Retrieving the Transmission Spectrum of HD209458b using CHOCOLATE: a new Chromatic Line-Profile Technique

Multi-band photometric transit observations or low resolution spectroscopy (spectro-photometry) are normally used to retrieve the broadband transmission spectra of transiting exoplanets in order to assess the chemical composition of their atmospheres. In this work, we present an alternative approach for recovering the broadband transmission spectra using chromatic Line-Profile Tomography. To validate the method and examine its performance, we used new observational data obtained with the ESPRESSO instruments to retrieve the transmission spectra of the archetypal hot Jupiter HD209458b. Our findings indicate that the recovered transmission spectrum is in good agreement with the results presented in previous studies, which used different methodologies to extract the spectrum.