Histograms of the difference between the phase of LSP minimum light and the phase of mean rising LSP radial velocity. The top panel shows the phase difference for MACHO M_B, the middle panel M_R and the bottom panel OGLE I. Radial velocity is defined with respect to the observer: a positive radial velocity corresponds to matter moving away from the observer, that is, infalling to the centre of the star in a radial pulsation model.