  In this work we present scanning Fabry-Perot H$\alpha$ observations of the
isolated interacting galaxy pair NGC 5278/79 obtained with the PUMA Fabry-Perot
interferometer. We derived velocity fields and rotation curves for both
galaxies. For NGC 5278 we also obtained the residual velocity map to
investigate the non-circular motions, and estimated its mass by fitting the
rotation curve with a disk+halo components. We test three different types of
halo (pseudo-isothermal, Hernquist and Navarro Frenk White) and obtain
satisfactory fits to the rotation curve for all profiles. The amount of dark
matter required by pseudo-isothermal profile is about ten times smaller than,
that for the other two halo distributions. Finally, our kinematical results
together with the analysis of dust lanes distribution and of surface brightness
profiles along the minor axis allowed us to determine univocally that both
components of the interacting pair are trailing spirals.
