M22 — Sagittarius Cluster
Globular Cluster in Sagittarius
About
A globular cluster in Sagittarius, about 10,600 light-years away and among the brightest in the sky. It is one of only four Milky Way globular clusters known to contain a planetary nebula, and radio and X-ray studies have found two stellar-mass black holes in it.
Imaging tips
- Framing: roughly 1,010–1,680 mm on APS-C, or 1,550–2,580 mm on full frame.
- It does not need long integration: nine 1-minute frames at 420 mm gave a usable image, and 40 minutes (four 10-minute subs) at 1,025 mm served another imager.
- Dust toward the galactic centre dulls its colour and contrast, so allow time for colour balance in processing.
- Broadband suits a globular cluster. It stays low for northern observers (about 16° at most from 50°N), and is best around June and July.
Facts
- Size
- 24′
- Magnitude
- 5.1
- Coordinates
- RA 18h 36.4m, Dec −23° 54′
- Framing, APS-C
- 1010–1680 mm
- Framing, full frame
- 1550–2580 mm
- Best months
- Jun, Jul
- Peak altitude
- 16° from 50°N, 31° from 35°N