Light curves of the transition. The cyan line shows the JEM-X count rate (3–10 keV; left y-axis), the purple line shows the ISGRI count rate (20–40 keV; y-axis, count rate divided by 5 for better scaling), and the red diamonds show the optical V-filter light curve (right axis). The solid and dashed lines show the low-state and the post-transition mean ISGRI count rate and the 2σ deviation from it, respectively. The inset shows a zoom-in of the transition, with blue and yellow lines indicating the deviation from 2σ and 3σ deviation (dotted line) from the low-state and post-transition mean count rates, respectively.