Upper panel: comparison between the fitted and integrated EW_862.1. The colour represents the number density (estimated by a Gaussian KDE) of the data points in a linear scale. The grey colour bars show the uncertainty of fitted EW_862.1. The dashed red line traces the one-to-one correspondence. A zoom-in panel shows the distribution of the EW difference (ΔEW = EW_fit − EW_int). The mean (Δ) and standard deviation (σ) of the EW difference are indicated. Lower panel: the distribution EW difference as a function of fitted EW_862.1.