M81 - Bode's Galaxy in Ursa Major

Object data: M81 (NGC3031, Bode's Galaxy) is a large magnitude 7 galaxy located in Ursa Major. It has a bright core and is therefore easily observed with small instruments. It was discovered by JE Bode in December 1774 and catalogued by Messier in February 1781. M81 is relatively close, at about 12 million light years. The long dimension is estimated to be about 36,000 light years across and the total mass is equivalent to about 250 billion suns. Date: 09/02/05 Location: Southern France Conditions: Calm, no dew, transparency=9, seeing=8 Optics: Ritchey-Chretien 12.5" f/9 (from RCOS)working at f/6.7 with AP reducer Mount: AP 900 GTO on Portable Pier Camera: SBIG ST-8E / CFW-8 Guiding: Integral ST-8E autoguider Exposure: LRGB: Luminance: 8x10 minutes; RGB: 10:10:20 minutes binned 2x2 Processing: Image acquisition and initial processing was done using Maxim DL, subsequent processing was done using RegiStar and Photoshop. The processing method has been recently updated based on Russell Croman's resources page and advice from Adam Block for which I am indebted. Notes: This is my first CCD attempt at M81 and replaces my earlier film image. Sky conditions were excellent with superb transpareny and seeing around 2.4 arc seconds.