Object of the Week September 16, 2018 – VV 738

[deepskytraveler]

Object of the Week September 16, 2018 – VV 738

VV 738, UGC 12342, PGC 70414, MCG +3-58-30, CGCG 453-61
Type: Interacting Galaxy System
VV Type: PC – pair of coalescents
Constellation: Pegasus
RA: 23 04 53.4
Dec: +16 40 42
Size: 13’ x 5’
Mag: 15.0

This week’s Object of the Week features a guest observation from amateur astronomer and Deep Sky Observing Guide author, Alvin Huey. I expect you will find Alvin's OOTW, VV 738, to be quite intriguing. Though best observed in telescopes larger than 20”, it is not necessarily out of reach for moderate size telescopes in the 15" to 20" range. Regardless the size of your telescope give it a go and let us know!

This interacting galaxy system VV 738 is from the Vorontsov-Velyaminov Catalogue, which comprises of 2014 objects (based on the highest VV catalogue number). Dr. Boris Vorontsov-Velyaminov (1904-1994) of Sternberg Astronomical Institute, Moscow University, created a series of lists of interacting galaxies starting in 1959. A majority of the systems were found on the POSS plates from the Palomar 48-inch Schmidt astrograph. The original list, Part I, contained 355 systems. It should be noted that the more famous list, Arp Peculiar Galaxies, was done AFTER Boris’s list. Approximately half of Boris’s Part I list was listed as an Arp as Boris’s paper was the inspiration for Arp’s list. Dr. Halton Arp has access to the 200-inch reflector, which in turn gives Arp the ability to dig deeper and get a clearer image of the structure within these galaxies. As Steve Gottlieb pointed out, a number of Vorontsov-Velyaminov “nests” and chains turned out to be late- type single dwarf irregulars (e.g., VV124 and VV104) with active star formations regions mimicking the appearance of multiple galaxies.
Then in 1977, Vorontsov-Velyaminov (V-V) published Part II of his list, containing an additional 497 interacting systems, labeled as VV356 through VV852. Lastly, in 2001, an additional 1162 objects were added from the Morphological Catalogue of Galaxies by Vorontsov-Velyaminov et.al. These objects have numbers ranging from VV853 to VV2014.V-V has classified each interacting galaxies within several categories, and for most objects, he classified some unique details. Categories include M-51 types, Nested galaxies, Pairs of galaxies, Chain of galaxies, Ring galaxies and Enigmatic galaxies. Some details he listed include tails, bridges and disruptions to list a few.

Alvin has observed this VV 733 twice with his 22” f/4 reflector under very good dark skies. Here are his observing reports and sketches.

October 1, 2016 at Blue Canyon at 5,200 feet elevation. NELM was at 6.5, transparency at 4/5 and seeing was average at 3/5.
22” f/4 reflector at (230, 255, 328, 383 and 575x) - The galaxy is picked up as a considerably faint and fairly low surface brightness glow at 230x. However, the bent shape was easily seen with the northwest part a little brighter than the southern part. Cranking the magnification from 230 to 383x, the bent shape was more readily apparent with the noted part being brighter than the rest. The extensions were not picked up with my 22” at any magnification. A faint arc of three 16.8 to 16.9 mag stars were picked up about 1’ south of the galaxy, only at 383x. Interesting object!

VV738_10_01_16__1537156981_40287.jpg

I took at second look at this object earlier this month on September 1, 2018 at the same location. This time the skies were a bit better at NELM = 6.8 and the object was higher in the sky, 60 degrees above horizon versus 45 degrees when I last observed it in October 2016.
22” f/4 reflector at (230, 255, 328, 383 and 575x) – This object was immediately picked up as a faint bent glow at 230x with the NW part noticeably brighter than the southern part. Increasing the magnification to 383x, the extensions became very faintly, yet intermittingly visible. It was not easy to pick up, but held only 50% of the time at 383x. At 575x, the extensions were still there, but a little less apparent. A faint arc of 16.8 to 16.9 mag stars was detected even at 328x, but best seen at 575x.

