(poorly) re-setting the target

[Hy Murveit]

Wolfgang,

Sorry I didn't mention this earlier, but Jasem and I hashed out what the
issue is, based on some extra logging I inserted, and Jasem is working on a
fix.  In short:

In align.cpp,
https://invent.kde.org/education/kstars/-/blob/master/kstars/ekos/align/align.cpp#L3841
syncTargetToMount() gets triggered
https://invent.kde.org/education/kstars/-/blob/master/kstars/ekos/align/align.cpp#L3291
when capture goes through a state sequence, that I believe is triggered
when the scheduler repeats a sequence that finishes and the scheduler is in
"Repeat Until Terminated" mode.

What syncTargetToMount does is set the align target (e.g. the target that
would be used after the next meridian flip) to the current mount's
(internal) position instead of setting it to the target that was specified
by the user in the scheduler job's setup.

One might think those are the same things, since the mount is sync'd after
the alignment succeeds, but if the job ran for a while, and there is some
drift that is corrected by the guider, as the guider sends correction
pulses, then the mount's internal position will vary from the original
target/sync.

I believe the align target should be reset to the original user-specified
target (or the solution to the FITS file target) and not the mount's
internal position.

Hy


On Fri, Sep 3, 2021 at 10:48 PM Wolfgang Reissenberger <
sterne-jaeger at openfuture.de> wrote:

> Had the same problem last night. I will try to find out what happens.
>
> Am 02.09.2021 um 19:34 schrieb Hy Murveit <murveit at gmail.com>:
>
> The other night I saw my image move several arc-minutes after a meridian
> flip.
> After putting in some extra log statements and re-running last night, I
> traced the image issue to the following.
>
> Align::syncTargetToMount()
>
> https://invent.kde.org/education/kstars/-/blob/master/kstars/ekos/align/align.cpp#L3825
> resets the target on some capture status change (which I'm assuming
> happens because I was running with scheduler mode "Repeat until Terminated"
> and the scheduler job completed and started its repeat, and that caused the
> capture status change). If the target isn't used anymore, then this target
> change is harmless, but if there's a meridian flip, then it would be used
> again and can move the image position.
>
> I don't understand this code well, but* it seems to me that this is a
> bug.* The target is set by the user in the scheduler -- e.g. a certain
> coordinate, or the solution of a certain fits file -- and the mount has
> nothing to do with that, at least if we're plate solving to refine the
> position.  Is there any good reason to reset the target position in the
> above code link?
>
> Hy
>
>
>
>
>
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