# Space Weather Effects from Observations by Moscow University Cubesat Constellation
## 5 Sub-Relativistic Electrons near the Geomagnetic Equator  
Another example of phenomena associated with the features of the distribution of charged particle fluxes in near-Earth space is the existence of stable sub-relativistic electron fluxes under the radiation belts at low latitudes. The presence of such electrons near the geomagnetic equator (at drift shells with \(L<1.2\)) is very interesting because, theoretically, the stable electron fluxes should not exist at such \(L\)-shells due to mortality in the SAA during less than one drift period. Nevertheless, they are observed by various space experiments (see, e.g., [20; 21; 29] at different phases of the solar cycle regardless of geomagnetic activity level. As an example, we can mention the RELEC experiment onboard the Vernov satellite, in which electron fluxes at low \(L\)-shells were studied in detail. In particular, it was shown that these fluxes are most clearly manifested in the equatorial region near 120\({}^{\circ}\) east longitude [21]. A study of electron fluxes near the geomagnetic equator can also be provided with the use of CubeSat satellites. Here we present examples of such observations with the DeCoR instrument onboard Moscow University CubeSat satellites, i.e., the AmurSat and DECART missions. Figure 6 shows a map with the projection of one AmurSat satellite orbit on 30 August 2019, which crosses the geomagnetic equator region in the eastern part of the Pacific Ocean. Figure 5: Profile of the event in solar cosmic rays according to data from the Norbi satellite (colored triangles, measurements were made in the polar caps—electrons with energies \(>300\) keV, as well as bremsstrahlung gamma quanta with energies \(>100\) keV) and the ACE spacecraft (black line, electrons with energy 175–315 keV). The corresponding monitor time dependences (with 1 s time resolution) of counting rate in plastic scintillator (main electrons with energies > 300 keV), CsI(Tl) (mainly gamma quanta with energies > 100 keV), and total from DeCoR instrument during one orbit of AmurSat CubeSat in 2019, August 30 are presented in Figure 7. The figure clearly shows the maxima at the moments when the satellite is in the outer radiation belt of the Earth. During the flight near the equator (10:55-11:10 UTC), a smooth increase in electron fluxes is seen, while the counting rate of background gamma quanta remains unchanged. A similar picture was obtained from observations with the DeCoR instrument onboard the DECART CubeSat. Map with the projection of one DECART satellite orbit on 12 August 2021 is presented in Figure 8. The corresponding count rate time dependences (electrons with energies > 300 keV, gammas with energies > 100 keV, and total) are presented in Figure 9. A significant maximum in electron counting rates is observed near the geomagnetic equator (~11:50 UTC). Figure 6: The AmurSat satellite orbit projection on the map for time interval 30 August 2019, 10:1320-11:36:40. The big dot corresponds to the beginning of interval. Figure 7: Monitoring counting measured 30 August 2019 during AmurSat satellite one orbit in plastic scintillator (green points), CsI(Tl) (red points), and total (blue points). As it could be seen from the presented above figures, the near-equatorial electrons observed at the same region in epochs separated in time by about 2 years. It indicates that this is quite a stable phenomenon. Since electron fluxes on drift shells \(L<1.2\) must be destroyed by SAA as a result of drift, there should be a constantly existing mechanism for replenishment of stable electron fluxes near the geomagnetic equator. The classical mechanism of precipitation from the radiation belts through pitch-angle diffusion can hardly explain this phenomenon since it does not provide transfer across the magnetic field lines and, accordingly, the movement of particles between drift shells. The shells \(L<1.2\) correspond to the heights of the magnetic field line tops below the internal radiation belt.