al-Manhal al-adhb al-zulal fi hall al-taqwim wa-ru'yat al-hilal (Ibn al-Majdi)

Al-Manhal al-adhb al-zulal fi hall al-taqwim wa-ru'yat al-hilal, also known as al-Manhal al-adhb al-zulal fi ma'rifat hisab al-hilal (al-Azhar Library no. 10/4383, first treatise), is by Ahmad ibn Rajab ibn Taybugha al-Majdi. ^{2 1}

The book describes it as a short, concise treatise for finding the beginning of the Arab months by calculation and for the methods of sighting the crescent, showing the author's command of the astronomical terms and symbols of his day; it dates it to the early ninth century AH because it discusses finding the crescent of Ramadan for 812 AH. ¹ It also treats extracting mean motions from tables. ¹

The book says Ibn al-Majdi (767–850 AH) was born and raised in Cairo and wrote nearly fifty books and treatises, among them Irshad al-ha'ir ila ma'rifat wad' khutut fadl al-da'ir and Kashf al-haqa'iq fi hisab al-daraj wal-daqa'iq. ^{2 1}