There are two types of shutter on the spectrographs:
The slit shutter, which opens and closes for each exposure, is positioned in the wall separating the main coudé east room from the pre--slit area. It is controlled through the VAX terminal (from OBSERVER with CCD, or from UCLES with the IPCS) or via a ``panic button" in the control room. These controls are in series, so both must be open for the shutter to operate.
Camera shutters are located directly in front of the detectors and are used as dark slides. They are controlled by switches on a panel in the coudé east anteroom, and also by microswitches on the doors to the main coudé room and to the preslit area which close the shutters if either of these doors is opened.
The ``panic" indicators are red when shutters are open.