Gart Westerhout was an astronomer who gained international renown in the early 1950s when he helped chart the Milky Way galaxy with unprecedented precision, and who later created the astronomy programme at the University of Maryland in the United States.
Westerhout made the first of his achievements – principally in radio astronomy – in the Netherlands in the years after the Second World War. He was among the youngest in a pioneering group of scientists taught and led at the University of Leiden by the astronomer Jan Oort, who has been compared to a "modern Copernicus."
Westerhout joined the nascent field of radio astronomy and set out to study the heavens using radio waves emitted by stars, galaxies and other celestial bodies. conducted his earliest research on a wartime relic, a large radar antenna left behind by the German military and later commandeered by Dutch scientists.
Together with his colleagues, and on increasingly sophisticated equipment, Westerhout tracked the radio waves emitted by interstellar hydrogen gas to compile the first detailed map of the spiral structure of the Milky Way. "For the first time, we could see with some precision that what appears to be a random collection of stars up there is really organised," said Kurt Riegel, Westerhout's first doctoral student at Maryland who later headed the national astronomy centres at the National Science Foundation. "The radio observations ... allowed astronomers to get a handle on our own galaxy." Westerhout was not yet 30.
His work attracted the attention of scientist John Toll, a future president of the University of Maryland who at the time was building the school's physics department. In 1961, Westerhout received an invitation from Toll – "out of the blue," he recalled – to go to Maryland and create an astronomy programme.
He built a programme that later became a full-fledged department. "He basically got the programme going," said Stuart Vogel, the current department chair. "He was the one who hired a lot of our astronomers and made us into what we are."
Westerhout, who was born in The Hague, became interested in astronomy after seeing his architect father's design for a sanatarium for tuberculosis patients. He had drawn up plans for the ceiling of the recreation hall to be painted with the constellations and the signs of the zodiac, so the patients might have something to look at as they lay on their backs.
Westerhout fashioned his first telescope from an eyeglass lens and a magnifying glass. It helped him find a degree of comfort during the deprivations of the war. The skies darkened because of the black-outs, he wrote in a biographical sketch, and he had "a beautiful view of the skies."
In the US, where he became a naturalised citizen, Westerhout deepened his research through use of the Green Bank Telescope in West Virginia. Besides his work on mapping the Milky Way, he created the Westerhout Catalogue of radio sources in the cosmos, which include supernova remnants, colliding galaxies and what were later identified as quasars.
In 1977, Westerhout left Maryland to become scientific director at the US Naval Observatory.
Gart Westerhout, astronomer: born The Hague 15 June 1927; married (two daughters, two sons); died 14 October 2012.