Thank you very much everyone
M33 at first sight looks bright, it even looks reasonable on the monitor - but in fact it has an extremely low surface brightness. If you look at the outer regions of the galaxy they are very faint even with such a long exposure time. The galaxy itself may even look (at first sight) noisy, but this is in fact unresolved stars.
Nexstar 11 GPS, 2 x Sky 90, M25C, MaximDL, Photshop CS3, Noel Carboni's Photoshop actions, 7 foot Pulsar fibreglass dome, Canon 40D, 100mm macro lens, 28-200mm zoom lens, 17-55mm f#2.8 zoom lens, 100-400mm zoom lens, 1.4x converter, 2x converter.