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M47
open cluster in Puppis
M47 is a bright, loose open cluster in Puppis, just west of M46. It is much closer than M46 and contains a few bright stars, making a pleasing pair with the fainter, richer M46.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- M47
- Type
- open cluster
- Constellation
- Puppis
- Size
- 30′ across
- Brightness
- Magnitude 4.4
- Distance
- about 1,600 light-years
- Peak month (any location)
- Jan
- Typical prime months
- Oct to Mar
- Difficulty
- Beginner
- Filter
- No filter (broadband)
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How to image M47
- Frame both M46 and M47 together at about 300 mm on APS-C.
- Winter evenings suit it, though it is low (dec -14) from northern sites.
- Short exposures work, because the stars are bright.
Framing: what focal length?
The focal length at which M47 spans about 60% of the long side of the sensor, leaving room around it. Treat it as a starting point; the right framing is a matter of taste.
| Sensor | Focal length |
|---|---|
| 1-inch sensor (13.2 mm) | about 910 mm |
| APS-C (23.5 mm) | about 1620 mm |
| Full frame (36 mm) | about 2480 mm |
How high does it climb from your latitude?
The highest point M47 reaches in the sky. Above about 60° is excellent, 30° to 60° is workable, and under 30° you are looking through a lot of air.
| Latitude | Highest point | Rating |
|---|---|---|
| 55°N (Scotland, Alaska) | 21° | Stays low |
| 45°N (Minneapolis, Milan) | 31° | Workable |
| 35°N (Los Angeles, Tokyo) | 41° | Workable |
| 25°N (Miami, Cairo) | 51° | Workable |
| 35°S (Sydney, Santiago) | 70° | High in the sky |
Also worth imaging
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