Brightness temperature evolution of all the detected components in observer’s frame at 43 and 86 GHz. Top: T_b, obs evolution versus time, before the appearance of knot M at 43 GHz. Middle: T_b, obs evolution versus time, after the appearance of the knot cluster Ca, Cb, Cc at 43 GHz. Bottom: T_b, obs evolution versus time, after the appearance of the knot cluster Ca, Cb, Cc at 86 GHz. In all three panels the red dotted line is the fit of the radial distribution of T_b, obs before the appearance of knot M.