M13 - More data and a brutal cull

[mightymonoped]

M13 The Great Globular Cluster in Hercules

 

Added another 1.5 Hrs to this on Wednesday night in windy and mediocre seeing. Bringing total capture over 4 sessions to approx 9 Hours.

This was stacked and brutally culled down to 7 hours in Astro Pixel Processor, using its excellent Analysis Graphs. Then used APP to reduce Light Pollution before passing honours to Pixinsight.

 

Ran a SPCC against the image and then a minor NoiseX before a 'restrained' BlurX deconvolution followed by a full NoiseX.

 

Then ran a Super Hyperbolic Stretch using the BB stretch tools before saving the resulting Tiff file and passing final duties to Photoshop.

 

First a push on Colour Saturation using Image/Adjustments/Match Colour (this is a good tool for pushing saturation without introducing noise/artefacts).

 

Finally, used AstroFlat Pro Plugin to sort out the problems caused by rubbish flats over 4 separate sessions.

 

Tony

[mightymonoped]

Have blown the core a bit on this one. Planning on reprocessing the linear data with a less aggressive stretch and maybe use masking and curves….to be continued. 
 

Tony

[RaDec]

Agree that the core is a bit blown, but that is one cracking image Tony! If you tame down the central stretch a bit it'll be absolutely top notch. I love the star colours and perfect roundness right across the whole fov.

Is that NGC6207 at 2.0 oclock? 

[mightymonoped]

After having another go at this I decided that the last hour and a half of capture was just muddying things up.

 

I made the decision to go back to the previous version and see if I could apply a gentle stretch, keeping the core stars just below saturation while trying to bring out the outer parts of the globular.

 

Going to come back to this once the snow-blindness has subsided 😊

 

Tony

 

 

 

 

 

 

Edited April 23 by mightymonoped

[mightymonoped]

Here's the version stretched in Photoshop very gradually using curves only. A bit of sharpening and a teeny bit of NoiseX.

 

That's it now, not going near this target again unless it's with a bigger/better scope.

 

Tony

[RaDec]

Absolutely brilliant Tony. Such a great natural look and wonderful star colours.

Love it! 

[Adam Y]

Gorgeous and wonderfully detailed image!

[mightymonoped]

Thanks @Adam Y and @RaDec 😊

[Adam Y]

Curious @mightymonoped, what did you settle on for exposure time?  I was thinking of giving this a go, and maybe using 30 sec subs so as not to saturate the stars and core (per a suggestion from Terry some time back).  Up till now I've been keeping everything consistent, but ready to try tweaking the variables a bit now and this seems like a good one to try.  I can probably get 4-5 hours realistically in one go.

 

Set up is Celestron 8" SCT > .63 reducer > LP filter > ASI294MC Pro.  If I polar align very carefully, I can get < 1" guiding if it is perfectly windless.  Bortle 4-5 area.  What do you think?  I'm inspired by this pic!

[mightymonoped]

Adam, knowing what I know now, having done around 4 sessions on this in Bortle 4 skies, I would stick to <=120s. The general quality of the subs is better than at 180s and you are not as likely to blow out the core and colour. 
 

Tony