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Thread: Object of the Week October 19, 2014 - Shakhbazian 317 Galaxy Chain

  1. #1
    Member Steve Gottlieb's Avatar
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    Object of the Week October 19, 2014 - Shakhbazian 317 Galaxy Chain

    Shakhbazian 317

    Galaxy Chain (6' length)
    Cetus
    RA: 02h 10m 41s
    Dec: -06° 35' 12"
    Magnitude: V ~ 14.5-16.5

    If you enjoy galaxy chains or linear galaxy groups such as HCG 55, 56 and 27, Shakhbazian 16 and 166, Burbidge's Chain, etc., then check out Shakhbazian 317!

    If you're not familiar with Shakhbazians, these are compact clusters of compact galaxies catalogued by Armenian astronomer Romela Shakhbazian. These groups are similar to several of the fainter Hicksons -- in fact, HCG 97 = Shkh 30 and HCG 50 = Shkh 5. The members, in general, are very compact, reddened ellipticals and some of the groups consist up to 15 members. It is not uncommon that some of the individual objects in the groups have turned out to be single stars.

    Many of the Shakhbazians are extremely challenging targets with magnitudes from 14 down to 19 or 20. In fact, Shkh 1, discovered in 1957, was so distant (1.5 billion light years) and compact (1.2' diameter), that is was first thought to be a distant star cluster. I would consider it one of the ultimate deep sky challenges. During the 1970's, Shakhbazian and collaborators, found 376 additional compact clusters by examining a selection of 200 POSS plates and published the results in a series of papers.

    For more on the Shakhbazians, including visual observations, check out Andreas Domenico's site.

    Several of the galaxies in Shakhbazian 317 were first catalogued by Russian astronomer Boris Voronstov-Velyaminov in the MCG during the mid-1960's, so carry PGC designations. Officially, there are 7 Shkh 317 members that were catalogued by Romela. Here's the important data ...

    Shkh 317-1 = MCG -01-06-064 = PGC 8340
    02 10 53.4 -06 33 34
    Size 0.5'x0.4'; PA = 145d
    Mag 15.7B

    Shkh 317-2 = PGC 96667
    02 10 53.2 -06 34 54
    Size 0.35'x0.3'; PA = 107d
    Mag 16.7B

    Shkh 317-3 = MCG -01-06-062 = PGC 8329
    02 10 43.2 -06 34 47
    Size 0.35'x0.3'
    Mag 16.3B

    Shkh 317-4 = MCG -01-06-061 = PGC 8330
    02 10 40.9 -06 35 05
    Size 0.4'x0.25'; PA = 36d

    Shkh 317-5 = MCG -01-06-060 = PGC 8328
    02 10 36.6 -06 36 01
    Size 0.35'x0.15'; PA = 147d
    Mag 16.7B

    Shkh 317-6 = MCG -01-06-059 = PGC 8316
    02 10 35.6 -06 36 23
    Size 0.3'x0.2'; PA = 179d
    Mag 16.9B

    Shkh 317-7 = MCG -01-06-058 = PGC 8315
    02 10 32.8 -06 36 59
    Size 0.4'x0.4'
    Mag 15.9B

    With my 18-inch, I had no problem pulling in 5 of the galaxies in this 6' southwest to northeast chain from my local "blue/green" site (elevation 1200 ft). Shkh 317-7, at the southwest end, was the easiest in the chain and appeared faint, round, 15" diameter. A mag 12 star lies 2' south-southwest. About 3' northeast is the double system Shkh 317-3 and 317-4 (38" between centers). I logged Shkh 317-3 as very faint, round and slightly brighter (more condensed core) than Shkh 317-4. Sometimes this close pair merged into a single object. Another 3' east lies Shkh 317-2. It appeared very faint, round, 10" diameter A mag 12 star lies 1.9' NNW. Finally just 40" SE of the mag 12 star is Shkh 317-1, a very faint, extremely small glow, 10" diameter.

    I've yet to look at this group with my 24-inch, but in Jimi's 48-inch, all 7 were easily resolved as well as a few additional fainter members such as 2MASX J02105688-0633464 and 2MASX J02110254-0632537. Extending the direction of the chain further to the northeast will eventually lead to the edge-on MCG -01-06-067 = FGC 258.

    Shkh 317.jpg

    I'm guessing a 12-inch or 14-inch will show at least a few of the brighter members from an excellent site. Will a 16-inch or 18-inch show all 7 members?

    “Give it a go and let us know”
    Last edited by Steve Gottlieb; October 18th, 2014 at 08:14 PM.
    Steve
    24" f/3.7 Starstructure
    18" f/4.3 Starmaster
    Adventures in Deep Space
    Contributing Editor, Sky & Tel

  2. #2
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    Unfortunately I never tried this fine group with my 16". As you mentioned Steve it could be possible from the b magnitudes to see all in 16" or maybe 14"? I'm also interested in observation with this aperture. For sure a wonderful group beside the more famous HCG groups.

    My only note and sketch is from the bigger 27" under very good skies. All 7 members were visible easily. As a tougher challenge were some galaxies in the near neighborhood as you already mentioned. S of PGC 8315 I could also pick up 4 more fainter galaxies.

    27", 419x, fst 7m+, Seeing II
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  3. #3
    Member FaintFuzzies's Avatar
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    Good object Steve,

    The last time I looked at this object as during CalStar in 2008. I saw a total of ten galaxies, which are labeled below.

    Shk317.jpg

    22” (287 and 460x) - Nice string of galaxies. 6 were immediately seen at 287x. Upon further observation, two more galaxies were detected at the east end, -64 and 65. At 460x, one more galaxy, which is unlabeled “B” was detected.
    The six seen, from west to east, were MCG-1-6-57, 58, 59, 60, 61 and an unlabeled “A”. The unlabeled galaxy, which is the brightest of the chain, is closest to the 13.6 mag star.
    Clear skies,
    Alvin #26
    faintfuzzies.com

  4. #4
    Member Steve Gottlieb's Avatar
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    Great observation, Alvin. NED uses different assignments for the MCGs, but in any case your "A" = Shkh 317-1 and "B" = Shkh 317-6.
    Steve
    24" f/3.7 Starstructure
    18" f/4.3 Starmaster
    Adventures in Deep Space
    Contributing Editor, Sky & Tel

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