My Nemesis….

We all have one. We all have that one thing that is destined to do its utmost to thwart us. It might be a work colleague, a neighbour, a traffic warden or something even less rational (less rational than a traffic warden???)

For me it’s a particular deep space object. I have been trying to capture a decent image of this one since I first started DSO imaging years ago. I’ve had so many attempts at it that it’s going to get its own series reboot soon. It’s not even as though it’s an especially hard one to actually capture an image of. Unless, you’re like me, and trying to capture it with something that wasn’t designed to go after objects like this.

I use a planetary camera for my DSO work, the ZWO ASI178MC (uncooled.) It would probably go better were I to use the cooled version. But here I am using not only the wrong camera type, but also one where I can’t even deal with the noise effectively, other than to sink as much exposure time into it and do calibration frames for each and every session. And when you’re up to 13 sessions…my poor laptop is straining with this one. The temporary files alone are coming up on 150Gb!

The Iris Nebula is a bright reflection nebula in the constellation Cepheus, and lies some 1300 light years away. The designation NGC 7023 refers to the open cluster within the larger reflection nebula, which is designated LBN 487. The area is characterised by a surrounding darker dust area, which is notoriously difficult to pull out of the background without introducing too much noise. This is one reason that it’s important to put as much time as possible into it in order to improve the signal-to-noise ratio, or SNR as we call it.

Often for deep space objects (DSOs) we need to use filters that isolate specific bandwidths, such as hydrogen, oxygen and sulphur. But for a reflection nebula this would serve no benefit, and so we’re able to image in true broadband with a one shot colour (OSC) camera.

This has been a labour of love for me. I say that, but there’s also been a lot of sheer bloodymindedness involved as well. But I think it’s time for me to say enough on this one. There’s so much sky up there that I’m hardly likely to ever run out of things to capture. And I think going across 3 years is long enough for me!

So I’ll happily leave you with my final (for now) image of NGC 7023, the Iris Nebula, my nemesis, my astro-arch-enemy. Thank you for reading, and clear skies all.

NGC 7023 Iris Nebula 16hrs 50mins 72ED and ASI178MC, taken across 3 years, including 13 separate nights and 40Gb of data

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