ASTRO: Abell 2197 an amazing field

Abell 2197 is a moderately condensed galaxy cluster containing over 50
galaxies, most "big and bright" at least compared to most Abell
clusters. It is about 420 million light-years from our galaxy and
located in Hercules, just not THE Hercules Galaxy cluster which is Abel
2151. The cluster is rather linear in nature with two widely spaced
large elliptical cD galaxies, each the center of a portion of the
cluster designated as Abell 2197E and 2197W.

NGC 6160 anchors the western half of the cluster. Interestingly the two
rather bright galaxies nearest it belong to a group about 3 times
further away so are not members of the cluster. NGC 6163 anchors the
eastern half. Besides being a cD elliptical it houses an AGN. Likely
its massive black hole is still feeding.

I've labeled all galaxies with redshift data that are likely cluster
members. Since, as members of the cluster, they are all about the same
distance -- a bit over 400 million light-years -- I've not noted
distance as I usually do. Those listed only in catalogs that list them
only in terms of sky coordinates (SDSS, 2MASS etc.) are simply noted as
ACM for Abell Cluster Member. Otherwise the labels would be difficult
to fit on due to length. Galaxies and quasars (UvES objects are quasar
candidates) are labeled by type (G for galaxy etc.) and distance in
billions of light-years using NED's 5 year WMAP calculations for light
travel distance. Labels are immediately right of the object unless a
line connects the object and label.

There's a major problem with NGC 6174. Is it III Zw 082 or IV Zw 063?
NED says the latter but notes Identification as NGC 6174 is very
uncertain." But makes no remarks about III Zw 082 also being a candidate
for that galaxy. The NGC project has extensive notes on it that are
quite interesting. It prefers III Zw 082 as being NGC 6174. Their
explanation is too long to include here. There's no direct link
unfortunately. Go to http://www.ngcicproject.org/dss/dss_n6100.asp and
then scroll down to the button for NGC 6174 and click it (not the
picture). Then scroll down to Historical Research Notes. This shows
the problem with visual astronomy. Problems of this sort happened all
too often with the NGC and other catalogs.

Between the two NGC 6174 candidates is a cluster galaxy I labeled ACM
Plume. It appears to be a dwarf member of the cluster with a huge
plume. It is known only as SDSS J162937.03+405054.0. NED has nothing
on it to help with the plume. It has obviously interacted with some
other cluster galaxy. Was it the huge cD NGC 6173 or some other smaller
galaxy?

14" LX200R @ f/10, L=8x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

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