Cross-correlation analysis of potential H₂O signals in the transmission spectrum of GJ 436 b observed with CARMENES in the near-infrared on the night of February 02, 2017. We show the crosscorrelation matrix, CCF (v,i), in the Earth’s rest frame as a function of the velocity Doppler shifts applied to the template (horizontal axis) and the planet’s orbital phase (vertical axis). The cross-correlation was derived using a 10× solar metallicity template with a cloud deck at 10 mbar, co-adding all useful spectral orders. Dashed-dotted black horizontal lines mark the start and end of the transit, while the dotted red line indicates the expected exoplanet velocities with respect to Earth, accounting for eccentricity.