The concept design of the Discovery Channel Telescope mount

The 4.2 m Discovery Channel Telescope requirements create interesting challenges for the Mount mechanical and control system design. The wide field of view survey telescope incorporates two operational foci: prime focus and cassegrain, either one must be available during any night's observing. The mission for observing requires fast slewing / offsets between each exposure with fast settling timesto maintain the mission requirements. The prime focus arrangement includes a dedicated camera on the spiderassembly and the cassegrain configuration includes a secondary mirrorat the spiderassembly with a dedicated instrument located at the cassegrain focus. This requirement challenges the design team to incorporate a prime focus / secondary mirrorflipping mechanism within the secondary spider. The configuration requires a substantial prime focus and cassegrain payload with long focal distances creating a large inertia on the altitude axis. These are a few of the interesting challenges that are presented in this paper along with the design, trade-offs of different solutions, and the recommended design for the telescope Mount.