M33 'Pinwheel Galaxy' - Triangulum

Object data: M33 (NGC 598, the 'Pinwheel Galaxy') is a prominent member of the Local Group of galaxies, along with the Milky Way, M31 and some smaller galaxies. With a diameter of around 50,000 light years it is not a large galaxy (compared for example to the 200,000 light year diameter of M31) but its large apparent diameter (73 arc minutes) and relatively high visual brightness (Mag. 5.7) are both attributable to its close proximity of only 3 million light years. This makes it only fractionally more distant than M31. A feature of M33 is the lack of a bright core and low overall surface brightness. With a brighter core M33 should be an easy naked eye object. The mass of M33 has been estimated at around 25 billion solar masses. It has probably been observed as long ago as the 17th century but was independently discovered and catalogued by the great comet hunter Charles Messier in August 1764. Date: 06/09/03 Location: Southern France Conditions: Calm, no dew, transparency=8, seeing=6 Optics: Astro-Physics 155 EDF f/7 working at f/5.2 with AP reducer. Mount: AP 900 GTO on Portable Pier Camera: SBIG ST-8E / CFW-8 Guiding: Integral ST-8E autoguider Exposure: LRGB: Luminance: 6x10 minutes; RGB: 10:10:20 minutes binned 2x2 Processing: Image acquisition and initial processing was done using Maxim DL and AIP4WIN, subsequent processing was done using Registar and Photoshop. Notes: This image replaces my earlier film image taken on 10th and 17th October 1999 from Wiltshire, England.