2 Attachment(s)
Object of the Week March 24th 2019 - Abell 1367
Abell 1367
ACO 1367
Leo Cluster
R.A.: 11h44m30.0s
Dec.: +19°50'00"
Size: 24.6'
Galaxy Cluster Abell Class 2 1 Bautz-Morgan Class II-III
The third brightest galaxy cluster, at least for northern hemisphere observers, is the Leo cluster, Abell 1367. It is often overlooked in favour of the more
popular Abell 1656 which is a pity as it offers some fine galaxy observing. Abell 1367 is thought to be a dynamically young cluster with two sub groups
in the process of merging and lies at the point where two filaments join. One group is centred around the active galaxy NGC 3842 with its optical jet
and the other is around NGC 3862 and contains the X-ray centre of the cluster. The high number of spirals also suggest this is a dynamically new cluster.
The cluster lies at a distance of about 330 million light years and is part of a filament of galaxies that included the Coma Cluster Abell 1656 as
well as numerous smaller galaxy groups. All of these make up
part of the great wall of galaxies. The brightest galaxies in the cluster, NGC 3842 and 3862, were as perhaps expected discovered by William Herschel but
his son John added a lot more of the galaxies in the cluster that ended up in the NGC. The NGC contains 26 galaxies in the cluster area, although not all
are members of the cluster. There are also a number of IC galaxies in the cluster. One of the challenges of observing the cluster is the large spatial area
it covers over a square degree of sky. Albert Highe found over 200 galaxies listed within 1.25 degrees of the cluster centre, however most studies suggest
the cluster contains maybe 80-129 galaxies, Albert also provided a very useful chart of the cluster but unfortunately his web page has now gone,
although undoubtedly it could be retrieved with the Internet Wayback machine. Probably one of the first amateur studies of the cluster was published in
the Webb Society Deep Sly Observers handbook in 1981 and this included observations with 16 and 36" telescopes. Lughinbubl and Skiff also published
a chart and observations in the Observing Handbook and Catalogue of Deep Sky Objects in 1990. Steve Gottlieb with his older 17.5” telescope records 60
cluster members so I assume that many more can be seen with larger telescopes. My first experience of the cluster was under the dark skies of Wales
with a 15” when I was surprised by the number of galaxies I could see. Unfortunately it also showed me that observing galaxies from my home location was
going to be a waste of time as the high levels of light, and other forms of pollution meant it was a disappointing experience going back to these observations,
even with a larger telescope. Interestingly the sizes given for the cluster vary widely with Megastar quoting 100’ and others suggesting around 24’. This may
represent either just the core area or the whole cluster. As the cluster galaxies are relatively bright this is a fine cluster for observing with medium sized telescopes
as well as large ones.
Attachment 3464
Attachment 3465
As always give it a go and let us know.
