H-NGC6940
Open Cluster in Vulpecula
About
A rich, loosely scattered open cluster in Vulpecula, about 2,510 light-years away and about 25′ across. More than 20 of its stars are red giants, the brightest being the variable FG Vulpeculae. It is visible in small binoculars.
Imaging tips
- At 780–1300 mm on APS-C or 1200–2000 mm on full frame the cluster takes up a third to half of the frame.
- Some of the brighter blue stars in the field are not members; they lie in the same direction but are younger and in the background.
- One imager shot it under a full Moon, arguing that open clusters suit bright nights, and used 1 h 36 min in total.
- Surface brightness is 22.4 mag/arcsec². Best in July and August, reaching about 68° from 50°N.
Facts
- Size
- 31′
- Magnitude
- 6.3
- Coordinates
- RA 20h 34.5m, Dec +28° 17′
- Framing, APS-C
- 780–1300 mm
- Framing, full frame
- 1200–2000 mm
- Best months
- Jul, Aug
- Peak altitude
- 68° from 50°N, 83° from 35°N