Spectroscopic observations of β Pic obtained on April 29, 2025. The HARPS spectrum is not flux-calibrated and was simply re-normalised to a flux level similar to that of the STIS data. Numerous saturated absorption lines are visible in the STIS and HARPS spectra, attributed to Si II, C I, Al II, Fe II, Mg II, and Ca II. The HST spectra are consistent with a stellar model from the PHOENIX library (thick grey line; Husser et al. 2013) at T_eff = 8000 K (see Sect. 4.1).