M54
Globular Cluster in Sagittarius
About
A dense globular cluster in Sagittarius, about 80,000 light-years away. It is not part of our Galaxy's own halo population: since 1994 it has been linked to the Sagittarius Dwarf Galaxy, possibly as that galaxy's core. A black hole of intermediate mass was reported at its centre in 2009.
Imaging tips
- Only 9′ across: 2,690–4,490 mm on APS-C, and too small for a full-frame sensor to frame usefully; it needs a long focal length.
- Its stars pile up so tightly toward the centre that, even with logarithmic scaling, the core and outer stars were hard to show together in a 16-inch R-band image.
- It never climbs above 10° from 50°N (25° from 35°N), so a low southern horizon and a clear atmosphere decide the result.
- Best around June and July.
Facts
- Size
- 9′
- Magnitude
- 7.6
- Coordinates
- RA 18h 55.1m, Dec −30° 29′
- Framing, APS-C
- 2690–4490 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jun, Jul
- Peak altitude
- 10° from 50°N, 25° from 35°N