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Old 13-04-2018, 07:27 AM
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John K
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Join Date: Sep 2005
Location: Melbourne
Posts: 1,371
Originally Posted by codemonkey View Post
Mostly looks like seeing to me based off the fact that Ra and Dec are pretty close on most of the graphs.

Could be worth disabling Dec guide output to see how it fluctuates. Given that Dec isn't tracking like Ra is, barring any cable snags and assuming a good calibration, all you should see is drift due to polar misalignment and seeing. If it's bouncing around a lot, with guide output disabled you can be pretty confident it's seeing. I think the guide assistant will give you a good idea of this too.

As a side note, have you definitely got the right focal length / pixel size set up in PHD? I note the imaging scale seems oddly close to 1"/px. If you're using the 174 (?) with 1.7m FL that should be 0.71"/px
The mount has been polar aligned with Pempro so there is little/no movement in Dec even though it's a portable set up.

The guide camera is a Lodestar so with it's 8.2 mu pixels it gives me 0.99" per pixel in terms of resolution.

One thing I have thought about doing is to use my ASI290mm camera as the guide camera so with it's 2.9mu pixels which would lower the resolution to 0.35" per pixel but this may be overkill as I will be limited by seeing anyhow.

With my ASI1600 my theoretical imaging resolution is 0.46" per pixel which is right on the Dawes limit and below most of the seeing conditions I will generally get.

Further thoughts welcomed.
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