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Thread: Object of the Week June 17, 2012 – Arp 171 and the NGC 5718 galaxy group

  1. #1
    Member Howard B's Avatar
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    Object of the Week June 17, 2012 – Arp 171 and the NGC 5718 galaxy group

    Arp 171 and the NGC 5718 galaxy group

    Galaxy Group
    Virgo
    J2000
    RA 14 40 43
    DEC +3 27 57

    MAG 13.9 (N5718) 14.3 (IC1042)

    Arp 171 is only a small part of the NGC 5718 galaxy group, which I didn’t realize before observing it on the night of May 18, 2012. I went expecting to see two relatively bright galaxies close to each other, but in the eyepiece I saw two similar pairs equally close – which was Arp 171?
    Arp171_N5718 group crop.jpgN5718 group, Arp171_dss_search.jpg

    Turns out it’s the pair on the left – NGC 5718 and IC 1042, but the real fun was slowly realizing there where even more galaxies in the field of view. I ended up seeing ten using 408x with my 28 inch f/4 Newtonian under a 21.48 SQM sky, but there are a few more in the neighborhood for the patient observer to find.

    "GIVE IT A GO AND LET US KNOW"

    GOOD LUCK AND GREAT VIEWING!
    Howard
    30-inch f/2.7 alt-az Newtonian
    https://sites.google.com/site/howardbanichhomepage/
    https://sites.google.com/site/sprays...pemirrors/home
    Contributing Editor, Sky & Telescope magazine

  2. #2
    Member Steve Gottlieb's Avatar
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    Howard, your excellent pick for Object of the Week and sketch inspired me to take a look at this group last night with my new 24" at my local site (mag 21.40-21.45 SQM skies) just north of Santa Rosa. The group has the designation MKW 8 and WBL 518. The MKW groups are from this paper -- http://articles.adsabs.harvard.edu/f...pJ...199..545M

    I ended up logging 21 galaxies in a 1 degree circle centered on NGC 5718, though there were many more faint ones I didn't have the patience to chase after. I checked NED and all 21 are members of the group (z = .028). I noticed Megastar does not correctly identify IC 1043 -- it's the galaxy listed as a MAC just east of IC 1041. There's not much structure in any of these galaxies but here are my notes ---

    CGCG 047-128 = PGC 52372
    14 39 18.0 +03 22 06
    V = 14.1; Size 0.9'x0.7'; PA = 157d
    faint, small, round, even surface brightness, 15" diameter. Located 5.6' E of a mag 11 star on the southwest side of the MKW 8 group.

    CGCG 047-129 = MCG +01-37-043 = PGC 52384
    14 39 37.8 +03 08 48
    V = 13.8; Size 0.9'x0.6'; PA = 21d
    fairly faint to moderately bright, small (outer halo not noticed), oval 4:3 NW-SE, 20"x15", broad concentration with a brighter nucleus that increases to the center. Nearly collinear with a mag 11 star 2.6' SSW and mag 9.6 HD 128922.

    2MASX J14393976+0343153 = PGC 3124863
    14 39 39.8 +03 43 15
    V = 15.4; Size 0.4'x0.25'; PA = 15d
    faint, extremely small, round, 10" diameter, no details. Located 3.5' SE of a mag 10.0 star on the northwest side of the NGC 5718 group (MKW 8).

    CGCG 047-130 = PGC 52382
    14 39 41.2 +03 55 27
    V = 14.4; Size 0.9'x0.4'; PA = 61d
    faint to fairly faint, small, irregularly round, 20"x15". Located on the north side of the NGC 5718 group (MKW 8).

    2MASX J14401689+0339321 = PGC 1256360
    14 40 16.9 +03 39 32
    V = 15.1; Size 0.4'x0.25'; PA = 130d
    faint, extremely small, round, 10" diameter. A mag 15.2 star is just 14" W of center. This member of the NGC 5718 group (MKW 8) is located 13' NNW of NGC 5718.

    CGCG 047-131 = WBL 518-001 = PGC 52423
    14 40 26.0 +03 35 56
    V = 15.0; Size 0.5'x0.25'; PA = 35d
    faint, very small, round, 12"-15" diameter, occasional faint stellar nucleus. Situated 9' NNW of NGC 5718/IC 1042 = Arp 171 in the core of the MKW 8 group.

    IC 1039 = CGCG 047-133 = WBL 518-002 = PGC 52428
    14 40 29.4 +03 25 58
    V = 14.7; Size 0.6'x0.3'; PA = 43d
    faint, very small, slightly elongated SW-NE, 15" diameter. Located 3.7' SW of NGC 5718 in the core of the galaxy group MKW 8.

    IC 1041 = MCG +01-37-045 = CGCG 047-134 = WBL 518-004 = PGC 52434
    14 40 37.9 +03 22 37
    V = 13.9; Size 0.8'x0.6'; PA = 165d
    fairly faint, fairly small, elongated 4:3 NNW-SSE, well concentrated with a small bright core. Forms a close pair with IC 1043 1.4' E. Located 5.5' S of NGC 5718/IC 1042 in the MKW 8 cluster.

