Globular Cluster in Ophiuchus

Messier 9 is a densely packed globular cluster. Compare its appearance to my image of Messier 10, which is shown at approximately the same scale. These two clusters actually have about the same diameters, but Messier 10 is closer to us, and it is a more impressive sight in amateur telescopes. However, M9 is estimated to have about twice the mass of M10, due to its greater density of stars.

There are many stars of the Milky Way in the background, but fewer are visible in the lower right corner of this image. This because M9 is bordered to the southwest by a dark nebula, Barnard 64, which obscures the light of the stars beyond it.

Magnitude 8
Apparent Size 9'
Distance (light yrs) 25,000
Right Ascension 17:19.2
Declination -18 31
Field of View 21' x 16'

Image details: Exposure times of 15 minutes luminance and 6 minutes each of red, green and blue, taken with an SBIG 8300M imager and a 12" Meade telescope at f/10. 

June 2012