From the upper left to the lower right: PKS 2155-304 light curves from Bronberg optical data (black points) for the five nights of observation that coincided with the H.E.S.S. campaign in 2006 (MJD 53 945, 53 946, 53 947, 53 951, 53 952), for the night MJD 53 954 and for three nights in September (MJD 53 987 to 53 989). The flat light curve of a reference star is shown for comparison (light blue points). For the nights with simultaneous H.E.S.S. coverage, the VHE light curve is shown for comparison (red points, y-axis on the right). The data have not been corrected for Galactic absorption.