Regiomontanus
a German astronomer, whose real name was Johann Müller; born in Königsberg (in Latin Regiomontum, whence came his name), in Franconia, June 6, 1436. He was educated at Leipsic; studied mathematics at Vienna; accompanied_Cardinal Bessarion to Rome, where Beza gave him further instructions in Greek literature, which enabled him to complete a new abridgment in Latin of the Almagest of Ptolemy.
Ptolemy. In 1471 he built an observatory at Nuremberg, but he returned to Rome on the invitation of Sixtus IV., who employed him in the reformation of the calendar. His "Kalendarium Novum" (New Calendar) is believed to be the first almanac issued in Europe. He died July 6, 1476.