Astronomers have captured the deepest images ever obtained of IC 1101, allowing them to identify the galaxy’s outer edge for the first time. IC 1101 sits at the center of the Abell 2029 galaxy cluster and belongs to the class of brightest cluster galaxies (BCGs). Credit: arXivAs described in the preprint, these measurements confirm IC 1101 as the largest known individual galaxy whose size has been directly established through observations. “IC 1101 stands as the largest galaxy known to date, yet its outskirts reveal signs of ongoing mass assembly,” the authors wrote. This side-by-side graphic compares X-ray and optical views of the galaxy cluster Abell 2029. Credit: X-ray: NASA/CXC/UCI/A.Lewis et al.