The Pinwheel Galaxy (M101)

The Pinwheel Galaxy (also known as Messier 101M101 or NGC 5457) is a face-on spiral galaxy distanced 21 million light-years (six megaparsecs) away in the constellation Ursa Major.
M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is seventy percent larger than the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small bulge of about 3 billion solar masses.

Another remarkable property of this galaxy is its huge and extremely bright H II regions, of which a total of about 3,000 can be seen on photographs. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by large numbers of extremely bright and hot young stars.

Imaging telescopes or lenses: GSO Newton 8″ f/5
Imaging cameras: Canon EOS 350D / No filter
Mounts: Sky-Watcher EQ6 Syntreck
Guiding telescopes or lenses: GSO Viewfinder 8X50
Guiding cameras: Orion SSAG
Focal reducers: TS Koma Korrektor
Software: PHD guiding, photoshop
Filters: Astronomik 12nm Hydrogen Alpha Filter ha12nm ccd clip, Astronomik CLS CCD Filter
Dates: Feb. 9, 2013, Feb. 18, 2013, March 11, 2013
Astronomik CLS CCD Filter: 10×240″ ISO800
Astronomik CLS CCD Filter: 34×300″ ISO800
Astronomik 12nm Hydrogen Alpha Filter ha12nm ccd clip: 18×300″ ISO800
Integration: 5.0 hours
Darks: ~12
Flats: ~12
Bias: ~12

Author: Fredéric Segato

AstroPhotography of the day by SPONLI
9 April 2014