M54 (Globular Cluster)
A small, bright globular cluster in Sagittarius, 86,000 light-years away and the second most massive in the Baumgardt database. It is thought to belong to the Sagittarius Dwarf, a small galaxy beside ours, rather than to the Milky Way.
Globular cluster in Sagittarius. Magnitude 7.6.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 53° above the southern horizon at its highest; from Lethem (3.4° N), to 56° above the southern horizon. It is highest at midnight on the night of 3 Jul, in the middle of its season. The page works out tonight's rise, highest point and set for both towns in Guyana time (UTC-4), and where the Moon is.
What you'll see
- Your eyes: Not visible to the eye. It lies 1.7° west of Ascella.
- 10x50 binoculars: A round glow, brighter towards the middle.
- A small telescope (80 to 100 mm): Small and bright, like a fuzzy star; its core stays unresolved even at high power.
- A camera: Tiny on camera: it needs 2,000 mm or more of focal length on a tracking mount.
How big, how bright, how far
- Size on the sky: 5.1′, 16% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 7.6. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 86,000 light-years. The light reaching your eye left it about 86,000 years ago.
- True size: 130 light-years across its catalogued outline; light crosses it in 130 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Globular cluster
- Mass
- About 1.59 million times the Sun's mass
- Notable
- About 1.59 million Suns, the second heaviest of the 167 globulars in the Baumgardt database; it lies inside the Sagittarius Dwarf galaxy.
Measured: Which generation its red giants belong to (2,358 measured near its centre).
- Second generation: 73.3%, born from gas the first stars enriched
- First generation: 26.7%, ± 1.2%
Milone et al. class it Type II: it also holds a third, iron-enriched group of stars, so this two-way split is the simplest reading. Gas: searches of globular clusters mostly find only upper limits (Pancino et al. 2024, arXiv:2404.05548). Hubble ultraviolet colours split its red giants into a first generation and later, chemically enriched ones: 26.7% ± 1.2% first generation among 2,358 red giants (NGC 6715; Milone et al. 2017, MNRAS 464, 3636, Table 2).
Also in it, not measured:
- Stellar remnants: white dwarfs and neutron stars
- Almost no gas or dust: not in this tally
How we know: Distance from Gaia, Hubble and earlier distances to its stars, combined: Baumgardt & Vasiliev 2021, MNRAS 505, 5957; Baumgardt globular cluster database, combined_table.txt, retrieved 2026-10-21 (NGC 6715: 26.28 +/- 0.33 kpc). True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2). Mass: Baumgardt globular cluster database, combined_table.txt (NGC 6715: 1,590,000 ± 28,400 Suns), retrieved 2026-10-21; Baumgardt & Vasiliev 2021, MNRAS 505, 5957.
More deep-sky objects: M70 (Globular Cluster) · M69 (Globular Cluster) · Globular Cluster M22 · M28 (Globular Cluster) · M55 (Globular Cluster) · M25 (Open Cluster IC 4725)