HI Observations of Galaxies in the Southern Filament of the Virgo
  Cluster with the SKA Pathfinder KAT-7 and the WSRT
  We map the Hi distribution of galaxies in a $\sim 1.5^\circ \times 2.5^\circ$
region located at the virial radius south of the Virgo cluster using the
KAT$-$7 and the WSRT interferometers. Because of the different beam sizes of
the two telescopes, a similar column density sensitivity of $\rm N_{Hi} \sim
10^{18}\,cm^{-2}$ was reached with the two observations over 16.5 km/s. We
pioneer a new approach to combine the observations and take advantage of their
sensitivity to both the large and small scale structures. Out to an
unprecedented extent, we detect an Hi tail of $\sim 60$ kpc being stripped off
NGC 4424, a peculiar spiral galaxy. The properties of the galaxy, together with
the shape of the tail, suggest that NGC 4424 is a post-merger galaxy undergoing
a ram pressure stripping as it falls towards the centre of the Virgo Cluster.
We detect a total of 14 galaxies and 3 Hi clouds lacking optical counterparts.
One of the clouds is a new detection with an Hi mass of $\rm 7\times10^7\,
M_\odot$ and a strong Hi profile with $W_{50} = 73$ km/s. We find that 10 out
of the 14 galaxies present Hi deficiencies not higher than those of the
cluster's late spirals, suggesting that the environmental effects are not more
pronounced in the region than elsewhere in the cluster.
