The California nebula (NGC 1499). Date of image 28/11/2016.
Hardware details: Camera: Canon 600D (astro modded). Telescope: SW Evostar 120 with Baader UHC-S filter. Mount: AZ-EQ6 guided using a ST80 synguider. Image details: Lights: ~40 x 3min at ISO 800, Darks: 43 x 3min at ISO 800 (taken at the end of imaging), Lights and darks all separated by 15 sec intervals. Flats: 50 x 1/350s (taken from laptop monitor screen) at ISO 800, Bias: 50 x 1/4000 at ISO 800. Temperature ~-2 to -4 deg.
Image was precessed in DSS. Stacking was in median mode. Star detection 30%. Colours have been stretched and saturation is 30%. No drizzling.
As before, the weather was excellent. No clouds and very dry on the ground. There was also no wind and the seeing was very clear - the stars were really very still that night.
I was planning on making a mosaic of two frames to cover more of the nebula. Unfortunately the batteries on my auto guider died and I had to resort to 30 sec subs for the other stack. I don't have the darks for that, I'll get them soon!
As in previous images, I'm getting a strong gradient towards the lower end of my images. In the image of M81/82 I found that this is most likely to be caused my local lights. I could try some further processing to remove it or alter the scope to remove unwanted light. The latter seems like a more robust solution.
The Ha red shines through here giving the impression of a thin, sparse nebula that dissipates steadily into space.