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Great Information
Matthew - thanks for that - I must admit I have been non-plussed by the mysteries of autoguiding more often than I care to think about - sometimes it works sometimes not and here is a qantative way to tune your guide paramters to the seeing - fantastic.
I have been thinking (until now) that I could compensate for bad seeing by increasing the expusure time (ie the guide image is then the average of the star posn over n secs - typically I used 2-5 secs). BUT this approach is better, I need to do more tests but I have already seen a big improvement in DEC stability and think I can get there on RA as well. Attached is a trace from last night of my guide errors from Guidemaster, I set the min error to 1" (I had previously used 0.5 or less), exposures were 1s and max guide pulse was 500ms at 0.5x.
I have plotted the correction signals as well as the errors - I am pretty happy with DEC but RA is still a little unstable leading to slightly out of round stars (m8 test shot attached shows this). I am not sure how far I can go with this I would like to get to +/-1" in RA as my imaging scale is 1.75"/pixel and such a small error would therefore be close to invisible. I might need a little more offset in RA balance to calm down the jitter I will try next that if the weather permits.
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