Spiral Galaxy M96 (NGC 3368), type Sa, in Leo.  M96 is the brightest member of the Leo I group of galaxies and is estimated to be about 41 million light years distant. 

The apparent diameter of its brighter central region, 6 arc minutes, corresponds to a linear dimension of 66,000 light years. However, as can be seen, this galaxy has faint extensions, an outer ring of filaments (spiral arm fragments). This ring has a diameter of at least about 9 arc minutes, corresponding to about 100,000 light years.

Image info

Telescope:  Celestron 9.25" Schimdt-Cassegrain at f/6.3

Focus:  Prime focus

Filter:  Celestron LPR

Mount:  Vixen GPD with Skysensor2000

Camera:  Modified Canon EOS 300D, at ISO400

Guiding:  700mm refractor guidescope, SAC7 camera, autoguided with Guidedog software

Exposure:  Total 76 mins (19 x 240s)

Date:  15th January 2005

Processing:  RAW file conversion, Offset and Dark subtraction, flat fielding, registering and stacking done in IRIS.  Curve stretching and colour saturation enhancement by Luminance Layering in Photoshop CS.

Comments

One of the first images taken with autoguiding - there is a slight ovalling of stars in RA due to mount excursions.  However a very transparent night!  The dim halo around the galaxy is visible - notice the edge-on background galaxy on the left edge of M96, as well as other background galaxies (all the PGC galaxies on my chart are visible in this image, and then some).  With reference to USNO-B faintest star visible is about 18.3 mag.