Abell 1656 The Coma Cluster of Galaxies

[tomato]

After individual galaxies, clusters of them are my favourite targets, what I would call proper deep sky imaging. 

This is Abell 1656, centred on NGC 4889. 7.43 hrs of integration made up of 145 x 2 mins Lum with the Esprit150/QHY268mono and 78 x 2 mins RGB with the Esprit150/QHY268OSC. 80% of the subs were taken with an 80% illuminated moon about 40 degrees away. 

Calibrated and stacked in APP, processed in PI and Affinity Photo. For the record, I have one reference which says there are 106 galaxies in this cluster.

Abell 1656's  main claim to fame is that this cluster was studied by the astronomer Fritz Zwicky who published an article in 1933. Based on his determination of the distribution of relative velocities and some assumptions he was able to derive the gravitationally active mass from the velocity dispersion and found the mass to be appreciably  larger than the total mass of luminous material in the cluster. Zwicky called this the missing matter in the cluster, we now refer to this material as Dark Matter, a key element in current cosmological thinking.

Thanks for looking.

Annotated Image

[glafnazur]

Very nice. 106 galaxies, I'll take your word for it 😉

[wimvb]

3 hours ago, tomato said:

106 galaxies

Nice! More than 1000 according to wikipedia, and 4291 registered entries in Simbad when you look up the Coma super cluster (but those may not all be unique entries).

[tomato]

Thanks, I got the quote from a recently acquired copy of “Observing the Abell Galaxy Clusters”, so that number of 106 may be a visual estimation.