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NGC 6543 - The Cat's Eye


Clarkey

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Probably the hardest image to process I have done so far. The core is very bright, but the out regions are pretty faint. Anyway, this is about 8 hours of data, mainly O3 and Ha with a bit of RGB for the stars. It probably took me longer to process than to image! Still not completely happy with the result - but it is the best so far. Data from Roboscopes 12" F3.8 Newtonian using a 2600MM camera. All processed in PI.

Critical comment welcome.

NGC 6543 Cats Eye Nebula.jpg

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Nice job, and the detail in the core is superb. It almost looks like a mini Ring Nebula in there.

I've not imaged this one before, but a lot of images show it a lot greener, perhaps they are over-saturated maybe? I quite like this one 🙂

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11 minutes ago, WolfieGlos said:

Nice job, and the detail in the core is superb. It almost looks like a mini Ring Nebula in there.

I've not imaged this one before, but a lot of images show it a lot greener, perhaps they are over-saturated maybe? I quite like this one 🙂

Thanks for the comment.

The core was the difficult bit. I used 1 min subs, but they really needed to be 30 seconds or less. Trying to get the detail from an over-exposed image was tricky. I ended up merging the RGB data with the 60s narrowband in the core, then blending this into the outer ring.

You might be right regarding the colour, but I was working on the predominantly blue from the strong O3 signal. There is a little Ha, but it is pretty faint. 

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I agree with you on the processing challenges of this one. The dynamic range is monstrous and harder to deal with than M42. No doubt about it, though, this is a very good image.  In this case I do think the reflector star spikes are an issue since they dominate part of the nebulosity - but that's not your fault.

Regarding the colour, my feeling is that the Ha may lack contrast, meaning that it is pulling the blues generally towards magenta. I suspect that with more contrast the Ha would play less in the middle brightnesses and more in the high ones, which I think is true to the target - but I can't be sure. As for the green-blue balance, we know that OIII lies on the blue-green border, often known as Teal Blue. I'd up the greens a bit, but that's me.

Olly

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1 hour ago, ollypenrice said:

In this case I do think the reflector star spikes are an issue since they dominate part of the nebulosity - but that's not your fault.

I know. Us poor folk who can't afford 12" refractors🤣

1 hour ago, ollypenrice said:

As for the green-blue balance, we know that OIII lies on the blue-green border, often known as Teal Blue. I'd up the greens a bit, but that's me

Boosted the green a bit - had trouble not messing up other part of the colour balance and making it look 'natural' without starting from scratch. No sure which version I prefer though...

NGC 6543 Cats Eye Nebula v2.jpg

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11 hours ago, Clarkey said:

I know. Us poor folk who can't afford 12" refractors🤣

Boosted the green a bit - had trouble not messing up other part of the colour balance and making it look 'natural' without starting from scratch. No sure which version I prefer though...

NGC 6543 Cats Eye Nebula v2.jpg

I like the second one. The outer shell is mostly OIII and OIII is at the green end of blue, the opposite end to magenta.

A 12 inch refractor would be nice :grin: but you'd probably reach the limit of the seeing with a 5 inch - thank goodness!

Olly

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