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donsinger1
sage
Reged: 10/28/07
Posts: 298
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Is there a polar alignment routine with the Gemini like the All Star Polar Alignment on the Celestron mounts?
If so, how well does it work and how does it work?
Thanks
Don
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Fun Stuff:)
Portland, OR
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Cotts
Just Wondering
Reged: 10/10/05
Posts: 912
Loc: Richmond Hill, Ontario
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Yes, the one I use assumes you can get around a degree or less from the pole on your own. I use the polar scope for this and can get quite close. Then the steps are:
1. Develop a good pointing model using at least a half-dozen widely spaced stars in the 'Additional Align' routine.
2. Pick a star from the database on the meridian, close to the equator. Let the Gemini slew to that star. You then start the Polar Align routine and the scope slews to where the star would be if you were perfectly aligned.
3. You then use the mount's altitude and azimuth adjustments to re-center the star. NO SLEWING! Loosen the bolts, turn the knobs, tighten.
4. Finally you develop a new pointing model with six widely spaced stars etc.
5. For super accuracy you can do another iteration of #2,3 and 4 (I have never found this necessary - one time through this routine gets me within 30 arcseconds of the pole!)
One thing to note. With the Gemini it is always essential to precisely center objects being used for additional aligning with a cross-hair eyepiece. Centering by eye, even at your highest power, limits your accuracy and pevents your Gemini from achieving its true degree of accuracy.
When I have done all the above I am consistently only a few arcseconds from the pole - the limiting factor is the amount the mount moves as you tighten the bolts.
This level of accuracy allows the Gemini to put everything in the center, dead-center, of a 150x eyepiece and to take several minute unguided exposures with a 300mm lens...
It is all nicely described in the manual.....
Dave
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David Cotterell
14th Floor Observatory
Richmond Hill, Ontario
200 mm Intes f/10 Mak-Cass
80mm WO Zenithstar FD
66mm WO ED
Losmandy G-11 mount with Gemini
Ioptron minitower
Canon XSi
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donsinger1
sage
Reged: 10/28/07
Posts: 298
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From reading the Gemini manual, what you are describing is the Polar Axis Correction, which I assume is done if you are somewhat already close to the Pole (you described you start out with a Polar scope...I cannot because my house blocks the north sky view completely).
I have a Parallax Portable Pier setup on my porch, essentially sits there permanently (wife did not want holes drilled into the porch for a more permanent setup), but at times it will get jostled.
What about the Polar Align Assist function, how does that differ?
Thanks,
Don
--------------------
Fun Stuff:)
Portland, OR
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Cotts
Just Wondering
Reged: 10/10/05
Posts: 912
Loc: Richmond Hill, Ontario
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I can't help you with that one, Don. I have never used it. My guess is that it works about as well as every other Gemini function - superbly.
Dave
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David Cotterell
14th Floor Observatory
Richmond Hill, Ontario
200 mm Intes f/10 Mak-Cass
80mm WO Zenithstar FD
66mm WO ED
Losmandy G-11 mount with Gemini
Ioptron minitower
Canon XSi
|
donsinger1
sage
Reged: 10/28/07
Posts: 298
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Will let you know how it goes:)
--------------------
Fun Stuff:)
Portland, OR
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