Cross-correlation between the sequence of spectra of HD 189733 observed with GIANO on July 11, 2015, and a model spectrum for the planet HD 189 733 b containing H₂O at VMR = 10⁻⁴, shown as function of radial velocity and planet orbital phase. Ingress and egress of HD 189 733 b are marked with horizontal dashed lines. In the left panel, we co-added all the GIANO orders after removing telluric lines similarly to past CRIRES observations (Brogi et al. 2014, 2016). In the right panel, we applied an additional mask at the position of telluric H₂O lines. The latter step removes the majority of time-correlated residual telluric noise, leaving a faint trail of positive correlation along the expected planet radial velocity (marked by slanted dashed lines). Details can be found in Sect. 3.1.