Further observations are needed to confirm and understand the timing variations of WASP-4b. Symbols are as in Figure 4. Lines are 100 random draws from the posteriors of the apsidal precession model (orange) and the orbital decay model (blue). The prior for the precession model assumes ﹩{k}_{2,{\rm{p}}}\sim { \mathcal U }[0.015,1.5];﹩ dashed orange lines emphasize samples with planetary Love numbers below 0.75.