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INDI Library v2.0.7 is Released (01 Apr 2024)

Bi-monthly release with minor bug fixes and improvements

EQMod alignment/slewing

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@eric/TFM

Hi Eric,
your advice seems to be linked to the main reason for my problems.
When clearing the alignment model and starting from the Polaris region without prior syncing the mount again, it slews roughly to to target, but this is no problem thanks to platesolving and further correction.

Unfortunately further slews aren’t precise and can again lead to strange movement.

CU & CS Chris
5 years 5 months ago #31216

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Replied by Eric on topic Re:EQMod alignment/slewing

For people with a relatively large initial offset, I recommend reading the thread about the eqmod parking issue, and the impact of the incoherence between the parking position and the home position.
About the use of sync points, I don't know the exact theory. Obviously, the best gotos are obtained near a sync point. Obviously again, one single sync point won't be enough to adjust the full representation of the hemisphere. Usual three-stars alignments use targets that are relatively far from each other. Add to this the cone error and the effect of atmosphere...

-Eric
5 years 5 months ago #31244

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Chris,

Can you enable mount logging and attach the logs? Here is what I would do:
0. Enable the logs in Ekos. Set to file & verbose. Click INDI, Alignment, and Mount checkboxes.
1. Power up the mount in the home position (looking at celestial pole with weights down).
2. Make sure EQMod is looking at the celestial pole. Double check time & location in INDI Control Panel (ICP).
3. Go to Options in ICP and make sure "EQMod Align" is selected.
4. Slew to a star some 20-30 degrees away.
5. Run Alignment in Ekos with "Slew to Target" selected.
6. If all goes well, it should center it after a couple of iterations.
7. Slew to a different target and test.

Attach the logs when the above doesn't work.
5 years 5 months ago #31247

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Hi Jasem,

I hope the sky is clear tonight...
Just to be sure - what do you mean with #2 (EQMod is looking at the celestial pole)? Time and location is obvious...

The main part of my problem really seems to be linked to the initial syncing near the NCP. Yesterday I was able to complete a M31-sequence without problems - afterwards I had to park and unpark to slew to IC434 reliably.

Cheers & CS Chris
5 years 5 months ago #31255

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It is the reason. Remember that the pole is a singular point (there is no RA at the pole). So the RA value you deduce from a plate solve at the pole is basically random, depending on the quality of your polar alignment.

I just polar align, have the telescope in park position/point to NCP, power on the controller, connect INDI/EKOS and point to the first target. That might be somewhat off, but that is what plate solving is for. If you want to align, just do some three-star alignment (with any three positions, but away from the pole, and one of them on the other side off the pier).
5 years 5 months ago #31262

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Hi Pit,

the more I think about it and with the quite stable results yesterday I think that you (and others) are right and it makes sense btw ;)
I'll have to sort out the problems with the slewing to a secondary target, but I'm pretty sure that there is no real problem due to INDI/Kstars involved.

Unfortunately tonight the sky over Bochum won't clear up, so that I have to delay the testing for some days.

CU & CS Chris
5 years 5 months ago #31265

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Dear star-friends,

I‘d like to sum up my findings of the last nights...
First of all, your advice concerning my sync near the NCP was right. When I just start my session with slewing to a target or solve/slew a photo already taken and check the slew to target box in the alignment section everything is fine.

This leads me to thinking if it wouldn’t be helpful to give a warning if the FIRST alignment point of a model is within, let‘s say, 1 degree of a celestial pole.

What do you think?

Thanks and CS

Chris
Last edit: 5 years 5 months ago by Christian Deppe.
5 years 5 months ago #31673

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