  Four small moons (Styx, Nix, Kerberos and Hydra) are at present known to
orbit around the barycenter of Pluto and Charon, which are themselves
considered a binary dwarf-planet due to their relatively high mass ratio. The
central, non-axisymmetric potential induces moon orbits inconvenient to be
described by Keplerian osculating elements. Here, we report that observed
orbital variations, may not be the result of orbital eccentricities or
observational uncertainties, but may be due to forced oscillations caused by
the central binary. We show, using numerical integration and analytical
considerations, that the differences reported on their orbital elements, may
well arise from this intrinsic behavior rather than limitations on our
instruments.
