The optical design and operation of the Coravel direct-correlation spectrograph system used to measure stellar radial velocities at the University of Cambridge 36-inch telescope, are described. The optical layout of the Cambridge Coravel is similar to that of the Coravels at the Observatoire de Haute Provence and ESO, comprising an echelle grating and a prism cross-disperser working in double pass. Particular attention is given to the calibration and scanning systems, the collimator-echelle-camera assembly, the mask and mask holder, the microprocessor-controlled photomultiplier detection system, the control and user interface, and the observing procedure. Diagrams, photographs, and sample observational data are included.
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