Messier 15

Lum - 9 x 15 minute subs (no binning)
Lum - 8 x 5 minute subs (no binning)
R - 8 x 5 minute subs (no binning)
G - 8 x 5 minute subs (no binning)
B - 8 x 5 minute subs (no binning)

Total exposure is 295 minutes or just under 5 hours. The data was captured with a 16-inch f/8.9 RCOS on a Paramount ME, SBIG STL11000M CCD with Astrodon LRGB filters, field flattener located at the Sierra Remote Observatories outside of Fresno, California at 4600 feet elevation.

All image calibration (Lights, Bias, Darks and Flats) and processing was done in PixInsight. RGB files combined and then used Dynamic Background Extraction, Photometric Colour Calibration, ArcSinH stretch followed by mild Histogram Transform stretch and Noise Reduction (ACDNR). Luminosity used Dynamic Background Extraction, ArcSinH stretch followed by mild Histogram Transform stretch, HDR Multiscale Transform and Noise Reduction (ACDNR). LRGB was then created from processed RGB and Lum data. A bright blue star is just out of the field on the bottom right causing the glow in that corner.

Image Credit: Steve Mastellotto and Paul Mortfield