M 75 Deep sky · Globular cluster in Sagittarius · M 75 · NGC 6864
M 75
One of the most tightly packed globular clusters known, far out in Sagittarius — one of the more remote in Messier’s list.
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- Type
- Globular cluster
- Designations
- M 75 · NGC 6864
- Constellation
- Sagittarius
- Apparent magnitude
- 9.2
- Apparent size
- 7′ × 2′
- Position (J2000)
- RA 20h 06m · Dec −21° 55′
The full Moon, about 31′ across, is 4.6 times as wide. The Sun passes 2° from it around mid January, and for about 30 days of the year it sits within 15° of the Sun, lost in its glare.
When to see it
On the night of Wed 21 Jul 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 21:11 | 01:10 · 17° | 05:08 |
| New York EDT | 20:26 | 01:04 · 27° | 05:43 |
| Singapore GMT+8 | 19:18 | 01:15 · 67° | 07:12 |
| Sydney GMT+10 | 17:05 | 00:06 · 78° | 07:07 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 18° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 77° up in the north.
- When is the best time of year to see it?
- Around late July, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid October it is highest in the early evening, and in mid April not until the hours before dawn.
- How bright is it?
- Magnitude 9.2 in total, but that light is spread over 7′ × 2′ of sky: on average 20.6 magnitudes per square arcsecond. That is concentrated enough to stand out even against a city’s glow.
- Naked eye, binoculars or telescope?
- Binoculars. At magnitude 9.2 it is past the eye, but a 50 mm pair under a dark sky reaches about magnitude 11.0.
Look for
It lies in eastern Sagittarius, well away from the Milky Way. A telescope shows a small, bright core in a faint halo.
Look for
From 50° north it climbs to 18°; from 35° north it climbs to 33°; from the equator it climbs to 68°; from 35° south it climbs to 77°.
Look for
Magnitude 9.2 against the faintest star each can show: the eye under a city sky, 4.5 (4.7 short); the eye under a dark country sky, 7.0 (2.2 short); 50 mm binoculars under that dark sky, 11.0 (1.8 to spare); a 100 mm telescope there, 12.5 (3.4 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 2% of the field’s width; through a 100 mm telescope at 50×, a field about 1° across, it spans 11% of the field’s width.
Words used here
Its constellation
Nearby in Sagittarius
- Nebula Lagoon Nebula
- Nebula Trifid Nebula
- Globular cluster Great Sagittarius Cluster
- Nebula Omega Nebula
- Open cluster Black Swan Cluster
- Open cluster Webb's Cross
- Open cluster M 23
- Open cluster Small Sagittarius Star Cloud
- Open cluster M 25
- Globular cluster M 28
- Globular cluster M 54
- Globular cluster Specter Cluster
- Globular cluster M 69
- Globular cluster M 70