Werner Landgraf
He also developed a method of eliminating systematic errors in positioning brighter comets that resulted in a more accurate prediction of the Halley's Comet. A recalculation of the path of Halley's comet to 2317 BC confirmed that the Greeks had already seen the comet on 466 B.C.
He discovered seven minor planets including 3683 Baumann, 4378 Voigt (named after Hans-Heinrich Voigt), 9938 Kretlow and 4349 Tibúrcio at ESO's La Silla Observatory in northern Chile.
Thomas Bopp
Thomas Joel Bopp (October 15, 1949 – January 5, 2018) was an American amateur astronomer best known as the co-discoverer of comet Hale–Bopp (with Alan Hale) in 1995. At the time of the comet discovery he was a manager at a construction materials factory and an amateur astronomer. On the night of July 22, Bopp was observing the sky with friends in the Arizona desert when he made the discovery. It was the first comet he had observed and he was using a borrowed, home-built telescope. Hale and Bopp both discovered the comet by chance at approximately the same time.