  The WASP-18 system, with its massive and extremely close-in planet, WASP-18b
(M$_{p}$ = 10.3M$_{J}$, a = 0.02 AU, P = 22.6 hours), is one of the best known
exoplanet laboratories to directly measure Q', the modified tidal quality
factor and proxy for efficiency of tidal dissipation, of the host star.
Previous analysis predicted a rapid orbital decay of the planet toward its host
star that should be measurable on the time scale of a few years, if the star is
as dissipative as is inferred from the circularization of close-in solar-type
binary stars. We have compiled published transit and secondary eclipse timing
(as observed by WASP, TRAPPIST, and Spitzer) with more recent unpublished light
curves (as observed by TRAPPIST and HST) with coverage spanning nine years. We
find no signature of a rapid decay. We conclude that the absence of rapid
orbital decay most likely derives from Q' being larger than was inferred from
solar-type stars, and find that Q' $\geq $1$\times10^{6}$, at 95\,\%
confidence; this supports previous work suggesting that F-stars, with their
convective cores and thin convective envelopes, are significantly less tidally
dissipative than solar-type stars, with radiative cores and large convective
envelopes.
