Line profile evolution of neutral C and O during the early decline monitored at Mercator/HERMES. The C I 7713 Å, [O I] 5577 Å, and [O I] 6300 Å lines are offset with respect to each other by 0.8, 0.75 and 0.75, respectively. The first 5 spectra of OI 8446 Å were offset by 0.5 while the last four were scaled to 0.25 and offset by 1.33 × n, with n being the spectrum position in the sequence. The “0.5, 0.75” and “0.4−0.6” tick-marks indicate the scale in those panels whose x-axis is not matching the 0 ADU level of the y-axis.