  High resolution HST/ACS images of the galaxy cluster RX J1347-1145 have
enabled us to identify several new multiple image candidates in the cluster,
including a 5 image system with a central image. The multiple images allow us
to construct an accurate 2-dimensional mass map of the central part of the
cluster. The modelling of the cluster mass includes the most prominent cluster
galaxies modelled as truncated isothermal spheres and a smooth halo component
that is described with 2 parametric profiles. The mass reconstruction is done
using a Markov chain Monte Carlo method that provides us with a total projected
mass density as well as estimates for the parameters of interest and their
respective errors. The mass profile is in reasonable agreement with previous
mass estimates based on the X-ray emission from the hot intra-cluster gas,
however the X-ray mass estimates are systematically lower than what we obtain
with gravitational lensing.
