"Skinning the CAT"
Opening the telescope is done from the coude slit room, located in the south part of the 120-inch's basement. Before opening any part of the telescope, be sure to check that weather conditions are within the prescribed telescope limits.The order in which the various parts of the telescope are opened and closed is important. Please follow the directions carefully.
 Siderostat Housing and Mirror Cover Control Panels |
Opening the Telescope
1. Turn on the control power from the toggle switch on the right-hand side of the panel.
2. Begin retracting the roof of the siderostat by pushing the "open" button on the right-hand side of the panel.
3. While the roof is retracting, hold the upper shutter toggle switch up until the green "open" indicator lights.
While waiting for the roof to retract, open the primary mirror
cover by pushing and holding the "open" button on the small red box
(not illustrated) labeled "CAT MIRROR COVER", located on the ledge above and
to the right of the guide camera. Continue holding the button until the
"open" indicator lights. You will also hear a pronounced "clunk" when the
primary mirror cover is fully open. Opening the primary cover may require
a minute or more.
At this time you may also open the portal cover on the ceiling above the slit by pulling down on
and turning the red "T" handle, hanging from the ceiling above the slit.
By now, the siderostat shed roof should be fully retracted. This is indicated by two green lights to the right of the "open" button on the control panel. Check that all green lights are illuminated across the top of the right-hand side of the control panel and proceed to the step #4.
4. When the roof is fully retracted, open the siderostat mirror cover by pushing the "open" button on the left-hand side of the panel.
On your way out the door turn the fan on (door nearest to the CAT read out room). Medium should be high enough but on warm days high might be needed. The dial is in the middle of the fan.
The CAT is now fully open.