PixInsight Forum

PixInsight => Gallery => Topic started by: Astrodoc on 2014 November 22 09:57:50

Title: Sh2-170
Post by: Astrodoc on 2014 November 22 09:57:50
I am continuing to explore the Sharpless catalogue of faint nebulae.  This is Sh2-170, an emission nebula in Cassiopeia. The nebula is about 20' in diameter.

http://astrodoc.ca/sh2-170-emission-nebula/

Thanks for looking!

Clear skies,
Ron
Title: Re: Sh2-170
Post by: Zocky on 2014 November 22 11:48:00
If I may ask. Why your subexposures are only 5 minutes long?
Title: Re: Sh2-170
Post by: Astrodoc on 2014 November 22 14:07:04
The RGB frames were acquired in in mediocre conditions.  Based on a test frame, 5m was enough for exposure to be sky limited, so no benefit to going longer in those conditions.  Also, shooting more shorter subs ensured enough subs for sigma clipping.  I usually shoot 10 or 15m subs in RGB.

The Ha subs for this image were 20m.

Clear skies,
Ron
Title: Re: Sh2-170
Post by: Astrodoc on 2014 November 23 10:47:21
UPDATE - I reprocessed using a synthetic luminance made by taking the R,G,B and Ha stacks and ingegrating them with noise weighting.  I then processed the synth-L as I would a real L and added it to the HaRGB image.  This produced a much nicer result showing more detail in the nebula, tighter and more stars, and a smoother background.  Image and text at:

http://astrodoc.ca/sh2-170-emission-nebula/

Clear skies,
Ron
Title: Re: Sh2-170
Post by: rvillaverde on 2014 November 26 13:04:28
Good Job.