  Since the discovery of the transiting super-Earth CoRoT-7b, several
investigations have yielded different results for the number and masses of
planets present in the system, mainly owing to the star's high level of
activity. We re-observed CoRoT-7 in January 2012 with both HARPS and CoRoT, so
that we now have the benefit of simultaneous radial-velocity and photometric
data. This allows us to use the off-transit variations in the star's light
curve to estimate the radial-velocity variations induced by the suppression of
convective blueshift and the flux blocked by starspots. To account for
activity-related effects in the radial-velocities which do not have a
photometric signature, we also include an additional activity term in the
radial-velocity model, which we treat as a Gaussian process with the same
covariance properties (and hence the same frequency structure) as the light
curve. Our model was incorporated into a Monte Carlo Markov Chain in order to
make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We measure
the masses of planets b and c to be 4.73 +/- 0.95 Mearth and 13.56 +/- 1.08
Mearth, respectively. The density of CoRoT-7b is (6.61 +/- 1.72)(Rp/1.58
Rearth)^(-3) g.cm^(-3), which is compatible with a rocky composition. We search
for evidence of an additional planet d, identified by previous authors with a
period close to 9 days. We are not able to confirm the existence of a planet
with this orbital period, which is close to the second harmonic of the stellar
rotation at around 7.9 days. Using Bayesian model selection we find that a
model with two planets plus activity-induced variations is most favoured.
