Rheticus[retikus], originally Georg Joachim von Lauchen
Astronomer and mathematician, born in Feldkirch, Austria. He became professor of mathematics and astronomy at Wittenberg from 1536. He is noted for his trigonometrical tables, some of which went to 15 decimal places. For a time he worked with Copernicus, whose De revolutionibus orbium coelestium he was instrumental in publishing. His own Narratio prima de libris revolutionum Copernici (1540) was the first account of the Copernican theory.