VV738_09_01_18__1537157003_35926.jpg

In both observations, this object is best seen if the 11th magnitude double star about 3.2’ ENE from the object is kept off the field. I used several orthoscopic eyepieces (10mm ZAO-II, 9mm BGO and 7mm BGO) and with its narrow field it helped to keep the double star off the field. Best viewed with the 6mm ZAO-II giving 383x with a 6.2’ field. I (Alvin) attempted to use the 4mm ZAO-II at 575x, it was a bit too much magnification.

VV738-SDSS.jpg
SDSS image

If you have a large telescope and wish for a challenging observing project, you can download the the Vorontsov-Velyamino observing guide from Alvin’s website, www.faintfuzzies.com. Navigate to the Downloadable Observing Guides. VV 738 is found on page 46 of “The Vorontsov-Velyaminov Catalogue of Interacting Galaxies (Part II)”.

Give it a go and let us know.

[Steve Gottlieb]

24" (8/30/16): at 375x; easily visible though fairly faint at best, elongated roughly 2:1 ~N-S. There appeared to be a brighter knot at the north end that bulged out towards the northwest. An unequal 5" to 6" double star [mag 11-11.5 primary] is 3.3' NE. Located 7.3' NNW of mag 6.4 HD 218101. UGC 12350 lies 13' NE.


On the SDSS the "knot" appears to be the nucleus of one of the two distorted, interacting galaxies. The appearance reminds me of VV 560 = UGC 10402.

[Uwe Glahn]

Cool object Mark. I caught it under very good transparency but only average seeing. Both wings were visible with the 27-inch as very thin ejections, similar to Alvin's sketch.

27", 419x-586x, NELM 7m0+, Seeing III
UGC12342.jpg

[KidOrion]

I observed this object in a 12.5" Dobsonian this morning under 21.5 (SQM) skies at 112x and 157x. It showed almost no detail at all, but was clearly visible. Notes later once I have them transcribed.

[KidOrion]

My notes:

08/03-08/04/19

LINSLAW POINT (43 58’ 48” N. 123 42’ 4” W)
SUNSET: 8:34 PM
MOON: 3 days (set at 10:36 PM; 14% illuminated)
SEEING: 7
TRANSPARENCY: 6
SQM: 21.54 (west, CrB), 21.42 (Pegasus)
NELM: not checked
WEATHER CONDITIONS: temps mid 50s, cool, slight breeze, no dew

Others present: DB, AG

All observations: 12.5″ f/5 Discovery truss-tube Dobsonian, 14mm ES 82˚ eyepiece (112x, 0.7˚ TFOV) or 10mm TeleVue Delos (157x, 0.5˚ TFOV) unless otherwise noted

2:48
NGC 7468A/UGC 12342 (Peg): This is another insane “get!” This eye-bleedingly faint galaxy was the DSF Object of the Week almost a year ago (see here). Better known as VV 738, it’s a colliding/coalescing pair, throwing out long tidal streamers at the ends of its major axis. Visually, it’s a very difficult little spot, no more than 0.5’ x 0.25’, if that, elongated N-S. [In the 14mm at 112x, it’s difficult to judge the galaxy’s size, as it’s listed at magnitude 15.0.] There’s no detail visible or brightening at all, just a difficult little glow. The galaxy has F somewhat N of it by 3.5’ a 12th-magnitude star; continuing that direction for another 1.75’ is a pair that’s very close and very faint: these are both magnitude 14.5 and separated by 0.25’ NP-SF. From the galaxy 8’ S very slightly F, and making a mess of the field, is a 6th-magnitude star; S very very slightly F that star by 4.3’ is an 8.5-magnitude star that has a 13.5-magnitude star F slightly S of it by 0.5’. The galaxy is very very tough to hold steady; I’m actually surprised to have found it in a “mere” 12.5” scope. With the 10mm Delos, the galaxy is a little more obvious, just barely holdable in direct vision. [I’m trying to nudge the bright stars out of the field, which helps viewing the galaxy.] In the Delos there’s not much more in the way of detail but the extra magnification and the better quality of the eyepiece makes the galaxy just “brighter.” Every now and then, there’s a suggestion of very faint central brightening (no trace of the tidal tails, of course). I’m surprised to have found it at all, though, yet it’s unmistakably there!