O-C diagrams (with residuals) from linear ephemeris for planet Kepler-9b (top panel) and Kepler-9c (middle panel) with the discovery paper’s parameters (see column two of Table 6); observations plotted as solid black circles, simulations plotted as open blue circles. The parameter N, in the abscissa, has the same meaning of Fig. 7. Bottom panel shows the RV observations as solid black circles, simulations at the same BJD_UTC as open blue circles, and the dotted blue line is the RV model for the whole simulation.