32"/35.6", f/3.75 Cassegrain Schmidt.
The ADH telescope was of the Baker-Schmidt C4 type, being designed by Professor James Baker of Harvard University (see Proc. Amer. Phil. Soc., 82, 339-349, 1940). It came into operation in 1950, and in 1951 the then world's largest objective prism, 33" in diameter, was provided from funds contributed by Harvard and the Department of Astronomy at Queen's, Belfast (see Sci. Amer., p.46, July 1952). The telescope was placed on the Fecker mounting of the 24" Bruce refractor at the Boyden Station of the Harvard Observatory in Bloemfontein, South Africa. The two- mirror and corrector system give a flat field and reduced tube length (168") compared with the classical Schmidt telescope (see H.C. King, "The History of the Telescope"). Among the objects studied with photographs from the ADH have been globular star clusters, cluster Cepheids, and the Magellanic Clouds. The ADH optics are currently at Dunsink Observatory, though still jointly owned by the two Irish Observatories.
See also: A Short History of Armagh Observatory
Last Revised: 2009 November 5th