M69
Globular Cluster in Sagittarius
About
NGC 6637, a globular cluster in Sagittarius about 28,700 light-years away and roughly 5,200 light-years from the Galactic Centre. It is one of the more metal-rich globular clusters known, and Messier found it the same night as M70.
Imaging tips
- About 9′ across, so 2,690–4,490 mm on APS-C; it is too small for full frame to fill, so use a long focal length.
- It sits very low from northern sites: it stays below 8° altitude from 50°N, and only reaches 23° from 35°N.
- One imager shot it near the horizon in southern France with a red filter: six 5-minute frames on an f/4.8 refractor.
- The cluster lies in dense bulge starfield; a university team used logarithmic scaling to keep both the core and the surrounding stars visible.
- Best around June and July.
Facts
- Size
- 9′
- Magnitude
- 7.6
- Coordinates
- RA 18h 31.4m, Dec −32° 21′
- Framing, APS-C
- 2690–4490 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jun, Jul
- Peak altitude
- 8° from 50°N, 23° from 35°N