  Gamma ray earthbound and satellite experiments have discovered, over the last
years, many galactic and extra-galactic gamma ray sources. The detection of
astrophysical neutrinos emitted by the same sources would imply that these
astrophysical objects are charged cosmic ray accelerators and help to resolve
the enigma of the origin of cosmic rays. A very large volume neutrino telescope
might be able to detect these potential neutrino emitters. The apriori known
direction of the neutrino source can be used to effectively suppress the
$^{40}K$ optical background and increase significantly the tracking efficiency
through causality filters. We report on advancing filtering and prefit
techniques using the known neutrino source direction and first results are
presented.
