Response functions to temperature with log τ₅₀₀ as function of wavelength in Ca II K (top row), Ca II 8542 Å (middle row) and Mg II (bottom panel) for three of the selected pixels from Figs. A.1 and A.2. Results are shown for the red sampling (first column and bottom panel) and green sampling (second column) of event A, and the cyan sampling of event B (third column), under the assumption of non-LTE hydrogen ionisation. Corresponding observed Ca II and Mg II profiles are shown for reference and have been plotted on arbitrary scale to maximise visiblity of profile features. In each panel the response function is displayed in red-white-black colour scale (with red being positive response, black negative and white none), at each wavelength normalised to its maximum with height log τ₅₀₀. The blue lines indicate the log τ₅₀₀ heights as function of wavelength for which the response function peaks in the case of LTE (dashed) and non-LTE (solid) electron densities.