Click for larger image (50%)


Catalogue and alternative designations NGC 6231


Type Open Cluster 
Position  16 54.0, -41 48
Constellation Scorpius
Camera and Telescope STL11000M and FSQ106ED
Focal Ratio F5
Exposure Details Two panel HaLRGB mosaic with Baader filters.  About 11 hours total imaging time
Description Possibly one of the best open clusters in the sky, NGC 6231 is easily visible in binoculars and under very dark skies can be glimpsed without optical aid.  It was discovered by Lacaille in 1755.  This cluster is part of the Scorpius OB1 association.  The interesting nebula IC 4628 can be seen above.  It is sometimes known as the "prawn".  The Scorpius "dark tower" can be seen to the right.