Light curves of the −7.4 km s⁻¹ methanol maser feature at 12.2 (black) and 6.7 GHz (red) for G107.298+5.639 (upper panel). Temporal changes in the 6.7–12.2 GHz flux density ratio are plotted (blue) (lower panel). The thick vertical error bars denote the flare maxima at 12.2 (black) and 6.7 GHz (red) calculated as the average value of the peak times obtained with the use of three methods (Table 2), whereas the thin horizontal error bars mark the corresponding standard errors.