Thor's Helmet (NGC2359) in HOO(RGB)

[glowingturnip]

Here's my latest, and my second experiment in bicolour narrowband:

31x 600s Ha, 29x 600s OIII, 10 each x 180s R, G and B. Flats, darks and bias, equipment as per sig, Pixinsight processed.

 

Taken over three nights - I'd done a night each on Ha and OIII, but decided I needed a few more OIII (not least since I had a big guiding hiccup which meant that after I'd caught it and lazily not bothered to correct it, half the run were off-centre, though I still used them), so the third night I grabbed about 10 more OIII, but also thought I'd gather a little R,G & B.  I've used that RGB just as chrominance only for the stars and a little bit from the blue channel for the 'cage' around the bubble.  I've gone through various iterations of green-blue colour balance in processing it - I wanted to be true to the OIII wavelength and leave a decent amount of green in there, but it tends to be a bit overwhelming on some monitors, so I've leaned more towards the blue - hopefully I've found a pleasing balance.

 

Thor's Helmet (NGC 2359) is an emission nebula in the constellation Canis Major. It is approximately 12 thousand light years away and the central bubble is 30 light-years across. The central star is the Wolf-Rayet star WR7, an extremely hot star thought to be in a brief pre-supernova stage of evolution. It is similar in nature to the Bubble Nebula, but interactions with a nearby large molecular cloud are thought to have contributed to the more complex shape and curved bow-shock structure of Thor's Helmet. Wolf-Rayet stars are characterised by a rapid loss of stellar mass, driven by chemically enriched high-speed stellar winds.

The nebula has an overall bubble shape, but with complex filamentary structures. The nebula contains several hundred solar masses of ionised material, plus several thousand more of un-ionised gas. It is largely interstellar material swept up by winds from the central star, although some material does appear to be enriched with the products of fusion and is likely to come directly from the star. The expansion rate of different portions of the nebula varies from 10 km/s to at least 30 km/s, leading to age estimates of 78,500 - 236,000 years. 

 

Comments and cc welcome, hope you enjoy !

 

Stuart

[Petergoodhew]

That's a lovely Helmet Stuart.  Crisp clear details of the bubble, and plenty of nebulosity in the outer regions. Nice tight stars. It's a matter of personal preference but I would choose a bit less green and more blue.  Well done.

[carastro]

Very nice Stuart, this is one I need to get more data on, but never seem to be at the right place at the right time.

Did you try an Sii?  Just wondering whether to bother as this looks really nice as is.

Carole 

[glowingturnip]

Thanks both !

Actually Carole, I don't have an SII filter yet, will have to wait for a birthday for that.  I only got the OIII filter for Christmas, but I'm loving the bicolour so far.  Still, it'll give me an excuse to revisit all my pictures again when I get an SII.

[ollypenrice]

Looking pretty good to me. Not an easy target!

Olly

[glowingturnip]

Thanks Olly !  

[Rodd]

Looks great.  As you add data you will discover that in this FOV there is no background--just nebulosity.  I like your palette--subtle.  Perhaps a bit under saturated, but ever so slightly, causing they eyes to hunt for the color the brain thinks it  sees....and this makes it a very dynamic image.  Well done.

Rodd 

[glowingturnip]

Thanks Rodd,  interesting comment about the saturation - I always do err on the side of less rather than more, and usually find I have to go back and add some extra, and even then still look undersaturated compared to some of the stuff on the web.  Glad it works though, cheers.

[MarsG76]

Very nice result... you have captured good detail... 

If I had a clear night for every time this has happened to me.. ie, losing a guide star and "re-capturing it", or thinking I have captured the same one with out checking, I'd have so many clear nights it would make the Atacama desert look perpertually cloudy.

[glowingturnip]

Thanks very much !

Yes, I've even built into my setup routine that I bookmark several stars in the PHD window, so that if I do lose a guide star, I can nudge it back to get the stars in the same pattern and carry on.  Unfortunately this procedure doesn't seem to account for the laziness of this particular operator, who several hours later is tired, wants to go to bed (and may have had a glass or two of wine with his wife) - meh, I can still see it on the screen, it's still good...

I don't think I actually used any of the non-overlapped area in the final crop, even though I did a pretty good job of blending them.