  In this work we aim to characterise the dust motion in the inner coma of
comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma
models. The OSIRIS camera onboard the Rosetta mission was able for the first
time to acquire images of single dust particles from inside the cometary coma,
very close to the nucleus. We analyse a large number of particles, performing a
significant statistic of their behaviour during the post perihelion period,
when the spacecraft covered distances from the nucleus ranging between 80 and
400 km. We describe the particle trajectories, investigating their orientation
and finding highly radial motion with respect to the nucleus. Then, from the
particle brightness profiles, we derive a particle rotational frequency of v <
3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation.
We use scattering models to compare the observed spectral radiance of the
particles with the simulated ones in order to estimate their size, finding
values that range from millimetres up to centimetres. The statistics performed
in this paper provide useful parameters to constrain the cometary coma
dynamical models.
