Robert H. Koch said he never tired of looking at light that had spent 1,000 years traveling through the universe before it got to him.
Though the best equipment at the University of Pennsylvania could see stars only as far as 1,000 light-years away, it still showed an ever-changing universe.
"That's the real excitement of it," he told an Inquirer interviewer in 1990. "Nothing is ever the same. It's just about impossible to get bored."
On Monday, Oct. 11, Dr. Koch, 80, a member of the astronomy department at Penn from 1967 to 1996 and its chairman from 1969 to 1973, died of a brain tumor at his home in Ardmore.
As director of Penn's Flower and Cook Observatory near Malvern from 1989 to 1994, Dr. Koch presided over an operation that had lasted for almost 50 years.
In 1932 at his home, Gustavus Wynne Cook had set up stargazing equipment that, at his death in 1940, he willed to Penn. Time magazine called the Cook facility "the world's most elaborate private astronomical observatory."
Penn combined it with equipment given by another wealthy amateur astronomer, Reese Wall Flower, and in 1956 opened its Flower and Cook Observatory.
The 1990 Inquirer interview with Dr. Koch reported that the 35-acre site had been chosen not only because it was distant from the lights of Philadelphia but also because at 550 feet above sea level it was less troubled by smog.
Penn sold the observatory and its last four acres to neighbors in 2004.
"The observatory was infrequently used after Dr. Koch retired, since it was devoted to double-star research, which was his specialty," said Benjamin Shen, Penn's Reese Flower Professor of Astronomy and Astrophysics from 1972 to 1996.
A double star is a set of two or more stars that are, or appear to be, next to each other.
Born in York, Pa., Dr. Koch graduated from York Catholic High School in 1947 and earned a bachelor's degree in mathematics at Penn in 1951.
After he served in the Army Quartermaster Corps until 1953, Penn records show, he earned a master's degree in astronomy there in 1955.
Dr. Koch's research took him to the Steward Observatory of the University of Arizona, where he earned a second master's in astronomy in 1957 before returning to Penn to earn his doctorate in astronomy in 1959.
He then worked in the four-college astronomy department in Amherst, Mass., teaching first at Amherst College, then at the University of Massachusetts campus there, until 1966, said his wife, Joanne.
After an academic year at the University of New Mexico in 1966-67, she said, he began his 29-year career at Penn, where he was named professor in 1969.
Dr. Koch wrote a privately published history of his department, Observational Astronomy at the University of Pennsylvania 1751 to 1996, which he later updated.
In 2007, when he was 77, he showed his unending curiosity when he began to learn to play the mandolin, his wife said.
Besides his wife, Dr. Koch is survived by sons Thomas and James, daughters Elizabeth Koch and Patricia Budlong, a brother, a sister, and seven grandchildren.
A visitation was set for 9:30 a.m. Tuesday, Dec. 21, at St. Colman Church, 11 Simpson Rd., Ardmore, followed by a Funeral Mass there at 10.