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Procedure for the CGE Cone Calibration

The CGE manual is very clear that it is required that you perform the DEC Switch/Cone calibration in order to get accurate GoTo performance.  This generally must only be done once for your mount, although if you change optical tubes, you will need to recalibrate each time you swap tubes due to the potential differences in the optical axis of the two tubes.

While the manual is clear that you must perform the calibration, the instructions on the "Calibrating the CGE Mount" sidebar are not exactly correct.  Here is the correct procedure:

  • Perform an Auto Two Star Align as described in the manual, but be sure the two stars you use are both on the same side of the meridian.  For example, both stars might be in the eastern half of the sky.
  • Here is where the manual is not clear.  Next, use the List button, scroll to Named Stars, press Enter, then scroll to a star that is on the opposite side of the meridian.  Following the example we started above, select a star in the western half of the sky.  Press Enter to GoTo the star.
  • Press Undo until CGE Ready is displayed.  Press the Menu button, select the Utilities menu, Calibrate Mount, DEC Switch/Cone and then press Enter.  Then as the display is prompting, center the star in the eyepiece using the Up and Right arrow buttons (to eliminate the effects of gear backlash).  After the star is centered, press Enter to complete the calibration.

Again, as long as you are using the same optical tube, you should not normally need to redo the calibration, though if you start to experience poor GoTo performance on one side of the sky, you should try recalibrating.

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Michael Swanson
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