Alpha Persei Cluster (Melotte 20)
A brilliant and sprawling open cluster surrounding the star Mirfak (Alpha Persei) in Perseus, easily visible to the naked eye.
Open cluster in Perseus. Magnitude 1.2.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 47° above the northern horizon at its highest; from Lethem (3.4° N), to 43° above the northern horizon. It is highest at midnight on the night of 9 Nov, 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 from a dark site as a scatter of stars around Mirfak, low in the north (47° from Georgetown).
- 10x50 binoculars: Dozens of bright blue-white stars: one of the finest binocular sights.
- A small telescope (80 to 100 mm): Far too big for a telescope; use binoculars.
- A camera: Spans about 40% of an APS-C frame at 135 mm (field 9.9° × 6.6°); needs a tracking mount.
How big, how bright, how far
- Size on the sky: 243′, 7.8 Moons across (the Moon is about 31′ wide).
- Brightness: magnitude 1.2. Brighter than the faintest stars Georgetown shows (4.3), and Lethem's (6.0).
- Distance: 557 light-years. The light reaching your eye left it about 560 years ago, around the year 1470.
What it is made of
- Type
- Open Cluster
- Distance
- Approx. 557 Lightyears
- True size
- Approx. 30 Lightyears diameter
- Young Hot Stars (B-type): Including Alpha Persei (Mirfak)
- Other Young Stars: Loosely bound group
More deep-sky objects: Double Cluster (NGC 869 & NGC 884) · Kemble's Cascade & NGC 1502 · M103 (Open Cluster) · NGC 752 (Open Cluster) · NGC 457 (ET Cluster / Owl Cluster) · Pleiades (M45)