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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Polar Alignment with a restricted view

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Hi,
I would like to try EKOS Polar alignment but I have a restricted view north. I can see Polaris and about 10-15 deg East and very little west. On the South side I have close to 180 deg. The PA documentation suggests a 30 deg window West or East is required. How tight can it be or are there other options?
Thanks
5 years 8 months ago #27270

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I use the following github.com/ThemosTsikas/PhotoPolarAlign to polar align my mount.
Was involved in the original script that led to this one ^
5 years 8 months ago #27271

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There isn't a minimum per se, but 30 is optimal to cover a wide range of the sky to measure the center of rotation more accurately.
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5 years 8 months ago #27272

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OK, with the aid of a chain saw managed to get 20 deg view to east and set PA going at 15 deg to be safe. . Using canon 450 DLSR as camera attached to 90mm, 500mm FL scope. Got to solution and alignment diagram but Stellarmate hung during continuous refresh while i tried to adjust., possibly due to size of refresh files. Will try again in next few nights setting capture to jpeg. However also have Orion StarShoot AutoGuider - with camera. This is a 50mm scope 162mm focal length. Would I be better off using this guide scope for PA. is it accurate enough, is the FOV too wide?
5 years 8 months ago #27330

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I use an ASI120MC-S on a 50 mm F=280 mm finder scope which yields a FOV of about 1 degree and I very often use that successfully for PA. I also use a Canon DSLR on a WilliamOptics 71 mm ZenithStar with F=427 mm (including flattener) and that gives a FOV of 3 x 2 degrees and that works very well as well.
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5 years 8 months ago #27331

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Still struggling to get PAA to work. I tried Canon 450D on a 90mm Refractor FL 500 mm which has a FOV of 2.49° x 1.66°. I first tried using native RAW files it solved and displayed the offset diagram but then hung during looping exposures. I assume because of the file size. I then changed the format to "Medium fine Jpeg It took and solved 3 images and then crashed before displaying the offset diagram.. I did this twice. I tried my ZWO ASI 178MC on the 90mm frac but this gave a FOV of 0.85° x 0.57° and it refused to solve.

I also have an 50mm GuideScope + Orion SSAG with a FOV = 2.35° x 1.88° or I could put the ZWO on the guide scope and with a FOV = 2.62° x 1.76°. However the guidescope is mounted on the main telescope and therefore offset from the telescope axis. Does this matter or am I misunderstanding the geometry.

What do you think is my best bet for a successful PA? Also does it matter how good the PA is when you start the process?

I am also struggling with the internal guider but think I need to get the PA spot on to improve my chances of good guiding.
5 years 8 months ago #27391

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Can you share the logs please? Ekos _should_ work with all the above. For Canon, the format has to be FITS for this to work. But otherwise, it wouldn't be a problem even with large size. Same with ZWO ASI.
5 years 8 months ago #27393

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I have a similar issue at one of my observation sites where i cannot see the South Celestial Pole (SCP) region (too many trees in the way).

Before i started using kstars, I was doing a drift align using phd2. Does the ekos polar align tool work if you cannot see the pole? Can you just slew to an area that is in view and use the polar alignment method in kstars? O do you have to be very close to the pole?

regards
5 years 8 months ago #27394

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I use RAW with my Canon EOS 700D and polar alignment always works even if it is slow due to the large file size and the fact that I am using a raspberry pi. FYI I am using the offline solver.
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5 years 8 months ago #27395

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OK thanks for the advice. I will make sure I use FTS and switch logs on for next time. I am now away for around 4 weeks so it will be a while before I can report on my new attemps
5 years 8 months ago #27398

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I managed to get the Polar Alignment system to work but the error reported was 25 mins even after 3 attempts.

My process was as follows:
I have an HEQ5-Pro mount on a steel pier set in a concrete block.
I used my Orion Starshoot autoguider and Orion 50mm guide scope for the PA.
I started by using the HEQ5 built in polar scope to get the best manual alignment using the George Varros PA app.

I ran PA and it completed all three images and gave me an adjustment image.
After adjusting the mount I re-ran the PA process expecting the error to be much smaller, but It still showed the same magnitude of error and needed a significant adjustment.
I ran it again, same result.
I then checked the PA using the HEQ5 built in scope and it was way off.

Any idea what is happening here?
5 years 7 months ago #28504

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Got log? Someone else reported this issue before.. i.e. they had to do reverse direction to get it right. Maybe optical system affects this, I'm not sure.
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5 years 7 months ago #28507

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