Epoch 19, 2010 February 21. a) Core spectrum, where Cb and Qa represent the core at the C and Q bands. Qb is the feature moving downstream. For comparisons, see Figure 4e. Core-shift vectors of all frequency pairs using b) Qa and c) Qb. In this epoch it is clear that Qa and Qb have different effects on the KQ core-shift vector direction. The use of Qb leads to the wrong core-shift direction. Power-law fits (red curve) using d) Qa and e) Qb. Similarly, as in previous epochs, the flare appears to affect the location of the core at the Q band (43 GHz). In this observation, the flare effect is less pronounced but increases the core-shift values at the high frequencies, as seen in d).