Top-left panel: observed fluxes of emission lines across He₅₈₇₆ spectral region at the dates of minimum and maximum activity, shown by red and blue lines, respectively. Uncertainties of the flux determination are shown by the green and pink colours, respectively. Bottom-left panel: uncertainties of the flux determinations at the phases of minimum and maximum activity shown in larger scale. Top-right panel: observed fluxes of emission lines across CaII H and K and H_ɛ spectral regions at the same dates of minimum and maximum activity, shown by red and blue lines, respectively. Bottom-right panel: part of the observed spectra shown in larger scale. Flux measurement uncertainties are also shown.