  The BL-Lac family of active galaxies possess almost featureless spectra and
exhibit rapid variability over their entire spectral range. A number of models
have been developed to explain these extreme properties, several of which have
invoked the action of microlensing by sub-stellar mass objects in a foreground
galaxy; this not only introduces variability, but also amplifies an otherwise
normal quasar source. Here we present recent spectroscopy and photometry of the
southern BL Lac PKS 0537-441; with an inferred redshift of z~0.9 it represents
one of the most distant and most luminous members of the BL Lac family. The
goal of the observations was not only to confirm the redshift of PKS~0537-441,
but also to determine the redshift of a putative galaxy along the line of sight
to the BL-Lac; it has been proposed that this galaxy is the host of
microlensing stars that account for PKS 0537-441's extreme properties. While
several observations have failed to detect any extended emission in PKS
0537-441, the HST imaging data presented here indicate the presence of a
galactic component, although we fail to identify any absorption features that
reveal the redshift of the emission. It is also noted that PKS 0537-441 is
accompanied by several small, but extended companions, located a few arcseconds
from the point-like BL-Lac source. Two possibilities present themselves; either
they represent true companions of PKS 0537-441, or are themselves
gravitationally lensed images of more distant sources.
