The Pinwheel Galaxy (M 101)

clic for 36% size 1372 x 939 (380 kB)

Clic here for 60% size 2286x1565 (750 kB)


About this Image

The Pinwheel Galaxy M 101 is one of the most prominent face on spirals in the sky. While quite symmetric visually and in very short exposures which show only the central region, it is of remarkable unsymmetry, its core being considerably displaced from the center of the disk.
Close gravitational interaction with a neighboring galaxy created waves of high mass and condensed gas which continue to orbit the galaxy center. These waves compress existing gas and cause star formation.
Halton Arp has included M101 as No. 26 in his Catalogue of Peculiar Galaxies as a "Spiral with One Heavy Arm". It lies at 25 million light years distance in the constellation of Ursa Major. North is to the left.

Checkout a wider image taken at F/3: here.

A closeup at the center of M101 in 50/80% size is shown below.

Hubble mosaic of M 101: 1.
Tidal Interaction in M 101: 2.

clic for 80% size (278 kB)


Technical Details


16" cassegrain in secondary focus at f/10

Mount MK-100 GEM
Camera SBIG STL-11000M at -20C, 1x1 bin, internal filter wheel
Filters Astronomik LRGB
Date May 20-21, 2007.
Location Wildon/Austria
Sky Conditions mag 5 sky, FWHM = 1.6-2" for L, temperature 15 C
Exposure L = 240 minutes (30-minute sub-exposures), color from F/3
Processing Image aquisition in Maxim DL 4.56, Preprocessing and deconvolution in CCDStack; Fitsliberator; Curves, high pass filter, unsharp mask, color balance in Photoshop;