M13 – 300000 Suns on a ball
M13 is one of the best globular clusters on the Northern hemisphere. It has 300000 stars on a 150 light-years sphere.
Photographically, this object is very attractive due to its brightness and size although requires a careful processing of the core to avoid burning the stars on the dense center of the cluster.
A tiny galaxy 15.2 magnitude (IC4617) is on the scene background.
Visually, the twinkling stars on the border of the cluster provides a touching effect when observed through a good amateur telescope with enough diameter.
This image has not required a very long exposure time. Five hours exposure have been enough to show all the magnificence of this cluster.
Optics: Ritchie-Chretien GSO RC10 f/8 scope
Camera: SBIG STL-6303
M13 image is a LRGB composition of:
– Luminance: 27 images, 180 seconds each using L filter (binning 1x1) (81 minutes)
– Red channel: 17 images, 300 seconds each using R filter (binning 2x2) (85 minutes)
– Green channel:11 images, 300 seconds each using G filter (binning 2x2) (55 minutes)
– Blue channel: 14 images, 300 seconds each using B filter (binning 2x2) (70 minutes)