Cross-correlation results for searching for Fe I in a single transit. On the left are the results for the HARPS-N spectrograph on the TNG, and on the right we show the results for the FOCES spectrograph for the night of 18 July 2022. Top panel: cross-correlation maps for FeI. The pixels covering the trace of the planet are outlined to help guide the eye to where to expect the signal. Middle panel: K_pV_sys maps for each Fe I detection. The detections are the bright features in the centres of the plots. The dashed cross-hairs show the row where the one-dimensional CCF (bottom panel) has been extracted and the expected systemic velocity of KELT-9b (−20 km s⁻¹). Bottom panels: one-dimensional CCFs for the single transits, showing the average line depth for the given signal. The dashed line shows the expected systemic velocity of KELT-9 b, which is the same as in K_pV_sys map.