Experience with the Palomar Double Spectrograph

Abstract

The now retired Multichannel Spectrometer on the 5-meter Hale telescope was almost certainly the first double instrument designed for use on a large telescope. It was really a broad-band spectrophotometer rather than a proper spectrograph, but its purpose was to provide the widest possible simultaneous spectral coverage with the highest obtainable quantum efficiency. The Double Spectrograph for the same telescope was probably the first true spectrograph designed from the beginning to be double. Since it remains one of the few such instruments, Joe Miller has asked me to talk about the use of the instrument and in particular to discuss whether it was actually worth while making it double. Could a single instrument have done just as well? These questions are discussed below.