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a deep Rosette

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#1 whwang

whwang

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Posted 19 January 2021 - 10:26 AM

Hi,

 

Last time when I imaged Rosette was 10 years ago.  So I recently decided to challenge it again.  I imaged it for a full night in November last year, and I found I need more S/N.  Last week I further spent two full nights on it, bringing the total integration time to more than 14 hours.  The final S/N is nice, but there are some other headaches.

 

The main issue is the variable seeing.  All three nights have different seeing.  In one of the nights, the seeing was extremely poor for about 3 hours, and then improved to something barely acceptable.  Directly combining all data does not give nice looking stars.  So I end up with only using good seeing data for stars, OK seeing data for the brighter parts of the nebulas, and all data for the very dark outer part where noise is higher but details are lacking.  Not only seeing is variable, some exposures were probably taken through very thin cirrus.  I couldn't identify exactly which exposures were affected.  I just know that the stars in the stacked image have very faint, extended halos around them.  These halos become visible after a strong stretch.  Suppressing them in post processing is not easy.  It took me quite some time.

 

About 40% of the integration were made through the STC Duo Narrowband filter, to suppress the light pollution to get high S/N H-alpha, and also to get more [OIII] and H-beta.  This makes the color of the nebulas a little richer.

 

I prepared two versions, a normal one:

get.jpg?insecure

 

and one with more strongly stretched outer part:

get.jpg?insecure

 

Let me know how you think.

 

Cheers,

Wei-Hao


Edited by whwang, 19 January 2021 - 10:14 PM.

  • Mert, elmiko, epdreher and 8 others like this

#2 MHamburg

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Posted 19 January 2021 - 11:13 AM

They are both superb images. This is the kind of result not even professionals could achieve a generation ago!

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#3 Ron (Lubbock)

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Posted 19 January 2021 - 01:56 PM

I think I like the original version better than the more strongly stretched revision.  The colors really pop.  I wonder if your data will allow you to tone down the one star that is so bright?  Great image overall, and thanks for sharing it!



#4 Mert

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Posted 19 January 2021 - 02:03 PM

IMHO they are simply fantastic, that with a OSC and Extreme filter = great job!

Well done

Ah btw, on colors et... that's totally a personal choice, valid in all ways!!

 

Thanks for sharing!!

Stay well,

 

Mert



#5 charlieb123

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Posted 19 January 2021 - 02:08 PM

Holy amazing images. Someday I will have results approaching this <shakes fist>.

Thank you for sharing.



#6 whwang

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Posted 19 January 2021 - 10:17 PM

Hi everyone. Thank you for the comments.

 

Ron, I used the intermediate processing product (less stretched) to tone down the bright stars a bit.  It does look better.  Thank you for the advice.  Unfortunately there is a limit of how far I can go.

 

Cheers,

Wei-Hao




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