Galaxy Cluster Abell 154 - more than meets the eye

Galaxy Cluster Abell 154 - more than meets the eye

Galaxy cluster Abell 154, centered around IC 1635, is not all that it
seems. It is listed in Vizier as having a cluster radius of 31 arc
minutes. However when the supplied co-ordinates are put into the NASA
Extragalactic Database the distribution of the 30 galaxies with
redshift data - see below - suggests a much smaller cluster. It is
harder to argue a case for a radius greater than 12 arc minutes.

http://www.martin-nicholson.info/abell154/abell154.htm

Martin Nicholson, Daventry, England.
http://www.martin-nicholson.info/1/1a.htm
Visit the Astronomical Hall of Shame at http://www.geocities.com/queen5658/

On 5 Nov, 12:56, ukastronomy
wrote:
Galaxy Cluster Abell 154 - more than meets the eye

Galaxy cluster Abell 154, centered around IC 1635, is not all that it
seems. It is listed in Vizier as having a cluster radius of 31 arc
minutes. However when the supplied co-ordinates are put into the NASA
Extragalactic Database the distribution of the 30 galaxies with
redshift data - see below - suggests a much smaller cluster. It is
harder to argue a case for a radius greater than 12 arc minutes.

http://www.martin-nicholson.info/abell154/abell154.htm

Martin Nicholson, Daventry, England.http://www.martin-nicholson.info/1/1a.htm
Visit the Astronomical Hall of Shame athttp://www.geocities.com/queen5658/

Is the Hall of Shame open to nominations?

John H wrote:

On 5 Nov, 12:56, ukastronomy
wrote:
Galaxy Cluster Abell 154 - more than meets the eye

Galaxy cluster Abell 154, centered around IC 1635, is not all that it
seems. It is listed in Vizier as having a cluster radius of 31 arc
minutes. However when the supplied co-ordinates are put into the NASA
Extragalactic Database the distribution of the 30 galaxies with
redshift data - see below - suggests a much smaller cluster. It is
harder to argue a case for a radius greater than 12 arc minutes.

http://www.martin-nicholson.info/abell154/abell154.htm

Martin Nicholson, Daventry, England.http://www.martin-nicholson.info/1/1a.htm
Visit the Astronomical Hall of Shame athttp://www.geocities.com/queen5658/

Is the Hall of Shame open to nominations?

Please explain. I'm a newbie, unwashed in the Country Club
here, so fill the rest of us in on your private case against your
accused? This isnt the Supreme Court! Its SAA ???

Waiting -

On Nov 5, 7:56 am, ukastronomy
wrote:
Galaxy cluster Abell 154,... is listed in Vizier as having a cluster radius of 31 arc
minutes. However when the supplied co-ordinates are put into the NASA
Extragalactic Database the distribution of the 30 galaxies with
redshift data - see below - suggests a much smaller cluster. It is
harder to argue a case for a radius greater than 12 arc minutes.

http://www.martin-nicholson.info/abell154/abell154.htm

Non-existence of redshifts doesn't imply non-membership. No one has
time to measure redshifts for all galaxies in the sky. Most likely
someone measured a few redshifts near the cluster center and didn't
bother with more.

What is the original source of the diameter estimate? Galaxies that
might well be cluster members are visible in your image all the way to
its edge.

Sorry, I didn't mean to imply that non-existence of redshifts implied
anything specific. However those galaxies in the immediate area that
did have measurements were concentrated in a narrow band of values.
Other galaxies in the area that had very or rather different values
are probably at different distances to the proposed group members.

Non-existence of redshifts doesn't imply non-membership. No one has
time to measure redshifts for all galaxies in the sky. Most likely
someone measured a few redshifts near the cluster center and didn't
bother with more.