NGC 2477 (Open Cluster)
A very rich open cluster in Puppis, with about 3,500 Gaia member stars. It weighs about 12,000 Suns, the third heaviest open cluster on this site.
Open cluster in Puppis. Magnitude 5.8.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 45° above the southern horizon at its highest; from Lethem (3.4° N), to 48° above the southern horizon. It is highest at midnight on the night of 16 Jan, 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: Visible to the eye only from a dark site, as a hazy knot of stars; lost in city skies. It lies 2.7° north-west of Naos.
- 10x50 binoculars: Resolves into dozens of stars. NGC 2451 is 1.5° away.
- A small telescope (80 to 100 mm): A dense swarm of faint stars, like a loose globular; NGC 2451 is 1.5° to the west.
- A camera: Spans about 40% of an APS-C frame at 1,500 mm (field 0.9° × 0.6°); needs a tracking mount.
How big, how bright, how far
- Size on the sky: 18.6′, 60% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 5.8. Fainter than Georgetown's faintest stars (4.3) but brighter than Lethem's (6.0).
- Distance: 4,500 light-years. The light reaching your eye left it about 4,500 years ago.
- True size: 24 light-years across its catalogued outline; light crosses it in 24 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Open cluster
- Mass
- About 12,100 times the Sun's mass, in its stars
- Age
- About 700 million years (range 490 million years to 1.1 billion years)
- Notable
- Rich and heavy: 3,543 Gaia member stars and about 12,100 Suns.
What is in it, not measured:
- Stars born together: from one cloud of gas, at one time
- Red giants: stars that have already aged and swollen
How we know: Distance from Gaia parallaxes of its stars: Hunt & Reffert 2024, A&A 686, A42 (Gaia DR3 cluster catalogue, VizieR J/A+A/686/A42), retrieved 2026-10-21: NGC 2477 1,384 pc; statistical 4,511-4,516 ly (16th-84th percentile); Gaia DR3 parallax zero-point systematics (about 0.02 mas) add about 3%. True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2). Mass: Hunt & Reffert 2024, A&A 686, A42 (Gaia DR3 cluster catalogue, VizieR J/A+A/686/A42), retrieved 2026-10-21, NGC 2477: total 12,080 ± 507 Suns.
More deep-sky objects: NGC 2451 (Open Clusters) · NGC 2547 (Open Cluster) · NGC 2467 (Nebula and Cluster) · IC 2395 (Open Cluster) · M93 (Open Cluster) · NGC 2362 (Open Cluster)