NGC 457 is a young open star cluster well known for its striking, character-like appearance in wide-field astrophotography. It lies within the rich Milky Way star fields of Cassiopeia, making it visually impressive even in modest telescopes. The cluster contains several hot blue stars along with a few prominent evolved members that dominate its visual structure. Its distinctive shape has made it a favorite target for both visual observers and astrophotographers.
Names and Catalog numbers
Dragonfly Cluster
Owl Cluster
ET Cluster
NGC 457
Caldwell 13
Melotte 7
Position and the cosmic neighborhood
NGC 457 is located in the northern sky within the familiar “W” asterism of Cassiopeia, positioned near the bright stars Ruchbah (Delta Cassiopeiae) and Phi Cassiopeiae. The cluster sits against a dense Milky Way backdrop, which provides a rich surrounding star field for imaging. Nearby are several dark dust lanes and faint emission regions that can be captured with longer exposures and careful processing. Its high declination makes it circumpolar for many northern observers, allowing imaging sessions throughout much of the year.
Nice to Know
1. Two bright foreground stars give the cluster its famous “eyes,” strongly defining its dragonfly- or owl-like appearance in images.
2. The cluster is relatively young, which explains the dominance of blue-white stars that respond well to broadband RGB imaging.
3. NGC 457 works well with both short focal length refractors and longer focal length telescopes, making it very versatile for astrophotography setups.
4. Because of its compact size and brightness, it is an excellent target for beginners while still rewarding advanced imagers with fine stellar color detail.
Brightnes, distance and size
The Dragonfly Cluster has an integrated apparent magnitude of about 6.4, placing it near the limit of naked-eye visibility under very dark skies. It lies approximately 5,200 lightyears away and spans roughly 20 lightyears in physical diameter. On the sky, the cluster covers an area of about 20 arcminutes, making it well suited to medium-field astrophotography. Its combination of moderate brightness and compact angular size allows for detailed star color capture without extremely long exposure times.