M13 was discovered by Edmond Halley in 1714, and catalogued by Charles Messier on June 1, 1764.With an apparent magnitude of 5.8, it is barely visible with the naked eye on a very clear night. Its diameter is about 23 arc minutes and it is readily viewable in small telescopes. Nearby is NGC 6207, a 12th magnitude edge-on galaxy that lies 28 arc minutes directly north east. A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular's center.
M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is the variable starV11 with an apparent magnitude of 11.95. M13 is 25,100 light-years away from Earth.
Instruments and exposure data:
W.O FLT110 with dedicated TMB field flattener
FeatherTouch 3'' focuser
Starizona MicroTouch autofocuser
W.O ZS80 ED
SBIG ST10XME CFW9
Meade DSI
Filters: LRGB Baader Planetarium
Sky-Watcher EQ6 Pro
L:60*3min bin1x1
R:15*3min bin1x1
G:15*3min bin1x1
W.O FLT110 with dedicated TMB field flattener
FeatherTouch 3'' focuser
Starizona MicroTouch autofocuser
W.O ZS80 ED
SBIG ST10XME CFW9
Meade DSI
Filters: LRGB Baader Planetarium
Sky-Watcher EQ6 Pro
L:60*3min bin1x1
R:15*3min bin1x1
G:15*3min bin1x1