Galaxy in Draco
Spindle Galaxy (M102)
A genuine unsolved entry. Méchain later wrote that it had been a duplicate observation of M101 and should be struck out; others matched his description to NGC 5866, the Spindle Galaxy in Draco, which is what most lists now use. Both positions are still defended.
NGC 5866 itself is a lenticular seen within a degree of edge-on, and the dust lane running its length is unusually sharp for its class. The catalogue keeps both readings because both have evidence behind them, which is the honest thing to do with a two-hundred-year-old ambiguity that nobody alive can resolve.
- Catalogue
- M102
- Type
- Galaxy
- Constellation
- Draco
- Distance
- 50 million light-years
- Apparent magnitude
- 9.9
- Surface brightness
- 21.0 mag/□″
- Apparent size
- 5′ × 2′
- Right ascension
- 15h 06m
- Declination
- +55.77°
- Found by
- Pierre Méchain, 1781
Small enough that its 9.9 magnitudes arrive concentrated rather than smeared: 21.0 per square arcsecond, which is why it stands out from the sky better than its brightness alone suggests. Why surface brightness is the number that matters.
Could you see it?
Straightforward with 10×50 binoculars from Bortle 4; with a 200mm from Bortle 5.
| Sky | Eye | 10×50 | 80mm | 130mm | 200mm |
|---|---|---|---|---|---|
| Bortle 1 21.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 2 21.7 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 3 21.4 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 4 20.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 5 20.3 mag/□″ | No | No | Easy | Easy | Easy |
| Bortle 6 19.3 mag/□″ | No | No | Challenge | Challenge | Challenge |
| Bortle 7 18.6 mag/□″ | No | No | No | Challenge | Challenge |
| Bortle 8 18.1 mag/□″ | No | No | No | No | No |
| Bortle 9 17.8 mag/□″ | No | No | No | No | No |
At the eyepiece
Whatever you decide it is, NGC 5866 is worth looking at: a sharp-edged lens of light with a dust lane splitting it lengthways, visible at 200mm. It is the most distinctly shaped galaxy in Draco and among the neatest edge-on objects anywhere.
When, and from where
Highest in the middle of the night in May. Well placed for the northern hemisphere and overhead for anyone near 56°N. South of 34°S it stays below the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 86° | Never sets |
| 51°N London, Calgary | 85° | Never sets |
| 40°N New York, Madrid | 74° | Never sets |
| 30°N Cairo, Houston | 64° | |
| 0°N the equator | 34° | |
| 33°S Sydney, Cape Town | 1° | Low — in the murk |
Nearby in the sky
The whole catalogue →Nothing else in the catalogue is especially close; the nearest is 9.2° apart, which is a separate trip rather than a nudge of the tube. Everything below is measured from M102 itself, not from the middle of Draco.
- M101 Pinwheel Galaxy 9.2° apart Ursa Major · magnitude 7.9 · needs more than binoculars
- M51 Whirlpool Galaxy 17° apart Canes Venatici · magnitude 8.4 · binoculars from Bortle 5 or darker
- M40 Winnecke 4 22° apart Ursa Major · magnitude 8.4 · binoculars from Bortle 7 or darker
- M63 Sunflower Galaxy 23° apart Canes Venatici · magnitude 8.6 · binoculars from Bortle 5 or darker
One of 110. Positions J2000; the sky is the final authority.