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The Utrecht Echelle Spectrograph (UES) is the principal high-resolution spectrograph for the William Herschel Telescope. It offers the means to obtain spectra of objects as faint as magnitude with a resolving power R between and . The spectrograph has been designed to operate from 3000 to 10000 Å; the wavelength interval covered in a single exposure depends on the detector in use, and is typically in excess of 1000 Å. UES is permanently located in a thermally stable enclosure on one of the Nasmyth platforms at the f/11 focus of the WHT and can normally be deployed quickly from one of the other focal stations. The optical design of the spectrograph is very similar that of the University College London Echelle Spectrograph in use at the coudé focus of the Anglo-Australian Telescope, described by Walker & Diego 1985 (MNRAS, 217, 355). A detailed description of UES and its operation is given in the UES manual by S. Unger, M. Pettini and N. Walton (User Manual No. XXIII).

Tue Aug 15 16:42:46 BST 1995