Go / no go for deep skyGo / no go for deep sky imaging
Great Pegasus Cluster (M15)
globular cluster in Pegasus
M15 is one of the densest globular clusters known. Its core has collapsed into an extremely tight concentration of stars, and it is one of the few globulars known to contain a planetary nebula, Pease 1. It is bright and easy to find in Pegasus, and well placed in the autumn evening sky.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- M15
- Type
- globular cluster
- Constellation
- Pegasus
- Size
- 18′ across
- Brightness
- Magnitude 6.2
- Distance
- about 33,600 light-years
- Peak month (any location)
- Aug
- Typical prime months
- May to Oct
- 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 Great Pegasus Cluster
- The very bright, crowded core clips easily. Short exposures blended in are essential for a clean center.
- Use 1,000 mm or more to show the dense core and outer halo of stars.
- Pease 1 is tiny and faint, so it only shows in very long focal length or high-resolution work.
Framing: what focal length?
M15 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 22% |
| 2,000 mm | about 45% |
| 3,000 mm | about 67% |
How high does it climb from your latitude?
The highest point M15 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) | 47° | Workable |
| 45°N (Minneapolis, Milan) | 57° | Workable |
| 35°N (Los Angeles, Tokyo) | 67° | High in the sky |
| 25°N (Miami, Cairo) | 77° | High in the sky |
| 35°S (Sydney, Santiago) | 43° | 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