Re: Adjust CP4 Clock Frequency


Ray Gralak
 

On the other hand, if you are working on improvements to an unguided solution and need a test site I would be
glad to help. ATrack is both a correction tool but also an analysis tool. Because it gives you the exact tracking
rates required for unguided imaging, you can compare the values with a modeled approach and see where the
problems are. The goal of the model should be to provide tracking as good as ATrack or an autoguider.
But why? Using APCC Pro's modeling I have had no problem doing 20-30 minute images unguided at 1.74 arc-sec/pixel with round stars. I've posted maybe about a dozen here before. A number of users have also done unguided images.

Some scopes need closed loop guiding because they are hard to model. I think yours is one of them.

Even the concept of using drift to set the tracking rate was done long ago. My own PulseGuide did something similar over 15 years ago. You would center a star, start a timer and let the star drift. The user would re-center the star and click another button andPulseguide would set the tracking rate in both declination and right ascension. It could be used for any object too, like comets.

And what might be even more crazy is that PulseGuide could do this *before* custom tracking rates could be set in the AP control boxes. It did this by sending evenly spaced, well-timed guider pulses, thus its name, "PulseGuide". You can still download it from here: https://www.pulseguide.com.

And it's not like I don't have experience with lots of telescopes, from refractors, SCTs, MakCass's, Newts, RC's, etc. I've experience with scopes with serious flexure issues that can make dramatic changes in focus as temperature swings, like my old18-inch Newt on a 1200GTO circa 2003 (and a younger me! :-)

https://raygralak.smugmug.com/Astronomy/18-CPT/

For now, APCC hasn't been able to do miracles with your particular truss tube scope so it's necessary for you to do closed loop autoguiding. For people with solid, repeatably pointing scopes APCC Pro's tracking rate correction already sets the tracking rate well enough to do unguided imaging, and even to dither without having to do plate solves. :-)

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Craig Young
Sent: Tuesday, May 5, 2020 7:49 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Adjust CP4 Clock Frequency

Ray,
No problem, let me know if you want to discuss further offline.

But as I said above, it is not really necessary because ATrack provides excellent tracking with whatever condition
the scope/mount are in. APCC tracking is not that robust, it blindly sets the tracking rate, based on a model, with
no feedback. Given any factors not accounted for accurately in the model you should not expect a perfect
tracking solution. Both ATrack and autoguiders use feedback to correct tracking rates. So rather than try to
research the source of the tracking error it is a lot simpler to let ATrack or an autoguider correct for it and not use
a tracking model.

On the other hand, if you are working on improvements to an unguided solution and need a test site I would be
glad to help. ATrack is both a correction tool but also an analysis tool. Because it gives you the exact tracking
rates required for unguided imaging, you can compare the values with a modeled approach and see where the
problems are. The goal of the model should be to provide tracking as good as ATrack or an autoguider. The
problem with an autoguider is it doesn't tell you what the tracking rates should be .. ATrack provides that.

But hopefully a model solution will be coming, and from what I have heard over the last year, it might be coming
from AP. Looking forward to it.

Craig

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