Search for transits of HD 143105b. Top: photometry. The differential photometry is plotted as a function of the phase of the searched transits. The telescopes (CROW or ROTAT) and the dates are indicated for each of the six observations, which have been shifted in y-axes for clarity. The horizontal lines represent the mean of the data (or mean outside the event for 2013-08-26 with ROTAT). The original data (plus signs) have been binned to have a point approximatively every 120 s (diamond signs) to facilitate the comparison. The vertical dashed lines represent the hypothetical ingress, center, and egress phases for central transits. The transit-like event observed on 2013-08-26 with ROTAT was not confirmed by other observations. Bottom: spectroscopy. SOPHIE radial velocities measured during a possible transit (2013-09-17). The expected Rossiter-McLaughlin anomaly is shown as a dotted line (for an aligned, prograde orbit); it is not detected. The solid line shows the Keplerian model with no transit (Figs. 2 and 4, Table 3).