Cygnus Loop Widefield
June 17th, 2010
This is part the Cygnus Loop (The Veil Nebula), a vast supernova remnant, taken on the evening of the 16th of June from the roll off roof shed. The loop comprises several well known objects, one of which, the Western Veil (NGC6960) I have previously imaged with the 250mm reflector. Also included in this widefield image are the Eastern Veil (NGC6992) on the left and Pickering’s(Fleming’s) Triangular Wisp (NGC 6979) in the centre right.
This area was another target for my summer widefield nebula mission, and is located not far from my previous target the Eagle nebula. Unfortunately it’s just a bit to big to fit in the area corrected by the William Optics field flattener on the ZS66, I’d like to try the new Skywatcher flattener with it at some point to see if that does a better job.
Imaging Equipment
- William Optics ZS66SD
- William Optics MkII 0.8 Field Flattener
- Canon EOS 1000D (unmodified)
- Astronomic CLS CCD Filter
Guiding and Mount
- Vixen A70LF Refractor
- Modified Philips SPC900NC Webcam
- IR/UV Cut Filter
- 0.6x Focal Reducer
- Celestron CGEM Mount
Exposures
- 40 x 5 minutes (200 minutes total)
- 31 x bias
- 31 x dark
- 31 x flat
The images were calibrated and debayered in Iris then aligned, stacked and processed in Pixinsight.
Very nice image once again Tim.
Is there a slight gradient left to right or is that a function of stellar density/nebulousity? Either way, it’s a really well framed shot, well done.
Thanks Dave, definitely some gradient there, I’m still playing around with the dynamic background extraction tool in pixinsight trying to find the right combination of settings to properly remove it. Unfortunately with my light pollution it’s never going to be easy.
Had another play with this last night, the issue is not so much gradient as it is the unflattened field area. The left side of the image if you look at it resolution is not flattened, so that stars are bloated and misshapen. That means that when I do the star size reduction is doesn’t work as well on that area of the image, mostly the bottom left corner and right edge. Which leaves us with a gradient of larger, brighter stars to one side of the image, but the background behind them not that bad, which is to say there is definitely some gradient there but not as much as the bloated stars make it look like..
Thanks for your analysis, I see what you mean now that I’ve looked much closer. As I said in my 1st post, this is a wonderful image that you should be proud of. Well done, and I’m looking forward to your next!