Shakhbazian 166 in Ursa Minor

MCG+14-8-17 14.9
MCG+14-8-15 15.3
MCG+14-8-16 15.3
MCG+14-8-18 15.4

A few years ago I ran across a series of articles in Astronomische Nachrichten on Shakhbazian compact galaxy groups. These distant groups were catalogued in the 1970's in a series of articles but are little known to amateurs since most of the galaxies in the groups are 18th magnitude or fainter.

Leafing through the Digitized Sky Survey images in the A.N. articles one of the most promising visual targets appeared to be Shakhbazian 166, which is also catalogued as UGC 10638 and described as a linear chain of 11 galaxies in Ursa Minor. Several of the individual members (which are virtually stellar on the DSS) are catalogued in the Morphological Catalogue of Galaxies (MCG), but their positions are too rough to sort out the individual identities. In any case armed with a Guide Star Catalogue chart of the field this was one of first targets when the astronomy class at the Sierra Nevada Field Campus last summer ended on Monday night.

Once the field was identified on the GSC chart, two or three faint galaxies were immediately seen at 220x. Several minutes of carefully scrutinizing the area at 280x reveal a total of five members in a chain less than 7' in length oriented SW-NE! All of these galaxies appeared as 15"-25" round "knots" of approximately 15th magnitude and hidden among a number of faint field stars. The brightest member is catalogued as MCG +14-08-017 = CGCG 367-021 as is situated 50" following a mag 13 star. A couple of these objects required averted vision to glimpse. - Steve Gottlieb

Observing Notes on Shakhbazian 166

M+14-08-015 = (U10638) = Z367-019 = NPM1G +81.0089 = Shkh 166-2
16 50 58.7 +81 34 29

17.5" (7/9/99): very faint and small, round, 15"-20" diameter. Requires averted for best view. Located less than 2' NW of a mag 12.5 star.

17.5" (7/20/98): first in the Shakhbazian 166 galaxy group with five members observed in a 6.7' chain oriented SW-NE!! This object was typical of the members of the group (3rd brightest) - extremely faint, round, 15"-20" diameter. Located 1.6' NW of a mag 12 star. This object is actually a triple system although the faint companions to the NE and S were not visible.

M+14-08-016 = (U10638) = NPM1G +81.0090 = Shkh 166-3
16 51 45.0 +81 35 31

17.5" (7/9/99): very faint, round, ~20" diameter. This is probably the second easiest member of Shkh 166.

17.5" (7/20/98): second of five in the UGC 10638 chain (Shkh 166) and very similar to M+14-08-015 located 2' SW. Appears as an extremely faint round "knot" perhaps 15" in diameter.

Anon = GIN 616
16 51 58.7 +81 30 43

17.5": this threshold galaxy is located close south of the Shkh 166 (U10638) chain in the same field of view. With averted and concentration appears for moments as a 10" knot 45" SW of a mag 13 star and 1.5' NW of a wide mag 12/13 pair. The detection was repeated several times. Member of Abell 2247.

NPM1G +81.0091 = (U10638) = Shkh 166-4
16 52 12.9 +81 37 13

17.5" (7/9/99): very faint, round, ~15" diameter. Situated just 0.7' SW of a mag 13 star and 1.5' WSW of Shkh 166-1. Easily visible with averted but cannot hold steadily.

17.5" (7/20/98): third of five in a compact galaxy chain (Shkh 166). This extremely compact object appeared as a 10" knot just 40" SW of a mag 13 star and was the fourth brightest in the group.

M+14-08-017 = (U10638) = Z367-021 = NPM1G +81.0092 = Shkh 166-1
16 52 47.7 +81 37 58

17.5" (7/9/99): brightest (barely) in Shkh 166. Situated less than 1' following a mag 13 star and collinear with NPM1G +81.0091 = Shkh 166-4 just 1.5' WSW and M+14-08-018 = Shkh 166-7 just 1.4' NE. Appeared faint, round, ~20", very weak concentration.

17.5" (7/20/98): brightest in the UGC 10638 chain (UGC notes 11 members - I viewed five of these) located 30' SE of mag 4.2 Epsilon UMi. Like all members, this object appeared as a featureless round spot ~20" diameter (a bit larger than the other members) situated 50" E of a mag 13 star. NED lists this compact group as part of Abell 2247.

M+14-08-018 = (U10638) = NPM1G +81.0093 = Shkh 166-7
16 53 17.0 +81 38 51
Size 0.7x0.3; PA = 5d

17.5" (7/9/99): this member of Shkh 166 is situated 1.4' NE of M+14-08-017 = Shkh 166-1. Appears extremely faint, very small, requires averted to comfortably view. In moments of steady seeing the galaxy is clearly elongated 2:1 ~N-S with dimensions ~20"x10".

17.5" (7/20/98): last and furthest NE in a linear chain of five galaxies with a 7' total length. I recorded this object as the faintest in the group appearing as a 15" round spot with averted vision. Located 1.4' NE of M+14-08-017 (brightest in group).