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The Henrietta Swope Telescope


1. General

  In 1971, the Carnegie Institution put into operation the first telescope at its new observatory on Cerro Las Campanas in Chile. The Swope Telescope, a 1-meter (40-inch) reflector, is named after a former Carnegie astronomer, Henrietta Swope, a collaborator of Walter Baade and the author of several classic papers, whose generous gift made possible the construction of the telescope.

The Swope telescope was built by the Boller and Chivens Division of the Perkin-Elmer Corp. The optical characteristics are discussed in detail by Bowen and Vaughen (1973, Applied Optics, 12, 1430). The optical design is an f/7 Ritchey-Chrétien in which the radii of curvature of the primary and secondary are equal, thereby achieving a zero Petzval sum and a flat field. Astigmatism is eliminated with a Gascoigne corrector lens. This design achieves a well-corrected field about 3 degrees in diameter. However, to do this it was necessary to use a secondary one-half the diameter of the primary, thereby intercepting 25% of the incident light.

An f/13.5 secondary used for infrared imaging is also available through a top-end "flip".


2. Optical Design


 The following table gives the optical specifications of the f/7 Cassegrain configuration.


Diameter primary: 1,016 mm
Focal length primary: 4,118 mm
Focal length Cassegrain: 7,112 mm
Diameter hole in primary: 386 mm
Diameter secondary: 508 mm
Diameter corrector plate: 386 mm
Distance between mirrors: 2,384 mm
Focal point distance behind surface of primary: 610 mm
Radius of curvature of focal surface: infinity
Unvignetted/corrected field of view: 1.92 degrees
Vignetting @ 88 arcmin field angle: 5%
Scale: 0.0345 mm/arcsec



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