Messier 13. The Great Globular Cluster in Hercules.

Note
I aquired the subs of M13 under two different occasions and at both times the main problem was light pollution and windy conditions.


About
Messier 13 or M13 (also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster) is a globular cluster in the constellation of Hercules.
M13 was discovered by Edmond Halley in 1714, and catalogued by Charles Messier on June 1, 1764.
It is located at right ascension 16h 41.7m and declination +36° 28'. With an apparent magnitude of 5.8, it is barely visible with the naked eye on a very clear night. Its diameter is about 23 arc minutes and it is readily viewable in small telescopes. Nearby is NGC 6207, a 12th magnitude edge-on galaxy that lies 28 arc minutes directly north east. A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular cluster's center.
M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is the variable star V11 with an apparent magnitude of 11.95. M13 is 25,100 light-years away from Earth.
The Arecibo message of 1974, designed to communicate the existence of human life to hypothetical extraterrestrials, was transmitted toward M13. The reason was that with a higher star density, the chances of a life harboring planet with intelligent life forms, were higher. Even though the message was transmitted, M13 will no longer be in that location when it arrives. The sending of the message was more of a technological demonstration, rather than an actual attempt to contact life.

Processing
CCD Stack and CS5

Exposure
Lum 10 x 5 min. RGB 5 x 5 min

Calibration
Darks, bias and flats.

Filters
Baader LRGB.

Cooling temp
-20´ C

Mean FWHM
3.10"

Date
March 31st 2011

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

Image aqusition
MaximDL Pro

Scope control
Sky X Pro Native drv, and Maxim DL with Astro-Physics V2 drv.

Telescope
TEC APO 140

Mount
Astro-Physics Mach 1 GTO

Camera
QSI 583 WSG

Guiding
OAG guiding with Lodestar Guider

Focus system
Starlight Micro Touch and Focus MAX.


Inverted B/W image