NGC 6946 is a face on intermediate spiral galaxy, its structure being between those of a full spiral galaxy and a barred spiral galaxy, with only a slight bar at its center. It is also classed as a starburst galaxy, because it has an exceptional rate of star formation. While its nickname, The Fireworks Galaxy, reflects the brightness of its star forming regions, it comes also from the fact that it has had 10 observed supernova events in the past century [1]; the most recent being discovered by amateur astronomer, Patrick Wiggins on May 13, 2017 [2,3] ([2] shows an animation showing the supernova clearly). For comparison, our Milky Way averages around 1 or 2 supernova per century .
The formation of a black hole has also been observed in NGC 6946. In May 2009 a red supergiant or or yellow hypergiant star with around 25 times the mass of the sun, exploded as a failed supernova (the increase in luminosity being too small for a supernova) and by 2015 the star was no longer visible but infra-red images show activity, thought to be from matter falling into the black hole formed by the implosion of the star [4,5].
NGC 6946 is about 25.2 million light-years from earth, along the border of the northern constellations of Cepheus and Cygnus (The Swan).
The image was taken using the 16" F6.8 corrected Dall Kirkham using a ZWO 2600mm and Baader LRGB filters (RoboScopes Pier 9).
Lum 177x60s
Red 28x120s
Green 30x120s
Blue 41x120s
Total integration 6.08 h
[1]h[1]ttps://www.nasa.gov/image-feature/goddard/2021/hubble-views-a-dazzling-fireworks-galaxy
[2] https://skyandtelescope.org/astronomy-news/observing-news/possible-bright-supernova-discovered-in-fireworks-galaxy-ngc-6946/
[3] https://unews.utah.edu/u-educator-discovers-supernova-in-fireworks-galaxy/
[4] https://en.wikipedia.org/wiki/N6946-BH1
[5] Nowogrodzki, Anna (12 September 2016).
"First glimpse of a black hole being born from a star's remains".
New Scientist.
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