From top to bottom, zoom of the NIR, optical, and X-ray (Swift/XRT) light curves of J1023 around the time of the X-ray low-high transition. With the dashed black line we indicate the exact time of the transition and with the solid black line we show the time corresponding to the centroid of the NIR flare. The top x-axis reports the orbital phases of the system, which have been evaluated starting from the ephemeris of Archibald et al. (2009), phase 0 being the inferior conjunction of the companion star.