M13 Globular Cluster

clic for 50% size 1915 x 1290 (600 kB)


About this Image

M13, also called the `Great globular cluster in Hercules', is one of the most prominent and best known globulars of the Northern celestial hemisphere. At its distance of 25,100 light years, its angular diameter of 20' corresponds to a linear 145 light years. It contains several 100,000 stars, most of them very old. Towards its center, stars are about 500 times more concentrated than in the solar neighborhood. Older stars appear yellow, hotter stars appear blue.

Background galaxies shine through the cluster in the widefield image above. North is up.

Below you see a crop on the center of the above image in 30/70% size.

clic for 70% size 1611 x 1299 (590 kB)


Technical Details


16" cassegrain in secondary focus at f/10

Mount MK-100 GEM
Camera SBIG STL-11000M at -25C, internal filter wheel
Filters Astronomik LRGB
Date Apr 02, 2005.
Location Wildon/Austria
Sky Conditions mag 5 sky, raw FWHM 1.8-2", temperature 5 C
Exposure L:R:G:B = 40:20:20:20 minutes (10-minute sub-exposures for RGB, 5 min subs for L),
Processing Image aquisition in Maxim, image calibration, aligning, DDP in ImagesPlus; color balance, curves, unsharp mask in Photoshop; Noise reduction by Neatimage;
north is up;