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M75
globular cluster in Sagittarius
M75 is a distant, compact globular cluster in Sagittarius, on the sparse northern edge of the Milky Way's star clouds. It is small and dense, and at this distance the individual stars are faint.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- M75
- Type
- globular cluster
- Constellation
- Sagittarius
- Size
- 6′ across
- Brightness
- Magnitude 8.5
- Distance
- about 67,500 light-years
- Peak month (any location)
- Jul
- Typical prime months
- May to Oct
- Difficulty
- Advanced
- Filter
- No filter (broadband)
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How to image M75
- Only 6 arcminutes across, so aim for 1,500 mm or more.
- It is a long way off, so dark skies and a long total exposure help bring out stars.
- Dec -22 places it low from northern latitudes.
Framing: what focal length?
M75 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 7% |
| 2,000 mm | about 15% |
| 3,000 mm | about 22% |
How high does it climb from your latitude?
The highest point M75 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) | 13° | Stays low |
| 45°N (Minneapolis, Milan) | 23° | Stays low |
| 35°N (Los Angeles, Tokyo) | 33° | Workable |
| 25°N (Miami, Cairo) | 43° | Workable |
| 35°S (Sydney, Santiago) | 77° | High in the sky |
Also worth imaging
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