Abell 2537, Galaxienhaufen
The galaxy cluster "Abell 2537" has a redshift of z=0.295, which results in a light travel time of 3.4 billion years. Because of the expansion of our universe,
it moves away from us by another 75,800 kilometers every second, which corresponds to 25.3% of the speed of light.
The mass was determined to be 552 trillion solar masses, which is approximately half the mass of the Virgo supercluster. Due to its high mass and the
strong concentration of galaxies towards the center, Abell 2537 contains four most lenticular galaxies, which can be seen as elongated arcs in images
of the HST. The largest galaxy in the center (BCG) has an apparent elongation of 8.3", which corresponds to a true diameter of 140,000 light-years.
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The galaxy cluster is extremely difficult to see in my 20" f/3.2 telescope due to the huge distance and requires good seeing in addition to a very dark sky.
The 5 galaxies were extremely faint and even with indirect vision they flashed out of the darkness only a few times very briefly.
