NGC 6124, mag. +5.8, is a fine open cluster located in the constellation of Scorpius. It's faintly visible to the naked eye, appearing as a hazy unresolved patch of light, and a superb sight in binoculars and small telescopes. The cluster covers 29 arc minutes of apparent sky, which is equivalent to the apparent diameter of the full Moon. In total, NGC 6124 contains over 100 stars and is fully resolvable in large amateur scopes. This rewarding cluster would almost certainly be much better known if it weren't located at such a southerly declination.
NGC 6124 was discovered by Nicholas Louis de Lacaille during his 1751-1752 journey to South Africa. It's best seen from southern and equatorial locations during the months of May, June and July.
Positioned in the southwestern corner of Scorpius, NGC 6124 is close to the Norma and Lupus constellation boundaries. Red supergiant Antares (α Sco - mag. +1.0), the brightest star in Scorpius, is positioned 14 degrees directly to the north.
Binoculars reveal a large round patch of light that hints on resolution. Switching between direct and averted vision causes a sprinkling of stars to pop in and out of view. Through a 100mm (4-inch) refractor, many members are resolvable including several 9th magnitude examples at the centre. A 200mm (8-inch) scope reveals a loose cluster of dozens of stars that easily fills the eyepiece field of view. There are several nice chains visible and a few lovely pairs of double stars. Even larger scopes, resolve the cluster completely.
NGC 6124 is number 75 in the Caldwell catalogue. It's 1,670 light-years distant and spans 15 light-years in actual diameter.
NGC 6124 Data Table
|Object Type||Open Cluster|
|RA (J2000)||16h 25m 20s|
|DEC (J2000)||-40d 39m 13s|
|Apparent Size (arc mins)||29|
|Age (years)||140 Million|
|Number of Stars||125|
|Other Names||Collinder 301, Melotte 145|