AGCS 805 stands for Abell Galaxy Cluster South 805. The cluster includes at least eight major galaxies and probably several dozen dwarf galaxies. In this image, all the galaxies seem to be equally distant from us. Most here are true members of AGCS 805 about 220 million light-years away. The brightest galaxy in the centre of the image is IC 4765 — a 12th magnitude super giant elliptical galaxy that gravitationally dominates the lesser cluster members.
Adding an extra dimension to this big picture, because AGCS 805 is about 220 million light-years distant, we cannot see these galaxies in “real time”. We can only see them as they were 220 million years ago because it takes that long for their light to reach our telescopes. The light from these galaxies we see now left them about the same time the first true dinosaurs roamed the Earth in the mid-Triassic period.
AGCS 805 is a massive cluster of dozens of galaxies containing trillions of stars (so vast and remote as to be beyond meaningful human comprehension). However, it is just one component of a vastly bigger Pavo-Indus super-cluster of galaxies including more than a dozen other similar galaxy clusters: a cluster of galaxy clusters. (*)
(*) Sydney Observatory Essay on AGCS 805