Another fantastic astro image by CADSAS member Graham Caller. this is NGC7635, the Bubble nebula in Cassiopeia.
He gathered data for this Oct 2016 to Jan 2017. It’s a compilation of 35 single frames with exposure times of 5 minutes for Ha and 10 minutes for SII and OIII – total of 2 hr 55 mins of data capture.
OSH (OIII SII Ha) narrow band filters were used. He has colour mapped them to the RGB channels to give this false colour representation, in order to show a better contrast between the different channels.
OIII (oxygen) – red
SII (sulphur) – green
Ha (hydrogen) – blue