Melotte 15 bicolour (28 hours)

[x6gas]

This is undoubtedly one of my favourite emission nebulae targets - the gas and dust around the Melotte 15 star cluster at the heart of the Heart Nebula.  Melotte 15 comprises of mostly young, hot, blue stars which are 'only' around 1.5 million years old.  Some of these are around 50 solar masses but most are smaller than our sun.

I collected 10 hours of Ha in 600s subs and a further 18 hours of OIII in 1200s subs.  I think this is the most data I've ever captured on a target and the first time I've gone over 100,000 seconds; it made the data a dream to process.  The Ha signal is very strong and OIII covers most of the frame so I spent most of my time playing with endless variations of the balance between golds and purples - and I could have posted a dozen variants!  As it is I've taken my time and settled on this as my favourite rendition.  The data meant even the lowest signal areas were pretty clean and after much procrastination this version does have some noise reduction applied.  I'd be really interested in views on whether it's too much and I should have left it alone - I really hope that I've done the data and the target justice.

I first imaged this back in 2013 but vowed to go back with a longer focal length so this is with my 130mm TS apo (860mm focal length, f/6.6).  I've gone for a similar palette to my earlier version because I like the colours so much.  I did capture about 5 1/2 hours of RGB data but I haven't used it in this image as it didn't really add anything (most of the stars a blue anyway) but I will come back to the data and do a version where I add some of the narrowband data to the RGB.

Kit used was TS Optics 130 Apo; iOptron CEM40; Atik OAG with QHY5L II; Atik EFW2 with 5nm Ha and 3nm OIII Astrodon filters; Atik 460 ex.  Captured using SGPro and processed using PixInsight and PS.

Thanks for looking, Ian

Edited June 27, 2020 by x6gas
added hyperlink

[Kinch]

Nice one...... Not my favourite colours on this.....(but that always is a personal call on NB images).....but you have pulled out great detail. As for noise reduction...as long as it is not obviously smoothing out the image, I don't really have any problem with using it but to answer your question, it would be easier to make a comparison on two images rather than stating whether it is better with/without.

[x6gas]

2 minutes ago, Kinch said:

Nice one...... Not my favourite colours on this.....(but that always is a personal call on NB images).....but you have pulled out great detail. As for noise reduction...as long as it is not obviously smoothing out the image, I don't really have any problem with using it but to answer your question, it would be easier to make a comparison on two images rather than stating whether it is better with/without.

That's a fair point - I guess I was sensitive to posting more than one version because I've been looking at so many variants.

Anyway here's the version with no noise reduction.  To be honest I have to pixel-peep to see the difference but then my eyes get crossed when I've been looking at an image for too long!

[MarkAR]

Both stunning images (TBH I couldn't spot any difference 😊)

[rubecula]

What a wonderful image, there's so much detail to look at.  The dramatic illumination of the gas clouds, the gently fading blue areas, sumptous!  After investing 28hrs you deserve such a glorious result.

[newbie alert]

My favourite part of the heart.. the heart of the heart...

Wonderful image, I like it alot 

[Kinch]

Agree 100% - I can't spot any difference between them. That happens me sometimes during processing - when I do a step then stop to look see the overall difference it has made.....If I can't detect any difference (of note) then I undue and just leave it out. Here, you could have done the same with the NR that you were a little concerned about....nobody but you can see any difference. So.....both are fantastic images 😊

[Wyvernp]

Utterly stunning, I can only hope do do something like this someday.

[x6gas]

1 hour ago, MarkAR said:

Both stunning images (TBH I couldn't spot any difference 😊)

 

49 minutes ago, Kinch said:

Agree 100% - I can't spot any difference between them. That happens me sometimes during processing - when I do a step then stop to look see the overall difference it has made.....If I can't detect any difference (of note) then I undue and just leave it out. Here, you could have done the same with the NR that you were a little concerned about....nobody but you can see any difference. So.....both are fantastic images 😊

Thanks guys.  I feel a bit embarrassed that I asked now.  I guess I got a bit carried away zooming in... here is the difference by the way:

As you've said I should have just left it without the NR since the difference is imperceptible... but it's good to have it confirmed that the noise reduction doesn't make the image look plasticky...

Really appreciate the comments - thanks!

 

[x6gas]

Thanks Robin, newbie alert, Wyvernp - appreciate you taking the time to comment.  I'm pretty pleased with this one (though a lot of data helps!)

Cheers, Ian

[DaveS]

Brilliant image.

I had a go at this last year, but the results were dire. I'll try to have another go this year when we get some darkness back.

[x6gas]

Thanks Dave.  I found this to be a fun target because there is fairly strong signal in OIII and Ha across the frame so there is endless opportunity to experiment with the balance and interplay of the colour and contrast of the channels which lead to radically different results... it does make it tough to decide exactly which way to go - which isn't my strong point - but it's fun nonetheless so I would strongly encourage you (and indeed others) to give this target a go.

I forgot to mention that I captured this data back in January / February this year so was able to get good chunks of good SNR data on each, rare, clear night.