Altitude behavior of subrelativistic electron fluxes in the region of the south atlantic anomaly according to measurements on the SiriusSat-1 satellite

Electron fluxes with energies $>0.3$ MeV have been measured on the SiriusSat-1 satellite in the final stage of its flight in the altitude range from $\sim 400$ to $180$ km in the region of the South Atlantic anomaly. The existing models of distributions of electron fluxes in the near-Earth space such as the AE8 and AE9 models primarily concern trapped particles in radiation belts at altitudes above $400$ km. Data on subrelativistic electron fluxes at altitudes below 300 km are almost absent. Since the SiriusSat-1 satellite operated until its burning in the atmosphere, unique measurements of the altitude behavior of subrelativistic electron fluxes have been performed, in particular in the region of the South Atlantic anomaly.