    IC 1042 = Arp 171 = UGC 9457 = MCG +01-37-046 = WBL 518-003 = PGC 52433
    14 40 39.0 +03 28 10
    V = 13.3; Size 1.1'x1.1'; Surf Br = 13.3
    fairly faint, fairly small, round, 24" diameter, weak concentration. Fainter member of a double system (Arp 171) with NGC 5718 at the WSW edge (haloes virtually in contact.

    NGC 5718 = Arp 171 = UGC 9459 = CGCG 047-137 = MCG +01-37-047 = WBL 518-005 = PGC 52441
    14 40 42.9 +03 27 55
    V = 12.9; Size 1.5'x1.1'; Surf Br = 13.3; PA = 85d
    moderately bright, fairly small, oval 3:2 or 4:3 E-W, ~35"x25", large bright core, brighter along the major axis. Forms a double system with IC 1042 (Arp 171), 1.0' WNW. A mag 10.7 star is 1.2' NE and detracts a bit. Brightest member in the poor group MKW 8 and over 20 members tracked down within 30' of NGC 5718.

    IC 1043 = PGC 2800989
    14 40 43.4 +03 22 26
    V = 14.8; Size 0.6'x0.3'; PA = 22d
    faint, very small, slightly elongated SSW-NNE, 15"x10", faint stellar nucleus with direct vision. Located 1.4' E of IC 1041 in the core of the NGC 5718 group (MKW 8). This galaxy is not identified as IC 1043 in Megastar or HyperLeda and is not listed in the original PGC.

    CGCG 047-136 = WBL 518-006 = PGC 52442
    14 40 43.5 +03 15 15
    V = 14.7; Size 0.7'x0.5'; PA = 29d
    faint, small, round, 15" diameter, weak concentration to center.

    CGCG 047-138 = WBL 518-007 = PGC 52448
    14 40 46.1 +03 05 56
    V = 15.0; Size 0.5'x0.35'; PA = 167d
    faint, very small, round, 15" diameter, occasional stellar nucleus. A mag 14.4 star is 35" SW and a triangle of mag 14/15 stars is close north. UGC 9463 lies 4' NE.

    CGCG 047-140 = WBL 518-008 = PGC 52452
    14 40 52.7 +03 25 06
    V = 14.6; Size 0.5'x0.3'; PA = 50d
    faint, very small, round, 15" diameter, faint stellar nucleus. This member of the NGC 5718 group (MKW 8) is located just 3.7' SE of NGC 5718.

    CGCG 047-141 = WBL 518-009 = PGC 52451
    14 40 56.6 +03 31 41
    V = 15.3; Size 0.6'x0.3'; PA = 167d
    very faint, very small, 0.4'x0.2', elongated 2:1 N-S, low surface brightness. Located 5' NE of NGC 5718 in the core of the MKW 8 group. Situated less than 1' NW of wide 34" pair of mag 10.8/12.1 stars (HJ 1257).

    UGC 9463 = CGCG 047-139 = WBL 518-010 = PGC 52453
    14 40 59.3 +03 08 13
    V = 14.2; Size 1.0'x0.3'; PA = 43d
    faint to fairly faint, fairly small, oval 2:1 SW-NE, 20"x10", broad concentration. Two mag 15.5-16 stars aligned NW-SE are on opposite sides of the NE end of the galaxy. CGCG 047-138 lies 4' SW.

    2MASX J14410613+0339399 = PGC 1256400
    14 41 06.1 +03 39 40
    V = 16.0; Size 0.4'x0.3'; PA = 123d
    extremely faint and small, round, 12" diameter. Only glimpsed with averted but confirmed. Located 13' NE of NGC 5718 and 1.8' SE of a mag 10.4 star in the MKW 8 group.

    CGCG 047-143 = WBL 518-011 = PGC 52475
    14 41 32.1 +03 35 57
    V = 14.8; Size 0.5'x0.3'; PA = 60d
    faint to fairly faint, very small, round, 15" diameter, gradually increases to a very small brighter nucleus. Located 15' NE of NGC 5718 in the MKW 8 group.

    CGCG 047-145 = WBL 520-001 = PGC 52502
    14 41 58.7 +03 23 24
    V = 14.4; Size 0.5'x0.4'; PA = 145d
    faint, very small, round, 18" diameter, weak concentration. Located 10' ESE of mag 8.4 HD 129229 in the NGC 5718 group (MKW 8).

    CGCG 047-146 = PGC 52508
    14 42 06.3 +03 19 51
    V = 15.4; Size 0.5'x0.5'
    extremely faint, very small, irregularly round, ~15" diameter. Located 22' SE of NGC 5718 in the MKW 8 group.

    CGCG 047-147 = WBL 520-003 = PGC 52525
    14 42 25.7 +03 13 55
    V = 14.0; Size 0.9'x0.35'; PA = 110d
    fairly faint, fairly small, elongated 2:1 WNW-ESE, 25"x12", broad concentration.
    Last edited by Steve Gottlieb; June 20th, 2012 at 04:37 AM.
    Steve
    24" f/3.7 Starstructure
    18" f/4.3 Starmaster
    Adventures in Deep Space
    Contributing Editor, Sky & Tel

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