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NGC 2403
spiral galaxy in Camelopardalis
NGC 2403 is a loose, patchy spiral galaxy in Camelopardalis, one of the brightest galaxies outside the Local Group. Its arms are dotted with pink star-forming regions, which show up well in color. It rides high in the northern sky and is a rewarding break from the usual galaxy lineup.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- NGC 2403
- Also known as
- C 7, Caldwell 7
- Type
- spiral galaxy
- Constellation
- Camelopardalis
- Size
- 22′ across
- Brightness
- Magnitude 8.9
- Distance
- about 10 million light-years
- Peak month (any location)
- Jan
- Typical prime months
- Oct to Mar
- Difficulty
- Intermediate
- Filter
- No filter (broadband); a light-pollution filter is optional
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How to image NGC 2403
- Shoot at 800 to 1,500 mm; it is about 22 arcminutes long.
- Some of the pink knots are large emission regions. Extra exposure in hydrogen-alpha, or a modified camera, helps them stand out.
- It is circumpolar from northern mid-latitudes, so it is available on many nights.
Framing: what focal length?
The focal length at which NGC 2403 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 NGC 2403 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) | 79° | High in the sky |
| 45°N (Minneapolis, Milan) | 69° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 59° | Workable |
| 25°N (Miami, Cairo) | 49° | Workable |
| 35°S (Sydney, Santiago) | below horizon | Never rises |
Also worth imaging
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