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2.2 Slit Viewing TV

The slit and decker assembly is mounted at an angle of 13 to reflect light from the slit jaws to an intensified CCD TV for aquisition and guiding. A zoom lens is installed before the TV for changing the field of view and optimizing the apparent slit width in the digital memory guider box. A slit width of about one third the width of the guider box will be satisfactory for auto-guiding. See §7.4 for a discussion of operating the leaky memory guider. The AC power switch on the left side of the slit head control panel must be on to operate the zoom lens, but it may be controlled either at the panel or by buttons on the coudé observing room control rack.