an Arabic prince of Batan, in Mesopotamia, and a celebrated astronomer, who lived about the year 880, as appears by his observations. He is also called Muhammed ben Geber Albataeni, Mahomet the son of Geber, and Muhammed Aractensis. He made astronomical observations at Antioch, and at Racah or Aracta, a town of Chaldea. He is highly spoken of by Dr Halley, as a man of great genius, and an excellent observer. He received the title of the Arabian Ptolemy.

Instead of the tables of Ptolemy, which were imperfect, he computed new ones; these were adapted to the meridian of Aracta or Racah, and were long used as the best among the Arabs. He also composed in Arabic a work under the title of The Science of the Stars, comprising all parts of astronomy, according to his own observations and those of Ptolemy. This work was translated into Latin by Plato of Tibur, and published at Nuremberg in 1537, with some additions and demonstrations of Regiomontanus. It was reprinted at Bologna in 1645, with this author's notes. Dr Halley detected many faults in these additions. (Philosophical Transactions for 1693, No. 204.) In this work Albategni gives the motion of the sun's apogee since Ptolemy's time, as well as the motion of the stars, which he makes one degree in 70 years. He makes the longitude of the first star of Aries to be 18° 2', and the obliquity of the ecliptic 23° 35'. Upon Albategni's observations were founded the Alphonsine tables of the moon's motion.