Cross-correlation maps in S/N units for potential atmospheric signals as a function of v_rest and K_p for the primary expected absorbing species in the atmosphere of GJ 436 b. For CARMENES (five combined transits; top row) and CRIRES⁺ (one transit; bottom row) we explored, water vapour (left), methane (middle), and carbon monoxide (right, only for CARMENES). Horizontal and vertical red lines indicate the expected K_p and v_rest eccentric orbital models. These example maps were derived using a 10× solar metallicity template with a cloud deck at 10 mbar. No molecular signals were detected in our cross-correlation analyses.