Ptolemy's Cluster
Open cluster in Scorpius
An object in the observing catalogue.
Also catalogued as M7, Messier 7, NGC 6475, Ptolemy's Cluster
Measurements and positionShowHide
- Position
- Right ascension 17h 53m 51.2s Declination −34° 47′ 34″J2000
- Where the object sits on the sky, in the coordinate system astronomers use. Right ascension is the east–west figure and declination the north–south one; J2000 names the reference date they are measured against.
- Brightness
- 3.30
- Apparent magnitude. The scale runs backwards — a smaller number is brighter, and around 6 is roughly the faintest the unaided eye can see from a dark site.
- Apparent size
- 22.2 arcminutes
- How large the object looks from here, not how large it is. The full Moon is about 30 arcminutes across, which is a useful thing to compare against.
Catalogue data from OpenNGC (Mattia Verga) · CC-BY-SA-4.0