A. Phase Dispersion Minimization (PDM) plot for all epochs of 2M J0746+20B, after subtraction of the primary’s 3.32 hours period. The theta statistic was determined from 10⁵ Monte-Carlo simulations. The minima theta indicates the most likely rotational period of ∼2.14 hours, in agreement with the rotation period resulting from the LS periodogram seem in Figure 3. B. The same PDM theta plot, zoomed into the area around the minimum theta statistic.