  Evidence for a disturbed velocity structure in the outer regions of the
galaxy NGC1399 comes from a re-analysis of the planetary nebulae data from
Arnaboldi et al. (1994). We find a strong rotation along a P.A.=140 degrees for
R<=140'' which is followed by a rapid drop off at larger radii, where the
velocity dispersion starts to increase. This kinematical behavior can be
interpreted as an indication for an interaction scenario. Interaction is
advocated in previous analysis of the halo regions of this system, based on
different dynamical tracers such as globular clusters and X-rays, but in all
these studies the mass distribution is derived under the equilibrium
hypothesis, which is not appropriate when an interaction takes place. Here we
attempt a non-equilibrium dynamical analysis of NGC1399: with a simple model
and under the impulse approximation, we show that the observed kinematics is
consistent with an energy injection caused by a flyby encounter of NGC 1399
with the nearby system NGC 1404. In this approach, we find a mass-to-light
ratio, M/L_B=26 within R=400'', which is about half of that requested when
equilibrium is assumed, i.e. M/L_B=56.
