Coyne joined the Vatican Observatory as an astronomer in 1969 and became an assistant professor at the LPL in 1970. In 1976 he became a senior research fellow at the LPL and a lecturer in the UA Department of Astronomy. The following year he served as Director of the UA's Catalina Observatory and as Associate Director of the LPL. Pope John Paul I appointed him Director of the Vatican Observatory in 1978, and also Associate Director of the UA Steward Observatory. During 1979-80 he served as Acting Director and Head of the UA Steward Observatory and the Astronomy Department. He spent five months of the year in Tucson as adjunct professor in the University of Arizona Astronomy Department.