Re: Unguided dumbbell stars insights

Roland Christen

Just run a guide graph in PHD2 with guide corrections turned off. Run it for 15 or 20 minutes so you can see the tracking rate over several worm cycles. Then you will know what you are dealing with. These older mounts sometimes had small subharmonics which roll thru at different gear angles and do not respond to PE correction. It's probably just a few arc seconds +- but shows up easily on any long exposures.

To do proper trouble shooting requires digging a bit deeper. Just posting a picture with eggy stars only shows the problem, but doesn't show the why.


-----Original Message-----
From: Bruce McMath <bruce.mcmath@...>
Sent: Sat, Sep 25, 2021 7:32 am
Subject: Re: [ap-gto] Unguided dumbbell stars insights

thanks Roland, but the problem is I have already trained the PEC curve just a month ago, and got a really great result.  I ran the mount with the new curve turned on to perhaps refine it and the deviations were so small and random that there was no point in trying to refine it. Turning the spur gear was done before not after making the PEC curve.  Furthermore, not every 6'+  image shows such motion, which is why I am puzzled.  

Roland Christen

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