Object of the Week, July 27, 2014: A galaxy chain near Vega

Object data:
UGC 11341: RA 18h 42’ 51” Dec +40 22 00
NGC 6695: RA 18h 42’ 43” Dec +39 32 51
NGC 6686: RA 18h 40’ 07” Dec +40 08 17
NGC 6685: RA 18h 39’ 59” Dec +39 58 55
IC4772: RA 18h 39’ 56” Dec +40 01 34
NGC 6675: RA 18h 37’ 26” Dec +40 03 30
NGC 6663: RA 18h 33’ 34” Dec +40 02 57
IC 1289: RA 18h 30’ 02” Dec +39 57 52
NGC 6646: RA 18h 29’ 39” Dec +39 51 54
IC 1288: RA 18h 29’ 23” Dec +39 42 48


The tiny constellation of Lyra is well known for its superb planetary nebula, M57, and of course for its bright lucida, zero - magnitude Vega. Rarely would anybody associate Lyra with interesting galaxies. Yet, today’s object of the week is a fine chain of ten galaxies all located within a 2-degrees semicircle north of Vega! I first “discovered” this chain two years ago, while exploring this area after observing NGC 6745, http://www.deepskyforum.com/showthre...-s-Head-Galaxy.

This galaxy chain has both bright and (mostly) faint members. The main challenge is to ferret these galaxies out of the myriad stars surrounding them, this being a rather star-rich area of the sky. You will need good star-hopping skills to jump from one galaxy to the other, and the fact that most galaxies are not plotted in many atlases adds to the challenge. A combination of custom-made Megastar charts and DSS images made it possible to navigate though the many faint stars. I have provided a chart here, but you will need to make close up charts.

GlxChainVega.jpg

Our starting point is the Double-double, Epsilon Lyrae, a fine sight on its own. 20 arc minutes to the west of Epsilon lies tiny UGC 11341. Through my 18” at 275X it appeared as a small, faint spindle of light about 1’ long. It has a listed photographic magnitude of 15.4, and it should appear a bit brighter visually. Moving Epsilon out of the field certainly helps in finding this little guy.

About 40 arc-minutes due north of UGC11341 we can detect NGC6695. This 13th magnitude galaxy appeared as a N-S oriented faint oval with a subtle central brightening, with a rather low surface brightness. At a recent star-party I was able to detect (albeit with difficulty) NGC6695 with an 11” SCT, so this galaxy is definitely within the reach of medium-sized scopes.

N6695a1.jpg

Forty-five arc-minutes to the SW of NGC6695 is the first of two galaxy triplets that we can find in this chain. Although NGC 6685 is listed as the brightest of the trio, I found NGC 6686 more distinct and more readily visible in my 18”. At high powers 6686 appears round with a distinct core and a faint halo. NGC 6685 appears smaller, but the lack of halo made it less apparent to me. The trio is rounded up with faint IC 4172, appearing as a barely detectable tiny puff of light between the two NGC galaxies. Both NGC galaxies were visible with an 11”SCT as averted vision objects.

6685c1.jpg

Half a degree due west from the 6685 trio lies NGC 6675, the brightest and most distinct of the chain’s galaxies. At magnitude 12.4, this galaxy is within reach (under good skies) of smaller instruments. In my 18” at medium and high powers it appears as a roundish patch slightly more than one arc-minute across, with a distinct core. Through an 11-inch SCT under very dark skies it appeared as a small faint circular glow, ever so slightly brighter in the middle. To my surprise, NGC 6675 was readily visible in my 6” achro from my SQM21 skies as an extremely faint tiny round patch that grew slightly with averted vision. I believe that under very dark and steady skies it should be detectable even with the popular 4-inch refractors.

6675a1.jpg

The next move to NGC 6663, 45 arc-minutes due west of NGC 6675 is the longest astro-hop. A triangle made of 7-10th magnitude stars just to the west helps to pinpoint the galaxy. NGC 6663 through my 18” at 294X appears as a very faint and diffuse oval oriented E-W, a bit less than one arc-minute across. Although the listed magnitude is around 13, it visually appears harder than the numbers indicate. I was unable to detect it in an 11”SCT under SQM 21.4 skies, so NGC 6663 is reserved for rather large scopes.

6663a1.jpg

The Vega galaxy chain concludes with a fine galaxy triplet, 45 arc-minutes west of NGC 6663. A distinct N-S line of 8th to 10th magnitude stars is located halfway across the starhop from NGC 6663 and it helps in pointing the triplet’s location. The brightest of the three galaxies is NGC 6646, a roundish faint patch of light in my 18” at high power, with a distinctly brighter center. NGC 6646, which seems to be harder than the listed 12.6 magnitude would suggest, was visible with direct vision in an 11” SCT at high power, and was detected – albeit only with averted vision and then barely – in my 6” achro. Eight arc-minutes northeast of 6646 is IC1289, a tiny circular 14th magnitude patch of faint light. About 15 arcminutes south of NGC 6646 the tiny spindle of IC 1288 may be seen. At magnitude 14, it has a higher surface brightness than IC 1289 and it was readily detected with the 18” at high power, within a trapezium of faint stars. IC 1289 is almost as easy to see as NGC 6646, and was detectable with direct vision in an 11” SCT under dark skies.

6646a1.jpg

So, during the next time you are out, under dark and transparent summer skies, turn your scope to Vega, and
"GIVE IT A GO AND LET US KNOW"
GOOD LUCK AND GREAT VIEWING!