William L. Kraushaar, an astrophysicist who used early satellites to measure gamma rays and X-rays in space and then theorized about the ultimate sources of the cosmic radiation, died on March 21 in Gorham, Me., near Portland. He was 87.
He moved to the University of Wisconsin in 1965 and remained at Madison as a professor of physics for the rest of his career. He retired in the 1990s.