SUNSET: 
0
Photographer:
Rod Pommier
Location of Photo:
Pommier Observatory, Portland, OR, USA
Date/Time of photo:
2018-08-14 through 2018-08-18
Equipment:
Celestron Compustar C14 with Starizona LF reducer/corrector (f/7.5), SBIG STL 11000M CCD with Baader Planetarium LRGB filters, SBIG AO-L adaptive optics at 8 Hz
Description:
NGC 6946 is a face-on spiral galaxy in the constellation Cygnus. It is also known as the Fireworks Galaxy because it exhibited ten supernovae during the 20th century. One of these in 1917 was pivotal in convincing Heber Curtis of the Lick Observatory that the "spiral nebulae" were in fact other galaxies. Another unusual thing about this galaxy is that it lies fairly close to the plane of the Milky Way in the sky. You can tell this by the large number of field stars in the image. This was known as the "zone of avoidance" because spiral nebulae aren't seen along the Milky Way. That was used by Curtis as another argument that they were galaxies outside the Milky Way, because dense dust clouds within it completely obscure our view of distant objects beyond. Our view of this galaxy is still significantly dimmed by intervening dust within our Milky Way. NGC 6946 lies 25-million light-years from Earth. Exposures: L:R:G:B=230:55:55:50 minutes=6 hours 30 minutes total exposure at f/7.5.
