A CHEWIE first bite: the transmission spectrum of WASP-69b

The CHEWIE survey (Clouds, Hazes and Elements vieWed on giant Exoplanets) aims to study the impact of the stellar environment on planet atmospheres and their aerosols at the day-night terminator through transmission spectra of planets in the Jupiter to Neptune mass range. It does this with ground-based, medium resolution observations with the FORS2 instrument on the VLT. In this talk we present the first transmission spectrum of the survey, WASP-69b. This Saturn-mass planet has a puffed up atmosphere, making it an excellent target for atmospheric characterisation.