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Dates & Location

1st February 2012 using the SMAP site at Weed, New Mexico. Elevation 7269 ft. Lat 32.8°N Long 195.5W  

Catalogue identification

M 13 .
NGC 6205.
The Great Hercules Globular Cluster.

Equipment Used

Officina Stellare RC400 at 3278mm focal length, F8.2.
Paramount ME German equatorial Mount.
Camera SBIG ST-11000M with FW-8L filter wheel.
AstroDon MMOAG with SBIG Remote Guide Head.
Optec Pyxis 3" Rotator.
TheSky V6 telescope control.
CCDSoft V 5.0 camera control.
ScopeDome remote observatory.


Where it is in space

In the constellation of Hercules and approx 2.5° South of the Eta Herculis. In this image North is in the 2 o'clock direction. It sits in the halo (central bulge) of maybe 150 globular clusters that orbit our Milky Way galaxy. The M13 is about 20,000 light years from us. It is visible to the naked eye in dark sky conditions.

Remote session using RADMIN PC control from Ravenshead, UK.
Exposures: 1 x 5 min Lum + 1x5 min each for R:G:B at,
-25°C. All images binned 1x1. Image acquired using CCDAutoPilot.
First image to be taken with the new off-axis guider, the new Officina Stellare secondary focuser and CCDAP.

  What it is

M 13 is a spherical, gravitationally bound, agglomeration of several hunderds of thousands of stars. Spectroscopic study of globular clusters shows that they are much lower in heavy element abundance than stars such as the Sun that form in the disks of galaxies. Thus, globular clusters are believed to be very old and formed from an earlier generation of stars (Population II). More recent estimates yield an age of 12 to 20 billion years; the best value for observation is perhaps 14 to 16 billion.Radial velocity measurements have revealed that most globulars are moving in highly eccentric elliptical orbits that take them far outside the Milky Way; they form a halo of roughly spherical shape which is highly concentrated to the Galactic Center, but reaches out to a distance of several 100,000 light years, much more than the dimension of the Galaxy's disk. As they don't participate in the Galaxy's disk rotation, they can have high relative velocities of several 100 km/sec with respect to our solar system; this is what shows up in the radial velocity measurements.

Processing Methods

Image acquisition with CCDSoft V5/ TheSky6.  
  Data reduction with CCDStack. Lum and RGB masters and RGB colour combine prepared and in CCDStack.  

Final LRGB processing using PhotoShop CS2.