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.
Historical comet observations in China
A computer calculation of the past orbits of Halley using numerical integration could not continue past 837 AD because a very close approach to Earth made calculation of orbits prior to that too inaccurate. The researchers had started with accurate European measurements from 1759, 1682 and 1607 AD and calculated backwards. However, no accurate European records exist for 837 AD so the researchers looked to Chinese records. From these they obtained a good estimate of the perihelion of Halley for that year. They used that, together with perihelions found from Chinese data for 374 and 141 AD, to provide constraints for their calculation. They were finally able to calculate the orbits of Halley back to 1404 BC.