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Okay. Assuming the mount is accurately polar aligned and that you were imaging through the WO 110 (F7?) with the Pentax K200D, then what you are looking at appears to be the periodic error of the mount.
The WO 110 at F7 will have a focal length of 770mm giving an image scale of around 2 arcsec/pixel.
I don’t know the tech specs for your mount but I suspect the periodic error would be around 15 to 20 arcsecs. So, if the mount is just tracking, you would expect a star to make excursions of around 15 to 20 arcsecs over the period of a single worm revolution (say 7 to 10 minutes?) so what you appear to have recorded is the PE of your mount?
To “negate” this order of PE, I would have to use a 70mm focal length lens on my Canon 40D which gives an image scale of around 16 arcsecs/pixel.
Autoguiding will allow you to expose for longer periods, at longer focal lengths, but this will require a guidescope and guide camera to actively control the mount via corrections made every say, 3 to 5 secs from the autoguider.
Cheers
Dennis
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