Re: diagonal oval stars

Stuart Heggie <stuart.j.heggie@...>

Ross, I also was thinking it could be guider calibration. Perhaps closer to the pole, the corrections are too aggressive? I think it is ideal to calibrate near the equator so reducing aggressiveness of the corrections might also help. 


On Wed, Feb 18, 2015 at 4:48 PM, Ross Salinger rgsalinger@... [ap-gto] <ap-gto@...> wrote:

I’m wondering if the guider calibration accuracy might be off leading to the problem. With DEC compensation turned on, the move will be much less at +50 than it will be a 0. The algorithm uses the cosine(?) of the DEC as the factor for reducing the compensation from 0 to 90. So, that means that the number gets smaller and smaller as you near the pole. I think I’d try calibrating the guider at the equator with as long a calibration as possible – small steps and many of them and see if the greater accuracy might do the trick. I’ve been having problems myself and the first thing that AP told me (I use Maxim) was to make my calibrations 30 seconds rather than the default 10 seconds and see if that fixed it. Just a thought.



From: ap-gto@... [mailto:ap-gto@...]
Sent: Wednesday, February 18, 2015 1:33 PM
To: ap-gto@...
Subject: Re: [ap-gto] Re: diagonal oval stars




If there was a tilt in the mechanical connection the prior imaging would have shown it as well. As the original post said, this apparently has been introduced by imaging away from the equatorial region.

---In ap-gto@..., <J.Zeglinski@...> wrote :


    Another possibility might be the camera coupling or nosepiece is not quite machined or threaded properly, so the camera is already angled. I have read another case where this was the case – a bad coupler.

Perhaps try rotating the camera 90 degrees, and compare the directions of the ovals, If it a mechanical issue in the camera, the  flares should rotate with the camera angle change, between the two perpendicular frames.



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