M 15 Deep sky · Globular cluster in Pegasus · M 15 · NGC 7078
Pegasus Cluster
A dense globular cluster off the nose of Pegasus, with a collapsed core and a planetary nebula hidden among its stars.
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- Type
- Globular cluster
- Designations
- M 15 · NGC 7078
- Constellation
- Pegasus
- Apparent magnitude
- 6.3
- Apparent size
- 18′
- Position (J2000)
- RA 21h 30m · Dec +12° 10′
The full Moon, about 31′ across, is 1.7 times as wide. The Sun comes no nearer to it than 25°, around mid February, so it is never lost in the Sun’s glare, which reaches about 15° out.
When to see it
On the night of Wed 11 Aug 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 18:08 | 01:10 · 51° | 08:13 |
| New York EDT | 18:23 | 01:05 · 62° | 07:47 |
| Singapore GMT+8 | 19:16 | 01:16 · 79° | 07:16 |
| Sydney GMT+10 | 18:41 | 00:07 · 44° | 05:32 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 52° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 43° up in the north.
- When is the best time of year to see it?
- Around mid August, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early November it is highest in the early evening, and in mid May not until the hours before dawn.
- How bright is it?
- Magnitude 6.3 in total, but that light is spread over 18′ of sky: on average 21.2 magnitudes per square arcsecond. Against a dark country sky that average stands out; a city’s glow drowns all but its brightest parts.
- Naked eye, binoculars or telescope?
- The naked eye, from a dark country sky, which shows stars to about magnitude 7.0; from a city, binoculars.
Look for
Follow the line from Enif, the horse’s nose, and look north-west: binoculars show a star that will not focus.
Discovery
In the twentieth century it became the first globular cluster known to hold a planetary nebula, Pease 1 — a tiny shell lost in the crowd.
Look for
From 50° north it climbs to 52°; from 35° north it climbs to 67°; from the equator it climbs to 78°; from 35° south it climbs to 43°.
Look for
Magnitude 6.3 against the faintest star each can show: the eye under a city sky, 4.5 (1.8 short); the eye under a dark country sky, 7.0 (0.7 to spare); 50 mm binoculars under that dark sky, 11.0 (4.7 to spare); a 100 mm telescope there, 12.5 (6.2 to spare). Those limits are for a point of light; its light is spread over its whole size, so it needs some of that margin in hand. Through 7×50 binoculars, whose field is about 7.1° across, it spans 4% of the field’s width; through a 100 mm telescope at 50×, a field about 1° across, it spans 30% of the field’s width.