The spectrograph is operated from from the 3-m or CAT control room,
addording to which telescope is being used (though some observers,
especially those using the image rotator, may find it more convenient
to observe from the CAT control room even when using the 3-m).
The basic system of spectrograph controls is illustrated below. The
acquisition/guide TV is as much a part of the telescope control system
as of the spectrograph, but is included here for completeness, and because
TV focus and magnification are handled by the spectrograph controller.
User interfaces, running on their respective hosts, communicate to hardware
controllers either directly or through intermediate hosts. From the observer's
standpoint, all spectrograph functions are controlled through two programs,
the data-taking program
, on a single display. In the case of the CAT,
acquisition and guiding
are carried out by the
observer on a separate display; when observing with the 3-meter, these
operations are handled by the telescope operator.