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Elephant's Trunk (IC 1396)
emission nebula in Cepheus
IC 1396 is a very large emission nebula in Cepheus surrounding a hot, bright star. Within it lies the Elephant's Trunk, a dark, curved dust cloud that is being eroded by the star's radiation and where new stars are forming.
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// Key facts
- Catalog
- IC 1396
- Type
- emission nebula
- Constellation
- Cepheus
- Size
- 2.8° across
- Brightness
- Magnitude 3.5
- Distance
- about 2,400 light-years
- Peak month (any location)
- Aug
- Typical prime months
- Jun to Oct
- Difficulty
- Intermediate
- Filter
- Narrowband: Ha / OIII / SII, or a dual-band / UHC filter
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How to image Elephant's Trunk
- Ha, OIII or dual-band work well. The nebula is wide, so 200 to 300 mm shows the whole region.
- For a close-up of the Elephant's Trunk, use 600 to 1,000 mm.
- Cepheus is high in the sky from northern sites in autumn.
Framing: what focal length?
The focal length at which IC 1396 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 160 mm |
| APS-C (23.5 mm) | about 290 mm |
| Full frame (36 mm) | about 440 mm |
How high does it climb from your latitude?
The highest point IC 1396 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) | 88° | High in the sky |
| 45°N (Minneapolis, Milan) | 78° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 68° | High in the sky |
| 25°N (Miami, Cairo) | 58° | Workable |
| 35°S (Sydney, Santiago) | below horizon | Never rises |
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