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WJ derotation and Jupiter's moons/transits/shadow transits

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#1 BGazing

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Posted 18 September 2023 - 04:20 PM

Not sure how that stuff works.

Image derotation of transits/shadow transits, I suppose, should not work. Likewise for the moons outside the planet disc. In other words, moons are useful as anchors, but have to be edited out - if that is possible.

How about video derotation? The same applies?



#2 Ittaku

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Posted 18 September 2023 - 05:04 PM

WinJupos can derotate moons outside the planet, but can't deal with transits so they just smear. Ganymede crosses Jupiter's surface almost at the same rate it rotates so you can get away with it. Video derotation has the same issues, unless you're simply talking about alt/az correction derotation only which is fine.


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#3 dcaponeii

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Posted 18 September 2023 - 09:37 PM

Not sure how that stuff works.

Image derotation of transits/shadow transits, I suppose, should not work. Likewise for the moons outside the planet disc. In other words, moons are useful as anchors, but have to be edited out - if that is possible.

How about video derotation? The same applies?

When you are setting up to do the de-rotation, look in the Options tab above the workspace window which has the controls for dealing with moons.  Best if moons are off the disc but if your image measurement is accurate enough then it works for moons or shadows in transit as well.
 


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#4 BGazing

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Posted 19 September 2023 - 03:18 AM

When you are setting up to do the de-rotation, look in the Options tab above the workspace window which has the controls for dealing with moons.  Best if moons are off the disc but if your image measurement is accurate enough then it works for moons or shadows in transit as well.
 

That did the trick, thank you!

What are the image measurement optimization options...should they also be checked?

There is a masking radius value...it can be set low actually, but it appears that it merely cuts out one of the moons in the image.

So, to sum up, this works for moons outside disk, does not work for transit and does not work for shadow transits. Derotation of videos neither.


Edited by BGazing, 19 September 2023 - 03:30 AM.

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#5 BGazing

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Posted 19 September 2023 - 03:30 AM

WinJupos can derotate moons outside the planet, but can't deal with transits so they just smear. Ganymede crosses Jupiter's surface almost at the same rate it rotates so you can get away with it. Video derotation has the same issues, unless you're simply talking about alt/az correction derotation only which is fine.

Doesn't video derotaion normally do both? You cannot separate one from the other, right?



#6 Tulloch

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Posted 19 September 2023 - 04:21 AM

Doesn't video derotaion normally do both? You cannot separate one from the other, right?

You can do either one seperately or both at the same time. If you are using an eq mount, then you obviously won't want to correct for field rotation (as there is none).



#7 BGazing

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Posted 19 September 2023 - 04:43 AM

You can do either one seperately or both at the same time. If you are using an eq mount, then you obviously won't want to correct for field rotation (as there is none).

Hm yes, I always checked for altaz field derotation on the side, without it I understand it only does surface. Was not aware you could uncheck surface...but it probably does not matter practically.




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