Re: Unguided Imaging with a SCT



I have a 14.5" corrected Dall-Kirkham (f.l. 2470 mm) on a non-AE 1100 in a permanent observatory.  Typical setup is an image scale of 0.4 "/pxl!

With a 200 or more point APPM model, I can go unguided for up to 15 minutes at times.  It is likely related to the Dec of the target, but I can't quantify that theory.  I have not tried Dec arc modelling yet.

Attached is a comparison of three images with the above setup.  "Corrected tracking" = using the APPM derived model.

My conclusion is that, while unguided at this focal length is achievable, the real goal is good images.  Hence, I tinker with unguided, but I usually guide.  OAG and PHD2.

With a 910 mm focal length refractor (image scale 1.5), I image unguided all the time.  PHD2 is fine when needed, but it adds a layer of potential 'disruption.'  Its all a tradeoff!


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