About image
Messier 12 (NGC 6218) is a globular cluster in the constellation of Ophiuchus.
It is about 16,400 light-years from Earth and has a diameter of about 75 light-years: its brightest stars are of 12th magnitude.
It is rather loosely packed for a globular and was once thought to be a tightly concentrated open cluster
[text adapted from Wikipedia].
It is nice to see through the cluster’s stars those two faint galaxies (catalogued as PCG 1103219).
Technical data
Optic GSO RC12 Truss - Aperture
304mm, focal lenght 2432mm, f/8
Mount 10Micron GM2000 HPSII
Camera ZWO ASI 2600 MM Pro with filter wheel 7 positions
Filters Astrodon Gen2
E-Serie Tru-Balance 50mm unmounted RGB
Guiding system ZWO OAG-L with guide camera ASI 174MM Mini
Exposure details L 30x120" bin3 -15C
R 13x120" bin3 -15C
G 14x120" bin3 -15C
B 12x120" bin3 -15C
Total integration 2h18'
Acquisition Voyager, PHD2
Processing Pixinsight 1.8,
Photoshop CS5, NoiseXTerminator
SQM-L 21.00
Location Promiod (Aosta
Valley, Italy), own remote observatory
Date 27 May/26 June 2023