Simplifying the prime focus corrector of the Discovery Channel Telescope

The Discovery Channel Telescope (DCT) is planned to have a state-of-the-art prime focus corrector which was described previously. The initial design contained I-line glasses which had long procurement times. Goodrich Corp. undertook a study funded by Lowell Observatory to determine whether significant savings in cost and schedule would be possible with an acceptable reduction in the performance of the telescope. This paper reports on changes in the optical design of the wide-field optical corrector (WFOC) with a view to eliminating the long-lead materials. The consequent changes in performance are also discussed. The required FWHM of the telescope was relaxed somewhat and the imaging requirements of the ultraviolet (U) band were eliminated. The new design meets the two-degree field of view requirement and recovers most of the performance in the ultraviolet.