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: Motions

There are no slew motors for either dec or RA; the telescope must be slewed by hand. The dec lock is the 6" metal wheel below the finder telescope (Fig. 15). It requires only a half turn counterclockwise to unlock, and an easy clockwise turn to clamp. The RA clamp is electrically controlled from its own paddle which is usually hanging near the top of the telescope to the right of they eyepieces (Fig. 15). The paddle has two buttons labelled "R.A. CL" (for clamp) and "R.R. UNCL" (unclamp). You must hold these buttons down for 4 or 5 seconds to fully clamp and unclamp the RA. If you listen closely you can hear the clamp operating as you hold the buttons.

The set and guide motions are controlled by yet another paddle (the "guiding paddle" or the "telescope paddle") usually hanging below the eyepieces (Figs. 15 and 16). The guiding paddle is metal and octagonal in shape, with N, S, E and W buttons for guiding and a center button for set rate. On the sides of the guide paddle are two more buttons for adjusting the RA drive rate (Fig. 16). If the E button is consistently required to keep the object centered, a tap or two on the side button near the E button will slow the right ascension drive oscillator rate; tapping the button on the side of the paddle near the W button speeds up the oscillator.

There is an auxiliary guiding paddle in the upper left corner of the east wall of the office to be used with remote guiding systems (none presently available). If the switch on the wall near the paddle marked "aux" and "main" is in the "aux" position, the regular paddle is disabled and vice versa.

Figure 15

Figure 16