Double Cluster (NGC 869 & NGC 884)
Two brilliant open clusters (h Persei and Chi Persei) close together in Perseus, a stunning sight for the naked eye and binoculars.
Open cluster in Perseus. Magnitude 3.8.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 40° above the northern horizon at its highest; from Lethem (3.4° N), to 36° above the northern horizon. It is highest at midnight on the night of 24 Oct, 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.
- 10x50 binoculars: Two rich clusters side by side in one field.
- A small telescope (80 to 100 mm): Both clusters fit at low power: hundreds of stars.
- A camera: Spans about 40% of an APS-C frame at 500 mm (field 2.7° × 1.8°); needs a tracking mount.
How big, how bright, how far
- Size on the sky: 59′ × 30′, 1.9 Moons across (the Moon is about 31′ wide).
- Brightness: magnitude 3.8. Brighter than the faintest stars Georgetown shows (4.3), and Lethem's (6.0).
- Distance: 7,500 light-years. The light reaching your eye left it about 7,500 years ago.
What it is made of
- Type
- Open Cluster Pair
- Distance
- Approx. 7,500 Lightyears
- True size
- Approx. 70 Lightyears combined diameter
- Young Hot Stars (O & B type): Thousands in each cluster, very luminous
- Red Supergiants: A few evolved massive stars present
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More deep-sky objects: M103 (Open Cluster) · NGC 457 (ET Cluster / Owl Cluster) · Alpha Persei Cluster (Melotte 20) · Kemble's Cascade & NGC 1502 · NGC 7789 (Caroline's Rose / White Rose Cluster) · NGC 752 (Open Cluster)