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De Mairan's Nebula (M43)
emission nebula in Orion
M43 is a small, comma-shaped nebula separated from the Orion Nebula (M42) by a dark dust lane. It is lit by a single young star, and it is almost always photographed as part of the M42 field.
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// Key facts
- Catalog
- M43
- Type
- emission nebula
- Constellation
- Orion
- Size
- 20′ across
- Brightness
- Magnitude 9
- Distance
- about 1,350 light-years
- Peak month (any location)
- Dec
- Typical prime months
- Sep to Feb
- Difficulty
- Beginner
- Filter
- Dual-band / UHC, or no filter (bright, mixed emission and reflection)
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How to image De Mairan's Nebula
- It fits inside the M42 frame, so shoot them together at 400 to 800 mm.
- Because M42 is so bright, take short exposures as well so M43 is not lost in the glow.
- Orion is high in the winter sky from both hemispheres.
Framing: what focal length?
The focal length at which M43 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 1360 mm |
| APS-C (23.5 mm) | about 2420 mm |
| Full frame (36 mm) | about 3710 mm |
How high does it climb from your latitude?
The highest point M43 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) | 30° | Workable |
| 45°N (Minneapolis, Milan) | 40° | Workable |
| 35°N (Los Angeles, Tokyo) | 50° | Workable |
| 25°N (Miami, Cairo) | 60° | High in the sky |
| 35°S (Sydney, Santiago) | 60° | High in the sky |
Also worth imaging
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