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

Exposure details:


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)