M 106 Deep sky · Galaxy in Canes Venatici · M 106 · NGC 4258
M 106
A spiral galaxy in Canes Venatici with an active centre and two extra, ghostly arms that glow in radio and X-rays.
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- Type
- Galaxy
- Designations
- M 106 · NGC 4258
- Constellation
- Canes Venatici
- Apparent magnitude
- 8.4
- Apparent size
- 19′ × 7′
- Position (J2000)
- RA 12h 19m · Dec +47° 18′
The full Moon, about 31′ across, is 1.7 times as wide. The Sun comes no nearer to it than 44°, around early September, so it is never lost in the Sun’s glare, which reaches about 15° out.
When to see it
On the night of Wed 24 Mar 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | Never sets | 00:11 · 86° | — |
| New York EDT | 14:36 | 01:06 · 84° | 11:37 |
| Singapore GMT+8 | 19:12 | 01:17 · 44° | 07:22 |
| Sydney GMT+11 | 22:14 | 01:08 · 9° | 04:02 |
Common questions
- Can I see it from 50° north?
- Yes, on any clear night of the year. From there it never sets: it is circumpolar, circling the pole and still 7° up at its lowest.
- Can I see it from 35° south?
- Only just. At its highest it is 8° above the northern horizon, so it needs a clear, flat view that way and clean air.
- When is the best time of year to see it?
- Around late March, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late June it is highest in the early evening, and in late December not until the hours before dawn.
- How bright is it?
- Magnitude 8.4 in total, but that light is spread over 19′ × 7′ of sky: on average 22.4 magnitudes per square arcsecond. Against a dark country sky that average stands out; a city’s glow drowns all but its brightest parts.
- Naked eye, binoculars or telescope?
- Binoculars. At magnitude 8.4 it is past the eye, but a 50 mm pair under a dark sky reaches about magnitude 11.0.
Science
Water molecules orbiting its central black hole act as natural lasers. Tracking them gave the black hole’s mass and the galaxy’s distance with rare precision.
Look for
It lies south of the Big Dipper’s bowl, towards Cor Caroli. A small telescope shows a long, bright oval.
Look for
From 50° north it is circumpolar and never sets; from 35° north it climbs to 78°; from the equator it climbs to 43°; from 35° south it barely clears the horizon, at 8°.
Look for
Magnitude 8.4 against the faintest star each can show: the eye under a city sky, 4.5 (3.9 short); the eye under a dark country sky, 7.0 (1.4 short); 50 mm binoculars under that dark sky, 11.0 (2.6 to spare); a 100 mm telescope there, 12.5 (4.1 to spare). Those limits are for a point of light; its light is spread over its whole size, so it needs some of that margin in hand. Through 7×50 binoculars, whose field is about 7.1° across, it spans 4% of the field’s width; through a 100 mm telescope at 50×, a field about 1° across, it spans 31% of the field’s width.