37th DPS Meeting, 4-9 September 2005
Session 40 Radio Astronomy II
HAD Oral, Wednesday, September 7, 2005, 4:00-5:30pm, Umney Theatre, Robinson College

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[40.03] Discovery and First Observations of the 21-cm Hydrogen Line

W. T. Sullivan (U. Washington)

Unlike most of the great discoveries in the first decade of radio astronomy after World War II, the 21 cm hydrogen line was first predicted theoretically and then purposely sought. The story is familiar of graduate student Henk van de Hulst's prediction in occupied Holland in 1944 and the nearly simultaneous detection of the line by teams at Harvard, Leiden, and Sydney in 1951. But in this paper I will describe various aspects that are little known: (1) In van de Hulst's original paper he not only worked out possible intensities for the 21 cm line, but also for radio hydrogen recombination lines (not detected until the early 1960s), (2) in that same paper he also used Jansky's and Reber's observations of a radio background to make cosmological conclusions, (3) there was no "race" between the Dutch, Americans, and Australians to detect the line, (4) a fire that destroyed the Dutch team's equipment in March 1950 ironically did not hinder their progress, but actually speeded it up (because it led to a change of their chief engineer, bringing in the talented Lex Muller).

The scientific and technical styles of the three groups will also be discussed as results of the vastly differing environments in which they operated.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.