NGC 6940 is a richly populated open star cluster in the constellation Vulpecula that presents a rewarding target for wide-field astrophotography. Spanning roughly 0.5° (30′) across the sky, it comfortably fills the frame of short focal-length refractors and telephoto lenses, making it accessible for imagers working at modest apertures. Its scattering of stars set against the dense Milky Way star fields of this region provides a colorful, textured backdrop that rewards longer integration times. Because the cluster is bright and loosely concentrated, it responds well to careful star-color calibration, letting the mix of blue and golden suns stand out in processing.
Names and Catalog numbers
- NGC 6940
- Mel 232 (Melotte 232)
Position and the cosmic neighborhood
NGC 6940 lies in the small constellation Vulpecula at a right ascension of 20h 34m 30s and a declination of +28° 16′ 41″, placing it squarely within the glowing star clouds of the summer Milky Way. This setting means that any image of the cluster naturally captures a dense stellar backdrop, and framing can easily incorporate the surrounding star fields for a more immersive composition. Its northern-hemisphere-friendly declination keeps it high in the sky for observers at mid-latitudes, offering long, well-placed imaging windows through the season. The rich neighborhood also invites mosaic panels that connect the cluster to the broader Milky Way band running through Vulpecula and neighboring constellations.
Nice to Know
- NGC 6940 also carries the catalog designation Mel 232, a reference to its inclusion in the Melotte catalog of star clusters.
- With an apparent extent of 0.5° (30′), the cluster is roughly the width of the full Moon, making it easy to locate and frame in wide-field setups.
- Its physical diameter of about 22 light-years reflects a genuinely spread-out grouping of stars rather than a tight, compact swarm.
- The cluster’s measured radial velocity of 7.7 km/s corresponds to a tiny redshift of z = 0.0000256848, a hint of its motion relative to us.
Brightness, distance and size
It lies about 2,510 light-years from Earth and spans roughly 22 light-years across. On the sky it appears about 0.5° (30′) in size.
