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Deep into the Iris Nebula- C14 Edge ASI6200; 0.84 arc secs per pixel

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#1 pyrasanth

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Posted 29 July 2021 - 07:18 AM

The image presented is just one part of a set of data that I'm working with and is the unfinished L channel for the Iris nebula which I earlier posted as an RGB proof of concept image. The objective was to see how much dust can be captured from sites no better than Bortle 7

 

It was unfortunate that I had to fix the blue filter tilt so the camera is in a different position for the additional data which has caused me to have to crop the full frame a bit until I have sufficient data to fill out the edges of the misaligned subs.

 

I have currently captured about 10 hours of useable data- all as 60 second 3x3 bin LRGB subs. The L frame below is 225 60 second subs on the C14 using the reducer and Baader L/UVCUT filter.

 

The Iris nebula is circumpolar from my latitude so I will be able to get a lot more data and would hope to be able to get as many hours as possible throughout the year- returning when I can.

 

I still need more data in the L channel and perhaps a lot more RGB. I've just started to see more dust and a reduction in noise in the L channel after about 5 hours of data.

 

As always comments invited.

 

Stay safe

Best Wishes

Mark

 

 IRIS_MONO_CN.jpg


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#2 havasman

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Posted 29 July 2021 - 07:32 AM

Looking forward to watching this one develop. I think it's one of your best. 


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#3 pyrasanth

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Posted 29 July 2021 - 07:38 AM

Looking forward to watching this one develop. I think it's one of your best. 

Thank you for that kind comment. I think it will get better as the nights are now becoming darker. I'm looking forward to those crisp winter skies. There is an element of data loss under a twilight sky however that can be compensated for by more subs and of course when I add the winter subs that should achieve a nice balance.



#4 pyrasanth

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Posted 29 July 2021 - 10:12 AM

I found a very good way to remove the horrible blobby stars ready to add some fresh one later on.

 

The problem is that Starnet does a great job but I'm sure you are aware it can leave artefacts which look like small rings.

 

This is how I remove stars without leaving rings. You need to work at a per channel level as I've not tried this on an RGB image as I've not had time to test. You need to use Photoshop with the Starshrink plugin and Starnet in PI.

 

1. Remove the stars from your mono layer using Starnet at a stride setting of 16- and star mask selected  (GPU acceleration is a god send at that low setting)

2. Save the newly created Starmask

3. Open up the image with stars in Photoshop and use the Star mask created in Starnet as a mask on that image

4. Run Starshrink at an aggressive setting to shrink the blobby stars to nice round points. The mask will protect the main image data and the plugin will only focus on the stars

5. Flatten the newly created image and save it.

6. Run starnet against this new image with a stride of again 16 and it will completely remove all stars with no traces- you can play around with the mask settings to get something you like.

 

See the example image below:

 

IRIS_MONO_NOSTARS_CN.jpg


Edited by pyrasanth, 29 July 2021 - 10:16 AM.

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#5 Mert

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Posted 29 July 2021 - 10:33 AM

Looking good Mark, interesting to see the image develop


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