NGC 1129 in Perseus

December 2024 - Galaxy of the Month

This interactive image of NGC 1129 in Perseus was provided by the Sloan Digital Sky Survey (SDSS) using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies, as will this link for NGC 1129 on the Stellarium Web planetarium.

Our target this month is the small galaxy group surrounding NGC 1129 in Perseus.

NGC 1129 itself was first discovered by William Herschel in 1786 and is a giant elliptical galaxy (E5?) listed as the brightest cluster galaxy of a small cluster. It is by far the brightest galaxy in the group with NGC 1131 coming in at around 15.2 and IC 265 coming in at 15.5. The Rosse team examined this field with the 72” in 1855 and found two other galaxies which got labelled as NGC 1130 and NGC 1131. However, it Is not actually clear which galaxies they saw and the MCG messed up the identifications further. The only one that is clear is NGC 1129. It is not clear how Lord Rosse missed the brighter galaxy MCG 7-7-8 close by if he found the fainter ones. IC 265 was picked up by Lewis Swift using the 16” refractor in 1888, one assumes from Rochester, New York as he did not move to Echo Mountain until 1893.

There is a small galaxy within the halo of NGC 1129 and this pair was catalogued in Vorontsov-Veleyaminov’s catalogue of interacting galaxies as VV 85. As can be seen there is actually a small chain of three galaxies here. The distance to the group is not well known but the Hubble (redshift) distance gives about 74 Mpc. The group is also known as WBL 88 which lists 7 galaxies in the group. Perhaps unsurprisingly for such a faint group there have not been many studies of the galaxies, although the globular clusters in the group do appear to have come under recent study. It seems that the cluster is filled with hot X-Ray emitting gas, although there is no obvious current AGN in the group. The cluster is also classified as AWM 7 and is part of the Pisces-Perseus supercluster.

NGC 1129 itself may be relatively easy to find but I suspect the other galaxies in the group are going to be far more challenging to observe given their faintness. The group does make it into the Astronomical League’s Galaxy Groups and clusters list and also, perhaps surprisingly in the compilation of Walter Scott Houston’s columns where it is suggested that they may be visible in a 10” scope. I find this rather unlikely. Perhaps as expected NGC 1129 is too far off the beaten track to appear in The Night Sky Observer's Guide (NSOG) Volume 1 or any of the other standard observing guides.

Owen Brazell - Galaxy Section Director

If you'd like to try out the Clear Skies Observing Guides (CSOG), you can download observing guide for the current Galaxy of the Month without the need to register. CSOG are not associated with the Webb Deep-Sky Society but the work of Victor van Wulfen.