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

Bi-monthly release with minor bug fixes and improvements

Align module behavior

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The current align module behavior is giving me a lot of grief. I normally use Stellarium as my planetarium program, and I command mount moves from there. However, after doing a Goto from Stellarium, and then trying to do an align in Ekos, definitely causes undesired behavior, especially if I've done any slewing from KStars previously.

It seems the Align module remembers the last commanded position from KStars, and always wants to align to that, and not to what I've slewed the mount to. This is especially problematic, as the two positions can be many tens of degrees apart, and the Align module will plate solve and sync according to the old position, really throwing the model out of whack.

Why can't we just align to the current RA/Dec reported by the mount? When I do a slew, either from KStars, or from Stellarium, or any place really, the RA/Dec of the mount will be the desired position. Why can't Align just use that?

It seems if I select Sync, it works as intended. But then I have to slew again from Stellarium. Then go back to Ekos, and Sync again. And check the error. And repeat.

I seem to remember this working properly at some point in the past. Has this changed?
 
2 years 3 weeks ago #81131

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Slewing from outside KStars/EKOS and then using EKOS for alignment does not work unfortunately. We have tried it (see invent.kde.org/education/kstars/-/merge_requests/483) but it turned out to be impossible without altering INDI. As a short explanation: Tracking after SLEW and after SYNC is indistinguishable and therefore we cannot set the target simply from the last RA/DEC position, since the first alignment loop - where a sync to the observed position is executed - would also set the target - which will break alignment.

Sorry to say, but for using the alignment you need to use KStars/EKOS.

HTH
Wolfgang
2 years 3 weeks ago #81142

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Replied by Jasem Mutlaq on topic Align module behavior

Previously, it actually worked this way. But then an issue was observed where the Mount RA/DE can drift over time for a number of reasons (guiding, bad tracking, bad model)..etc, and if you align using RA/DE alone, you actually end up on a different spot. So Align module was then set to align to a specific target that is unaffected by the mount's drift, and the question is when do we set this target? It is set when the sequence is started or by the scheduler. This was later changed so that the mount's module is the one responsible for setting the target.

Attempts to fix this as explained above were not fruitful. I still would like to have a satisfactory solution to this, any suggestions?
2 years 3 weeks ago #81149

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