  We present a empirical study of orbital decay for the exoplanet WASP-19b,
based on mid-time measurements of 74 complete transits (12 newly obtained by
our team and 62 from the literature), covering a 10-year baseline. A linear
ephemeris best represents the mid-transit times as a function of epoch. Thus,
we detect no evidence of the shortening of WASP-19b's orbital period and
establish an upper limit of its steady changing rate, $\dot{P}=-2.294$ ms
$yr^{-1}$, and a lower limit for the modified tidal quality factor $Q'_{\star}
= (1.23 \pm 0.231) \times 10^{6}$. Both are in agreement with previous works.
This is the first estimation of $Q'_{\star}$ directly derived from the
mid-times of WASP-19b obtained through homogeneously analyzed transit
measurements. Additionally, we do not detect periodic variations in the transit
timings within the measured uncertainties in the mid-times of transit. We are
therefore able to discard the existence of planetary companions in the system
down to a few $M_\mathrm{\oplus}$ in the first order mean-motion resonances 1:2
and 2:1 with WASP-19b, in the most conservative case of circular orbits.
Finally, we measure the empirical $Q'_{\star}$ values of 15 exoplanet host
stars which suggest that stars with $T_\mathrm{eff}$ $\lesssim$ 5600K dissipate
tidal energy more efficiently than hotter stars. This tentative trend needs to
be confirmed with a larger sample of empirically measured $Q'_{\star}$.
