Strong variability of weak-core radio sources

Here we present direct observational evidence for core variability of two lobe-dominated (weak-core) radio sources, GT1945+241 and GT0304+575. In the context of the beaming model, weak-core sources have little Doppler boosting and any residual variability is mainly intrinsic. The extreme nature of the core variability of the two sources described here suggests that the intrinsic variability can dominate beaming-related variability. (author)