User's Guide to the Crossley Telescope

Table of Contents

Ground Level
Dome and Platform
Head Rotation
Dec Tangent Arm
Position Indicators
Mirror Cover
Dome Slit
Access Ports
RA Drive Preload
Operating Limits
New Telescope Drive

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The Telescope: RA Drive Preload and Master Switches

There are just three switches in the office downstairs that every observer is concerned with. The master switch (or "main switch") turns on power to the drive motions, dome paddle, etc., and is the left of the two switches on brass plates at eye level on the east wall of the office (Fig. 27). This may ordinarily be left on. The RA preload (the other switch on a brass plate next to the master switch) and the RA drive oscillator should be turned on just before actual observing and off at the end of the night. The oscillator is in the electronics rack in the southeast corner of the room (Fig. 27). It is the piece of equipment with the large (~5") black and blue-gray dial in the upper left hand corner. The only switch to activate is a toggle switch in the lower left corner; just flip it up for on, down for off. In 30 seconds or so you will hear the RA drive start up in the south polar axle housing and the meter on the oscillator will register about 110 volts.

On the floor in the northeast corner of the office is a cable with a switch on the end. The switch may be used to turn the drive oscillator on and off from upstairs in order to drift the telescope across objects at sidereal rate.

Figure 27