Messier 101, The Pinwheel Galaxy.

Note
Could have been streched somewhat further I think. Guiding errors present, the seeing was not perfect. I am still struggling with consistancy in the image processing.


About
The Pinwheel Galaxy (also known as Messier 101 or NGC 5457) is a face-on spiral galaxy about 23 million light-years away in the constellation Ursa Major. It was discovered by Pierre Méchain on March 27, 1781, and he subsequently communicated his discovery to Charles Messier who verified its position and added it to the Messier Catalogue as one of the final entries.

M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is nearly twice the size of 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.

On photographs M101 can be seen to be asymmetrical on one side. It is thought that in the recent past (speaking in galactic terms) M101 underwent a near collision with another galaxy and the associated gravitational tidal forces caused the asymmetry. In addition, this encounter also amplified the density waves in the spiral arms of M101. The amplification of these waves leads to the compression of the interstellar hydrogen gas, which then triggers strong star formation activity.

Processing
Maxim DL and CS2.

Exposure
16 x 200 sec.

Calibration
Darks only.

Filters
N/A

Cooling temp
-30´ C

Mean FWHM
3.30"

Date
April 19th 2011

Location
Krigslida, Stockholm, Sweden.
N59 06 52.4    E 18 03 54.5

Image aqusition
MaximDL Pro

Scope control
Maxim DL Pro

Telescope
WO FLT 110 DDG

Mount
Celestron CGEM

Camera
SBIG ST-8300C

Guiding
ZS 70 Doublet + QCam 5 Guider

Focus system
Lakeside motorfocus.


Inverted B/W image