Sterken, C. ; Duerbeck, H. W. ; Cuypers, J. ; Langenaken, H.

published in Journal of Astronomical Data, 10 (2004)

Abstract: In 1871, the Belgian astronomer Jean-Charles Houzeau developed a new approach to determine the solar parallax. His ``heliometer with unequal focal lengths" produces a large and a small solar image, as well as a large and small image of Venus. Making the small solar and the large Venus image coincide yields a measure of the distance of the centers of both objects. Two such instruments were build. After being appointed director of the Royal Observatory of Belgium in 1876, Houzeau obtained support to organize two Belgian expeditions to observe the Venus transit of December 6, 1882: one to San Antonio, Texas, and another one to Santiago de Chile. That enterprise was the first major expedition in the history of Belgian science. This paper describes the expeditions, gives some biographical information about the team members, and clarifies the principal instrument and its present-day whereabouts.

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