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M52
open cluster in Cassiopeia
M52 is a fairly rich open cluster in Cassiopeia, a modest sight on its own but conveniently located about half a degree from the Bubble Nebula (NGC 7635), so the two make a natural pair.
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// Key facts
- Catalog
- M52
- Type
- open cluster
- Constellation
- Cassiopeia
- Size
- 13′ across
- Brightness
- Magnitude 6.9
- Distance
- about 5,000 light-years
- Peak month (any location)
- Sep
- Typical prime months
- Jun to Nov
- Difficulty
- Intermediate
- Filter
- No filter (broadband)
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How to image M52
- A frame of about 1.5 degrees (roughly 600 mm on APS-C) includes both M52 and the Bubble Nebula.
- Use Ha/OIII for the nebula, which will be separate from the broadband cluster stars.
- Cassiopeia is high in the autumn sky from northern sites.
Framing: what focal length?
M52 is small, so a "60% of the frame" focal length would be impractical. Here is how much of an APS-C frame it covers at common long focal lengths; expect to crop.
| Focal length | Share of the frame width |
|---|---|
| 1,000 mm | about 16% |
| 2,000 mm | about 32% |
| 3,000 mm | about 48% |
How high does it climb from your latitude?
The highest point M52 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) | 83° | High in the sky |
| 45°N (Minneapolis, Milan) | 73° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 63° | High in the sky |
| 25°N (Miami, Cairo) | 53° | Workable |
| 35°S (Sydney, Santiago) | below horizon | Never rises |
Also worth imaging
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