Flourished: Damascus. Astronomical instrument-maker. Wrote an early Arabic treatise on the astrolabe. Opponent of astrology. Contributed to observations initiated by Ma’mūn. He took part with Khālid b. `Abd al-Malik al-Marwarrūdhī and others in an expedition to the Plain of Sinjār to measure one degree of latitude and, thus, the size of the Earth. Made astronomical observations at Baghdad in 829/830 and at Damascus in 832–833. He divided the mural quadrant used for the Damascus observations to confirm results of the earlier missions. [Ragep]; MAMS II:28; GAS VI:143-4; King, "Too Many Cooks..." Suhayl 1 (2000): 207–241.