After M31 and M33, M101 (NGC5457) is the most extended galaxy visible in the northern sky, with an apparent dimension of 30'x 26'. Its integrated magnitude is 7,7; however, this is very difficult to be observed, because the surface brightness is very low. This object appear beautiful with binoculars which have an exit pupil around 5-6 mm., because is used all the opening of the human eye. With telescopes, however, can be revealed many HII regions which are not visible with low power. With long exposures and the actual imaging setup, this Sc spiral galaxy appear really magnificent and is one of the most exciting target for all the astrophotographers.

Camera : Starlight Xpress SXV-H9 with Astronomik LRGB dichroic filters


Telescope : Takahashi FS-102 at F/8 on a GM2000-FS2


Guiding : ST4 on a Vixen 80/910mm.


Exposure : L 6x600sec. - RGB 3x300sec. each all unbinned


Processing : MaxIm (align, combine, DDP) - Photoshop (final enhancing)


Location : St. Barthelemy (Val d'Aosta) - 1800 mt. height


Date : December 12, 2004

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