Bicolor Crescent Nebeula-Where's the Blue-Please HELP!!!

[Rodd]

I liked the bicolor NGC6888 so much I figured I give it a try--for the last 3 weeks.  Clear nights are hard to come by.  But I managed to get a fair amount of data

Ha: 20-20minute subs

OIII-8 20minute subs and 6 30 minute subs.

I mage a synthetic Lum out of the Ha and OIII.  I combined the Channels assigning Ha to red and OIII to green and blue.  The attached images are the Ha stack, the OIII stack and my final image.  I do not see any blue.  I was hoping for the beautiful blue sheath around the Crescent--but it is not there.  The final image was calibrated (33 flats per channel, 33 darks and 400 bias), Background extraction, background neutralization, color calibration, a touch of curves for saturation and contrast, and a little denoising of the background and sharpening of the highlights.  This is not intended to be a final image.  But I want to know why there is no blue data around the crescent.  Is it just a matter of getting more data?  Or am I missing something.  Any input would be greatly appreciated.  I have put together many versions of this image--some lighter, some darker, some very saturated...etc.  None show the blue enveloped.  The surprising thing is you can see the blue data in the OIII stack.

 

Pic 1:  Lum-Ha-OIII-OIII

Pic 2:  Ha stack (20 20minute subs)

Pic 3:  OIII stack (8 20minute and 6 30 minute subs)

Pic 4: Another version of image that is less clipped--still no blue envelope.

 

 

[whipdry]

Hi Rod,

Here's a couple of full resolution screen shots of my OIII 3nm data a single 900sec sub & a stack of 24, this may not be a fair comparison.

Are you sure your OIII isn't SII data?

 

Peter

[wavydavy]

Am I right in saying that OIII needs much longer exposures than h-alpha, as I can pick up the outer blue bubble, but its very faint in comparison to h-alpha....

[Rodd]

3 hours ago, whipdry said:

Hi Rod,

Here's a couple of full resolution screen shots of my OIII 3nm data a single 900sec sub & a stack of 24, this may not be a fair comparison.

Are you sure your OIII isn't SII data?

 

Peter

How would I tell?  The other filters are correct-Do you have an SII for comparison?

[Rodd]

4 hours ago, whipdry said:

Hi Rod,

Here's a couple of full resolution screen shots of my OIII 3nm data a single 900sec sub & a stack of 24, this may not be a fair comparison.

Are you sure your OIII isn't SII data?

 

Peter

Peter--You are a genius--IT IS SII data.  I somehow revered the SII and OIII when I set up the filter wheel in Maxim (just got Maxim).  Wow.  Thank you.  I guess now I have a bunch of SII data on NGC 6888--that's something at least.

[whipdry]

Glad to help, sorry I missed you asking for an SII comparison.

I did think about posting SII data but mine looked weaker than yours & could have been misleading!  

 

Peter

[Rodd]

1 hour ago, whipdry said:

Glad to help, sorry I missed you asking for an SII comparison.

I did think about posting SII data but mine looked weaker than yours & could have been misleading!  

 

Peter

That's one solver lining--not many people acquire 6 hours of SII data on the Crescent Nebula.  Should make for an interesting pic when I have collected the OIII data.

[ollypenrice]

14 hours ago, whipdry said:

Hi Rod,

Here's a couple of full resolution screen shots of my OIII 3nm data a single 900sec sub & a stack of 24, this may not be a fair comparison.

Are you sure your OIII isn't SII data?

 

Peter

Well spotted!

Olly