Although Ha is rarely used in shooting galaxies, in this case it helped a lot to highlight the intense and numerous star formation areas in this galaxy, pointing it with many red “dots”. It is a composition of 20 Ha frames of 900s added 45 L of 900s and other 12 L of 1200s. Finally RGBs have been shot with 18+18+18 framed of 600s. Total exposition 29 hr 15m.
NGC 6946, also known as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 (NGC 5457) in the constellation Ursa Major. Both were once considered to be part of the Local Group but are now known to be among the dozen of bright spiral galaxies beyond the confines of the Local Group but still near to our Galaxy. NGC 6946 belong to the Virgo Supercluster.
Discovered by William Herschel on 9 September 1798. It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way, with a dimming of ~1.5 magnitudes. Due to its prodigious star formation it has been classified as an active starburst galaxy.