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  #1  
Old 21-05-2020, 01:16 PM
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marc4darkskies (Marcus)
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Ngc 4731

My first image in nearly 3 years ... happy chappie again!

NGC 4731 is not a particularly glamorous galaxy because it's so small (6.7 x 4.1 arc minutes) and lacks lots of colourful Ha blobs to enhance. Consequently, it's rarely imaged. It was a good and reasonably challenging first light target though. I reckon it's quite a pretty little thing though!

It's 65 million light years away and is a member of the Virgo cluster. The small galaxy to the lower left is an irregular galaxy designated NGC 4731A. There is also a galaxy out of frame (the giant elliptical NGC 4697) that has gravitationally distorted NGC 4731. Naturally, there are also a myriad tiny distant galaxies in the full frame.

This is a 15.3 hour LLsRGB (Luminance, synthetic luminance, red, green and blue) exposure.

Full Res crop HERE

Full Frame to swim around in HERE


Note: in the full frame there are a couple bright stars outside the FOV at the top right of centre that left some artefacts
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Click for full-size image (LLsRGB_1_merged_crop_small.jpg)
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  #2  
Old 21-05-2020, 02:08 PM
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strongmanmike (Michael)
Highest Observatory in Oz

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I'll have one of these too ...welcome back on board Marcus, look forward to the results of what will surely be your now endless retirement imaging sessions from your very own dark sky backyard

Yes, a bit of a lack luster galaxy I guess but every galaxy has it's interesting aspects and the perfect S shape here is definitely intriguing and you have done it justice none the less .

After your two-three year move/life transformation, must be good to know everything works properly again too...including you!

Mike
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  #3  
Old 21-05-2020, 02:38 PM
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Andy01 (Andy)
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That's onw funky shaped galaxy!
Well done & welcome back!
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  #4  
Old 21-05-2020, 04:27 PM
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Nice one Marcus!

I imaged this one a few years ago myself and recall it being a difficult target. You've done better with it than I did (not that I set the bar particularly high). I still think it's a pretty cool target if for no other reason than it's unusual shape.
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  #5  
Old 21-05-2020, 05:02 PM
Placidus (Mike and Trish)
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That's a gorgeous galaxy, beautifully photographed and processed. A wonderful return to action! Bravo!
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  #6  
Old 21-05-2020, 05:08 PM
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Unusual shape, nice image.
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  #7  
Old 21-05-2020, 05:15 PM
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That is a super image Marcus. Getting such a sharp image of such a small and dim object is very difficult and you have shown you have lost none of your maestro self.

Greg.
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  #8  
Old 21-05-2020, 05:40 PM
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Wow what an amazing looking galaxy - very cool capture Marcus & congratulations on getting back to imaging.
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  #9  
Old 21-05-2020, 05:51 PM
DJT (David)
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Love it. lack lustre? Naah, really very interesting given the distortion etc.

Very nicely done and as everyone says, welcome back.

David
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  #10  
Old 21-05-2020, 06:25 PM
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ChrisV (Chris)
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That's one interesting galaxy. Beautifully done!
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  #11  
Old 21-05-2020, 07:21 PM
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multiweb (Marc)
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Beautiful narrow field with great colors and details. It's alive again.
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  #12  
Old 21-05-2020, 10:56 PM
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marc4darkskies (Marcus)
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Quote:
Originally Posted by strongmanmike View Post
... the perfect S shape here is definitely intriguing and you have done it justice none the less .

After your two-three year move/life transformation, must be good to know everything works properly again too...including you!

Mike
Thanks Mike. Yes indeed - everything still worked, although my processing skills were a bit rusty.

Quote:
Originally Posted by Andy01 View Post
That's onw funky shaped galaxy!
Well done & welcome back!
Thanks Andy!

Quote:
Originally Posted by codemonkey View Post
Nice one Marcus!

I imaged this one a few years ago myself and recall it being a difficult target. You've done better with it than I did (not that I set the bar particularly high). I still think it's a pretty cool target if for no other reason than it's unusual shape.
Oh come now Lee - you're setting the bar pretty high these days - your recent images are excellent! Thanks mate.

Quote:
Originally Posted by Placidus View Post
That's a gorgeous galaxy, beautifully photographed and processed. A wonderful return to action! Bravo!
Thanks M&T! Or is that perhaps just M ... or maybe T?

Quote:
Originally Posted by Bart View Post
Unusual shape, nice image.
Thanks Bart.

Quote:
Originally Posted by gregbradley View Post
That is a super image Marcus. Getting such a sharp image of such a small and dim object is very difficult and you have shown you have lost none of your maestro self.

Greg.
Cheers Greg! You're too kind! The seeing for the Lum was poor - 2.7 arcsec FWHM. Decon got it down to 2 though. The RGB was much better averaging betweem 1.6 and 2.1 arcsec FWHM hence why I used it for synthetic Lum.

