Cresent Nebula (NGC6888)

[alan4908]

A bi-colour image of the Cresent nebula with Ha mapped to Red and OIII mapped to Blue and Green.  The OIII is very strong with this object to the point where it can overwhelm the Ha, reducing the redness, so I had to experiment with the relative contributions.

About 8.5 hours total integration time.

The image consists of 30min unguided subs taken through an Esprit 150 on a GM1000HPS. 

Processed in CCDstack, Pixinsight and PS CC.

Alan

 

LIGHTS: 6 Ha, 11 OIII x 1800s, BIAS: 100, DARKS: 30, LIGHTS:40 all at -20C.

[Tim]

Exceptional Alan, good control of the stars and excellent job on the Oiii envelope, your colour choices really show off the differences in the nebula and their relative distribution. 

[HunterHarling]

What camera?

[alan4908]

22 minutes ago, Tim said:

Exceptional Alan, good control of the stars and excellent job on the Oiii envelope, your colour choices really show off the differences in the nebula and their relative distribution. 

Thanks Tim !.

21 minutes ago, HunterHarling said:

What camera?

It was taken with my Starlight Xpress Trius 814.

Alan

[EdGregory]

Thank you for sharing Alan.  So beautiful. I've been struggling to get my stars right - you've really nailed that - do you use a Lum filter?  How do you get the stars so nice?  

[alan4908]

12 hours ago, EdGregory said:

Thank you for sharing Alan.  So beautiful. I've been struggling to get my stars right - you've really nailed that - do you use a Lum filter?  How do you get the stars so nice?  

Thanks for the comment.

In answer to your question: the image is bicolour with Ha mapped to RED and OIII mapped to Green and Blue. No Lum data was used. Since my narrowband filters have only a very small bandpass (3nm), they let through only a limited amount of light compared to wider bandwidth filters, this helps control the apparent star size. I've also found that the filters tend to highlight contrast which is particular good for some targets.

Alan

[HunterHarling]

Amazing image, I love the blue outer halo around the nebula.

[alan4908]

4 hours ago, HunterHarling said:

Amazing image, I love the blue outer halo around the nebula.

Thanks - yes, I also like this - it is a bit like the Crescent has been wrapped in blue bubble wrap !

Alan