Excerpts from Books and Wikipedia
He is director of the Maragha observatory. The revision appears in Copernicus's work three centuries later. [Lyons: House of Wisdom, p. xiii] "Muhammad ibn Muhammad ibn al-Hasan al-Tusi (…), better known as Nasir al-Din Tusi (…), was a Persian polymath, architect, philosopher, physician, scientist, and theologian. He is often considered the creator of trigonometry as a mathematical discipline in its own right. He was a Twelver Muslim. The Muslim scholar Ibn Khaldun (1332–1406) considered Tusi to be the greatest of the later Persian scholars." [Wikipedia]