Double, double toil and trouble; Fire burn and cauldron bubble…
Hi All,
Might as well kick off my 2008 imaging series with an evil stature, so I’m pleased to present
IC2118 – The WitchHead Nebula
A sinister shaped figure known as the WitchHead Nebula (IC2118) resides in the constellation Eridanus. The nebula primarily glows due to the reflected light from the bright star Rigel located 2.6 degrees away in the constellation Orion (seen top right of frame). The blue hues are due to the dusty characteristics of the nebula as dust reflects blue light more efficiently than red light. This is in contrast to interstellar reddening phenomenon where dust suppresses blue light near the center of our Milky Way galaxy. The WitchHead Nebula resides approximately 1,000 light years away.
About the image;
Technically, this data was acquired last year, but it takes me a while to process an image spending many nights working the data over. The image is a BRGB composite totalling 5 hours (R:90 mins; G:90 mins; B:120 mins). image has been reduce and cropped for web appearance. One thing for sure is IC2118 is not a strong Ha target, in fact when I went through the raw subs of the individual RGB frames, it was the blue frame which displayed the most detail due to its dusty characteristics. I decided to do something different and use the blue channel as the luminance, though I suspect I would have had a better result in reducing noise in the dim areas performing the standard LRGB methodology. I think this would be a good target for unmodded DSLRs, though it’s not bright. In my composition I made Rigel a feature, thus included it into the frame (top right). I experienced many difficulties in processing this object. In particular Rigel - This is one really bright star at mag 0.18 which washed out all nebulosity and colour in its vicinity. The only way I could bring back the WitchHead was use numerous layer masks for both luminosity and colour management. Certainly the most masks I’ve had to create in an astroimage before (total of 8) and quite a processing challenge. I’m not happy with the background as it’s not flat and still exhibits some colour shifts when equalised. Stars just off the edge of the frame also created flares that protruded into the frame. Ok, enough of my bantering on – I’ve spent way, way too long processing this image. Need a break from it - time to get “dirty” with some quality telescope time acquiring data for three other imaging projects I’ve started, but appear to never finish.
Thanks for looking. Hope you enjoy!
Cheers