Annotation off target

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donboy
Posts: 182
Joined: Sat Mar 25, 2017 1:57 am

Annotation off target

#1

Post by donboy »

It appears with my setup that the annotation aligns itself with the targets pre-plate solve position. Also annotation doesn't track the target with dithering.
Log_2022-05-21T20_40_46-8284.log
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Don
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Re: Annotation off target

#2

Post by admin »

Hi Don,

not really enough in the log to go on - I will have to have a think about how to diagnose this sort of problem, maybe needs more logging around the position of the plate solving and of the telescope.

cheers,

Robin
celkins
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Joined: Fri Apr 20, 2018 10:58 pm

Re: Annotation off target

#3

Post by celkins »

Robin, Don,
I have seen this same behaviour on some live stacks, where the annotations are just that bit off, but I fix it by just doing another <plate solve ONLY> from the tools menu: this makes them drop into place…
roelb
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Re: Annotation off target

#4

Post by roelb »

Same experience: do a new live stack only.
Roel
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Menno555
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Re: Annotation off target

#5

Post by Menno555 »

Same here: a plate solve only brings everything in the right spot.

Menno
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Re: Annotation off target

#6

Post by admin »

Hi folks,

if you are live stacking and dithering then I think you will end up getting small offsets, since the dither moves the mount co-ordinates a bit, but the live stacking process then corrects for that, putting things back where they were when the stack started. The annotation code however will be working off the new, slightly changed, mount co-ordinates and will place the annotations based on them. I had not considered the interaction between live stacking and annotation before - I will have to think about this one :)

cheers,

Robin
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Menno555
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Re: Annotation off target

#7

Post by Menno555 »

Hi Robin

It's not only with live stacking. I do a GoTo command for my mount and then a Plate Solve & sync. The annotation is spot on then.
But when I slew the mount a bit to get an object in the spot I want (for example from the left side to the right side in my FOV), the annotation seems to run behind. It does move with the slew but not enough. A plate solve only sets it right again.

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Re: Annotation off target

#8

Post by admin »

Hi Menno,

the most likely cause of this one is that the actual mount movement didn't quite match the change in co-ordinates reported by the ASCOM driver - perhaps due to backlash, periodic error, etc. A new plate solve fixes it because it will update the mount co-ordinates to match the actual pointing position in the sky. Of course, if you are running some sort of high precision, zero backlash, encoder driven mount then I might have to re-asses that conclusion !

cheers,

Robin
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