Effect of telluric contamination on observations of an aerosol-free HD189733b with HARPS-N (upper left panel), ESPRESSO (upper right panel), and GIANO (lower left panel). Red solid line: contamination-free transmission spectrum. Blue solid line: transmission spectrum in the presence of telluric residualso consistent with Allart et al. (2017). If the systemic velocity and the Barycentric Earth Radial Velocity combine such that the exoplanetary signal is shifted away from the telluric residual (here: 30 km s^-1), the signal is recovered in the , , J and H bands. In the Y band, a more careful analysis than what performed here is possible, and may lead to a detection (see main text). In the , and bands, water absorbs all the incident light making detection impossible from the ground.