User's Guide to the Lick 36" Refracting Telescope

Introduction
Dome
General
Floor
Slit (shutter)
Windscreen
Rotation
Lighting
Telescope
General
Balance
Lens Cover
Motion
Position Indicators
Finderscope
Tangent Arm
Reversal
Access Ports
Control Desk
Console
Contents
Limits
Pointing
Weather
Safety
Observing Hits
Checklist
Trouble Shooting
Mt. Hamilton Homepage

Motion

The telescope has two sets of motion control: manual and motorized. The slew and setting motion is manual. The guide/fine motion is motorized. The telescope also has an RA tracking motor which can be set at sidereal, lunar, or other non-sidereal rates.

Manual slewing or setting of the telescope can be done in two ways. The more common way of moving the telescope is pushing it using the white rope covered ring (Figure 1). Alternatively, one may use the ship's wheels (Figure 2) on top of the telescope pier. Using the ship's wheels may be necessary when moving the telescope to certain areas of the sky (e.g. high north declinations) or when reversing the telescope.

When moving the telescope, one must first unclamp the telescope in both Right Ascension and Declination. The RA axis clamp is electric and controlled by any of three switches. Two of the RA clamps switches are mounted on the telescope ring (Figures 3 and 4) for easy access when moving the telescope from the floor. A third RA clamp switch is on top of the pier near the ship's wheels (Figure 2). To unclamp the RA axis, hold the switch towards the off position (or push the unclamp button when at the top of the pier) for a few seconds (the sound of the RA clamp motor changes indicating that the clamps are released). To engage the clamp simply push the swith towards the on position (or push the clamp button at the top of the pier) for a few seconds. Again the sound of the motor will change indicating that the clamp is engaged.

The Declination clamp is the ship's wheel on the telescope (at the right in Figure 1). To unclamp the declination axis, rotate the wheel counterclockwise at least half a turn. To clamp the declination axis, rotate the wheel clockwise until snug. It is not necessary to turn the declination clamp more than one full turn to unclamp, nor tighten it too snuggly when clamping (which could make it difficult to unclamp).

Once the RA and Dec clamps are released, one may carefully push the telescope to the desired position, using the Selsyn position indicators to set to the proper RA (or HA) and Dec. When moving the telescope always be cautious and aware of obstacles and the pointing limits of the telescope. Also be cautious not to strain cables or hit the declination tangent arm on the pier railing. One may have to move the floor up or down while positioning the telescope. Once the telescope is in position, clamp both the RA and Dec clamps.

If one wishes to use the ship's wheels to move the telescope, use the following procedure:

  1. Clamp the RA axis.
  2. Unclamp the Dec axis.
  3. Go to the top of the pier.
  4. Lock the Right Ascension shipwheel by turning the RA wheel lock (see Figure 2) clockwise.
  5. Insert the declination shipwheel gear (Figure 5) by turning the red handle counterclockwise (Figure 6) until the gear is fully engaged.
  6. Unclamp the RA axis (clamp buttons shown in Figure 1).
  7. Turn the shipwheels in RA and Dec until telescope is in the desired position. One may use the RA and Dec Vernier dials on the telescope axes or have a companion look at the Selsyn position dials to read the current position. Always move the telescope cautiously and not too quickly, being aware not to run the telescope into the floor, pier, or any other obstacles. If you must leave the pier to move the floor, clamp the RA axis for safety of the telescope.
  8. Once one is done moving the telescope from the shipwheels do the following:
    1. Clamp the RA axis.
    2. Disengage the RA wheel lock by turning it counterclockwise.
    3. Disengage the declination shipwheel gear by turning red handle clockwise until the gear is fully disengaged.
  9. Carefully exit the pier and go back to the floor to adjust the telescope.
  10. Clamp the Declination axis.

Small motions of the telescope (e.g. centering the object in the eyepiece field of view or guide motions) can be done with the guide paddle (Figure 7). There are four buttons to move the telescope in the cardinal directions (North, South, East, and West) and two toggle switches to enable the motion. The left toggle switch enables the RA axis motion, where up enables motion and down disables it. Similarly the righthand toggle switch is for the declination axis.

Tracking motion of the telescope is controlled by a motor whose power supply and speed adjustment are on the desk console (Figure 8). The main tracking motor power switch is on the right of the unit. Once the main power is turned on, tracking can be started by setting the tracking toggle switch to on (in the center of the unit). The lefthand toggle switch sets the rate of the telescope to either the sidereal or lunar tracking rates. Fine adjustment of the tracking rate can be accomplished by moving the rate toggle switch either left to decrease the rate or right to increase it. The LCD screen displays the current tracking rate in arcsec per seconds.


Figure 1: Back of the telescope


Figure 2: Ship's Wheels and RA Clamp


Figure 3: RA Clamp (on the telescope ring)


Figure 4: RA Clamp 2 (on the telescope ring)


Figure 5: Declination gear in.


Figure 6: Declination gear handle


Figure 7: RA/Dec guide paddle


Figure 8: Tracking motor controller.