  Transit observations have become an important technique to probe exoplanets.
Therefore, there are many projects carrying on organized observations of
transit events, which make a huge amount of light-curve and transit timing data
available. We consider this as an excellent opportunity to search for possible
orbital decays of exoplanets from this big number of mid-transit times through
data-model fitting with both fixed-orbit and orbit-decay models. In order to
perform this task, we collect mid-transit-time data from several sources and
construct the most complete database up to date. Among 144 hot Jupiters in our
study, HAT-P-51b, HAT-P-53b, TrES-5b, WASP-12b are classified as the
orbit-decay cases. Thus, in addition to reconfirming WASP-12b as an orbit-decay
planet, our results indicate that HAT-P-51b, HAT-P-53b, TrES-5b are potential
orbit-decay candidates.
