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What's Wrong with the Celestron CGEM Mount?

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#26 Jeff2011



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Posted 26 July 2013 - 09:40 PM

I have observed the same problem with my AVX. I agree with Peter's second method. The perfect polar align takes too much time. Just do an ASPA. It will usually be close but not perfect. Then monitor which way it is drifting in Dec. Then set PHD to only correct in the opposite direction. You may need to initially have set the pulse kind of high to get the direction change to take effect, then when it takes effect you can set the Max Dec to a lower value. The alternative is to use the hand controller direction button to get the dec change to take effect. Ever since I have figured this out, it has worked for me every time and my Dec line has smoothed out. Now if I could only get the RA line to be that smooth. I recently recorded and averaged 5 PEC runs. Perhaps that will help with the RA.

#27 chijesep


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Posted 31 January 2014 - 12:07 AM

I have the same problem but I use a CG5 Advanced GT mount.

#28 airydisc


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Posted 22 February 2014 - 01:34 PM

More than 2 years after the article was published here (and much longer since it was first reported to Celestron), I have confirmation that the firmware update does indeed seem to fix the problem. I haven't seen it myself, as I got rid of my CGEM long ago, but a friend has one and reported his experience to me.

So I'm happy to recommend the CGEM again, although I'm still wary of Celestron's customer service and quality control.

#29 stevecoe


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Posted 22 February 2014 - 03:11 PM


My CGEM is four months old and has no problems. I just posted an image taken with a DSLR of M 46 in Puppis. The tracking is excellent with no guiding at all. I have also used it at 250X on Jupiter for several hours at a public viewing session, the mount kept that planet in the middle of field of view with no trouble.

I am very happy with the performance of this mount;
Steve Coe

Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics