  Hot Jupiters are predicted to have hot, clear daysides and cooler, cloudy
nightsides. Recently, an asymmetric signature of iron absorption has been
resolved in the transmission spectrum of WASP-76b using ESPRESSO on ESO's Very
large Telescope. This feature is interpreted as being due to condensation of
iron on the nightside, resulting in a different absorption signature from the
evening than from the morning limb of the planet. It represents the first time
that a chemical gradient has been observed across the surface of a single
exoplanet. In this work, we confirm the presence of the asymmetric iron feature
using archival HARPS data of four transits. The detection shows that such
features can also be resolved by observing multiple transits on smaller
telescopes. By increasing the number of planets where these condensation
features are detected, we can make chemical comparisons between exoplanets and
map condensation across a range of parameters for the first time.
