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Brocchi's Cluster (Cr 399)
open cluster in Vulpecula
Brocchi's Cluster, or the Coathanger, is a chance alignment of stars in Vulpecula that looks like a coat hanger, with a straight bar of six stars and a curved hook of four above. It is a bright, wide-field target and a favorite for lenses.
Save your telescope or lens on the planner to lay your camera frame over this diagram.
// Key facts
- Catalog
- Cr 399
- Also known as
- Collinder 399, Coathanger
- Type
- open cluster
- Constellation
- Vulpecula
- Size
- 1.0° across
- Brightness
- Magnitude 3.6
- Distance
- roughly 300 to 1,000 light-years (the stars are not all related)
- Peak month (any location)
- Jul
- Typical prime months
- Apr to Sep
- 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 Brocchi's Cluster
- Use 100 to 300 mm; it spans about an hour of arc.
- No filter is needed; short exposures give clean, colorful stars.
- M27, the Dumbbell Nebula, is only a few degrees away.
Framing: what focal length?
The focal length at which Cr 399 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 450 mm |
| APS-C (23.5 mm) | about 810 mm |
| Full frame (36 mm) | about 1240 mm |
How high does it climb from your latitude?
The highest point Cr 399 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) | 55° | Workable |
| 45°N (Minneapolis, Milan) | 65° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 75° | High in the sky |
| 25°N (Miami, Cairo) | 85° | High in the sky |
| 35°S (Sydney, Santiago) | 35° | Workable |
Also worth imaging
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