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RA: 22h 36m 3.4s
Dec: +33° 56′ 54″
Ch: MSA:1142, U2:123, SA:9
Ref: NGC/IC, SIMBAD
Type: galaxy, Sc
Mag: B=13.6, V=13.1
Size: 2.2′ x 1.1′
The RNGC (Sulentic and Tifft 1973) notes that this is a 14.0 mag galaxy. Their coded description reads SLELDSK,BKNSTR.
Loc.: Anderson Mesa, Flagstaff AZ
Weather: Clear, calm, temps in mid 30's
Scope: 10-inch, f/4.5 equatorial mount Newtonian
Eyepiece (Mag.): 18 mm SWA w/ 3x TeleVue Barlow (190x)
Northern Arizonans have been enjoying some glorious weather of late. We've lost just a couple of nights due to clouds since late September. Otherwise, conditions have remained photometric for several nights running. That's good for the paycheck as I've not missed a single LONEOS observing shift in the last four weeks. And it's been equally good for my personal observing. While the 24-inch Schmidt camera hunts for NEAs, I get to use my 10-inch Newt. This night began with a visit to Stephan's Quintet, a group of five galaxies about half a degree southwest of NGC 7331. The members include NGCs 7317, 7318A, 7318B, 7319 and 7320. Just a few arcminutes to the East, NGC 7320C chimes in as a magnitude 15.5 object and requires larger aperture to detect. The radial velocity measurements of the Quintet members, four of which fall within a 5700-6700 km/sec range, suggest that these galaxies belong to the same cluster. The sole exception is NGC 7320. Its radial velocity clocks in at a modest 786 km/sec. Could this be a foreground object at roughly the same distance as NGC 7331?
NGC 7320 is the brightest of the five and was the first to be spotted. This 12.6 magnitude spiral galaxy showed an oval contour, 1' x 0'.5, through my 10-inch. NGCs 7318A/B were next to show themselves. They're due north of 7320 and separated by just a couple of arcminutes. Initially, they appeared as a slight oval region of nebulosity. However after a few minutes, I began to notice an occasional dip in brightness in the middle of this oval.
Eventually, I was able to hold this dimming with direct vision and the galaxies were clearly split.
NGC 7317 was next to appear. This little 13.6 magnitude puffball kept distracting me by winking in-and-out near a 12th magnitude star directly west of NGC 7320. I turned my attention to it after splitting NGCs 7318A/B and was able to hold it with direct vision after a few minutes. Finally, I reeled in NGC 7319. At 13.1 magnitude, one might assume it would have been easier to detect than 7317. However, 7319's surface brightness is just 13.5 magnitudes per square arcminute, much fainter than 7317's 11.9 magnitude surface brightness.
Stephan's Quintet has been one of my favorite hunting grounds since I was introduced to it many years ago by Doug Wereb of the University of Virginia's Fan Mountain Observatory outside Charlottesville, VA. I guess the whole area has a special place in my memory. I had written to Walter Scott Houston about seeing other galaxies surrounding nearby NGC 7331. That was in the days before any readily available atlases plotted them. I think I was using Norton's Star Atlas and Atlas Coeli. He actually took the time to write back to me. I was 16 years old at the time, and couldn't believe the great WSH would take the time to write to this kid. I'm still enjoying the area, but unfortunately I'm not 16 anymore!
I was quite excited to have spotted the galaxy 7320C you mention (the faint galaxy lying to the east of the Quintet) at last month's "No-Frills Star Party" at Tuckahoe State Park in Queen Anne, MD. It wasn't easy, even in a 25", but sure enough I could see it "flash" on and off every once in a while. My sighting was confirmed by another observer. Truly, a great area of the sky.
= Stephan's Quintet
L&deV: nrby * V=14.58/0.72.
Arp (ApJ 183): gx in pa130.
25cm - 0'.8x0'.6 in pa150, w/*ar nuc suspected. 6' NW of grp, E of wide pair N of grp is neb which is three *s in line on photo.
30cm - lgst of grp, alone. halo 1'.25x0'.75 in pa110. wk broad concen w/o distinct nuc. m14 * 20" SE of center looks like nuc occas. CBL, 30Nov1983, USNO.
[amastro] posting, Sat Nov 25, 2006
82" telescope, McDonald Observatory near Fort Davis, Texas, USA
f/13.7, 35mm Televue Panoptic (5' fov, 812x)
This group was on everyone's object list, and rightly so. Spiral structure was noted in NGC 7320, and maybe in NGC 7318 (sometimes referred to as NGC 7318B). I had to scroll over a bit to pick up NGC 7320C (not one of the Quintet) because it would not fit into the 5 arc-minute FOV with the rest of the group. Quite a sight.
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT, 16-inch f/10 SCT (346x, 462x)
NGC 7320. Stephan's Quintet has always mesmerized me. On many occasions I have tried to spot it in my 6" but no luck so far. Last night, I managed to see two faint spots at the location of the Quintet. Comparing the view in the 10", I saw NGC 7320 and a combined blob of NGC 7318A and 7318B. The 10" showed both cores of NGC 7318 A and B as well as NGC 7317 and NGC 7319.
The Messier objects
The Bennett objects
The Caldwell list
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