Variation in the brightness temperature, T_b with distance along the jet for all available epochs and cross-identified components (presented in Tables A.6). The nearly vertical variation within 6   mas < r < 8   mas in region B reflect the temporal variation in the size of the fitted Gaussians. The solid lines correspond to power-law fits T_b ∝ r^a to the individual regions, and the dashed line to a power-law fit to the entire range 0.1   mas < r < 20   mas, which leads to an exponent a =  −1.8 (see text).