Folded light curves of the redshifted flaring emission for −0.5 (top) and −1.3 km s⁻¹ (bottom) features. The data points are black with grey error bars, while the black solid lines show the average profiles. Green points refer to the relative intensities of the blueshifted emission observable in cluster II; arrows mark upper limits for the blueshifted emission in epochs with no detection. The vertical dashed lines correspond to the computed phases of VLBI observations (magenta – EVN, blue – JVN); the epoch numbers (Table 1) are given above the top abscissa.