Bottom panel: spatio-temporal maps of wavelengths bands in the observed spectra (odd rows) and in the best-fit spectra (even rows) of the time series. The lower two rows show from left to right the continuum intensity at 630.4 nm, OW, MW1, MW2, MW3, and IW. The upper two rows show IW1, H_2V, core intensity, H_2R, RW1, and RW2. Top panel: corresponding temperature maps at several optical depths from −0.5 to −5.5 in log τ (denoted at the top in each subpanel). The minimum and maximum temperatures are denoted at the left and right ends of the grey bar, respectively. The three values on each side in the lower row correspond to the layers of log τ = −0.5/−1.5/−2.5 (from left to right), those in the upper row to log τ = −3.5/−4.5/−5.5.