The Pinwheel Galaxy (M101, NGC 5457) is a face-on spiral galaxy that can be found 25 million light-years away in the constellation Ursa Major. This 7.86 magnitude galaxy was discovered on March 27, 1781 by Pierre Mechain. After learning of the galaxy from Mechain, Charles Messier verified its position and added it the his famous catalog of Messier objects. Compared to our own Milky Way, M101 is relatively large. It has a diameter of 170,000 light years making it nearly twice the size of the Milky Way. This galaxy has many huge and extremely bright HII regions, of which about 3,000 of them can be seen in photographs. Telescope: Stellarvue SV80S LOMO @ f/6 Accessories: Stellarvue SFF6 flattener; Dew control by Dew Buster Mount: Orion Atlas EQ-G controlled by EQMOD, performance tuned by Astrotroniks Guiding: TS-OAG9 Off-axis, using a Starlight Xpress Lodestar via PHD Camera: Atik 314L+ monochrome CCD @ -10.0C / EFW2 Filters: Baader LRGB (IDAS-LPS-V2 for Luminance) Exposure: 72 x 5min. Luminance binned 1x1; 15 x 4min. each R,G & B binned 1x1 Acquisition: Images Plus Camera Control v4.0c Processing: Bias & flat calibration in Images Plus v4.0; bad pixel map in Nebulosity 2.3.6c; Registration in RegiStar; Min/Max excluded average & HDR-DDP in Images Plus Post-processing: Adobe Photoshop CS5; Carboni’s Tools; Gradient XTerminator; Noise Ninja; HLVG Temperature (begin - end): N1:52.1F-45.5F; N2:73.5F-72.3F; N3:49.8F-44.0F SQM reading (begin - end): N1:19.11-19.37; N2:18.92-19.09; N3:18.96-19.39 Date(s): April 2, 3 & 5 2011 Location: Hendersonville, TN, USA