Al-Sufi was an important astronomer of the Middle Ages. He lived in Persia in the 10th century CE. He is best known for his work entitled Book of Fixed Stars.
A good deal of Al-Sufi's work consisted of translating works by the ancient astronomer Ptolemy and updating those works. He took the knowledge that had been gathered by Ptolemy and other Hellenistic scientists and correlated it with the knowledge of the Persians and other Muslims. This work, along with his own descriptions of stars and their colors and magnitudes, formed the basis for Book of Fixed Stars.