Optomechanical design of the Discovery Channel Telescope prime focus assembly

The Discovery Channel Telescope (DCT) is a 4.2m aperture telescope with a unique front end pod assembly that incorporates a secondary mirror assembly on one end, and a prime focus corrector group with focal plane instrument on the other. By flipping the pod end-for-end, the DCT is quickly converted from an f/6.13 Ritchey-Chretien telescope with a 21 arcminute field of view, to an f/1.9 two degree wide field prime focus camera. This paper describes the conceptual opto-mechanical design and performance assessment of the Prime Focus Assembly (PFA), including the pod interfaces, structures, optic mounts and the functions and configurations of the various mechanisms within the pod.