M100 galaxy, in the Virgo cluster of galaxies. Dual camera imaging, 6 hours 51 minutes total exposure.

Luminance: 31 x 5 minutes
DSI Pro III, Hutech IDAS LPS, through Celestron C80ED at f/7.5

RGB: 15, 22, and 27 x 4 minutes
DSI Pro II, Meade RGB filters, Atik Manual Filter Wheel, through Sigma APO 175-500mm lens at 310mm focal length.

Mounted on 8" LX90, with DSI Pro guiding at f/5.

Raw frames dark calibrated and flat/flat-dark calibrated in Autostar Image Processing. Differential between Average Stack and Median Stack used to generate pixel map mask for Average Stack / Median Stack combining. Post processing in PhotoShop