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NGC6888 The Crescent Nebula


MartinB
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I love the wisps of OIII which surround this nebula but it is pretty faint.  So I planned on capturing OIII and Ha in a ratio of 2:1.  I was using my trusty old MN190 Maknewt with my mono ZWO294.  I reduced the proportion of OIII because of that monster strawberry moon.  I ended up with about 10 hours of OIII and similar for Ha all in 5minute subs.  Unfortunately when I did the flats I discovered some horrible black halos around a cluster of central hot pixels.  I'm still not sure what this was, possibly some dew, it was probably related to the heat.  I had to drop a couple of hours in both channels but I was still left with a total of 16 hours of useable data.

Scope: SW MN190
Camera: ZWO 294 binned x2
Captured using Maxim.  Combined in PI.  I allocated red to Ha and OIII to blue and green.  Initial stretch using 32bit data in PI.  Then moved over to PS for further pimping.  I wanted the OIII to really come through and am fairly happy with it.
 
.NGC6888_August_2022_Ha_OIII_V2.thumb.jpg.a7844f4d6c730662cc27c48266657f4a.jpg
 
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A great bi-colour Crescent Nebula, I also think you have succeeded in capturing the tenuous OIII nebulosity that surrounds the brighter Ha structure.

With regard to your lost subs due to artefacts, I recently had a problem on a whole run of subs and I had changed the camera configuration so could not repeat the flats. Fortunately the artefacts were outside of the prime target in the image so (sacralige!) I separated the stars out then used the cosmetic tools in Affinity Photo (Inpainting and clone tools) to smooth out the background before recombining. Is that cheating? I don’t know, but the approach allowed me to produce a final image rather than leave it hanging.

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5 hours ago, peter shah said:

Not see you in a while Martin hope you are keeping well.....What a cracking shot that outer shell is exquisite.

Thanks Peter.  I must admit, I'd kind of run out of ideas imaging wise but back on track now!

4 hours ago, assouptro said:

Beautifully done Martin!

i love the wispy Oiii shell, it’s like the crescent is wearing a negligee! 
 

Great work! 
 

Thanks for sharing 

Bryan 

Thanks Bryan, I like the negligee notion, I think that is what I was aiming for!

 

2 hours ago, tomato said:

A great bi-colour Crescent Nebula, I also think you have succeeded in capturing the tenuous OIII nebulosity that surrounds the brighter Ha structure.

With regard to your lost subs due to artefacts, I recently had a problem on a whole run of subs and I had changed the camera configuration so could not repeat the flats. Fortunately the artefacts were outside of the prime target in the image so (sacralige!) I separated the stars out then used the cosmetic tools in Affinity Photo (Inpainting and clone tools) to smooth out the background before recombining. Is that cheating? I don’t know, but the approach allowed me to produce a final image rather than leave it hanging.

Thanks Tomato.  There's nowt wrong with the odd bit of clone stamping and healing brush jiggery pokery

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