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NGC 6888 – The Crescent Nebula in Cygnus - ES Comet Hunter, D5300a

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#1 jgraham

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Posted 01 June 2020 - 09:40 PM

Telescope: ES DHL Comet Hunter MN6 at f/4.8, Orion Atlas EQ-G
Camera: Full Spectrum Modified Nikon D5300
Filter: Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro II, PHD
Exposure: 24x120sec, ISO 200, saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flats: 32x1/50sec, Tee shirt flats taken at dusk
Average Light Pollution: Red zone, Bortle 8, good transparency
Lensed Sky Quality Meter: 18.8 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard Nikon, Deep Sky Stacker, Nebulosity, Photoshop

 

NGC 6888 (5-30-2020)-1j.jpg

 

The Crescent Nebula is an emission nebula, usually a cloud of diffuse interstellar hydrogen set aglow by hot young stars born within it. However, in this case the nebula was made by a single, massive, fiercely energetic Wolf-Rayet star at its core. Some 250,000-400,000 years ago this star ejected its outer surface while it was a red giant, forming the expanding shell of the nebula. As the star collapsed it ejected a fast moving solar wind that is pushing against the slower moving gas in the shell forming a shock front giving the nebula its distinctive shape. The Crescent Nebula lies among the rich star fields in Cygnus and almost gets lost amongst the Milky Way. The five stars forming a “W” across the northern edge of the nebula makes a handy reference for locating this field visually or with a video system.

 

This was the last image from a recent all-nighter to make use of the last couple of hours between M20 reaching the meridian (my previous target) and the first blush of dawn. The last few images in this set that were taken right around 5am were quite beautiful with a soft veil of blue sunlight across the image. Of course these were not used in this stack, but I always get a kick out of seeing the last rays of the sun in the first subs of the night and the first blush of dawn in the last subs of the night. That shows that I made good use of the entire night!

Fun stuff.

 

P.S.

 

I'm luv'n this camera!

 

:)


Edited by jgraham, 01 June 2020 - 09:40 PM.

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#2 astrodom

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Posted 01 June 2020 - 09:45 PM

Nice image of a very challenging target. 



#3 sunnyday

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Posted 01 June 2020 - 09:45 PM

beautiful photo, what I like is that you always leave an explanation.
appreciate, thank you.



#4 17.5Dob

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Posted 01 June 2020 - 09:52 PM

I'm a little shocked how weak the SNR is using that fast OTA....

This is just 9 X 60", ISO 400, f2.8, Nikon 180mm


Edited by 17.5Dob, 01 June 2020 - 09:52 PM.


#5 jgraham

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Posted 01 June 2020 - 10:02 PM

Eh, f/4.8 isn't all that fast. My SNs are f/3.6 and f/4, and my classic 8" Celestron Schmidt camera operates at f/1.5. Now _that's_ fast. :)

BTW, both my 5.5" and 8" Schmidt cameras have been converted to digital, but not DSLR. While they are blazing fast, I can actually get wider fields with my DSLR and Meade 6" f/3.6 Comet Tracker.

What a fun hobby!


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