  With the new generation of space telescopes such as the James Webb Space
Telescope (JWST), it is possible to better characterize the atmospheres of
exoplanets. The atmospheres of Hot and Ultra Hot Jupiters are highly
heterogeneous and asymmetrical. The difference between the temperatures on the
day-side and the night-side is especially extreme in the case of Ultra Hot
Jupiters. We introduce a new tool to compute synthetic lightcurves from 3D GCM
simulations, developed in the Pytmosph3R framework. We show how rotation
induces a variation of the flux during the transit that is a source of
information on the chemical and thermal distribution of the atmosphere. We find
that the day-night gradient linked to Ultra Hot Jupiters has an effect close to
the stellar limb-darkening, but opposite to tidal deformation. We confirm the
impact of the atmospheric and chemical distribution on variations of the
central transit time, though the variations found are smaller than that of
available observational data, which could indicate that the east-west
asymmetries are underestimated, due to the chemistry or clouds.
