The galaxy was discovered by William Herschel on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a D25 B-band isophotal diameter of 26.77 kiloparsecs (87,300 light-years). It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way.[9] Due to its prodigious star formation it has been classified as an active starburst galaxy. NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center.
Various unusual celestial objects have been observed within NGC 6946. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars. There are also two regions of unusual dark lanes of nebulosity, while within the spiral arms several regions appear devoid of stars and gaseous hydrogen, some spanning up to two kiloparsecs across.[dubious – discuss] A third peculiar object, discovered in 1967, is now known as "Hodge's Complex". This was once thought to be a young supergiant cluster, but in 2017 it was conjectured to be an interacting dwarf galaxy superimposed on NGC 6946
Image Session Details
-Location: 50.23°N, 8.46°E
-Target: NGC 6946 – Fireworks Galaxy
-Integration: 102 × 120s = 3h 24m
-Camera: Nikon D3500 (APS-C DSLR) – ISO 400
-Telescope: Askar 103 APO + 0.8× reducer (576 mm)
-Mount: Bresser Exos-2 + OnStep
-Control: ASIAIR Mini
-Guiding: SVBONY SV165 + ASI120MM Mini
-Sky Quality: Bortle 4, SQM ~20.8
-Moon Phase: Waning Gibbous (~94%)
-Filter: None (stock DSLR)
-Date: 11 August 2025
-Object Type: Intermediate Spiral Galaxy
-Constellation: Cepheus (border with Cygnus)
-Apparent Size: 11.5′ × 10.5′
-Distance: ~22 million light years
NGC 6939
-Object Type: Open Cluster
-Constellation: Cepheus
-Apparent Size: ~8′
General Properties
-Coordinates: 20h34m52s, +60d09m14s (J2000)
-Apparent Magnitude: 9.6 (V)
-Angular Size: 11.5′ × 9.8′
-Distance: 7.72 Mpc (25.2 Mly)
-Constellation: Cepheus/Cygnus (border)
-Discovery: Discovered by William Herschel (1798)
Scientific Databases
[ POSITION ]
-RA: 308.718050°
-Dec: +60.153678°
-Redshift: 0.00015
-Radial velocity: 0.00015 km/s
[ PHOTOMETRY ]
-Catalog: B=10.50
-B: 10.50
-IRAS 12 µm: 0.26 Jy
-IRAS 25 µm: 0.42 Jy
-IRAS 60 µm: 0.41 Jy
-IRAS 100 µm: 128.00 Jy
-1.4 GHz flux: 0.03 Jy
[ DISTANCE ]
-5385000.00 pc (17.56 Mly, NED-D median, nDistance)
[ ALIASES ]
-2MASX J20345233+6009132, 2XMM J203452.4+600912, IRAS 20338+5958, IRAS 20338+5959, IRAS F20338+5958, LEDA 65001, MCG+10-29-006, NGC 6946, UGC 11597
-NED
Observation Notes
-Visual Magnitude: 7.86
-Photographic Magnitude: 8.46
