This
Astrobin Debut Object is a galaxy group of 4 galaxies, called Hickson 60, located 0.9 billion light years away in the constellation of Ursa Major at a declination of +52 degrees. 3 of the 4 galaxies are classified as elliptical galaxies, although it seems to me that they also could be lenticular. The magnitude of the group is 13.5.
This is a true cluster - the 4 galaxies are all about the same distance away. I see some odd structures in the elliptical haloes but it is impossible to tell at this distance whether they are close enough to be interacting with each other.
Several galaxies to the above left are also at the same distance and are part of this galaxy group, but their separation from the central four galaxies is too far for them to be considered part of the Hickson cluster.
The largest and brightest galaxy is the magnitude 14.4 galaxy Hickson 60a. It spans 0.5 arc-minutes, which corresponds to a Milky Way like diameter of 120,000 light years. The other 3 galaxies are slightly smaller in size.
The Hickson catalog is a collection of 100 galaxy groups, established by Paul Hickson in 1982. Hickson compact galaxy groups are strictly defined by 3 criteria: number of galaxies, total magnitude, and isolation from other galaxies. A typical Hickson group has 4 galaxies, but some have up to 8. You can see more about Hickson galaxy groups in my
Astrobin Hickson Collection.
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