NGC 6946 ...No Wonder It's Called the Fireworks Galaxy! (John Hayes)

NGC 6946 ...No Wonder It's Called the Fireworks Galaxy!

NGC 6946, the Fireworks Galaxy was discovered by William Hershel in 1798. It lies in the dense star fields of the Milky Way so much of it is obscured by interstellar matter. It is about 22.5 million lyrs distant with a diameter of about 40,000 lyrs so it is about a third the size of the Milky Way. With an apparent magnitude of 9.6, it is a fairly faint object for visual observers. Large regions of Ha emission nebula scattered through out the blue-ish spiral arms make it a very colorful and interesting galaxy when imaged. Those same extensive regions of Ha lead to the formation of super massive stars, which is why this galaxy has a supernova rate roughly tens times higher than our own galaxy. That's why it's called the Fireworks Galaxy.

I started on this image while the moon was still rising fairly early so I had to switch to narrow band fairly early in the evening. As the days passed, I was able to finally gather more RGB color data. I had wanted to gather another 10 luminous images as well as a couple more RGB images but our long string of perfect summer weather finally broke and I had to give it up a bit early than I wanted. I never experienced any nights with really good seeing so the mean FWHM was only around 2.3 arc-sec. I also had a few pretty breezy evenings so I had to toss out more data than I would have liked. Still the result is worth sharing. C&C is always welcome so feel free to let me know if you see a problem with the processing that I missed..

John

Version D is a reprocess of the original data. I was never really happy with this image and since the snow is deep and I haven't been able to take a new image for going on 2 months, this seemed like a good time to give it another try. The underlying problem is that this image needs a bit more color data. Feel free to let me know what you think.

Original
B
C
D
Final
E

Cloudy Nights

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Status	Advanced success
Started	...
Astrometry.net job	1419352
PixInsight job	0YIQC1Z5S79LMKNQ90NMTAHF104GQWPF
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	20h34m52s.713
RA (top/left)	20h33m08s.444
RA (top/right)	20h35m58s.250
RA (bottom/right)	20h36m37s.102
RA (bottom/left)	20h33m45s.924

Dec (center)	+60°08′56″.82
Dec (top/left)	+60°00′39″.79
Dec (top/right)	+59°55′57″.56
Dec (bottom/right)	+60°17′06″.48
Dec (bottom/left)	+60°21′56″.90

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