NGC7380 Wizard Nebula - HST

[strutsinaction]

Hi

Here's my first attempt at the Wizard in narrowband and mapped to the Hubble palette.

Details:

Ha 20x600s 1x1

OIII 10x600s, 5x900s 1x1

SII 10x600s, 5x900s 1x1

Superbias

Darks

Flats

Avalon Linear Fast Reverse

QSI690

FSQ85

Captured with SGPro, processed with PI and PS.

The 'Sony glow' issue (a feature of the QSI660 and 690) reared its ugly head, particularly with the 900s OIII subs, so this is the first time I've had to use dark frames to calibrate it out. I think I may need to send the camera back to QSI to get it fixed.

There's more work to be done with the processing I feel. Still looks a little green to me, having not quite managed to achieve the classic Hubble gold/blue hues. I should also tone down the stars a little more. I used the MorphologicalTransformation tool in PI to do this but could probably do with some more.

Thanks for looking! Any comments on how I could improve the image gratefully received!

Regards

John

[xtreemchaos]

great image mate,looks very goldy/blue to me.well done.  thanks for sharing  charl

[MartinB]

That's a cracking Wizard.  I don't think you should tone the stars down, they look plenty attenuated and if you go any further it will start to show.  I don't think you are far off Hubble colours although the trend now seems to redden things up a bit which seems to bring out the dust a bit more.  Really it's spot on!

What is a superbias?

[JamesF]

That's a lovely image.

James

[michael.h.f.wilkinson]

Very impressive

[KY Cygni]

wow thats amazing, a superb image

Steve

[laudropb]

Very nice image. Thanks for posting.

[strutsinaction]

Thanks everyone for your kind words!

Martin: Superbias is a PixInsight tool for improving a bias master. I have known about it for some time but did not create one until now. I was reminded about it very recently when reading Kayron Mercieca excellent PI tutorials (http://lightvortexastronomy.blogspot.co.uk/2015/07/tutorial-pixinsight-pre-processing.html). I thought I'd give it a go. I'm not sure if it makes a difference but it's trivial to create so why not try?

[swag72]

On a personal level I'd be fiddling with the colour select tool in PS to get a less green and cyan image, but that's just a colour opinion. The detail looks great and you should be pleased as punch  

As an aside, I did an experiment the other day with a bias and a super bias. It made absolutely zero difference to the noise level of the calibrated exposures and so I've not bothered again.

[Stratis]

The colour balance is a clear challenge with the Wizard... getting the beautiful azure blue interior is something I couldn't manage with my data.

I tend to use AstroArt's white balance function as guidance and go from there; it will attempt to balance the colour channels based on starpoints in the image. I also tend to choose a very different colour curve for the OIII data than I do for the Ha, OIII I've needed to enhance the contrast substantially more.

[strutsinaction]

On a personal level I'd be fiddling with the colour select tool in PS to get a less green and cyan image, but that's just a colour opinion. The detail looks great and you should be pleased as punch  

As an aside, I did an experiment the other day with a bias and a super bias. It made absolutely zero difference to the noise level of the calibrated exposures and so I've not bothered again.

Hi Sara

Yes, I used PS 'Selective Colour' but need to do this over a number of iterations I think. I'll give it another go.

Regarding Superbias - probably doesn't make any difference to sensitive CCDs but I'm all for trying new techniques.

Regards

John

PS I know you sent your QSI690 back to QSI for the 'Sony glow' fix. Looks like I'll be doing the same but will stick with the ICX814 

[strutsinaction]

The colour balance is a clear challenge with the Wizard... getting the beautiful azure blue interior is something I couldn't manage with my data.

I tend to use AstroArt's white balance function as guidance and go from there; it will attempt to balance the colour channels based on starpoints in the image. I also tend to choose a very different colour curve for the OIII data than I do for the Ha, OIII I've needed to enhance the contrast substantially more.

Yes, I haven't quite mastered this yet. It might be my data (possibly more OIII needed), or maybe I should use PixelMath rather than ChannelCombination to create the initial RGB mapped image.

Regards

John

[AndyUK]

Very nice indeed John - you've got some VERY good data, and you certainly wouldn't know there was any QSI "Sony-glow" issue so obviously it calibrates out fine . 

Obviously there's no correct colour for narrowband as it's all false and therefore down to personal taste, but for me, I too think it might be a tad green and a tad cyan.  I note that you list Pixinsight in your sig, but not Photoshop...  I have to admit I'm not familiar with PI at all but if you do have PS as well(?), there's a very good guide for achieving HST palette images here.   I just ran that process on your image (verbatim) and it came out as follows:

This may be a little too red for some tastes, but as Sara said, tweaking with selective colour you can pretty much make it any colour you like!  However, I do love the star colour you've got on this .

EDIT: I see you DO have PS - Sorry - I missed that post first time around!

[strutsinaction]

Thanks for your reply Andy! I also followed the advice on that site but didn't achieve the golden hues that you have. I'll have another go, and as stated earlier, maybe a number of 'Selective Colour' iterations will help.

BTW - Signature now updated 

[AndyUK]

.  That link is at the very top of my processing bookmarks, but as the film says, it's more of a guideline than a rule.  Once you can see what changes each selective colour step takes, it become very easy to apply it again (and again, and again....).  [And I still love those star colours ]

[swag72]

PS I know you sent your QSI690 back to QSI for the 'Sony glow' fix. Looks like I'll be doing the same but will stick with the ICX814 

I found that darks totally got rid of the 'Sony Glow' issue.

[strutsinaction]

Couldn't resist having one more attempt at reaching my goal of rendering this target in the classic Hubble gold/turquoise palette. I also reduced the star field a little more. I'll think I'll put this to bed now 

A little more info about this remarkable target:

- Diffuse nebula surrounding the developing open star cluster NGC 7380 in the constellation Cepheus

- 7200 light years distant, spanning 140 × 75 light years

- Moving towards us at 34 km/s

- Ionized primarily by binary star HD215835 and other energetic stars in the cluster