Left column: Light curves for the early M dwarfs of low stellar activity in NGC 3532 that have newly identified rotation periods. The orange line is a sine fit to the data with the newly identified likely rotation period. The first two light curves (from the top) are from V 120 s exposures, while all others are from I_c 600 s images. Centre column: Corresponding normalised generalized Lomb-Scargle diagram, with the selected rotation period marked by the orange vertical line. The dashed blue line indicates the rotation period estimated from the chromospheric activity measurement, and the dotted lines delineate the search range, which is derived from the period uncertainty. Right column: Same as the centre column but with the CLEAN periodogram. The offset between the peaks and the position of the best period for 102025 in the first row is due to the different peak positions in the phase-dispersion minimization and Gregory-Loredo periodograms (not displayed).