Go / no go for deep skyGo / no go for deep sky imaging
M10
globular cluster in Ophiuchus
M10 is a bright, fairly large globular cluster in Ophiuchus. It lies about three degrees from M12, and the two fit together in one wide frame, which makes a pleasing pair of clusters at different concentrations.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- M10
- Type
- globular cluster
- Constellation
- Ophiuchus
- Size
- 20′ across
- Brightness
- Magnitude 6.6
- Distance
- about 14,300 light-years
- Peak month (any location)
- Jun
- Typical prime months
- Mar to Aug
- Difficulty
- Beginner
- Filter
- No filter (broadband)
Pick a saved location or share your device location. Your coordinates are used only to calculate tonight and are not stored. To save locations, use the planner.
How to image M10
- A frame of about 3.5 to 4 degrees (roughly 200 to 300 mm on APS-C) captures both M10 and M12.
- Shoot it as a pair for a wider-field image, or at 800 mm or more for M10 alone.
- It is moderately low for northern observers, so wait for the meridian crossing.
Framing: what focal length?
The focal length at which M10 spans about 60% of the long side of the sensor, leaving room around it. Treat it as a starting point; the right framing is a matter of taste.
| Sensor | Focal length |
|---|---|
| 1-inch sensor (13.2 mm) | about 1360 mm |
| APS-C (23.5 mm) | about 2420 mm |
| Full frame (36 mm) | about 3710 mm |
How high does it climb from your latitude?
The highest point M10 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) | 31° | Workable |
| 45°N (Minneapolis, Milan) | 41° | Workable |
| 35°N (Los Angeles, Tokyo) | 51° | Workable |
| 25°N (Miami, Cairo) | 61° | High in the sky |
| 35°S (Sydney, Santiago) | 59° | Workable |
Also worth imaging
Want a GO / NO-GO verdict for tonight, with clouds, moon, seeing and a full dark-window timeline?
Open the planner