Quote:
Originally Posted by Retrograde View Post
Wow what an amazing looking galaxy - very cool capture Marcus & congratulations on getting back to imaging.
Thanks Pete - yeah , it kind of grows on you doesn't it!

Quote:
Originally Posted by DJT View Post
Love it. lack lustre? Naah, really very interesting given the distortion etc.

Very nicely done and as everyone says, welcome back.

David
Thanks Dave - good to be back. Hopefully down here I'll get more clear nights than I did in Sydney!!

Quote:
Originally Posted by ChrisV View Post
That's one interesting galaxy. Beautifully done!
Thanks Chris - yes it is. Truth of the matter is all galaxies are interesting even if they're not so glamorous. In the end, with some careful processing, they're all beautiful.

Quote:
Originally Posted by multiweb View Post
Beautiful narrow field with great colors and details. It's alive again.
Cheers Marc!
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  #13  
Old 22-05-2020, 09:07 AM
PeterSEllis (Peter)
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Hi Marc,
You shot inspired me to have a go at this one, for me it is not an easy shot from light polluted Suburbia. Very interesting seeing a galaxy being pulled apart by its neighbor, good ol gravity at work.
Well done.

Peter
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  #14  
Old 22-05-2020, 09:38 AM
markas (Mark)
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Not bad for an unglamorous galaxy
Great image!


Mark
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  #15  
Old 22-05-2020, 11:23 AM
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marc4darkskies (Marcus)
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Quote:
Originally Posted by PeterSEllis View Post
Hi Marc,
You shot inspired me to have a go at this one, for me it is not an easy shot from light polluted Suburbia. Very interesting seeing a galaxy being pulled apart by its neighbor, good ol gravity at work.
Well done.
Thanks Peter Go for it mate! It'll be interesting to see how you go!

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Originally Posted by markas View Post
Not bad for an unglamorous galaxy
Great image!
Thanks very much Mark.
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  #16  
Old 26-05-2020, 09:43 PM
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marc4darkskies (Marcus)
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Upgraded image

What the heck happened to the weather! I'm supposed to be sitting here processing another image but the cloud doesn't seem to be giving me a break! According to CFN my next clear-ish night (for a few hours at least) might be thursday! After that who knows!

Soooo ... I'm relegated to fiddle-farting around.

I applied Synthetic Lum (Ls) when processing the first time to improve s/n (provided the RGB data is of a similar FWHM to the Lum). I did this within CCDStack (as a mean combine) and it significantly reduced background noise and brought out a few more fainter stars. But, since the seeing was much better for the RGB data (FWHM 2.0 vs 2.7 for the Lum), I could also use Ls to naturally improve sharpness. This can't be done very effectively in CCDStack because averaging blurry with sharp only slightly improves sharpness. Because my processing skills have rusted, I forgot to apply the improved resolution of Ls to the high signal parts of the frame in PS. I've now done this for a noticeable (to me) improvement in sharpness. The brightness profile changed a bit too - for the better.

I've updated my PBase images but to clearly illustrate the difference, below is a before (left) and after (right) comparison.
Attached Thumbnails
Click for full-size image (LLsRGB_1_merged_BeforeEnhance.jpg)
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Click for full-size image (LLsRGB_1_merged_AfterEnhance.jpg)
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  #17  
Old 27-05-2020, 10:49 AM
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h0ughy (David)
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I can see the changes and looks good. Glad the image acquisition is working for you now. For the weather conditions well someone must be responsible, it was their fault.

You certainly haven't lost your touch
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  #18  
Old 27-05-2020, 01:31 PM
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astronobob (Bob)
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Yeah, wow, and a new target i havent seen; what an eye-catching pair, 2 spiked stars look good in there too.. .

Keool
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  #19  
Old 27-05-2020, 03:53 PM
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multiweb (Marc)
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That repro looks great. You got some extra details in there.
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  #20  
Old 27-05-2020, 05:02 PM
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marc4darkskies (Marcus)
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Quote:
Originally Posted by h0ughy View Post
I can see the changes and looks good. Glad the image acquisition is working for you now. For the weather conditions well someone must be responsible, it was their fault.

You certainly haven't lost your touch
Quote:
Originally Posted by astronobob View Post
Yeah, wow, and a new target i havent seen; what an eye-catching pair, 2 spiked stars look good in there too.. .

Keool
Quote:
Originally Posted by multiweb View Post
That repro looks great. You got some extra details in there.
Thanks a lot guys. I thought it was christmas finding extra detail!

It'd be nice to compare it to something though - I crave validation . But nothing much shows up when googling that's better than mine or comes from a super dooper pro obs. I stuck closely to what the colour data was telling me (with modest enhancement), so I'm confident I got the colours right ..... I think.
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