Relative integrated flux density evolution of significantly variable sources normalized to the integrated flux density in epoch 7 (32 ± 3 μJ, 224 ± 14 μJ, 214 ± 20μJ for M15C, AC211, and S2, respectively). From top to bottom: M15C, AC211, S2. For the pulsar M15C only 4σ upper flux density limits are indicated for epochs 2, 4, 5, and 6. For AC211 in epoch 3 the flux is integrated over both components.