Catalogue and alternative designations M4, NGC 6121   Type Globular Cluster  Position  16 23.6, -26 32 Constellation Scorpius Camera and Telescope STL11000M and 31.75 cm Ritchey Chretien (RCOS carbon tube model) Focal Ratio F9 Exposure Details LRGB 50:30:30:30 All 1x1 Description This bright globular cluster is one of the nearest to earth and is visible to the naked eye under a very dark sky.  The most noticeable feature is the bar of brighter stars running across the centre.  This is visible in quite small telescopes.