File: Mark II

Scope and Content

Includes early designs for the Mark II (or 125 ft telescope), and the original application to the DSIR for funding in 1960 (it was approved late 1961). Much of the correspondence is with the University of Manchester Bursar, H C Husband, the engineer, and DSIR officials mainly C Jolliffe, and James Tuson and ministry of works,(W L Wilson)memoranda on purpose and construction of the telescope

Administrative / Biographical History

The Mark II telescope project commenced in 1960. The telescope was intended to observe higher frequency wave lengths in the 21cm band and shorter, which the Mark I was unable to do. in addition, it was intended to work as part of an interferometer with the Mark I; work which was becoming increasingly important to the Observatory. The Mark II was intended as a prototype for the (cancelled) larger Mark IV telescope.

The Mark II had an elliptical rather than circular reflector, and its design was based on the larger radio-telescope which Husband designed at Goonhilly Downs. The telescope was a steel sheet paraboloidal reflecting bowl with an elliptical aperture of major axis 125ft (38.1m) and minor axis of 83ft 4in (25.4m). The focal length was 40ft (12.2m), and the mounting was alt-azimuth with 420 degrees of travel in azimuth and 0 to 90 degrees in elevation. The telescope sat on a turntable of pre-stressed concrete rather than structural steel for reasons of rigidity.

The Mark II was built on the site of the earlier 218ft Transit telescope. It was the first telescope in the world to be steered by digital computer ( a Ferranti Argus 104). The Mark II became operational in 1964.