Provençal, Jewish astronomer; born, probably at Marseilles, about 1236; died at Montpellier about 1304. He was a grandson of Samuel ben Judah ibn Tibbon. His Provençal name was Don Profiat Tibbon; the Latin writers called him Profatius Judæus. Jacob occupies a considerable place in the history of astronomy in the Middle Ages. His works, translated into Latin, were quoted by Copernicus, Reinhold, and Clavius. He was also highly reputed as a physician, and, according to Jean Astruc ("Mémoires pour Servir à l'Histoire de la Faculté de Médecine de Montpellier," p. 168), was regent of the faculty of medicine of Montpellier.
In the controversy between the Maimonists and the anti-Maimonists Jacob defended science against the attacks of Abba Mari and his party; the energetic attitude of the community of Montpellier on that occasion was due to his influence.
The two original works of Jacob are: (1) a description of the astronomical instrument called the quadrant (Bibliothèque Nationale, Paris, MS. No. 1054), in sixteen chapters, the last of which shows how to construct this instrument. This was translated several times into Latin; (2) astronomical tables, beginning with March 1, 1300 (Munich MS. No. 343, 26). These tables were translated into Latin and enjoyed great repute.