Abell 1689 is a massivegalaxy cluster
in the constellation, Virgo,
of interest both for its characteristics
(e.g., large number of globular clusters
and evidence of an ongoing galaxy cluster merger)
and for the gravitational lensing it produces,
which enable observations of extremely distant
objects.
The lensing also aids studies of the cluster itself,
providing hints regarding the amount and distribution of its mass.