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Old 16-04-2024, 03:11 PM
Startrek (Martin)
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NGC 5139 Omega Centauri under Sydney’s Skies

I’ve captured NGC 5139 Omega Centauri “the big daddy” of globular clusters many times before over the years with my old DSLR and more recently OSC 2600MC, However this is the first time using my 2600MM in LRGB
As my skies are B8 with a 30% waxing moon descending in the north and north west , I decided to stick to 30 sec subs on low gain as Luminance goes off the richter scale with this camera under heavy sky glow.
Quite pleased how this image turned out with respect to contrast and control of brightness across the huge main core region.
I tried not to oversaturate the colour too much to avoid the stars looking like M&M’s

30% Waxing Moon
B8 City suburban Skies
Seeing average to poor ( early heavy dew set in )
8” f5 Klaus Helmerich carbon fibre Newtonian
Skywatcher EQ6-R pro mount
ZWO 2600MM cooled to -10C , Gain 0
Antlia LRGB filters
Integration approx 2 hours
Lum 75 x 30 sec
Red 50 x 30 sec
Green 50 x 30 sec
Blue 55 x 30 sec
Dithered every 3rd sub
Bias from Library
Darks from Library
Flats for LRGB
Tracking and Goto EQMOD and Stellarium
Aquisition APT
PHD2 Multistar guiding ( 0.48 to 0.55 arc sec total )
Data Analysed , Calibrated, Stacked and Aligned in ASTAP
Post processed in Startools V1.8 via Compose L + Synthetic L , RGB

Astrobin link below for full resolution….
https://www.astrobin.com/fotczm/

Attached Native frame size 200KB
Crop version 200KB

Comments Welcome

Thanks for looking

Martin
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  #2  
Old 16-04-2024, 05:12 PM
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kosborn (Kevin)
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That's a great result Martin. Really good star detail all the way to the centre of the cluster. Looks good!
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Old 16-04-2024, 06:34 PM
Dave882 (David)
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Gorgeous pic Martin. I had a few nights with a 14” dob up in qld this last week and Omega Cen was a real standout but I love how much star-colour comes through in your image. Great work!
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Old 16-04-2024, 06:38 PM
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telecasterguru (Frank)
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Great image with clarity and colour.
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  #5  
Old 17-04-2024, 06:59 AM
Startrek (Martin)
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Thanks All,
Yes very pleased with my first LRGB globular cluster
30 sec for Luminance is the sweet spot for Gain 0 under my skies where the stars don’t get too saturated.
I still had a hard time with gradients as the moons glare did cause a heavy bias to one side but ST took care of that.
Down south at my Dome I can push 2 min with Luminance and no issues , huge difference between B8 and B3.
Yes I’ve observed Omega down south under dark skies with my 12” Dob, Paracorr and 21mm Ethos eye piece ( aka the hand grenade) and the view is spectacular.

Cheers
Martin
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Old 17-04-2024, 04:11 PM
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AlexN
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Really nice Martin!

Colours are great without too much pushing as you say, and overall resolution and control of the core brightness is spot on!
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Old 17-04-2024, 07:22 PM
Startrek (Martin)
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Quote:
Originally Posted by AlexN View Post
Really nice Martin!

Colours are great without too much pushing as you say, and overall resolution and control of the core brightness is spot on!
Thanks Alex

Considering heavy dew caused a premature end to my night , I’m pretty happy with resolution as seeing was quite poor
Startools has always done a good job at processing Globs ( even back in my DSLR days )
Another hour or so would have been nice too

Cheers
Martin
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Old 17-04-2024, 08:30 PM
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alpal
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Nice pic Martin -
well resolved stars and good colours.

cheers
Allan
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Old 18-04-2024, 11:16 AM
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strongmanmike (Michael)
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Very nice work Martone, who doesn't like a good Omega Cen

Mike
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  #10  
Old 18-04-2024, 02:55 PM
Startrek (Martin)
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Thanks Allan and Mike,
Appreciate your comments
Decided to reprocess this one again as you often find a few flaws in your own processing after a good hard look at the image

I feel this one is marginally better than the original
Cleaner core region
Star colours are more pronounced and still not over saturated
Reduced that slightly reddish/ pinkish hue

Astrobin link to my reprocessed image for full resolution…..

https://www.astrobin.com/fotczm/

Comments always welcome

Clear Skies
Martin
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  #11  
Old 18-04-2024, 03:21 PM
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Retrograde (Pete)
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Very nice Omega, Martin, despite the bright skies!
Globulars seem a bit less affected by LP than other broadband targets.
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  #12  
Old 18-04-2024, 09:43 PM
Startrek (Martin)
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Quote:
Originally Posted by Retrograde View Post
Very nice Omega, Martin, despite the bright skies!
Globulars seem a bit less affected by LP than other broadband targets.
Thanks Pete ,
Appreciate your comment
I don’t know about less affected by LP , my luminance frames at 30 sec were almost whited out
I had to work hard to mitigate gradients in this image , no different to imaging say a Galaxy in the same area of the sky, but I’m guessing your talking about stars and star colour
I think the key to Star colour is avoiding saturation and Gain 0 on my 2600Mm obviously worked out well. At Gain 0 my camera has a 50,000e well depth.

Cheers
Martin
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