Observed and modelled surface flux density. The m2F12-37-2.5 (dark green) and cF13-500-3 (light green) stellar atmosphere models are plotted at coefficients ${\widehat{X}}_1=1$ and ${\widehat{X}}_2=1$ (the theoretical assumption of the entire stellar surface exhibiting flaring activity). For AU Mic during a flare, the solid red and dashed orange lines show the fitted model spectrum at flare maximum using coefficients from the example fit (the flare data are stated in Table A.1 in Appendix A.2). The inverse H6 model at flare maximum, pre-flare, and the ‘fiducial flare’ model from Loyd et al. (2018b) with a comparable ED is plotted as dash-dotted blue, dash-dotted light-blue, and dashed purple lines, respectively. Blackbody curves for 3850 K, 6000 K, 8000 K, and 10 000 K are included in solid, dotted, dashed, and dash-dotted black lines. The panchromatic AU Mic flux from Feinstein et al. (2022) is plotted in light grey. Insets highlight the FUV (lower left) and TESS (lower right) wavelength ranges.