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M109
spiral galaxy in Ursa Major
M109 is a barred spiral galaxy in Ursa Major, close to the bowl star Phecda (Gamma Ursae Majoris), whose glare can complicate imaging. It is a fairly faint galaxy with a clear bar.
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// Key facts
- Catalog
- M109
- Type
- spiral galaxy
- Constellation
- Ursa Major
- Size
- 7′ across
- Brightness
- Magnitude 9.8
- Distance
- about 80 million light-years
- Peak month (any location)
- Mar
- 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 M109
- At 7 arcminutes, use 1,200 to 2,000 mm.
- Phecda is very bright, so keep it out of the field or deal with halos.
- High in the sky on spring evenings.
Framing: what focal length?
M109 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 9% |
| 2,000 mm | about 17% |
| 3,000 mm | about 26% |
How high does it climb from your latitude?
The highest point M109 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) | 88° | High in the sky |
| 45°N (Minneapolis, Milan) | 82° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 72° | High in the sky |
| 25°N (Miami, Cairo) | 62° | High in the sky |
| 35°S (Sydney, Santiago) | 2° | Stays low |
Also worth imaging
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