Top panel: S/N values of the CCFs for the four studied bands (see Table. 2). Bottom panel: water vapour absorption spectrum at the CARMENES resolution (in grey) when using the p–T profile A anda water VMR = 10⁻⁵, and the same model but Gaussian smoothed to the HST/WFC3 resolution (in blue). The lighter grey areas are the wavelength regions covered by the orders discarded during our analysis. Over-plotted in red are the HST/WFC3 measurements provided by McCullough et al. (2014). We detected the two strongest bands around 1.15 and 1.4 μm. We note that the S/Ns shown in the top panel cannot be directly compared to the HST absorption signals as shown in the bottom panel, since the former depend on the high-frequency component of the transmission spectrum, and are strongly affected by telluric absorption.