Same as in Fig. 7, but the lines and points of different colors mark different observing epochs, separated by 6 months. For the polarization fraction (right column) we plot the maximum likelihood value as a solid line and indicate a 68% confidence region or 95% upper limit with error bars. Top: An AGN (3C 353) displaying no significant changes in SED, and small, but apparently constant polarization. Bottom: a BL Lac object, PKS 1514–24, showing only mild variability, and no significant change in polarization.