Messier 12 (Ophiuchus)
Fig. 1 - With an unusually low number of low-mass stars: Messier 12 (NGC 6218) in Ophiuchus, photographed with a 16-inch f/4.5 Dob on an equatorial platform.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| Messier 12 (NGC 6218) | Serpens | 16h47m / -01°57' | 16' | 6.1 mag |
The globular cluster Messier 12 (NGC 6218, Gumball Globular) in the constellation Ophiuchus. Messier 12 is approximately 16,000 light-years from Earth, measures about 75 light-years in diameter and was discovered by French astronomer Charles Messier in 1764. The cluster contains about 200,000 stars and is only loosely packed (source: Wikipedia).
Exposure time: 1h 12min (24x3min) at gain 100 and -10°C, taken on June 10 / 11, 2023, were added for this shot with Astro Pixel Processor (APP) software and the final image processing was done in Photoshop. Darks, flats, darkflats and bias frames were used.
Equipment: Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform, Lacerta MGEN autoguider, Lacerta off axis system.
Field of view comparison: image of the moon with the same setup.
Fig. 2 - Another representation of Messier 12 (NGC 6218) in Ophiuchus, photographed with a 16-inch f/4.5 Dob on an equatorial platform. In addition to the twenty-four 3-minute exposures from June 10 / 11, 2023, seventy 1-minute exposures from July 8 / 9, 2023, have been used for this mosaic (142 minutes total exposure). A pair of distant galaxies shines through the globular cluster, the brighter of the couple being PGC 1103219 (15.8 mag), 870 million light-years from Earth.
Fig. 3 - Search chart for Messier 12. Copyright 2025 'The Mag-7 Star Atlas Project', www.siaris.net.