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:
“the green hells of the sea
Where fallen skies and evil hues and eyeless creatures be;
On them the sea-valves cluster and the grey sea-forests curl,
Splashed with a splended sickness, the sickness of the pearl;”
—Gilbert Keith Chesterton (1874–1936)