The Crescent Nebula NGC6888

[Jkulin]

I started this on the 30th May 2020 and it was n't until the 20th July that I finished grabbing all the subs.

I did capture some SII, but some how it didn't look right, maybe I need to have a longer play with it, so this is HOO with RGB for the stars.

I have quite enjoyed working on this as the NB part needed hardly any playing with curves.

With my Bortle 5 / bordering on 6 skies, I don't think it has come out too bad.

Total integration was 14hours: -

14 x 1200s Ha
14 x 1200s OIII
8 x 1200s SII but not used yet
8 x 396s Blue
8 x 348s Red
8 x 300s Green

Here's the Bumf: -

The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792.[2] It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000[3] to 400,000[citation needed] years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures.

It is a rather faint object located about 2 degrees SW of Sadr. For most telescopes it requires a UHC or OIII filter to see. Under favourable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or a Euro sign shape which makes some to call it the "Euro sign nebula".

Taken with my GSO/Altair 10" F7.9 RC, Moravian G2-8300 CCD, iOptron 120EC, Chroma 2" NB and RGB filters, Pegasus UPB and focuser, Ultrastar Guide Camera, processed in Pixinsight and PS 2020

More details here: https://www.astrobin.com/qxwsby/

Edited August 17, 2020 by Jkulin

[MarkAR]

Lovely image John, not an easy target to process.

[Jkulin]

28 minutes ago, MarkAR said:

Lovely image John, not an easy target to process.

Thanks Mark, indeed when I first processed with the SII I thought it might prove a problem as there was quite a bit there, but it wasn't too bad in HOO and took about 4 hours to get to what you see now.

Maybe when I get some time then I might have a play to include the SII.

[carastro]

The Nebula itself is great but there are some areas to the left and right in the sky background that don’t look quite right.   Wonder what has caused the milkiness each side?  

Carole

Edited August 17, 2020 by carastro

[tomato]

Great close in Crescent, lost of detail there. It's nice to see a RC being put to good use.👍

[Jkulin]

1 hour ago, carastro said:

The Nebula itself is great but there are some areas to the left and right in the sky background that don’t look quite right.   Wonder what has caused the milkiness each side?  

Carole

Hi Carole,

Glad to see you are fine.👍

There is so much nebulosity around that had it been a wider shot it would have shown up as that, but because it was done on my RC it it is a very close shot, the milkiness is nebulosity, but I stand to be corrected.

[MarkAR]

I reckon nebulosity as well, there is a lot of schmutz in the area.