M70 (Globular Cluster)
A small globular cluster in Sagittarius, 2.5° from M69 and at almost the same distance. Three quarters of its red giants are chemically enriched second-generation stars.
Globular cluster in Sagittarius. Magnitude 7.9.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 51° above the southern horizon at its highest; from Lethem (3.4° N), to 54° above the southern horizon. It is highest at midnight on the night of 30 Jun, 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 4.5° north-east of Kaus Australis.
- 10x50 binoculars: A round glow, brighter towards the middle.
- A small telescope (80 to 100 mm): A faint, round glow with a dense core; it looks like M69's fainter twin.
- 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: 6.6′, 21% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 7.9. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 30,500 light-years. The light reaching your eye left it about 30,500 years ago.
- True size: 59 light-years across its catalogued outline; light crosses it in 59 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Globular cluster
- Mass
- About 105,000 times the Sun's mass
- Notable
- Its first-generation share, 23%, is lower than in all but 5 of the 54 clusters Milone et al. measured.
Measured: Which generation its red giants belong to (527 measured near its centre).
- Second generation: 76.6%, born from gas the first stars enriched
- First generation: 23.4%, ± 1.9%
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: 23.4% ± 1.9% first generation among 527 red giants (NGC 6681; 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 6681: 9.36 +/- 0.11 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 6681: 105,000 ± 2,120 Suns), retrieved 2026-10-21; Baumgardt & Vasiliev 2021, MNRAS 505, 5957.
More deep-sky objects: M69 (Globular Cluster) · M54 (Globular Cluster) · M28 (Globular Cluster) · Globular Cluster M22 · Ptolemy Cluster (M7) · M55 (Globular Cluster)