M57 Ring Nebula (Ha / OIII bicolour)

[x6gas]

I spent most of Sunday evening sorting out the collimation on my SCT, and set an imaging run of M57 going mostly to check the results. I was surprised at how bright this planetary nebula is so I reduced the subs from 900s to 600s and I've had to stretch the star field harder than the nebula. It's a smallish object at ~2.5 arcminutes but I left the reducer because I wanted to check the field flatness. I'm glad I did as the guiding was far from perfect, I think because the scope was out of balance...

Ha - 6 x 600s, OIII - 6 x 600s, both binned 2x2

Scope: 11" EdgeHD @f/7 w/ Celestron 0.7 reducer

Camera: Atik 490 ex, 2" Baader Ha and OIII filters

Mount: CGEM DX

Guiding: Atik OAG, QHY IMG0H, PHD

And this is a closer crop:

I think I prefer the wider field as it gives a better indication of context...

Thanks for looking, Ian

[Gina]

Nice one - yes, I prefer the first one with the wider view too The close-up doesn't give anything more as the resolution isn't there, presumably due to the seeing or lack of transparency. I think the heat is causing high haze in the atmostphere - it's certainly very misty here. The last couple of nights have been spoilt by thin high cloud or haze. I think we could do with a shower or two to clear the atmosphere now.

[SimonfromSussex]

Lovely image Ian, really good detail on that outer halo!

How are you finding the 490?

[x6gas]

Nice one - yes, I prefer the first one with the wider view too The close-up doesn't give anything more as the resolution isn't there, presumably due to the seeing or lack of transparency. I think the heat is causing high haze in the atmostphere - it's certainly very misty here. The last couple of nights have been spoilt by thin high cloud or haze. I think we could do with a shower or two to clear the atmosphere now.

Yes I know what you mean Gina. My car is covered with sandy dust and that's obviously blowing around in the atmosphere. I am just enjoying the lack of cloud so I can live with it! There might be some more I can do to sharpen this up, but at the end of the day there is only an hour per channel here. I think it's probably an object that could stand shorter subs to get more detail in the bright parts of the nebula.

[Macavity]

Nice one. All those efforts to see the central star and

what you really need is a O(III) "fog" penetration filter?

Popular with uz VIDEO astronomers - But the central region can be significantly opaque / structured...

[x6gas]

Lovely image Ian, really good detail on that outer halo!

How are you finding the 490?

Thanks Simon. I haven't caugh the real outer halo, though - that's on display in the quite extrordinary image posted by Avdhoeven. But this is 2 hours worth of data vs 47.5 hours!!!! If I stretch it a lot then - as well as boat loads of noise - I can just see the beginnings of the outer halo but that would require much longer subs and more of them.

The 490 is a very good camera indeed. Oversampled on this scope even binned 2x2 so the 460 is actually better suited for this rig, but I've been hugely impressed with the 490 on my Tak...

Cheers, Ian

[x6gas]

Nice one. All those efforts to see the central star and

what you really need is a O(III) "fog" penetration filter?

Popular with uz VIDEO astronomers - But the central region can be significantly opaque / structured...

Thanks Chris. Yeah no hint of the progenitor in my data!

[Martin-Devon]

Ian, you've done well considering the conditions and imaging time - I've tried M57 before and struggled miserably, it's not an easy target to get sharp detail in. Your widefield version is really nice, and yes I can see the beginnings of a halo there. Sounds like you're still ironing out a few technical matters as well, join the club, I'm pulling my hair out with Focusmax at the moment!

Martin

[x6gas]

Ian, you've done well considering the conditions and imaging time - I've tried M57 before and struggled miserably, it's not an easy target to get sharp detail in. Your widefield version is really nice, and yes I can see the beginnings of a halo there. Sounds like you're still ironing out a few technical matters as well, join the club, I'm pulling my hair out with Focusmax at the moment!

Martin

Thanks Martin. The guiding issues were down to pure laziness - well, I suppose that the alternative take is that I was concentrating on getting the collimation right. I'd had the scope off of the mount, you see, but didn't want to waste time realigning the GoTo... so when I put the scope back on it was only very roughly balanced in RA - and a bit out of balance on this set-up makes quite a difference! It's silly really as realigning the GoTo only takes a few minutes - less than 5...

[Gina]

Yes I know what you mean Gina. My car is covered with sandy dust and that's obviously blowing around in the atmosphere. I am just enjoying the lack of cloud so I can live with it! There might be some more I can do to sharpen this up, but at the end of the day there is only an hour per channel here. I think it's probably an object that could stand shorter subs to get more detail in the bright parts of the nebula.

Yes, I agree, I think shorter subs would help the brighter parts. Several targets I've imaged have benefited from shorter subs (and more of them in the available time).