  In this paper we compute general-relativistic polytropic models simulating
rigidly rotating, pulsating neutron stars. These relativistic compact objects,
with a radius of $\sim 10 \, \mathrm{km}$ and mass between $\sim 1.4$ and $3.2$
solar masses, are closely related to pulsars. We emphasize on computing the
change in the pulsation eigenfrequencies owing to a rigid rotation, which, in
turn, is a decisive issue for studying stability of such objects. In our
computations, we keep rotational perturbation terms of up to second order in
the angular velocity.
