Abu Jafar Muhammad ibn Husayn Khazin (Persian: ابوجعفر خازن خراسانی; 900–971), also called Al-Khazin, was an Iranian^[1] Muslim astronomer and mathematician from Khorasan. He worked on both astronomy and number theory.

Al-Khazin was one of the scientists brought to the court in Ray, Iran by the ruler of the Buyid dynasty, Adhad ad-Dowleh, who ruled from 949 to 983. In 959/960, Khazin was required by the vizier of Ray, who was appointed by ad-Dowleh, to measure the obliquity of the ecliptic.

One of Al-Khazin's works Zij al-Safa'ih ("Tables of the Disks of the Astrolabe") was described by his successors as the best work in the field and they make many references to it.^[2] The work describes some astronomical instruments, in particular an astrolabe fitted with plates inscribed with tables, and a commentary on the use of these. A copy of this instrument was made, but it vanished in Germany during World War II. A photograph of this copy was taken and examined by the historian David King in 1980.^[3]

Al-Khazin also wrote a commentary on the Roman polymath Ptolemy's Almagest in which he gives 19 propositions relating to statements by Ptolemy, and proposed a different model of the cosmos.^[4]