Johannes Regiomontanus.

Johannes Müller von Königsberg was born on June 6^th, 1436. He adopted “Regiomontanus” as a pseudonym, derived from his birthplace who’s meaning was “King’s mountain”. Nothing is known of his early life, but in April of 1450 he enrolled in the University of Vienna. Two years later, in January, he graduated with a bachelor’s degree. Afterwards he held lectures in optics and ancient literature. He also built astrolabes and even a portable sundial for Pope Paul II.

In 1457 he became a colleague of Peuebach. He was persuaded to create a “briefer and more comprehensible” Latin version of Ptolemy’s Mathematical Syntaxes, but had died after finishing book IV and on his deathbed asked Regiomontauns to finish it. He returned to Rome in November of 1461, and had finished the epitome there. However, if was never printed until twenty years after the death of Regiomontanus. Despite this folly, the book contributed greatly to modern science, because in addition to translating the book Regiomontanus also included so critical analysis, revisions, and other observations to it. Errors in Ptolemy’s work regarding the moon were pointed out in the translation, and they would later influence Copernicus and his work.  

Over the next four years, Regiomontanus lived and worked in the home of Cardinal Bessarion. There he wrote De Triangulis Omnimodus (one of the first textbooks on trigonometry) and Epytoma in almagesti Ptolemei. In 1471 he moved to Nuremburg in Franconia. There he became famous for constructing the first observatory in Germany.

In 1475 he returned to Rome to work on calendar reform. En route he published his "Ephemeris" in Venice. He died in July of 1476, Most likely by the Plague, but there were rumors that he died by assassination.