Transit coverage and observing conditions during the observation of WASP-127 b on the night of 24–25 March 2022. Panel a: theoretical light curve based on literature parameters indicating the 98 exposures of 240s. Each data point corresponds to one exposure, and its width to the duration of the exposure. Blue crosses indicate nodding position A and red crosses nodding position B. The transit including ingress and egress (i.e. the first to fourth contact T1–T4) is covered by spectra 20–81; the second to third contact (T2–T3) is covered by spectra 26–75. Panel b: progression of the airmass. Panel c: mean signal-to- noise ratio (S/N) of the spectra over all covered wavelengths.