Cluster Lensing
The foreground lens is a galaxy cluster. In this case, the lens is usually powerful enough to produce noticeable both strong lensing (multiple images, arcs or rings) and weak lensing effects (ellipticity distortions).
Read more about this topic: Strong Gravitational Lensing
Famous quotes containing the word cluster:
“In a sense the world dies every time a writer dies, because, if he is any good, he has been a wet nurse to humanity during his entire existence and has held earth close around him, like the little obstetrical toad that goes about with a cluster of eggs attached to his legs.”
—E.B. (Elwyn Brooks)