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M93
open cluster in Puppis
M93 is a compact open cluster in Puppis with a wedge or arrowhead of bright stars. It is a modest target on its own, but it shares the Puppis region with M46 and M47, so a short mosaic can capture all three.
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// Key facts
- Catalog
- M93
- Type
- open cluster
- Constellation
- Puppis
- Size
- 22′ across
- Brightness
- Magnitude 6.2
- Distance
- about 3,600 light-years
- Peak month (any location)
- Jan
- Typical prime months
- Nov to Mar
- Difficulty
- Intermediate
- Filter
- No filter (broadband)
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How to image M93
- At 22 arcminutes, 600 to 1,000 mm suits it.
- Dec -24 makes it low from northern sites, so choose the meridian crossing.
- Combine with M46 and M47 for a trio of Puppis clusters.
Framing: what focal length?
The focal length at which M93 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 1240 mm |
| APS-C (23.5 mm) | about 2200 mm |
| Full frame (36 mm) | about 3380 mm |
How high does it climb from your latitude?
The highest point M93 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) | 11° | Stays low |
| 45°N (Minneapolis, Milan) | 21° | Stays low |
| 35°N (Los Angeles, Tokyo) | 31° | Workable |
| 25°N (Miami, Cairo) | 41° | Workable |
| 35°S (Sydney, Santiago) | 79° | High in the sky |
Also worth imaging
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