User's Guide to the Crossley Telescope


Table of Contents


Introduction
Dome
General
Ground Level
Mezzanine
Dome and Platform
Telescope
General
Balance
Head Rotation
Finder
Motions
Dec Tangent Arm
Position Indicators
Mirror Cover
Reversal
Dome Slit
Access Ports
RA Drive Preload
Operating Limits
New Telescope Drive

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The Telescope: Mirror Cover

CAUTION CAUTION CAUTION

NEVER hold things over the top of the telescope with the mirror cover open. It may save 60 seconds not to close the cover when changing diaphragms, exit slots or whatever but the risk is not worth it.

The mirror cover is a plywood slab about 4' above the mirror level. It is operated by 2 buttons (one to open, the other to close) in the center of a grey junction box just to the right of the hour angle dials (Fig. 21). The mirror cover moves only when the buttons are depressed, and the entire motion takes perhaps 5 seconds. If you listen closely you will hear the mirror cover motor. It is advisable to visually verify that the cover has opened/closed completely. If the lights are on you can watch the movement of the mirror cover counterweight arm which is outside the tube on the NE corner at the level of the mirror cover.

Figure 21