by Rod Pommier
Telescope/Mount: Celestron Compustar C14 telescope with 0.75x focal reducer (f/8). Camera: SBIG STL 11000M CCD at -25C,self-guided. Filters: Baader Planetarium LRGB filters. Location: Pommier Observatory, Portland, OR, USA. Dates: 2011-05-08 and 2011-06-15
Exposures:Left image: LRGB exposures=184:70:70:70 minutes=7hours:04minutes total exposure.Calibrated with bias, dark, and flat field frames Right image: Same, supplemented with LRGB=44:44:44:40 minutes=2hour:52minutes additional exposure, for grand total exposure=9hours:56minutes.
M51, the Whirlpool Galsxy, and NGC 5195 before and after supernova SN 2011dh. The left image is a 7hour:4minute LRGB exposure taken the month before the supernova appeared. The right image was composed by adding additional exposure time of LRGB=44:44:44:40minutes after the supernova appeared.