One of my recent observing projects has been working through the 1979 Karachentseva Isolated Triplets of Galaxies (KTG) catalogue by Karachentseva, Karachentsev and Shcherbanovsky. This catalogue contains 84 northern isolated galaxy triplets (a few are not physical triplets) found by examining the POSS. I'm really not sure what significant astrophysical interest these groups hold for professionals, but as all the component members are included in the CGCG (mag limit ~15.7pg), this is a nice observing project for 12" and larger scopes. With 16"-18" scopes, nearly all the members should be viewable.
Karachentseva classified the configurations as double, line, and triangle, but visually the important factor is that most of these groups are pretty compact -- say 3' to 7' in total size, so fit nicely in a high power eyepiece. A few though are quite separated like KTG 84, which consists of interacting Taffy Galaxies (UGC 12914/12915) and UGC 14, located 32' SE. Here are several KTG groups visible in late winter/early spring, mostly observed a couple of weeks back with my 24". If you check out Alvin Huey's observing reports, you'll find a number of the KTG groups included. If you're not familiar with these triplets, check them out!
KTG 11
07 05 21 +86 36 28
Size 7.4'
18" (8/1/11): This triplet resides only 2.5 degrees from the North Celestial Pole! UGC 3536A = KTG 11B is the brighter component of Arp 96 with UGC 3528A just 1.5' NW. At 225x it appeared fairly faint, compact, round, 20" diameter, steadily increases to a quasi-stellar nucleus. A mag 14.7 star is just off the SW edge, 23" from center. Situated 1.8' E of a mag 10.7 star and 13' SE of mag 6.6 HD 42885. CGCG 362-033 lies 7.4' NE. UGC 3528A = KTG 11A appeared faint, small, slightly elongated (E-W), 0.4'x0.3', very low even surface brightness. KTG 11C = CGCG 362-033 is faint, small, elongated 2:1 E-W, ~25"x12", broad weak concentration. A mag 13.4 star is less than 1' W. Located 14' ESE of mag 6.6 HD 42855.
KTG 11.jpg
KTG 12
06 46 13.9 +43 49 08
Size 3.5'
24" (1/12/13): this triplet is located ~15' NNW of 56 Aur (V = 5.3) and fits in a circle of 3.5'. At 375x, UGC 3535, the brightest member, appeared fairly faint, fairly small, slightly elongated WSW-ENE, 0.5'x0.4', brighter core. UGC 3532 lies 2.8' SW and CGCG 204-013 3.8' NW. UGC 3532, the second brightest member, appeared faint, fairly small, very elongated 3:1 E-W (central bar), even surface brightness, 0.6'x0.2'. CGCG 204-3532 is very faint, very small, round, 12".
KTG 12.jpg
KTG 13
07 07 14.4 +44 49 11
Size 6'
24" (3/9/13): This triplet is aligned in a 6' string oriented NW to SE. CGCG 205-017 = KTG 13B is the middle and brightest of the three galaxies in the KTG 13 triplet. At 282x it appeared fairly faint, fairly small, elongated 2:1 or 5:2 NW-SE, 25"x12", no zones but contains a faint stellar nucleus with direct vision. A mag 15-16 star is at the NW tip. UGC 3673 lies 3' NW and UGC 3679 is 3' SE. UGC 3673 appeared faint, small, round, 18" diameter (central core), low even surface brightness. The extremely low surface brightness arms were not seen. Located 10' E of mag 7.8 HD 53129. This galaxy has a redshift 2.6 times the other two members, so is probably in the background. Finally, UGC 3679, at the SE end, appeared faint to fairly faint, fairly small, round, 24" diameter, low even surface brightness.
KTG 13.jpg
KTG 14
07 09 47 +47 54 42
Size 2.7'
24" (3/9/13): This small triplet is in a 2.7' string oriented E-W. CGCG 234-077, at the west end, is the brightest member of the KTG 14 trio. At 375x it appeared fairly faint, fairly small, slightly elongated, roughly 20"x16", increases to a very small bright nucleus. UGC 3706 (double system) lies 2.5' E. This trio is located 0.7° S of the core of AGC 569 and has an identical redshift, so is probably an outlying member. MCG +08-13-083 is the second of three and the northwest component of an interacting double system (UGC 3706) with MCG +08-13-084. It appeared faint to fairly faint, small, slightly elongated, 15"x12" diameter. Based on the DSS, I viewed only the brighter core region. MCG +08-13-084 is attached on the southeast side, just 0.4' between centers, and was barely resolved. It appeared very faint very small, round, 8" diameter (probably the core region), though occasionally dominated by a relatively bright stellar nucleus.
