death in 1571. He was the primary reference in the Ottoman Empire on the science of timekeeping, and according to the Turkish explorer Evliya Çelebi his works were cited in Western Europe. Other than the title al-muwaqqit and müneccimbaşı, based on his offices, he was also known by the honorific Koca Saatçi ("the great timekeeper"). After Mustafa's death, Sultan Selim II appointed the prominent scholar Taqi ad-Din Muhammad ibn Ma'ruf—who just returned to Istanbul in 1570 after his service in the Egypt Eyalet—as his successor. Legacy Mustafa ibn Ali was one of the most important Ottoman astronomers of the sixteenth century. Because of his works on the theory and applications of the science of timekeeping and practical astronomy, Fazlıoğlu writes that he is considered to be "the founder of the Ottoman tradition" of those fields. He was one of the earliest authors of astronomy in Turkish, a tradition started by Muhammad al-Qunawi. References Bibliography Astronomers from the Ottoman Empire Scientists from Istanbul 16th-century births 1571 deaths 16th-century scientists from the Ottoman Empire