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Ghost of Jupiter (NGC 3242)
planetary nebula in Hydra
The Ghost of Jupiter is a bright planetary nebula in Hydra, a blue-green disc with a bright inner shell and a fainter outer halo. It is one of the brighter planetary nebulae, so it responds well to short exposures. It is small but easy to find.
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// Key facts
- Catalog
- NGC 3242
- Also known as
- C 59, Caldwell 59
- Type
- planetary nebula
- Constellation
- Hydra
- Size
- 0.7′ across
- Brightness
- Magnitude 7.7
- Distance
- roughly 1,400 to 2,000 light-years
- Peak month (any location)
- Feb
- Typical prime months
- Dec to May
- Difficulty
- Intermediate
- Filter
- OIII or dual-band / UHC filter
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How to image Ghost of Jupiter
- It is under 1 arcminute across; use 1,500 mm or more and plan to crop.
- OIII or a dual-band filter brings out the outer halo.
- Best in spring evenings, when Hydra is highest.
Framing: what focal length?
NGC 3242 is small, so a "60% of the frame" focal length would be impractical. Here is how much of an APS-C frame it covers at common long focal lengths; expect to crop.
| Focal length | Share of the frame width |
|---|---|
| 1,000 mm | about 1% |
| 2,000 mm | about 2% |
| 3,000 mm | about 3% |
How high does it climb from your latitude?
The highest point NGC 3242 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) | 16° | Stays low |
| 45°N (Minneapolis, Milan) | 26° | Stays low |
| 35°N (Los Angeles, Tokyo) | 36° | Workable |
| 25°N (Miami, Cairo) | 46° | Workable |
| 35°S (Sydney, Santiago) | 74° | High in the sky |
Also worth imaging
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