Phased V-band light curves of the confirmed RR0 variables in M 68. Data from different nights are plotted in different colours (electronic version only), with a colour bar provided for reference (top panel). On the light curves for which a good Fourier decomposition could be obtained, the fit is overplotted. The size of typical 1σ error bars is plotted in the top left corner. The magnitude scale is the same on all plots in order to facilitate comparison of variation amplitude.