Left: Lomb-Scargle periodogram of all 2MASS J0746+20A epochs, calculated from the combined dataset from Fig. 1. The three red dashed-dotted horizontal lines (top-to-bottom) represent a 5σ, 3σ and 1σ false-alarm probability of the peaks, as determined by the LS periodogram algorithm. The x-axis is plotted in days^-1, since each epoch was time-stamped in units of Heliocentric Julian Days (HJD) – for period accuracy over such a lengthy baseline. Right: phase dispersion minimization (PDM) plot of the entire ~2 year observation baseline. Here we plot the PDM “Theta (Θ) statistic” vs. Period (in hours), where the routines minimize the value at 3.32 h.