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Whale Galaxy (NGC 4631)
irregular galaxy in Canes Venatici
The Whale Galaxy is an edge-on spiral in Canes Venatici with a distorted, whale-like outline. A fainter galaxy, NGC 4656, curves nearby as the Hockey Stick, and a small companion, NGC 4627, sits beside the Whale.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- NGC 4631
- Type
- irregular galaxy
- Constellation
- Canes Venatici
- Size
- 15′ across
- Brightness
- Magnitude 9.2
- Distance
- about 25 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 Whale Galaxy
- A frame of about 1 degree (around 1,000 mm on APS-C) includes the Whale and the Hockey Stick.
- Dark skies bring out the faint companion.
- High in the sky on spring evenings.
Framing: what focal length?
NGC 4631 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 19% |
| 2,000 mm | about 37% |
| 3,000 mm | about 56% |
How high does it climb from your latitude?
The highest point NGC 4631 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) | 68° | High in the sky |
| 45°N (Minneapolis, Milan) | 78° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 88° | High in the sky |
| 25°N (Miami, Cairo) | 82° | High in the sky |
| 35°S (Sydney, Santiago) | 22° | Stays low |
Also worth imaging
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