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Rho Ophiuchi - harder than it seems. try my data?

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#1 mewmartigan

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Posted 31 May 2020 - 09:43 AM

Hey everyone,

 

This is just a hair under 9 hours of data with an ASI2600MC Pro and a Spacecat, taken over 2 nights. 4 minute subs at 0 gain and 0 degrees. It doesn't seem to get all that high in the sky around here which makes it difficult with the Pittsburgh light dome.

 

Looking at other pictures of the cloud complex, they are exploding with bright color and if the integration times are to be believed on Astrobin, I should have way more here.

 

I am not a Pixinsight expert by any means but I am not new either.

 

C&C welcome.

 

get.jpg?insecure

 

 

Here is a link to the stacked and otherwise untouched xisf file if anyone wants to try (300MB):

 

https://drive.google...iew?usp=sharing


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#2 Lead_Weight

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Posted 31 May 2020 - 11:43 AM

Here's my attempt at processing. I could have used a bit better star mask to protect the largest stars a little better, but was going through the process quickly.

 

I have this exact setup, and want to image the same object, so happy to try it out.

 

Your L-Pro filter should probably be taken out, as it's generating large halos on the brightest stars. Shorter subs, would help compensate for the light pollution without needing the filter. Otherwise there's plenty of good data here.

 

rho.jpg


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#3 mewmartigan

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Posted 31 May 2020 - 11:51 AM

Yeah, I noticed the Halo too. It is clear tonight. I wonder if it's worth removing the filter and seeing what results I get before going to another target.

You definitely pulled out more color than me, nice job. Mind if I ask the steps you used? After the normal linear stuff I did arcsinh stretch, histogram stretching and curves/ saturation with some range masks.

Thanks!

 

EDIT:  just looked at your work on a better screen than my phone and maybe it turns out I am still a processing newbie. That looks waaaay better than what I pulled.


Edited by mewmartigan, 31 May 2020 - 11:58 AM.


#4 johnpane

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Posted 31 May 2020 - 12:04 PM

I think you did a good job processing this data. I'm also north of Pittsburgh and deal with the same light pollution gradient. I'm hoping to head south of the city sometime to image this target. 


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#5 Lead_Weight

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Posted 31 May 2020 - 12:16 PM

Basically, I took it into Astro Pixel Processor to very selectively remove the light pollution. I was careful not to select any nebulosity while removing the LP. Then I color corrected the background to neutral gray, and then finally color corrected the stars. I prefer APP's LP and color correction tools to PixInsight, so prefer to do that here.

 

Took it into PixInsight at this point, and did a stretch using the screen transfer function. Which I don't usually use, but was being lazy. I usually use Masked stretch. I then created a star mask to protect all the stars, but didn't get it set quite enough to protect the largest star and it's halo. I further stretched using curves transformation with the star mask applied to bring out more nebulosity and increase the contrast. Finally I extracted a grayscale version of the image, and applied it as a mask to then use the same curves transformation tool to increase saturation without affecting the darker background. I might have also done some deconvolution or sharpening, but your image looks pretty good focus wise, and seeing must have been decent.

 

Antares is a very bright star, and your halos are only on that star. Removing the LP filter will get rid of the halo (since it's a reflection off the filter). Since you do have a fair amount of LP, the main thing is just not imaging so much that the LP saturates your frame covering the faint nebulosity. You'll still want the same amount of total integration time, but with shorter subs, you don't risk saturating your frames with the LP. Additionally, all LP filters remove some signal from your color images, so you might find that you get better color reproduction without the filter in place.


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#6 mewmartigan

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Posted 31 May 2020 - 12:27 PM

Thanks for the steps. Knowing there is more in there gives me something to work towards.

#7 johnpane

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Posted 31 May 2020 - 12:28 PM

Basically, I took it into Astro Pixel Processor to very selectively remove the light pollution. I was careful not to select any nebulosity while removing the LP. Then I color corrected the background to neutral gray, and then finally color corrected the stars. I prefer APP's LP and color correction tools to PixInsight, so prefer to do that here.

 

Took it into PixInsight at this point, and did a stretch using the screen transfer function. Which I don't usually use, but was being lazy. I usually use Masked stretch. I then created a star mask to protect all the stars, but didn't get it set quite enough to protect the largest star and it's halo. I further stretched using curves transformation with the star mask applied to bring out more nebulosity and increase the contrast. Finally I extracted a grayscale version of the image, and applied it as a mask to then use the same curves transformation tool to increase saturation without affecting the darker background. I might have also done some deconvolution or sharpening, but your image looks pretty good focus wise, and seeing must have been decent.

Hi Andrew,

 

Nice. What processing did you do in Photoshop?

 

From EXIF:

Creator Tool                    : Adobe Photoshop 2020 Macintosh


#8 Lead_Weight

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Posted 31 May 2020 - 12:30 PM

Actually the closer I look, there appears to be halos on all the large stars. Both a small, and a much larger bounce reflection. I prefer not to image with a filter and focus on good gradient removal. I think in your case, it would be helpful to not have it too. But if you feel like you have to have one, I would look for  one that has better anti-reflective coating.

 

Best of luck if you try imaging it again.


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#9 Lead_Weight

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Posted 31 May 2020 - 12:32 PM

 

Hi Andrew,

 

Nice. What processing did you do in Photoshop?

 

From EXIF:

Creator Tool                    : Adobe Photoshop 2020 Macintosh

Actually none for this image. I just took it into Photoshop to resize and save as a JPG with enough compression to fit the image posting guidelines here on CloudyNights. But I will often enhance saturation in Photoshop since it seems to do a better job than PixInsight. I did not do that with this image.



#10 vnc1218

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Posted 31 May 2020 - 02:12 PM

I gave it a shot in Pixinsight.  It took a bit of work to draw the color out, but it is there.

Attached Thumbnails

  • CN_mewmartigan.jpg

Edited by vnc1218, 31 May 2020 - 02:15 PM.

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#11 mewmartigan

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Posted 31 May 2020 - 05:07 PM

vnc1218, thanks, the colors look good. Would you mind sharing your processing steps? I can't tell if DBE/ABE is killing my color as it seems difficult to apply to a crowded scene.




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