September 2012: Sharpless 2-115

This seems to be one of thousands out-of-the-circuit objects, not being part of the regular image catalog of the amateur. I saw a picture of it in a magazine, and I set it as my next target.

I imaged this nebula in two different nights (a week in between). I then carefully selected the best subs, as the Last-Quarter Moon was quite a problem with the R, G and B images.

I had an unexpected problem with field rotation. I noticed it in most of my subs those nights. My polar alignment is not perfect, I know, but having field rotation using the same exposures I usually use (700 and 400 seconds) was surprising. This was because this object has a higher declination than that of my “normal” targets.

The small cluster Berkeley 90 can be seen embeded in this huge nebula left off-center.

The image contains 7 700-second subs through the H-alfa filter, 7 400-second subs through the R filter, 8 400-second subs of G, and 6 400-second subs of B filter. Some gradients at the edges, due to the moonlight, were almost impossible to fix without damaging the nebula. 

  Go to this object description and this image technical detail.