The Antlia Cluster (Abell S0636) is the 3rd closest galaxy cluster, behind only the Virgo and Fornax clusters, and lies about 133 million light-years distant. From my location in Southern California, the cluster’s -35° declination rises to about 28° above my southern horizon, certainly not optimal, but still good enough for a nice view. When I viewed this cluster from OzSky in Australia I counted at least a dozen galaxies in one field of view! While trolling the internet for facts and figures about this cluster I came across this interesting paper and learned that it contains at least 234 members, and possibly as many as 420!
Here is a spectacular APOD, but understand that in this photo south is up. Here, I’ve turned it over so north is up…
… and for those of you who like lots of information, here is an annotated version of the same photo! This astrophotographer, Rolf Olsen, has done an amazing job!
Here is a screenshot from SkyTools with some DSS overlays, and the circle there is 1/2 degree, for scale…
The Antlia Cluster is classified as a Bautz-Morgan type III cluster, which means that it does not have a single brightest central cluster member. The central area of the cluster is dominated by 2 elliptical galaxies, those being NGC 3258 in the southwest and NGC 3268 in the northeast. Each of these galaxies contain 5,000-6,000 globular clusters, which was the reason the above-referenced paper was written. As with most elliptical galaxies, there is not too much to say about them, in this case they are moderately bright, and round, with a brighter center.
About 2’ ENE of the mag 11.5 NGC 3258 is the mag 12.6 NGC 3260, and about 3’ to the SSW is the mag 13.1 NGC 3257, and for me they are just smudges.
The mag 11.5 NGC 3268 has a mag 13.7 companion 2’ to the west (NGC 3267), a nag 13.3 companion 6’ to the north (NGC 3269) and a mag 12.8 companion 6’ to the SE (NGC 3271). Although fairly dim, they are all in the same FOV and are a nice sight.
About 32’ to the NE of NGC 3268 is the biggest galaxy in the Antlia Cluster, that being mag 11.6 NGC 3281, an unbarred Seyfert spiral. In the eyepiece, this was a 3:2 elongated brighter smudge with no visible companions.
Reply With Quote