We are extremely sad to learn that Gart Westerhout has died on 14 October at the age of 85. Gart Westerhout was born on 15 June 1927 in The Hague and studied at Leiden, where he worked with Jan Oort and Henk van der Hulst as supervisors. Contemporaries and colleagues at Leiden included Hugo van Woerden, Maarten Schmidt, King Kwee, Lo Woltjer, and C. Lex Muller, Charles L. Seeger, Jr. (half-brother of Mike Seeger). While they were students, Wim Brouw, Mike Davis, Whitney Shane, Ernst Raimond and Jaap Tinbergen also worked with him.
Gart Westerhout was awarded a Leiden PhD in 1958 and is best known for the Westerhout Catalog of radio sources, done with the Dwingeloo telescope; and his survey of neutral hydrogen in the outer parts of our Galaxy. In other collaborations he demonstrated the first hints of spiral structure in the interstellar gas. This revealed differential rotation in our Galaxy, and established a revised Galactic coordinate system still in use today.
He left Leiden for the US in 1962, where he initiated an astronomy programme at the University of Maryland. He was Scientific Director at the U.S. Naval Observatory from 1977 until 1993.
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