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Whirlpool looking Sii Stars?

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#1 Higgsfield

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Posted 20 September 2021 - 02:51 PM

I'd like to ask the group as to what might be causing my bright Sii stars to have this whirlppol like quality to them? This effect does not appear in my Ha or Oiii data.

 

Whirlpool.JPG



#2 Higgsfield

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Posted 20 September 2021 - 02:51 PM

Here is a closer view.

 

Whirlpool2.JPG

 

Oh, the filter I'm using here is a 3nm Sii Antila.


Edited by Higgsfield, 20 September 2021 - 02:53 PM.


#3 sharkmelley

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Posted 20 September 2021 - 05:10 PM

We need a lot more information. 

 

What scope was used? 

What camera? 

Any focal reducer/flattener? 

Is the first image the whole frame or just a crop? 

Is it a single exposure or a stack?

 

Mark



#4 RogeZ

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Posted 20 September 2021 - 05:19 PM

With certain optics, my Ha Astronomiks also creates the Whirlpool pattern you describe here.

#5 Higgsfield

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Posted 20 September 2021 - 06:13 PM

We need a lot more information. 

 

What scope was used? 

What camera? 

Any focal reducer/flattener? 

Is the first image the whole frame or just a crop? 

Is it a single exposure or a stack?

 

Mark

Mark,

 

The posted images were from a zoomed view of the bright stars in the stacked Sii frame (140 x 400s) below. No processing except a stretch has been done on the image.

 

Scope is Skywatcher Esprit 100mm Ed. Filter is 3nm Antila. Camera is ASI 294M PRo. Image resolution is 0.85"/px.  

 

Sii.JPG


Edited by Higgsfield, 20 September 2021 - 06:19 PM.


#6 TareqPhoto

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Posted 20 September 2021 - 07:26 PM

Can you upload 2 files of this target?

 

1. The single exposure frame

2. The stacked file of this target

 

I want to see where is that from, also i have same equipment of yours except the scope, so i will test my scope with Antlia Ha 3nm and QHY294M Pro and see if i will have the same issue.



#7 Higgsfield

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Posted 20 September 2021 - 07:46 PM

Can you upload 2 files of this target?

 

1. The single exposure frame

2. The stacked file of this target

 

I want to see where is that from, also i have same equipment of yours except the scope, so i will test my scope with Antlia Ha 3nm and QHY294M Pro and see if i will have the same issue.

@TareqPhoto

 

Thanks for taking an interest in this problem.

 

Here is the single frame you requested: https://drive.google...iew?usp=sharing

 

Here is the stacked image: http://drive.google....iew?usp=sharing

 

Now that you brought my attention to the issue, I do not see this pattern detail in the single frames, only the stacked image.

 

Peter



#8 sharkmelley

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Posted 21 September 2021 - 12:48 AM

Here's a selection of stars from your stacked image (15 hours of data!!) at 200% scale with a PixInsight STF (screen transfer function) applied:

 

Weird_SII_Stars.png

 

I've no idea what is going on. 

 

Some stars have a nested series of apparently elliptical rings.  On other stars these rings have turned into something completely different. The direction of the ellipses/artifacts does not point towards anywhere obvious such as the centre of the image or in a radial direction, nor do they all point in a uniform direction.

 

I am mystified.

 

Mark


Edited by sharkmelley, 21 September 2021 - 01:31 AM.


#9 TareqPhoto

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Posted 21 September 2021 - 03:03 AM

@TareqPhoto

 

Thanks for taking an interest in this problem.

 

Here is the single frame you requested: https://drive.google...iew?usp=sharing

 

Here is the stacked image: http://drive.google....iew?usp=sharing

 

Now that you brought my attention to the issue, I do not see this pattern detail in the single frames, only the stacked image.

 

Peter

Thank you very much, Peter

 

This is why we ask for files, to know where it is started, most likely it can be in one single frame somewhere that affect all because it is included in the stack, when i have light exposure frames with so many frames round stars and only one or two frames with trails stars then the stacks will have the trails stars anyway.

 

Anyway, i will try to make something with mine to see if i can see same issues, i tried once with my Askar and new filter Ha but got zero light frames, nothing, so i will try again, thank you again.



#10 Higgsfield

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Posted 21 September 2021 - 07:45 AM

Here's a selection of stars from your stacked image (15 hours of data!!) at 200% scale with a PixInsight STF (screen transfer function) applied:

 

attachicon.gifWeird_SII_Stars.png

 

I've no idea what is going on. 

 

Some stars have a nested series of apparently elliptical rings.  On other stars these rings have turned into something completely different. The direction of the ellipses/artifacts does not point towards anywhere obvious such as the centre of the image or in a radial direction, nor do they all point in a uniform direction.

 

I am mystified.

 

Mark

Mark,

 

Thanks for looking at this for me. Yes, those ellipses become elongated as you move towards the edge of the frame. I've built my own planetary systems! 

 

Maybe this is one for Adam Block? I'm going to go back and integrate the registered frames without the use of NSG and see if the artifacts are present.  So to be clear these data are a product of Weighted Batch Processing, Normalized Scale Gradient, Integration, and STF only. 

 

This is quite fascinating!

 

Peter



#11 TareqPhoto

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Posted 21 September 2021 - 09:01 AM

Mark,

 

Thanks for looking at this for me. Yes, those ellipses become elongated as you move towards the edge of the frame. I've built my own planetary systems! 

 

Maybe this is one for Adam Block? I'm going to go back and integrate the registered frames without the use of NSG and see if the artifacts are present.  So to be clear these data are a product of Weighted Batch Processing, Normalized Scale Gradient, Integration, and STF only. 

 

This is quite fascinating!

 

Peter

Very simple put, make more imaging and see if it will happen again, most likely it happen to see issues once or twice due to something not in setup or you become lucky and fix it by sudden also, otherwise you will keep imaging and change something in the setup and then you will know where that is coming from.



#12 sharkmelley

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Posted 21 September 2021 - 09:15 AM

Maybe this is one for Adam Block? I'm going to go back and integrate the registered frames without the use of NSG and see if the artifacts are present.  So to be clear these data are a product of Weighted Batch Processing, Normalized Scale Gradient, Integration, and STF only. 

Certainly go ahead and reprocess your data but I don't think there's any need because I'm sure I can see the effects in your single exposure.

 

I think it's some kind of interference/diffraction effect but I don't know exactly what.

 

Mark


Edited by sharkmelley, 21 September 2021 - 09:16 AM.


#13 Higgsfield

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Posted 21 September 2021 - 11:42 AM

Certainly go ahead and reprocess your data but I don't think there's any need because I'm sure I can see the effects in your single exposure.

 

I think it's some kind of interference/diffraction effect but I don't know exactly what.

 

Mark

Mark,

 

Your right, it's in the data. Interestingly, I think there are two things perhaps going on. 1. The rounder shells correspond to either changing sky conditions (stars being larger or smaller), perhaps due to seeing or focus. 2. The rayed shells seem to correlate to a bright moon present in the sky. Perhaps the effect is exacerbated by the large number of frames taken over multiple imaging sessions.

 

I also found one star in my Ha data too. I think I have several options. Starnet++ did a good job of removing the stars without leaving residual artifacts in the monochrome images, so thinking I would integrate only those frames with the absolute tightest stars and insert those, or get me some RGB stars to insert. Thanks very much for the help!

 

Peter



#14 sharkmelley

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Posted 21 September 2021 - 12:30 PM

If crazy star artifacts interest you, then take a look at this selection:

 

I've now added yours to my list of interesting star artifacts - just in case we ever work out what's causing them.

 

Mark




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