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

Bi-monthly release with minor bug fixes and improvements

Are there situations where polar alignment does not work?

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Two outings ago I tried a "manual" method of PA, checked it with Ikos PA and it showed alignment within 5' . So I decided to use Ekos PA to improve that and it made it worse! What's the deal? Sometimes PA works and sometimes it doesn't.

Edit: im coming from a polar scope align. The scope is parked roughly aiming at the North Star. I start kstars, connect ekos, it reports the park position so I unpack it and go to the polar alignment tab and start PA using the guide camera. I don’t see that anything else is required. What’s wrong?.
Last edit: 6 years 4 months ago by Greg.
6 years 4 months ago #20937

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stellarmate.com/support/ekos/align.html

In the middle of the page you have the instructions for PA
Regards...
6 years 4 months ago #20939

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Understand that’s I’ve had PA working but something is not always working. I reviewed your post, video and all and the only possible glitch I see is that maybe sidereal tracking was not on. If this is the case and Ekos requires it, then it shouldn’t pretend it’s doing a PA. It should turn on sidereal tracking or tell the user to do so. This is about having a foolproof method. There aren’t (edit: ARE) so many things setup when you are doing AP in the field that the tools need to help. The tool should take care of this kind of issue.
Last edit: 6 years 4 months ago by Greg. Reason: correction of typo
6 years 4 months ago #20942

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The reason for the question is that there are various PA methods out there that you have to be careful with. They are dependent on the stars you choose and may not converge or may even diverge. The only foolproof method so far has been drift aligning. Ekos PA is very promising but it works as often as not. One reason I discovered was that I had to park the scope between iterations. This is definitely a flaw as there's no indication that that is required. I'll make sure the sidereal tracking is turned on and see how things go.
6 years 4 months ago #20953

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I would check for and eliminate any sources of differential flexure. If for any reason as the mount rotates over something shifts, that will throw off the results. This may require beefing up your guide scope mounts. If for instance if it only has one ring with 3 points of contact, upgrade to 2 rings with 6 points of contact.
6 years 4 months ago #21000

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Thanks for the suggestion. I tried it last night again and it worked perfectly! I just made sure the mount was tracking and that I start from Park. Results below :) If tracking is the issue then I hope the developers can put that check into the code, and also handle the non-park position problem somehow.
The following user(s) said Thank You: Jasem Mutlaq
Last edit: 6 years 4 months ago by Greg.
6 years 4 months ago #21015
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This is indeed a wonderful result. Congratulations!

-Eric
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6 years 4 months ago #21018

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I have a question about PA as done by Ekos: does the PA procedure sync the mount at the end of the solver step? This might explain why you need to park to somehow reset the adjustments, wouldn't it? I still have to run a successful PA via Ekos myself.

-Eric
6 years 4 months ago #21019

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It is a good idea to clear the alignment model after the PA procedure because adjusting the ALT AZ bolts will invalidate the model.
That being said I think it is done automatically for you, but in not sure.
6 years 4 months ago #21021

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I don't believe so. It just leaves the mount rotated after the PA sequence.
6 years 4 months ago #21028

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Good point. I think it does that at the start. I remember seeing that message. I have to check now. But I don't really do alignments anymore per se. I goto a target after PA and then do a plate solve, slew&sync. This also works great. It automatically retries until its accurately aligned. My targets are dead centre!
6 years 4 months ago #21029

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Do any of you park the mount in a direction other than the celestial pole? How do you start the alignment procedure in that case?

-Eric
6 years 4 months ago #21033

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