Disc-integrated-flux-to-disc-centre-intensity ratios for the S I 1045 nm triplet. Observations from the Hamburg atlas. The thickness of the plotted lines corresponds to the ±1σ uncertainty in the 3D non-LTE and 3D LTE abundances illustrated in Figure 3, which result from a ±5% uncertainty in the measured equivalent widths. An instrumental broadening of R = 3.5 × 10⁵ is included for the synthetic intensities and fluxes, and a rotational broadening of V_rot sin ι = 2 km s⁻¹ is included for the synthetic flux.