Open cluster in Cygnus
M29
Half a dozen stars in a rough box, and one of the weakest entries in the catalogue — it is only distinguishable from the Milky Way behind it because dust in front dims that background. Messier logged it while chasing a comet through Cygnus.
It sits behind roughly three magnitudes of dust, which is most of a factor of twenty in brightness. Strip that away and this would be one of the more obvious clusters in the northern sky rather than the afterthought it is — and the stars in it would show as the hot blue giants they actually are.
- Catalogue
- M29
- Type
- Open cluster
- Constellation
- Cygnus
- Distance
- about 7,200 light-years
- Apparent magnitude
- 6.6
- Surface brightness
- 19.5 mag/□″
- Apparent size
- 7′
- Right ascension
- 20h 24m
- Declination
- +38.53°
- Found by
- Charles Messier, 1764
Magnitude 6.6 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
Six or seven stars in a rough rectangle, and the honest verdict is that if it were not on this list nobody would point anything at it. Low power only. Its value is as a reminder that Messier was cataloguing things that fooled him, not things that impress us.
When, and from where
Highest in the middle of the night in July. Well placed for the northern hemisphere and overhead for anyone near 39°N. South of 51°S it stays below the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 69° | Never sets |
| 51°N London, Calgary | 78° | |
| 40°N New York, Madrid | 89° | |
| 30°N Cairo, Houston | 81° | |
| 0°N the equator | 51° | |
| 33°S Sydney, Cape Town | 18° | Low — in the murk |
Nearby in the sky
The whole catalogue →Nothing else in the catalogue is especially close; the nearest is 16° apart, which is a separate trip rather than a nudge of the tube. Everything below is measured from M29 itself, not from the middle of Cygnus.
- M39 Open cluster 16° apart Cygnus · magnitude 4.6 · binoculars from Bortle 9 or darker
- M56 Globular cluster 16° apart Lyra · magnitude 8.3 · binoculars from Bortle 5 or darker
- M27 Dumbbell Nebula 17° apart Vulpecula · magnitude 7.4 · binoculars from Bortle 5 or darker
- M57 Ring Nebula 19° apart Lyra · magnitude 8.8 · binoculars from Bortle 6 or darker
One of 110. Positions J2000; the sky is the final authority.