From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 10 |
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Abū al‐ʿUqūl: Abū
al‐ʿUqūl Muḥammad ibn Aḥmad al‐Ṭabarī
David A. King
Flourished Yemen,
circa 1300
Abū
al‐ʿUqūl was the leading
astronomer in Taiz, Yemen, circa 1300. His epithet al‐Ṭabarī indicates that he or his family came originally from northern
Iran. He was a contemporary of the ruler Ashraf
and Muḥammad ibn Abī Bakr al‐Fārisī,
the latter also of Iranian stock. No details of Abū al‐ʿUqūl's life are known
to us beyond the fact that he was the first teacher of astronomy appointed
at the Muʾayyadiyya Madrasa in Taiz by the Sultan al‐Muʾayyad,
brother and successor of al‐Ashraf.
Abū
al‐ʿUqūl compiled an
astronomical handbook (Arabic: zīj) for the Yemen and was not
shy about admitting to having taken most of it from other sources; indeed,
he called his work al‐Zīj al‐mukhtār min al‐azyāj
(The Zīj culled from other Zījes). In fact, the work
is based heavily on the Ḥākimī Zīj of the 10th‐century
Egyptian scholar Ibn Yūnus. What
is original are the various tables of spherical astronomical functions for
latitudes in the Yemen, and it is clear that spherical astronomy was the author's
forte.
Abū
al‐ʿUqūl compiled the
largest single medieval corpus of tables for astronomical timekeeping for
a specific latitude, with over 100,000 entries. This corpus, entitled Mirʾāt
al‐zamān (Mirror of Time), is computed for latitude 13° 37', an excellent value for
Taiz (accurately 13° 35'!) derived by either Abū al‐ʿUqūl
or al‐Fārisī, and obliquity 23° 35'.
In addition to tables of the hour angle and the time since sunrise for each
degree of solar altitude and solar longitude, such as are found in the Cairo
corpus associated with Ibn Yūnus, there are tables displaying the longitude
of the ascendant or horoscopus as a function of solar altitude and longitude,
and others displaying the altitude of various fixed stars at daybreak as a
function of the ascendant. The inspiration for the tables associated with
the ascendant seems to come from Iraq or Iran, where such tables are attested,
rather than from Egypt. Abū al‐ʿUqūl's extensive
tables are known from a unique manuscript copied in Mocca on the Red Sea coast
of Yemen in 1795. To what extent they were used over the centuries is unclear.
Abū
al‐ʿUqūl also prepared
an almanac in which astronomical phenomena were associated with aspects of
agricultural practice.
Abū
al‐ʿUqūl.
Al‐Zīj al‐mukhtār min al‐azyāj. London,
British Library, MS Or. 3624. (A unique copy.)
———. Mirʾāt
al‐zamān. Berlin, Deutsche Staatsbibliothek, Ahlwardt MS 5720.
(A unique copy.)
King, David A. (1983). Mathematical
Astronomy in Medieval Yemen: A Biobibliographical Survey. Malibu: Undena
Publications, pp. 30–32 (no. 9).
——— (2004). In Synchrony
with the Heavens: Studies in Astronomical Timekeeping and Instrumentation
in Medieval Islamic Civilization. Vol. 1, The Call of the Muezzin
(Studies I–IX). Leiden: E. J. Brill. I–2.1.2, 3.1.1, 3.3.2, 4.2.6, 4.5.1,
and II–12.1.
Varisco, Daniel Martin (1994). Medieval Agriculture and Islamic Science: The Almanac of a Yemeni Sultan. Seattle: University of Washington Press, pp. 10–11.