Go / no go for deep skyGo / no go for deep sky imaging
Surfboard Galaxy (M108)
spiral galaxy in Ursa Major
The Surfboard Galaxy is an almost edge-on spiral in Ursa Major with a mottled, dusty disc. The Owl Nebula (M97) is less than a degree away, so the two make a natural pair in one frame.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- M108
- Type
- spiral galaxy
- Constellation
- Ursa Major
- Size
- 8′ across
- Brightness
- Magnitude 10
- Distance
- about 46 million light-years
- Peak month (any location)
- Mar
- Typical prime months
- Dec to May
- Difficulty
- Intermediate
- Filter
- No filter (broadband); a light-pollution filter is optional
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How to image Surfboard Galaxy
- A frame of about 1.5 degrees (around 800 mm on APS-C) includes both M108 and the Owl Nebula.
- The galaxy is broadband and the nebula is faint, so choose exposure for the galaxy and blend OIII for the Owl.
- High in the sky on spring evenings.
Framing: what focal length?
M108 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 10% |
| 2,000 mm | about 20% |
| 3,000 mm | about 30% |
How high does it climb from your latitude?
The highest point M108 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) | 89° | High in the sky |
| 45°N (Minneapolis, Milan) | 79° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 69° | High in the sky |
| 25°N (Miami, Cairo) | 59° | Workable |
| 35°S (Sydney, Santiago) | below horizon | Never rises |
Also worth imaging
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