NGC 7243, cataloged as C 16, is a bright and loosely scattered open star cluster in Lacerta that makes an approachable target for wide-field astrophotography. At magnitude 6.4 and spanning roughly 0.5° (31′) on the sky, it comfortably fits within the frame of short-focal-length refractors and telephoto lenses, leaving room to capture the surrounding star field. Its stars are spread out rather than densely packed, so the cluster rewards moderate integration times and benefits from careful star-color rendering to bring out the mix of hot blue and warmer suns. Because it lies in a rich region of the Milky Way, imagers can compose it against a busy stellar backdrop that adds depth and context to the final picture.
Names and Catalog numbers
- C 16 (Caldwell 16)
- NGC 7243
- Mel 240 (Melotte 240)
Position and the cosmic neighborhood
Set within the small constellation Lacerta, NGC 7243 sits at a right ascension of 22h 15m and a declination of +49° 50′, placing it high in the northern sky for observers at mid-northern latitudes. This portion of the celestial sphere runs along the plane of the Milky Way, so the cluster is embedded in a dense carpet of foreground and background stars that makes for compelling framing. Lacerta bridges the region between Cygnus and Andromeda, giving astrophotographers an easy stepping-stone to nearby star fields and making C 16 a convenient anchor for wide-field mosaics of this crowded stretch of sky.
Nice to Know
- NGC 7243 carries several designations, including C 16 from the Caldwell catalog and Melotte 240, giving imagers multiple ways to locate it in planning software.
- With a physical diameter of about 25 light-years, the cluster’s loose, sprawling structure translates into a generous apparent size of 0.5° (31′) on the sky.
- At magnitude 6.4 it sits near the threshold of naked-eye visibility under dark skies, making it an easy and rewarding first target for beginners with modest equipment.
- Lying roughly 2,770 light-years away in the plane of the Milky Way, it is framed by a rich stellar background that lends extra depth to wide-field exposures.
Brightness, distance and size
The object has an apparent magnitude of 6.4 mag, it lies about 2,770 light-years from Earth and spans roughly 25 light-years across. On the sky it appears about 0.5° (31′) in size.
