Al-Sufi was one of the nine noted Muslim astronomers. His name implies that he was a Sufi Muslim. He lived at the court of Emir Adud ad-Daula in Isfahan, Persia. He translated and expanded Greek astronomical works, especially the "Almagest" of Ptolemy. He made several corrections to Ptolemy's star-list and did his own brightness and magnitude estimates which often differed from those in Ptolemy's work.