Patterns of Relativistic Electron Precipitation Observed by REPTile‐2/CIRBE: Comparison With CALET/ISS and MAXI/ISS

Relativistic electron precipitation from the radiation belts is one of the most important channels of radiation belt loss and an essential element of magnetosphere‐ionosphere coupling. While precipitation patterns associated with different mechanisms can be identified using pitch‐angle‐resolved measurements at low‐Earth orbit (LEO), many potentially valuable data sets contain only observations of locally trapped electrons. It therefore remains unclear whether distinct signatures of these precipitation mechanisms can be reliably identified using such measurements. Here we analyze conjunction measurements of relativistic electron precipitation using the Relativistic Electron and Proton Telescope integrated little experiment‐2 (REPTile‐2) onboard the Colorado Inner Radiation Belt Experiment CubeSat, together with the Monitor of All‐sky X‐ray Image (MAXI) and the CALorimetric Electron Telescope aboard the International Space Station (ISS). We demonstrate that three primary precipitation mechanisms, magnetic field‐line curvature scattering, whistler‐mode wave scattering, and electromagnetic ion cyclotron wave scattering, produce distinct and quantifiable signatures in the high‐energy‐resolution spectra of locally trapped electrons measured by REPTile‐2. Furthermore, cross‐comparison of REPTile‐2 and MAXI measurements enables the conversion of MAXI count rates to integral fluxes of keV electrons, extending the capability to interpret long‐term ISS observations in physically meaningful flux units. These results indicate that locally trapped electron measurements in LEO can contribute to the identification of precipitation mechanisms, thereby expanding the observational basis for studies of relativistic electron precipitation.