(a) Electron integral fluxes as a function of incident electron energy. Comparison of the two inversion methods described in the paper. The black curve corresponds to the full minimization method while the green dots with error bars correspond to the sensitivity analysis method. The calculated fluxes correspond to the day of 2023-04-01 observed by HotBird missions. In the case of inversion by sensitivity analysis, some energies are covered by different channels, which explains the overlap of some error bars. The red zones correspond to energies that have no influence, or very limited influence, on the instrument’s measurements. (b) Count rates observed (black full line) and reconstructed (red dashed line) during the same day.