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The Lagoon nebula (M8)

Astrophotography Imaging Refractor DSO
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#1 CptNautilus

CptNautilus

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Posted 13 June 2021 - 03:09 PM

M8-Lagoon-3nights_DSS_Siril_AP
 

The Lagoon nebula (M8), obtained by stacking the FITS from three nights (one in June 2020, and two more lately). Once again I was heartless when rejecting FITS, until I was reduced to the 731 very best.
Then I stacked them in DSS, did colour calibration and stretching (2 Asinh, one automatic) in SiriL.
Then I post-processed in Affinity Photo, using frequency calibration to apply different treatments to the stars and the nebula. I find it helps me keep the stars very sharp. I also made use of some of James Ritson's macros.
I also collected 66 new dark frames to get a masterdark for 20°C, as the nights are getting so warm now.

--- 
731 x 10'' (2h 2m)

Collected with a Stellina smart telescope, made by Vaonis

APO refractor 80 x 400 mm

Mechanical field derotator

City Light filter

Anti-dew heater

Taken from my balcony in a Bortle-5 sky.

 

You can see more images taken with Stellina in my gallery.

 

Stacked in DSS:
Stacking mode: Intersection
Alignment method: Automatic
Stacking step 1 ->244 frames (Gain: 200) - total exposure: 40 mn 40 s
RGB Channels Background Calibration: No
Per Channel Background Calibration: No
Method: Median Kappa-Sigma (Kappa = 2.00, Iterations = 5)
-> No Offset -> Dark: 1 frames (Gain : 200) exposure: 10 s
-> No Flat
Stacking step 2 ->31 frames (Gain: 200) - total exposure: 5 mn 10 s
RGB Channels Background Calibration: No
Per Channel Background Calibration: No
Method: Median Kappa-Sigma (Kappa = 2.00, Iterations = 5)
-> No Offset -> Dark: 1 frames (Gain : 200) exposure: 10 s
-> No Flat
Stacking step 3 ->456 frames (Gain: 200) - total exposure: 1 hr 16 mn 0 s
RGB Channels Background Calibration: No
Per Channel Background Calibration: No
Method: Median Kappa-Sigma (Kappa = 2.00, Iterations = 5)
-> No Offset -> Dark: 1 frames (Gain : 200) exposure: 10 s
-> No Flat
 

Revealed in SiriL:
Mirror X
Background neutralization
Color Calibration
Asinh Transformation: (stretch=1000.0, bp=0.00100)
Asinh Transformation: (stretch=   3.0, bp=0.05363)
Histogram Transf. (mid=0.456, lo=0.012, hi=1.000)

 

Final post-processing in Affinity Photo


Edited by CptNautilus, 13 June 2021 - 03:33 PM.

  • chrysalis, Thomas Marshall, Sky King and 4 others like this

#2 wizbang396

wizbang396

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Posted 13 June 2021 - 04:02 PM

I have never seen an image taken with your scope and I must say it is a terrific image.  I do know that you do a lot of processing, which I can't say is really needed but then again it is a terrific image.   


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#3 CptNautilus

CptNautilus

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Posted 13 June 2021 - 04:39 PM

I have never seen an image taken with your scope and I must say it is a terrific image.  I do know that you do a lot of processing, which I can't say is really needed but then again it is a terrific image.   

  Thank you very much.

 

  All the post processing is only needed if you want to take very long exposures. If you want to stack FITS over several nights, or refocus the scope because the temperature has dropped, at the moment it's the only way. Also, it allows you to select the subs with more care than what the on-board algorithm does.




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