masʿūdī, Hyderabad [Deccan], 1954-56, II, p. 612). Bīrūnī (Qānūn I, p. 66) cites Heravī’s definition of day and night, and quotes (Taḥdīd, pp. 167, 212, tr. pp. 129-30, 177-78, commentaries, pp. 100, 132) two passages from his lost Ketāb al-madḵal al-Ṣāḥebī, presumably dedicated to Ṣāḥeb Esmāʿīl b. ʿAbbād, the vizier of Moʾayyed-al-dawla, who ruled parts of Iran from 366/977 till 373/983. But Heravī’s only extant work is his revision of Māhānī’s edition of Menelaus’ Sphaerica, the Ketāb Manālāwos fi’l-aškāl al-korīya.
See also M. Krause, Die Sphärik von Menelaos, Berlin, 1936, pp. 32-42.
A. Sayili, The Observatory in Islam, Ankara, 1960, pp. 103-04.
Sezgin, GAS V, p. 329.
Originally Published: December 15, 1984
Last Updated: July 28, 2011
This article is available in print.
Vol. I, Fasc. 6, p. 647