Focal Pointe Observatory
Astrophotography by Bob Franke

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Gemini GoTo System

The Gemini System was developed mostly by
René Görlich and Scott Losmandy.

For visual use all you have to do is level the mount and point it to the North Star, by sighting through the RA shaft.  With proper selection, a good pointing model can be created with only about seven stars.  After that, you can expect to spend the evening observing objects instead of mostly just trying to find them.

Astrophotography alignment and pointing model creation requires a bit more work.  After leveling the mount I use a polar scope for the initial alignment.  Then I create a pointing model with about seven stars, using my ccd camera.  Because I only image to the west, I never include any stars to the east. 

If the Gemini indicates that I am greater that one arc minute from the pole I use the "Polar Axis Correction" (PAC) function to adjust the altitude and azimuth settings.  Then I create a new pointing model.  If Gemini still indicates an error greater than one arc minute, one more PAC followed by another model creation will do the job.

I find this degree of alignment more that adequate for 20 minute exposures with a 1600 mm focal length using the ST-7 ccd camera.  When I get a camera with a larger chip, better alignment may be required to prevent field rotation.

It's a great convenience to go the scope two weeks later, roll off the shed, do a warm re-start, sync on one star and everything is aligned and ready to go.  Set up time is often as short as 15 to 20 minutes.