M 29 Deep sky · Open cluster in Cygnus · M 29 · NGC 6913
Cooling Tower
A small open cluster in the Swan, whose few bright stars form a squat box that observers have called the Cooling Tower.
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- Type
- Open cluster
- Designations
- M 29 · NGC 6913
- Constellation
- Cygnus
- Apparent magnitude
- 6.6
- Apparent size
- 10′
- Position (J2000)
- RA 20h 24m · Dec +38° 31′
The full Moon, about 31′ across, is 3.1 times as wide. The Sun comes no nearer to it than 55°, 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 Sun 25 Jul 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never sets | 01:11 · 77° | — |
| New York EDT | 16:14 | 01:06 · 88° | 09:58 |
| Singapore GMT+8 | 19:13 | 01:16 · 53° | 07:20 |
| Sydney GMT+10 | 20:18 | 00:07 · 18° | 03:57 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 79° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 16° 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 late October it is highest in the early evening, and in late April not until the hours before dawn.
- 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
It lies just south of Sadr, the centre of the Northern Cross. Binoculars show its little box of stars.
Science
It sits behind thick dust in the plane of the Milky Way, which dims it far below how bright it would otherwise look.
Look for
From 50° north it climbs to 79°; from 35° north it climbs to 86°; from the equator it climbs to 51°; from 35° south it climbs to 16°.
Look for
Magnitude 6.6 against the faintest star each can show: the eye under a city sky, 4.5 (2.1 short); the eye under a dark country sky, 7.0 (0.4 to spare); 50 mm binoculars under that dark sky, 11.0 (4.4 to spare); a 100 mm telescope there, 12.5 (5.9 to spare). 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 17% of the field’s width.