  The simultaneous measurement of the isotopic fission-fragment yields and
fission-fragment velocities of $^{239}$U has been performed for the first time.
The $^{239}$U fissioning system was produced in one-neutron transfer reactions
between a $^{238}$U beam at 5.88 MeV/nucleon and a $^{9}$Be target. The
combination of inverse kinematics at low energy and the use of the VAMOS++
spectrometer at the GANIL facility allows the isotopic identification of the
full fission-fragment distribution and their velocity in the reference frame of
the fissioning system. The proton and neutron content of the fragments at
scission, their total kinetic and total excitation energy, as well as the
neutron multiplicity were determined. Information from the scission point
configuration is obtained from these observables and the correlation between
them. The role of the octupole-deformed proton and neutron shells in the
fission-fragment production is discussed.
