SH2-115

[alan4908]

SH2-115 is a faint emission nebula in the Cygnus constellation about 7500 light years distant. It is normally imaged in narrowband, however, since I prefer natural looking colours, I went for a LRGB composition with an Ha blend into the red and lum channels.  The image below represents about 17 hours and was taken with my Esprit 150.

 

I encountered an interesting challenge in the processing stage of the above image in that I discovered that I had also acquired high levels of scattered light from an out of field star. These rays appeared in all the Lum, Red and Green subframes.  Having analysed the likely candidates in the direction of the rays, led me to the conclusion that the most likely cause was the star Deneb, reflecting off some surface in my scope. I occasionally encounter this problem, but this was extreme, presumably due to the very high relative brightness of Deneb compared to the nebula.  On the good news side, the scattered light was not evident in the Ha captured by my 3nm filter and was only just visible in the red data. So, after Pixsinsight and PS manipulation, I think I've managed to reduce this effect to acceptable levels. 

Alan

LIGHTS: L:9, R:22, G:11, B:17 x 600s; Ha:14 x 1800s; DARKS:30, BIAS:100, FLATS:40 all at -20C.