This astronomical manuscript is comprised of notes by al-Birjandi on a treatise by Qadi’zadah, which is itself a commentary on a work by al-Jighmini entitled al-Mulkhkhas fi al-hay’ah (Précis of astronomy). The manuscript is thus the work of three scientists specializing in mathematics and astronomy. Included are extensive hashiyah (marginal notes) on Qadi’zadah’s sharh (commentary) on the principles of astronomy by al-Jighmini. The manuscript first covers the principles of geometry necessary for the study of the heavens. There follows extensive coverage of the position of celestial bodies in relation to the earth and the seasons. The three authors demonstrate the vitality from the 13th to the 17th centuries of what is called “Arab” astronomy. Research was passed from generation to generation and from academy to academy. But the work also reminds us that what is often termed “Arab science” is in fact a body of knowledge created by scholars from many lands who wrote in Arabic, the lingua franca of the learned. For example, astronomer-mathematician Qadi’zadah was born in Turkish-speaking Bursa, a city west of Istanbul. He moved to the Timurid city of Samarkand in Central Asia, where Persian and Turkish were commonly spoken but where scientific writing was largely in Arabic. Qadi’zadah wrote little, but his commentary was frequently copied and used as a textbook in many parts of the Islamic world. The central text is copiously annotated and there are a few geometric illustrations in the margins. The colophon mentions that the work was copied by Mustafa ibn ‘Ali al-Buluni (sic). On the front leaves are ownership statements and poetic couplets in Persian; on the back flyleaves is a long comment on the characteristics of fixed stars. None of the three works has been edited and published in a critical edition.