CINCINNATI, Aug. 28— Paul Herget, an astronomer and a pioneer in the space program, died yesterday. He was 73 years old. Mr. Herget retired in 1978 as director of the Minor Planet Center of the International Astronomical Union and head of the astronomy department at the University of Cincinnati.

In the 1950’s, he was responsible for computing trajectories and orbits in the development of the Atlas intercontinental ballistic missile, the Vanguard satellite program and the Mercury manned space flights. His 1948 book, ”The Computation of Orbits,” was a landmark work in the early days of the space program and is still required reading in the field of celestial mechanics.

In World War II, Mr. Herget developed a triangulation method for the United States Naval Observatory to determine the location of enemy submarines. Later he served as a consultant to the Manhattan Project in developing the atomic bomb. Member of Academy of Sciences

He was named to the National Academy of Sciences in 1962 and was awarded the James Craig Medal for research three years later. At Cincinnati, Mr. Herget coordinated the identification and registration of newly discovered asteroids. He also kept records of asteroid orbits and conducted searches for asteroids that had been lost to observers. In 1954, he rediscovered the asteroid Athelia, which had not been observed for more than 50 years.

Since his retirement, he had devoted his time to computer development and assisted in several scholarly papers. He is survived by his wife and a daughter. Services will be private.