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

Bi-monthly release with minor bug fixes and improvements

Re:New Polar Alignment Scheme and Features

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You can try it anytime you like--by using the nightlies. It's there.

Upon reflection, you are right that although it directs you to turn the elevation knob, if your mount is not level,
then that won't quite do the trick and you'd have to improvise.
Clearly best to level the mount as best as possible.

Still, if you iterate, you'd likely get close to a good alignment in any case.

Hy
3 years 2 months ago #65982
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You may as well level the mount. It only takes 2 mins.
3 years 2 months ago #65983
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In fact I always do. I'm not asking to shortcut that, I'm curious about how the software mechanisms work.

I will definitely have to try it. Please forgive my ignorance, but are there nightly builds for the Pi? I've downloaded and built it myself on the Pi before, but I'm lazy.
Last edit: 3 years 2 months ago by Rick Wayne.
3 years 2 months ago #65984
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I'm not on top of the nightly builds either, as I always compile from source.
Jasem's ubuntu builds are here:
launchpad.net/~mutlaqja/+archive/ubuntu/...field.series_filter=

The way the alignment works is that the system works out the altitude and azimuth angular offset of the mount's axis from the pole.
The UI then gives you a target position and asks you to adjust the "altitude knob" to correct the altitude offset,
then the "azimuth knob" to correct the azimuth offset.
As you point out, the mount may not be perfectly level, so this isn't entirely true. However, unless you're wildly out-of-level,
I think it would be reasonably effective anyway.
3 years 2 months ago #65985
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The error in alignment caused by the mount not being level will be a maximum of 1/60th of the level error.
So if your mount is 1 degree out of level a rotation of 1 degree in azimuth will give an error in altitude of up to 1 arc minute.
3 years 2 months ago #65990
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And in any case the tool also shows where you have to move the guide star to. It just means the star will not travel exactly along the alt and az lines shown. But its the destination that matters in this case, not the path.
3 years 2 months ago #65992
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I gave the measurement part a try yesterday. The mount is on a permanent pier outside, for adjusting I have to get a monitor etc. out - was too lazy to do that :o
But I did three runs, one pointing at the pole, then two more at declination 80 and 70. The three measurements were within 30" to each other - very nice!

One thing I noticed: The PA turns on the WCS grid display in the alignment tab. This stayed active also for the normal align afterwards, but the button for toggling it was inactive. When I pressed it, WCS grid was switched off, but now the button was in 'active' state. Not sure if that is always like that, or an outcome of me canceling the PA in the middle. Not a big deal either...

Next step will be actually adjusting PA. But as I said, I'll need the monitor outside, and ATM the conditions (snow and ice) don't encourage me to do that and fiddle with the knobs....
3 years 2 months ago #66000
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The alignment of the axes used for the correction matters because the correction is calculated in that coordinate system.
I discovered this beta testing the original Celestron Polar Align when I tried adjusting the tripod leg length to centre the PA star. It didn't work, not even close.
3 years 2 months ago #66010
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The polar alignment error is an angle calculated irrespective of the used coordinate system. The correction vectors are projections in the local azimuth and altitude system but could be any other coordinate system. As long as you make sure that the selected star ends up at the other side of those projected vectors, you’re good. Whether or not the mount is level is irrelevant.
3 years 2 months ago #66016
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Hy,

Thought I'd share my first experience using the tool in the southern hemisphere (Sydney)

I ran the PA routine using the steps provided for when I don't have a view of the SCP. I set it to slew East 20 degrees at a time. The routine ran and showed the PA error and triangle. I adjusted the Altitude and azimuth until the selected star was in the cross hairs.

I then ran the routine again, selecting roughly the same section of sky as my starting point (just east of the meridian, near the zenith). I expected that the PA error would be pretty small given how close I got to the centre of the bullseye the first time. The result I got was a larger PA error. So I corrected it as before and ran it again. Same thing. The PA error was greater than before.

This seemed very strange so I ran the routine again, but this time I selected an area of the sky that was west of the meridian. The first run gave me an error which I corrected. I ran it a second time, and this time I got a very small error, which is what I expected. I corrected that and decided to end it there.

So from that quick test there appears to be some issue when doing a PA east of the meridian in the southern hemisphere.

Rene
3 years 2 months ago #66024
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Rene

Thanks so much for testing!

Can you please say when you downloaded your code, assuming you compiled from source, or when you got your nightly, if you're running ubuntu.

That sounds just like an issue I fixed a few days ago.

Below is a recent 'git log' on my pretty up-to-date system, and the commit marked
Date: Wed Jan 13 01:01:14 2021 -0800 PAA: sample from the center of the image. Update test. minor bugfix.
is the one that fixed the issue I have in mind.

Are you running with that commit?
Hy
commit b90f3ef33d11933fef3bd91b96f75da8b8edd868 (HEAD -> master, upstream/master, origin/master, origin/HEAD)
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Wed Jan 13 20:58:04 2021 +0300
 
    Set maximum temperature diff to 1 up from 0.1 as many cameras coolers are not usually accurate enough to 0.1. This would allow for first image to kick in a bit faster at least while the cooler stabilizes further
 
commit 05510da0e0517c9979791cba1cf79b237dd5dbe6
Author: Hy Murveit <hy-2@murveit.com>
Date:   Fri Jan 15 17:35:39 2021 +0000
 
    PAA--cleanup test. Update user messaging.
 
commit 53f886c33d992e5de0bfe7f03faa0a19e4c54d3d
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Fri Jan 15 02:56:14 2021 +0300
 
    Send ekoslive events even when not fully connected
 
commit e15ef966fc27acad80f67a08fabf96ef84e79671
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Fri Jan 15 01:34:28 2021 +0300
 
    Use KSNotification on device connection failure
 
commit f87c3ba289a3b7c0f0b472877de01aff50726ef6
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Fri Jan 15 00:57:21 2021 +0300
 
    Use KSNotification::event instead of direct KNotification
 
commit 26c615d944dde77098bb89dcd50319004dbb1434
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Fri Jan 15 00:31:06 2021 +0300
 
    Use more sane defaults for INDI message notification and starting step size for most focusers
 
commit 29cda560e9ce7fe8f5cbd032220a885753a538c7 (paa-v2-fix2)
Author: Jasem Mutlaq <mutlaqja@ikarustech.com>
Date:   Wed Jan 13 20:38:21 2021 +0300
 
    Use Blocking Queued Connection again since deadlock issue temporarily fixed on INDI side
 
commit 0fa3935718e6d6330dbde253f110eeb6d0b538f5
Author: Hy Murveit <hy-2@murveit.com>
Date:   Wed Jan 13 01:01:14 2021 -0800
 
    PAA: sample from the center of the image. Update test. minor bugfix.
 
commit b7ac3bd531a3d59ca36a882808ae342d05cd8199 (origin/paa-v2-fix1, paa-v2-fix1)
Author: Hy Murveit <hy-2@murveit.com>
Date:   Mon Jan 11 11:23:51 2021 -0800
 
    Fix PAA type (purple -> green).
 
commit cbe33115a418d64aa6f79186fb3096117552980e (origin/paa-v2, paa-v2)
Author: Hy Murveit <hy-2@murveit.com>
Date:   Sun Dec 20 22:00:15 2020 -0800
 
    New polar-alignment scheme
 
3 years 2 months ago #66026
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It would have been 2-3 nights ago. I can't remember exactly. Before I run another test I'll make sure to download the latest nightly.

Rene
3 years 2 months ago #66029
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