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NGC 7243
open cluster in Lacerta
NGC 7243 is a loose, scattered open cluster in Lacerta, with about a hundred stars of varied color. It is large and bright, and fits well in small to medium fields. It sits in a rich star field between Cygnus and Cepheus.
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// Key facts
- Catalog
- NGC 7243
- Also known as
- C 16, Caldwell 16
- Type
- open cluster
- Constellation
- Lacerta
- Size
- 21′ across
- Brightness
- Magnitude 6.4
- Distance
- about 2,800 light-years
- Peak month (any location)
- Aug
- Typical prime months
- Jun to Nov
- Difficulty
- Beginner
- Filter
- No filter (broadband)
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How to image NGC 7243
- Use 300 to 800 mm; it is about 21 arcminutes across.
- No filter is needed. Short exposures keep star colors natural.
- A good filler target on autumn evenings.
Framing: what focal length?
The focal length at which NGC 7243 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 1300 mm |
| APS-C (23.5 mm) | about 2310 mm |
| Full frame (36 mm) | about 3540 mm |
How high does it climb from your latitude?
The highest point NGC 7243 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) | 85° | High in the sky |
| 45°N (Minneapolis, Milan) | 85° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 75° | High in the sky |
| 25°N (Miami, Cairo) | 65° | High in the sky |
| 35°S (Sydney, Santiago) | 5° | Stays low |
Also worth imaging
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