Jewel Box Cluster (NGC 4755)
A striking open cluster in Crux, near the Coalsack Nebula. Its colorful stars are visible with binoculars or a small telescope.
Open cluster in Crux. Magnitude 4.2.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 23° above the southern horizon at its highest; from Lethem (3.4° N), to 26° above the southern horizon. It is highest at midnight on the night of 2 Apr, 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. From Guyana it only reaches 23° above the southern horizon, so you need a clear, low view south.
- 10x50 binoculars: Resolves into dozens of stars.
- A small telescope (80 to 100 mm): A compact group with one orange star among blue-white ones.
- 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: 10′, 32% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 4.2. Brighter than the faintest stars Georgetown shows (4.3), and Lethem's (6.0).
- Distance: 6,440 light-years. The light reaching your eye left it about 6,400 years ago.
What it is made of
- Type
- Open Cluster
- Distance
- Approx. 6,440 Lightyears
- True size
- Approx. 14 Lightyears diameter
- Blue Supergiants: Young, hot, luminous stars
- Red Supergiant (Kappa Crucis): Bright, evolved massive star
- Other Young Stars: Variety of spectral types
More deep-sky objects: Wishing Well Cluster (NGC 3532) · Omega Centauri (NGC 5139) · Southern Pleiades (IC 2602) · IC 2391 (Omicron Velorum Cluster) · NGC 2516 (Southern Beehive / Diamond Cluster) · NGC 6231 (Northern Jewel Box)