Persian astronomy. 15th-century manuscript written in the north-eastern Timurid Empire, now Central Asia, in the 15th century. The manuscript is a commentary on an earlier work from the 13th century. The author of the commentary is Salah al-Din Musa ibn Muhammad (1364-1436), also known as Qadi Zada. He worked in Samarkand, the Timurid capital, at the court of Ulugh Beg. Here, he is commenting on the famous Islamic astronomy work known as the ‘Mulahhas fi al-Hay’a Al-Basita’ (‘The Compendium of Plain Astronomy’), written by Jighmini (died 1221). The text and diagrams describe the Earth and the orbits of the Sun and other planets.