September 2015 - Galaxy of the Month

NGC 48 Group in Andromeda

Browsing through the Clusters section of the Webb Society Deep-Sky Observer's Handbook (WSDSOH) Vol 5 I came across the description of the cluster of galaxies around NGC 48. Apart from their appearance in the WSDSOH the group does not appear to be in any of the other standard references and appears to have been neglected.

The galaxies appear to be a true physical group catalogued as WBL 005. The group consists of the three NGC galaxies NGC 48, 49 and 51 which were first discovered by Lewis Swift in 1885 using a 16” refractor and three IC galaxies IC 1534, 1535 and 1536, all discovered by Barnard in 1888 using a 12” refractor.

The clusters appears to be two parallel triplets with the NGC group and the IC group. Steve Gottlieb does have notes for all the galaxies in the group with a 17.5” telescope but describes them as fairly faint. NGC 51 would appear to be the brightest of the group. This may not be surprising as they have photographic magnitudes of around 14 for the NGC group and around 15 for the IC group.

The group lies on the border of the constellations of Andromeda and Cassiopeia and would appear to consist of two spirals and 4 lenticular S0 galaxies which is slightly interesting unless they are part of a much larger coarse grouping. There is a problem with the distance of NGC 48 as the redshift measurements are wildly discordant. However as it appears to be part of the group with the other 5 it must be at the 63 Mpc distance rather than 43 Mpc which some of the redshifts indicate. The galaxies may be an isolated group that is part of the western end of the Perseus supercluster.

They do however appear to be almost as ignored by the professional community as the amateur as apart from basic data there is really not a lot of information about them. NGC 51 may be a mild form of AGN known as a LINER. There are almost certainly gravitational interactions going on within the group which may be distorting the galaxies and causing some starburst behaviour. IC 1535 was home to SN 2000cz discovered by Mark Armstrong in the UK. IC 1536 is also classified as a Markarian starburst galaxy which is rather odd given is morphology of E/S0.

The will make both an interesting visual as well as imaging challenge as I could find no images apart from the DSS on the net.

Owen Brazell - Galaxy Section Director

Mike Wood made an observation of NGC 48 and its companions through his 20" reflector. If you have any observations please let us know.