Radial velocities of WASP-121b, phase-folded with the orbital period and detrended from stellar activity. Coralie data pointshave been obtained before (red) and after (blue) the fiber upgrade (Ségransan et al. 2010). HARPS datapoints are shown in gold. Our best-fit Keplerian model to the out-of-transit data is shown as a solid black line (datapoints obtained in the frame of transit observations were binned, see text). The first and fourth transit contacts are indicated bydash-dotted vertical black lines.