NGC 247 (Galaxy)
A large, faint spiral galaxy in Cetus, 2.9° south of Diphda. SIMBAD classes it as a low-surface-brightness galaxy: its light is spread thin over an oval 20 arcminutes long.
Galaxy in Cetus. Magnitude 9.2.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 63° above the southern horizon at its highest; from Lethem (3.4° N), to 66° above the southern horizon. It is highest at midnight on the night of 30 Sep, 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 2.9° south of Diphda.
- 10x50 binoculars: Just detectable in binoculars from a dark site, as a faint smudge.
- A small telescope (80 to 100 mm): A very faint, long oval glow; a dark site and low power are a must.
- 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: 19.7′ × 5.5′, 63% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 9.2. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 12 million light-years. The light reaching your eye left it about 12 million years ago.
- True size: 68,000 light-years across its catalogued outline; light crosses it in 68,000 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Spiral galaxy
What is in it, not measured:
- Stars: an older central bulge and a disc of younger stars
- Gas and dust: in the spiral arms, where new stars form
- Dark matter: inferred from how fast it spins
How we know: Distance from Cepheid variable stars and its brightest red giants (the tip of the red giant branch): NED-D (NASA/IPAC Extragalactic Database, redshift-independent distances), median of 18 Cepheids/TRGB estimates: 3.65 Mpc, 3.36-3.87 Mpc (16th-84th percentile); e.g. 2016MNRAS.457.1419M, 2016AJ....151...88B, 2010ApJ...715..277B; retrieved 2026-10-21. True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2).
More deep-sky objects: Sculptor Galaxy (NGC 253) · NGC 300 (Galaxy) · NGC 55 (Galaxy) · NGC 1097 (Galaxy) · M77 (Cetus A) · Fornax A (NGC 1316)