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CGEM Mount Calibration

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#1 Patrick Cl

Patrick Cl

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Posted 11 March 2011 - 05:31 PM

Can someone please enlarge on the information in the manual?
I'll set up my scope, level, balance, do a quick polar aligh w my (added) polarscope, set index marks, do a 2 star align and add 1 star, do a software polar aligh.
What now?
Do I need to point scope in any particular direction?
Can I leave it pointing at the last alighment star?
Any preferred sequence?

A step-by-step will be greatly appreciated. I am sure that the manual is fully understandable when you know how, but as I have not done a calibration before, I don't know how!

#2 Tarzanrock


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Posted 11 March 2011 - 07:44 PM

Hi Patrick:
I think that you should do four (4) calibration stars, not one (1) calibration star for better accuracy.

#3 nemo129



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Posted 11 March 2011 - 09:17 PM

Hi Patrick,
First off, welcome to Cloudy Nights. You came to the right place.
What is your mount not doing that you think it should? Can it not find objects after your initial routine? After you are done with the initial steps you outline, you should be able to hit M and enter a Messier object or NGC or Planet, etc. and the mount should slew your telescope to that object. Maybe if we know what you are expecting we could help you more. If is is not pointing correctly, Bill is correct, you should probably keep adding calibration stars (up to 4) until the mount slews to the star you want and you do not need to use the arrow keys to align the star in the finder or the EP. If this does not happen on calibration star 2, 3 or 4...you end up doing them all, don't worry it’s good practice! A good tip is when using the arrow keys to center a star in the finder or the EP, is to make the last mount movements with the up and right arrows. Even if you need to overshoot with left or down buttons, always use the right and up to make the final tweaks to center the star. This makes sure your gears are engaged and there is no backlash. Believe me if you do not understand, do it that way anyway. It becomes good habit after a while. I am not sure if you noticed that the alignment stars should be on one side of the meridian and the calibration stars should be on the other side of the meridian. The mount normally starts with alignment stars in the West, if you prefer alignment stars in the east and calibration stars in the west, press the Menu button when offered the first west alignment star and it will change to picking them in the east.
As you may have surmised, you need to know the names of at least 6 stars to accomplish this. You did not say what your level of stargazing experience was, so I will assume you are familiar with the sky. If not, you can use a star chart or a laptop with a planetarium program. I always plan which stars I intend to use before even going out.
Another good idea is to do some mock alignments during the day in the house or wherever your mount is during the day…observatory; so you are not struggling with reading a manual in the dark. I admit the CGEM manual is not the best, but it is complete and everything you need to know is in there. I just read it about 10 times when I first got my CGEM. If you are unclear on a concept, you can ask here.

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