Strong Gravitational Lensing by the Super-massive cD Galaxy in Abell
  3827
  We have discovered strong gravitational lensing features in the core of the
nearby cluster Abell 3827 by analyzing Gemini South GMOS images. The most
prominent strong lensing feature is a highly-magnified, ring-shaped
configuration of four images around the central cD galaxy. GMOS spectroscopic
analysis puts this source at z~0.2. Located ~20" away from the central galaxy
is a secondary tangential arc feature which has been identified as a background
galaxy with z~0.4. We have modeled the gravitational potential of the cluster
core, taking into account the mass from the cluster, the BCG and other
galaxies. We derive a total mass of (2.7 +- 0.4) x 10^13 Msun within 37 h^-1
kpc. This mass is an order of magnitude larger than that derived from X-ray
observations. The total mass derived from lensing data suggests that the BCG in
this cluster is perhaps the most massive galaxy in the nearby Universe.
