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Ceres as a disk - again!

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#1 happylimpet

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Posted 06 February 2018 - 04:07 PM

Following on from Bart DeClercq's excellent images with his 20" Newtonian, here's another effort with a 12".

 

It was immediately apparent when imaging that, just as Bart commented, Ceres looked like a small Galilean moon such as Europa - clearly nonstellar, especially when switching to the nearby HD78139 for comparison which looked utterly different, with clear diffraction rings. The difference on the AVI is actually much more striking than on the stacked result.

 

I've deconvolved both images in FITSWORK using the star for the PSF.

 

Also shown is a simulation of Ceres using NASA's frustrating 'eyes on the skies', reduced to the correct size of 7.55 pixels.

 

Presentation1_4.png

 

Here are the images of Ceres and HD78139 again, without having been churned through powerpoint.

 

2018-02-05-2324_0-N-610_AS_P12_lapl7_ap1_iterative_psf with 2328.png 2018-02-05-2328_1-N-610_AS_P12_lapl7_ap1_iterative_psf with 2328.png

 

Clear steady skies all!


Edited by happylimpet, 06 February 2018 - 04:10 PM.

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#2 Bart Declercq

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Posted 06 February 2018 - 04:30 PM

Awesome result, Nick!

 

I knew it was possible using a smaller scope (after all, I did manage to resolve Vesta some years ago) but it's still a challenging subject.


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#3 happylimpet

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Posted 07 February 2018 - 11:38 AM

Did some more iterations of deconvolution - 25. Better results! Ceres remains exactly the right size.

 

Left: Ceres                                                Right:star

 

comparison - 25 iterations.png


Edited by happylimpet, 07 February 2018 - 11:38 AM.

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#4 TonyStar

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Posted 07 February 2018 - 12:27 PM

Nice effort, Nick

 

I don't understand the result on the right, how can you de-convolute the experimental PSF with itself?? What's the purpose and why would you get a finite star size?


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#5 exaxe

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Posted 07 February 2018 - 04:14 PM

Superb !

over several days it is possible to record a difference in its rotation ... which would validate the disk (slightly deformer)?

Stephane


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#6 Bart Declercq

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Posted 07 February 2018 - 04:49 PM

Superb !

over several days it is possible to record a difference in its rotation ... which would validate the disk (slightly deformer)?

Stephane

Ceres is quite spherical and doesn't have significant dark and light patches on its surface, so there's no way such a thing could be recorded on it.

 

Vesta on the other hand is quite elongated and this elongation can be detected with telescopes like Nick's 12" scope, it also has a 6 hour day, so recording its rotation should be possible.


Edited by Bart Declercq, 07 February 2018 - 04:50 PM.

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#7 sfugardi

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Posted 07 February 2018 - 05:32 PM

Nick, excellent capture! Very impressive resolution. Congratulations on this one and thanks for posting it

 

Regards,

Steve


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#8 John Boudreau

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Posted 07 February 2018 - 08:09 PM

Fine job Nick!  waytogo.gif

 


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#9 happylimpet

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Posted 08 February 2018 - 08:02 AM

Nice effort, Nick

 

I don't understand the result on the right, how can you de-convolute the experimental PSF with itself?? What's the purpose and why would you get a finite star size?

Its a valid  point - what would have been nicer would be to deconvolve a different star image with the 'test' star image. In fact, as I have several datasets for the star (and Ceres) I can do this. It would be more meaningful to deconvolve a different dataset, rather than itself.

 

I still think it shows that the process isnt going wildly wrong and 'creating' a Ceres disc from any input data. And the finite disc size shows something about the limits of the process.




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