Diamonds in the sky - NGC2516

[AstroViking (Steve)]

Evening all,

Stellar clusters aren't really my "thing" when it comes to imaging, much preferring cool things like nebula or galaxies. However, when I saw an image of this one, I couldn't go past it.

I set out to replicate one of the images I saw of it - a handful of bright blue-white diamonds (complete with diffraction spikes) on a black background.

Interestingly enough, I had no technical issues with this image - the auto-focus routine ran perfectly and the auto-guiding error next got above 1 arc-second (usually it was somewhere between 0.5 and 0.7 arc-seconds, with the occasional dip below 0.5.) So I can only wonder what level of technical hell and frustration awaits me in my next imaging session...

In terms of processing, I did next to nothing with this one. The images were stacked and colour calibrated and any left-over green noise was removed via Siril's built-in routines. Then I separated the image into a starless 'background' and a star-mask image. When I looked, the 'background' had virtually nothing in it - some left over blue noise smudges from the stars in the centre of the image and the usual dusting of light pollution noise.

I decided to forget the background and concentrate my processing on the stars. Not that they needed much - a couple of tiny tweaks with one of James Ritson's macros and it was finished. This would have to be the quickest image I've ever processed...

I'm happy with both the full-size image and the cropped one. The extra negative space helps give a sense of perspective to the cluster, whilst the cropped one makes it 'up close and personal'.

As always, comments and feedback are more than welcome!

Cheers,
V.

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Image data:
* Gain: 100
* Offset: 10
* Temperature: 0 degrees C
* Exposure: 20 seconds
* Frames: 360 Lights, 50 Darks, 50 each of Flats and DarkFlats (120 minutes integration in total)
* Filter: UV-IR Cut

Processed with SiriL (stacking, then pre-processing, basic stretching and star removal with Starnet++) before tweaking in Affinity Photo v2

Equipment:
SW72ED@420mm / HEQ5-Pro / ASI183MC-Pro / SV165+SV305 / Kstars/Ekos

[Bodon (Steve)]

Steve great looking photo of the stars there! Very nice.

[leon]

Lovely stars indeed Steve, very crisp and clean, yet I don't know how i feel about the diffraction spikes, personal choice i guess, well done.

Leon

[Dave882 (David)]

Nice work Steve! Great to see you managed to get some clear sky for any kind of imaging. It’s a very charming cluster indeed! It could just be my screen (or eyes lol) but is the colour a little…blue/purple…?

[AstroViking (Steve)]

Thanks all!

Leon - I'm with you on the diffraction spikes. I don't like them in images of galaxies and nebulae, but think they look OK when imaging stellar clusters. It's an interesting conundrum.

Dave882 - The stars at the centre of the cluster are rather blue/purple. This is how they came out of the camera, and I was trying to emulate one of the images on Telescopius that showed them in a very similar way. Not to everyone's taste, I do admit.

Cheers,
V.

[bluesilver (Peter)]

pretty impressive result there.
I have to say i am a fan of the diffraction spikes in clusters, and this image has come out looking pretty good.
Well done.

[AstroViking (Steve)]

Thanks Peter!

[Plossl68 (Paul)]

Now that, is a truly beautiful jewel box. Nice shot!