New electron responses have been evaluated for the synchronous orbit particle analyzer (SOPA) that Los Alamos National Laboratory flies on geosynchronous satellites. The new responses include for the first time a comprehensive treatment of bremsstrahlung photons, as well as actual dimensions and electronic noise. The new responses yield energetic (0.05--1.5 MeV) electron fluxes accurate to within a factor of 2. Whenever the electron energy spectra are sufficiently soft, the new electron fluxes agree reasonably well with previous estimates. However, for hard electron energy spectra often found after geomagnetically active times, significantly lower electron fluxes are obtained from the same observed counts. For such cases, previously obscured spectral features are clearly observed, and the plasma analyzer and SOPA electron fluxes show much better agreement.