Object of the Week July 3rd, 2016 - NGC6946 The Fireworks Galaxy

[Dragan]

NGC6946
UGC11597
Arp 29

Cygnus

Galaxy

RA 20 37 52
DEC 60 09 15

Mag: 8.8

Size: 11.6' x 9.8'

Class: SAB(rs)cd

What a better way to pay tribute to Americas independence this week than to discuss our own deepsky fireworks! NGC 6946 or the Fireworks Galaxy, is a beautiful face-on spiral located in Cygnus near the border of Cepheus. Discovered on September 9th 1798 by William Herschel, 6946 makes its fame for not only being a wonderfully visual deep sky object in a telescope, but it claims title as being the most active galaxy as far as supernovae observed. Since 1917, we have observed 9 supernovae within NGC6946, with the most recent being in 2008 by UK amateur Ron Arbour.

Visually, a relatively close neighbor at only 18Mly, NGC6946 makes for a marvelous object. Between its spiral arms, its numerous challenging HII knots brought to our attention by our own Steve Gottlieb in his July 2013 issue of Sky & Telescope to its beautiful counterpart NGC 6939, an Open Cluster just over the border in Cepheus, these objects offer a wonderful sight in all sizes of telescopes. Lower power wide field views offer a stunning "Two-Fer" in the eyepiece, two differing objects visible in the same FOV.

Lastly, DSF had a short thread in 2013 touching upon those HII regions Steve mentions in his S&T article. You can find that thread here: http://www.deepskyforum.com/showthread.php?387-NGC-6946-article-in-July-issue-of-S-amp-T-by-Steve-Gottlieb&highlight=6946

For even further information, Universe Today has a great article located here: http://www.universetoday.com/17824/the-firecracker-galaxy-ngc-6946-by-dietmar-hager/

So next time you're out under some dark summer skies, be sure to swing north and find some fireworks in NGC6946. Just how many knots can you see?

Give it a go and let us know!

2179

[kisspeter]

This is a beautiful galaxy and a beautiful couple with the open cluster. I can contribute a drawing from 2012 with my 4" Newtonian. The spiral structure was visible but very difficult.

4", 40x (1.8° field):
2181

And an inverted, rotated and cropped version:
2182

[Ivan Maly]

I reobserved this galaxy a few nights ago with 12" in SQM 21.9 skies and noted the main familiar features. Observing with 16" from the same site three years ago (SQM 21.7 on that night) I recorded that the pair was nicely framed by the 2" Pentax. The cluster was grainy with partial resolution. 225x brought out the "rounded-tipped angle of stars in the cluster, as described by William Herschel". The galaxy sketch from that observation is below (140-225x). "a" and "b" are my own designations; H are Hodge (1969) HII regions, A are Ivanov and Krastev's (2000) OB associations, and HB are HII regions from Bonnarel et al., 1986.

http://2.bp.blogspot.com/-Df5TB5ZpNuk/UjnP1nzt7QI/AAAAAAAAAjs/RavGr3G6hJU/s400/2013-08-14+NGC+6946+marked.jpg

[akarsh]

This was one of my favorite galaxies in an 8" telescope, just because of the challenge it presented under poor sky conditions. My friend and I used it for a while as a measure of sky quality.

This beautiful spiral is so heavily obscured by galactic dust. I find it challenging to see detail in my 18", but here's what I logged under the exceptional skies of Okie-Tex Star Party 2015:

14mm Pentax eyepiece. Beautiful. Careful observation resolves spiral arms. Knot observed without UHC, but UHC seems to kill it. Galaxy dimly visible with UHC.
2186

I didn't know about Steve's article on the knots. Next time I give it a try, I'll make sure I have Steve's article with me.

Clear Skies

Regards
Akarsh

[Uwe Glahn]

Nice spiral Dragan.

My past 5" binocular did not bring out any detail, but shows nice views together with NGC 6946.
20x125, NELM 6m0+
2194

More intensive views with my former 14.5" shows the faint spiral structure with some HII regions, especially the huge SSC NGC 6946-1447.
14.5", 202x, NELM 6m5+
2195

Some actual attempts to show details (clusters) within NGC 6946-1447 failed. I once had a quick and dirty look years ago under superb seeing which shows some stellar peaks within the SSC.

[Howard B]

Better late than never, here's my most recent observation and sketch of 6946:

"Using the photo from Steve G's S&T article (July 2013 issue) I tracked down all the HII regions... 408x, 21.70 SQM"

2280 2281

I want to make another sketch, hopefully next year, when 6946 is near the meridian because my last few attempts were when the galaxy was well down in the sky. There's a lot to see in 6946 but most of it is rather subtle.