M100, aka NGC 4321, is a galaxy in Coma Berenices, and about 55 million light years away. It is classified as a grand design spiral, and one of the brightest in the Virgo galaxy cluster.
Technical details are as follows:
Imaged at MYHY Observatory in the Philadelphia suburbs in 2004 using a 10″ OGS RC @ f/9, SBIG ST10XME, and Paramount ME. Image scale 0.6″/pixel. LRGB with 140 minutes unbinned Lum, and 40 minutes/channel RGB (binned 2×2). Processing was originally in CCDsoft and Adobe PS, but reprocessed in 2015 using Maxim for calibration, PIxInsight for alignment/integration, PixInsight for deconvolution, and the rest in Photoshop.