Globular cluster in Ophiuchus
M62
Visibly lopsided, its core shoved off-centre by repeated close passes to the middle of the galaxy. Most globulars are balls; this one is being deformed while we watch.
It sits some six thousand light-years from the middle of the galaxy, which is where the deformation comes from — the tidal field there is strong enough to pull the cluster's outer stars into a trailing tail. It also contains an unusual number of X-ray binaries, which is what a crowded core does to the stars in it.
- Catalogue
- M62
- Type
- Globular cluster
- Constellation
- Ophiuchus
- Distance
- 22,500 light-years
- Apparent magnitude
- 6.5
- Surface brightness
- 20.9 mag/□″
- Apparent size
- 14′
- Right ascension
- 17h 01m
- Declination
- −30.12°
- Found by
- Charles Messier, 1771
Magnitude 6.5 sounds comfortable and is spread over 14′, which brings it down to 20.9 per square arcsecond — the number that actually decides whether there is anything to see. 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 6.
| 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 | Challenge | Challenge | Challenge | Challenge |
| Bortle 8 18.1 mag/□″ | No | Challenge | Challenge | Challenge | Challenge |
| Bortle 9 17.8 mag/□″ | No | No | No | No | No |
At the eyepiece
The asymmetry is visible: the bright core sits distinctly off to one side rather than in the middle, which takes a moment to accept as real rather than a trick of the eye. At 200mm the edges resolve. Low from northern latitudes, which blurs exactly the detail you came for.
When, and from where
Highest in the middle of the night in June. A southern object: overhead at 30°S, and low and murky from Britain and the northern United States even at its best. North of 60°N it never rises.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | — | Never rises |
| 51°N London, Calgary | 9° | Low — in the murk |
| 40°N New York, Madrid | 20° | Low — in the murk |
| 30°N Cairo, Houston | 30° | |
| 0°N the equator | 60° | |
| 33°S Sydney, Cape Town | 87° |
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 M62 itself, not from the middle of Ophiuchus.
- M19 Globular cluster 3.9° apart Ophiuchus · magnitude 6.8 · binoculars from Bortle 5 or darker
- M6 Butterfly Cluster 8.6° apart Scorpius · magnitude 4.2 · binoculars from Bortle 9 or darker
- M4 Globular cluster 9.0° apart Scorpius · magnitude 5.6 · binoculars from Bortle 5 or darker
- M7 Ptolemy's Cluster 12° apart Scorpius · magnitude 3.3 · binoculars from Bortle 9 or darker
One of 110. Positions J2000; the sky is the final authority.