This
Astrobin Debut Object is a galaxy group of 4 galaxies, called Hickson 66, located 1 billion light years away in the constellation of Ursa Major at a declination of +57 degrees.
This is a true cluster – all 4 galaxies are about the same distance away. All of these galaxies are officially designated as elliptical galaxies, but 2 (66b and 66c) look to me as if they could be spirals.
The largest and brightest galaxy, Hickson 66a, is a magnitude 14.5 elliptical that spans 30 arc-seconds, which corresponds to a large diameter of 160,000 light years. The overall magnitude of this group is 13.8, which makes it one of the dimmest Hickson groups.
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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