Lomb-Scargle periodograms showing the periodic variability for the UBr (left panels) and BAb (right panels) light curves. Top panels: periodograms covering the full investigated frequency domain. The periodograms of the light curve are given in red (UBr; left) and blue (BAb; right), while the variability of the residuals after the iterative prewhitening is given in black. Bottom panels: periodograms covering the frequency domain where significant periodic variability is recovered. The amplitude of the periodic variability is given in parts-per-thousand (ppt). The frequencies of the extracted variability is given by the small black ticks in the top part of each panel.