  GJ667C is the least massive component of a triple star system which lies at a
distance of about 6.8 pc (22.1 light-years) from Earth. GJ667C has received
much attention recently due to the claims that it hosts up to seven planets
including three super-Earths inside the habitable zone. We present a Bayesian
technique for the analysis of radial velocity (RV) data-sets in the presence of
correlated noise component ("red noise"), with unknown parameters. We also
introduce hyper-parameters in our model in order to deal statistically with
under or over-estimated error bars on measured RVs as well as inconsistencies
between different data-sets. By applying this method to the RV data-set of
GJ667C, we show that this data-set contains a significant correlated (red)
noise component with correlation timescale for HARPS data of order 9 days. Our
analysis shows that the data only provides strong evidence for the presence of
two planets: GJ667Cb and c with periods 7.19d and 28.13d respectively, with
some hints towards the presence of a third signal with period 91d. The
planetary nature of this third signal is not clear and additional RV
observations are required for its confirmation. Previous claims of the
detection of additional planets in this system are due the erroneous assumption
of white noise. Using the standard white noise assumption, our method leads to
the detection of up to five signals in this system. We also find that with the
red noise model, the measurement uncertainties from HARPS for this system are
under-estimated at the level of ~50 per cent.
