Ibn al-Raqqâm on Lunar Parallax

Abstract

The Tuniso-Andalusian astronomer and polymath Abý þAbd All×h Mu¬ammad b. Ibr×h÷m b. þAl÷ b. A¬mad (Mu¬ammad?) b. Yýsuf al-Murs÷ al-Andalus÷ al-Týnis÷ al-Aws÷, known as Ibn al-Raqq×m, is considered by Ibn al-KhaÐ÷b1 to belong to "the people of Murcia" (min ahl Mursiya). Since he died in Granada the 21st ½afar 715 (26th May 1315) at an advanced age (Ibn al-KhaÐ÷b) and a son of his was born in Tunis in 1266 (see below), he may have been born in Murcia - a city conquered in 1266 by James I of Aragon for his nephew Alfonso X, king of Castile ca. 1246. Before 1266 Ibn al-Raqq×m seems to have migrated to Tunis, and Ibn al-KhaÐ÷b says that he lived in Tunis and in Bij×ya, which belonged at that time to the kingdom of the ©af½ides of Tunis. Ibn al-KhaÐ÷b also states that he migrated from Bij×ya to Granada during the reign of Mu¬ammad II (1273-1302). We might conjecture that he moved to Granada after 1288-89 (the date of the table of the lunar mansions2 in the Sh×mil Z÷j, compiled in Bij×ya), or even after 1290 (the date calculated using the table of the solar equation extant in the Sh×mil and in the Qaw÷m, on which see more below). Another chronological detail can be obtained from the horoscope Ibn al-Raqq×m cast on the occasion of the birth of a son of his who was, beyond any doubt, born in Ifr÷qiy× in 685/1266).