KTG 14.jpg
KTG 15
07 11 21 +31 10 00
Size 3.2'
24" (3/9/13): This small triplet of CGCG galaxies is contained within 3.2'. CGCG 146-33 is the westernmost and brightest member (total mag) of KTG 15. It appeared faint, fairly small, round, 24" diameter, low nearly even surface brightness. CGCG 146-34 lies 1.9' SE and CGCG 146-36 is 2.9' NE. At 375x, CGCG 146-34 appeared faint, extremely small, round, 10" diameter (core). Although the CGCG mag = 15.7 is the faintest in the trio, this galaxy has a higher surface brightness than the other two members. A mag 14.2 star is 30" W and a mag 14.5 star is a similar distance south. Finally, CGCG 146-036 appeared faint, small, round, 18" diameter. A mag 15.5-16 star is attached at the west end.
KTG 15.jpg
KTG 16
07 17 05.3 +34 01 35
Size 11.4'
24" (3/9/13): this triplet of thin UGC edge-ons is spread out over 11'. UGC 3776 is the first and brightest member, appearing fairly faint, moderately large, elongated 5:2 SW-NE, 0.8'x0.3', broad concentration. Located 6' SW of mag 8.9 HD 56101. UGC 3780 11.6' NE and UGC 3779 11' E. UGC 3780 appeared as a faint, thin edge-on 6:1 SW-NE, 0.6'x0.1', low even surface with no core or zones. Located 5.2' ESE of mag 8.8 SAO 59943 and 6' NE of mag 8.9 HD 56101. Both UGC 3776 and 3780 are very elongated with similar PA's. UGC 3779, the third and faintest member (also a thin edge-on), is 6' S but was not visible in soft seeing.
KTG 16.jpg
KTG 17
07 40 09 +32 13 36
Size 5'
24" (3/9/13): CGCG 147-52 is the first of three 15th magnitude galaxies and appeared faint, small, slightly elongated, 18"x15", very small brighter nucleus. Situated 2' S of a mag 10.8 star. The redshift of 147-52 is twice the other members of the triplet, so this galaxy is probably not a physical member. CGCG 147-53, 2' ENE, appeared extremely faint, very small, round, 12" (core region only). Required averted and only visible 25% or less of the time. Situated 2.4' SE of a mag 10.8 star and 2.5' W of a mag 11.1 star. CGCG 147-52 appeared surprisingly faint to be included in the CGCG (V mag of 15.9). CGCG 147-54, 3.4' NE of 147-53 appeared very faint, fairly small, slightly elongated WSW-ENE, 24"x20", low surface brightness, very weak concentration. The group is ~13' N of mag 6.2 HD 61295.
KTG 17.jpg
KTG 18
07 44 11.5 +29 14 26
Size 4.4'
24" (3/9/13): this triplet contains UGC 3995, an overlapping pair which appeared moderately bright to fairly bright, moderately large, oval 2:1 E-W, 1.3'x0.7', sharply concentrated with a bright 20" core. The halo is fairly uniform except for the nucleus of superimposed KTG 18A, which was barely glimpsed as a stellar or quasi-stellar spot on the west side (30" from the center of the main component). Although UGC 3995 is a physical pair, studies reveal neither galaxy is tidally perturbed. A mag 11 star lies 1.8' S. CGCG 148-5 = KTG 18C lies 4' ENE and appeared faint to fairly faint, small, slightly elongated N-S, 15"x12", increases to a very small brighter nucleus.
KTG 18.jpg
KTG 19
07 47 13.5 +58 59 26
Size 10.9'
24" (3/9/13): UGC 4003 is the first and brightest in the KTG 19 triplet with UGC 4012 7.6' NE and UGC 4020 at 12' ENE. At 375x it appeared moderately bright, moderately large, elongated 2:1 WSW-ENE, 40"x20", well concentrated with a small bright core. UGC 4012 is the faintest in the trio and was logged as faint, fairly small, thin edge-on 5:1 WSW-ENE, 30"x6", faint stellar nucleus. Finally, UGC 4020 appeared fairly faint, oval 3:2 ~N-S, 25"x15", weak concentration. I observed the much brighter core region and I missed the very low surface brightness arms extending SSW-NNE. A mag 14.5 star is just off the south edge. Situated 5.8' SW of mag 8.0 HD 62667.
KTG 19.jpg
KTG 21
08 20 39.0 -01 23 45
Size 3.0'
24" (3/9/13): this triplet is located 16' NW of mag 6.5 HD 70340 and contains two thin edge-ons. UGC 4349 = KTG 21A is a challenging edge-on visible as a very faint "spike" extending west of a mag 13 star, ~20"x6". Located 2.9' N of a mag 9.5 star. First in the KTG 21 triplet with UGC 4352 (overlapping double system) 2.9' SE. The main component of UGC 4352 (KTG 21C) appeared faint to fairly faint, fairly small, round, 24" diameter. MCG +00-22-002 (KTG 21B) was visible as a very faint spike, extending out of the SW side of the larger glow. Situated 2' NE of a mag 9.5 star.
KTG 21.jpg
Reply With Quote
)...but left out the eye-candy, such as M-31, 32, 110 and M-81,82 and that nearby blazing NGC. I'm planning to go ahead and add them for the sake of completeness and add a column in my index for KTG for easy reference. I should have it done within a week and will post it on my website. I'll post here too.
Originally Posted by Dragan
