Hickson 56 in Ursa Major

56aMCG+09-19-1131.1X0.2 15.213.3
56bUGC 065271.1X0.3 15.314.1
56cPGC 356180.7X0.4 14.813.6
56dPGC 356150.4X0.3 16.8
56ePGC 356090.5X0.3 15.4

Another remarkable chain of galaxies, Hickson 56 in Ursa Major, is situated just 7' south of the barred spiral NGC 3718. This compact group has several catalogue designations including UGC 6527, VV 150, Markarian 176 and Arp 322. The UGC notes describe Hickson 56 as "a nonlinear chain of 4 galaxies." These four are connected and cover a length of 90" = 48kpc. The fifth galaxy is about 65" from the nearest member of the chain and is possibly at the same distance." Photographs reveal all five members with the central trio appearing as a linked chain, but visually splitting apart the members will challenge experienced deep-sky aficionados.

At 100x, this compact group merged into a faint elongated glow just 1' in length, elongated roughly east-west in a 3:1 ratio. Upping the power to 220x resolved a pair of "knots"; 56b at the east end and 56c at the west side. Hickson 56a is the largest member of the group but this low surface brightness edge-on required close attention. The observers using Lord Rosse's 72-inch Leviathan in Parsonstown, Ireland examined the field of NGC 3718 four times between 1852 and 1868 and missed this galaxy chain so just detecting this group is a satisfying experience. - Steve Gottlieb