Your deep sky companionYour deep sky imaging companion
NGC 4945
spiral galaxy in Centaurus
NGC 4945 is a large, tilted spiral galaxy in Centaurus, similar to our own Milky Way in size and structure. It shows heavy dust lanes across a bright bulge and lies not far from Centaurus A. It is a southern sky target, so it never climbs high from the northern US.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- NGC 4945
- Also known as
- C 83, Caldwell 83
- Type
- spiral galaxy
- Constellation
- Centaurus
- Size
- 20′ across
- Brightness
- Magnitude 9.3
- Distance
- about 11 million light-years
- Peak month (any location)
- Apr
- Typical prime months
- Jan to Jun
- Difficulty
- Intermediate
- Filter
- No filter (broadband); a light-pollution filter is optional
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How to image NGC 4945
- It is about 20 arcminutes long; 800 to 1,500 mm frames it well.
- Plan it near the meridian, where it is highest. It only gets about 10 degrees up from southern Texas and barely clears the horizon farther north.
- Pair it with NGC 5128 (Centaurus A), which is in the same part of the sky.
Framing: what focal length?
The focal length at which NGC 4945 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 NGC 4945 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) | below horizon | Never rises |
| 45°N (Minneapolis, Milan) | below horizon | Never rises |
| 35°N (Los Angeles, Tokyo) | 6° | Stays low |
| 25°N (Miami, Cairo) | 16° | Stays low |
| 35°S (Sydney, Santiago) | 76° | High in the sky |
Also worth imaging
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