Remote sensing of the energy of auroral electrons in Saturn's atmosphere: Hubble and Cassini spectral observations

► We report observations of Saturn's UV aurora with Hubble and Cassini. ► Spectra show signatures of absorption by methane from <3 × 1015 to 2 × 1016 cm−2. ► No local time dependence of the overlying column of CH4 is observed. ► The mean energy of the auroral electrons is estimated from below 3 keV to ∼10 keV.