History

The open star cluster NGC 6910 was discovered on 17 October 1786 by the German-British astronomer William Herschel. He cataloged it as VIII 56 (Class VIII = coarsely scattered clusters of stars) and noted: «A small cluster of coarsely scattered stars of various sizes. Extended like a forming one.» ^[464] Due to its size and low brightness the galactic nebula IC 1318 was discovered much later photographically by the American astronomer Edward Barnard in August 1893. ^[196]

Physical Properties

NGC 6910 is a small star cluster with about 7.4 mag apparent magnitude, an angular expansion of about 8 arcminutes and the Trumpler type I2p. The distance is given by WEBDA with 1139 parsecs (around 3700 light years) and the estimated age with around 13 million years. ^{[138, 196]}

IC 1318 is a larger H-II nebula complex with emission nebulae and dark nebulae, which belongs to the large Cygnux-X star formation region. ^[196] The Gamma Cygni Nebula is the remnant of a supernova (SNR G78.2+2.1), which occurred here about 6'800-10'000 years ago and triggered the formation of new stars through this shock wave. The distance is about 1.7-2.6 kpc. The pulsar PSR J2021+4026 is located roughly in the center. The Cygnus-X area is also a source of radio and X-rays. ^[378]

Finder Chart

As the name suggests, the Gamma Cygni Nebula (IC 1318) is located at the star γ Cygni (Sadr) in the constellation Cygnus (Swan). The best observation time is March to December.