9th-century astronomer and engineer Abū al-ʿAbbās Aḥmad ibn Muḥammad ibn Kathīr al-Farghānī, known as Alfraganus in the West, worked at the Abbasid court in Baghdad. He produced several works on astronomy that were widely distributed and influenced many scientists.
His best-known work, Kitāb fī Jawāmiʿ ʿIlm al-Nujūmi (Elements of astronomy on the celestial motions), summarised Ptolemy's Almagest. It provided data Columbus used in framing the submissions to the Spanish court that financed his voyages to America. In addition to his astronomical work, al-Farghani supervised construction projects on the Nile.
See here for a more detailed biographical sketch.