Open cluster in Scutum
Wild Duck Cluster (M11)
The Wild Duck, named by Admiral Smyth in the 1840s for a V of brighter stars leading the rest like birds in flight. It is packed tightly enough that at the eyepiece it is easy to mistake for a loose globular.
It is one of the richest open clusters known — something approaching three thousand stars in a space a few dozen light-years across — which is why it looks wrong for its class. At around two hundred and fifty million years old it is already past the age at which most open clusters have come apart, and it will not hold much longer.
- Catalogue
- M11
- Type
- Open cluster
- Constellation
- Scutum
- Distance
- 6,200 light-years
- Apparent magnitude
- 6.3
- Surface brightness
- 20.7 mag/□″
- Apparent size
- 14′
- Right ascension
- 18h 51m
- Declination
- −6.27°
- Found by
- Gottfried Kirch, 1681
Magnitude 6.3 for the cluster as a whole, though that is a sum rather than a thing you see: what reaches you is a scatter of separate stars, and whether you catch it depends on how bright the brightest of them are. Why surface brightness is the number that matters.
Could you see it?
Straightforward with the naked eye from Bortle 3 or darker; with 10×50 binoculars from Bortle 9.
| Sky | Eye | 10×50 | 80mm | 130mm | 200mm |
|---|---|---|---|---|---|
| Bortle 1 21.9 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 2 21.7 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 3 21.4 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 4 20.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 5 20.3 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 6 19.3 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 7 18.6 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 8 18.1 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 9 17.8 mag/□″ | No | Easy | Easy | Easy | Easy |
At the eyepiece
The one open cluster that genuinely surprises people. At 150mm the field fills with several hundred stars packed tight enough to look wrong for an open cluster, with the leading V picked out in brighter points. High magnification suits it, which is rare for this kind of object.
When, and from where
Highest in the middle of the night in July. Close enough to the celestial equator to rise from almost anywhere on Earth, and to pass overhead for anyone near 6°S.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 24° | |
| 51°N London, Calgary | 33° | |
| 40°N New York, Madrid | 44° | |
| 30°N Cairo, Houston | 54° | |
| 0°N the equator | 84° | |
| 33°S Sydney, Cape Town | 63° |
Nearby in the sky
The whole catalogue →One more of the catalogue sits within five degrees, close enough to take in on the same night without moving far. Everything below is measured from M11 itself, not from the middle of Scutum.
- M26 Open cluster 3.5° apart Scutum · magnitude 8.0 · binoculars from Bortle 9 or darker
- M16 Eagle Nebula 11° apart Serpens · magnitude 6.0 · binoculars from Bortle 2 or darker
- M17 Omega Nebula 12° apart Sagittarius · magnitude 6.0 · needs more than binoculars
- M18 Open cluster 13° apart Sagittarius · magnitude 7.5 · binoculars from Bortle 9 or darker
One of 110. Positions J2000; the sky is the final authority.