NGC 6946 & NGC 6939 (Cepheus)
Fig. 1 - Contrasting pair of objects: The open star cluster NGC 6939 (top left) and the Fireworks galaxy NGC 6946 (bottem right) in the constellation Cepheus, photographed with an 8-inch f/5 newtonian reflector on a ZWO AM5 mount.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| NGC 6946 | Cepheus & Cygnus | 20h35m / +60°09' | 11.5' x 9.8' | 9.0 mag |
| NGC6939 | Cepheus | 20h32m / +60°40' | 10' | 7.8 mag |
The intermediate spiral galaxiy NGC 6946 (Fireworks Galaxy, Caldwell 12) on the border between the constellations Cepheus and Cygnus and the open star cluster NGC 6939 in the constellation Cepheus. NGC 6939 is an ancient cluster: Its age is estimated to be about 1.6 billion years. It is approximately 4,000 light-years from Earth and contains more than 300 stars. It is a member of our Milky Way galaxy.
NGC 6946 is a productive supernova factory. In the 20th and early 21st century, ten supernova events have been registered. For this reason, NGC 6946 has been referred to as the Fireworks Galaxy. It is 25 million light-years from Earth (way beyond our Milky Way) and a member of the Virgo Supercluster. (source: Wikipedia).
Seventy-three 3-minute exposures (219 minutes total exposure) at gain 100 and -10°C, taken on August 5 / 6, 2024, were added for this shot with Astro Pixel Processor (APP) software and the final image processing was done in Photoshop. Darks, flats, and darkflats were used.
Equipment: Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 8" f/5 "ONTC" newtonian telescope riding on a ZWO AM5 Strain Wave Mount, ZWO OAG-L off axis system, ASI 174MM Mini guide camera, ASIAIR Plus.
Fig. 2 - Search chart for NGC 6946 and NGC 6939. Copyright 2024 'The Mag-7 Star Atlas Project', www.siaris.net.