Initial TRACERS Observations of Auroral Electron Precipitation: Case Studies of Diffuse and Discrete Aurora

The Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) is a recently launched NASA mission focused on investigating how temporal or spatial variations in magnetic reconnection drive cusp dynamics by employing multipoint, high-cadence measurements from two identical spacecraft. TRACERS successfully launched into a Sun-synchronous 590 km orbit around Earth on July 23, 2025. The two spacecraft comprising TRACERS are equipped with identical instrument payloads capable of measuring ions, electrons, and electromagnetic fields within low-Earth orbit. The primary goal of the TRACERS mission is to disentangle temporal and spatial variation of magnetic reconnection and associated processes by employing multipoint measurements within the cusp from two identical spacecraft (TRACERS-1 and -2), which are separated by 10 to 120 seconds. In addition to its primary science goals of examining cusp dynamics, TRACERS is also capable of measuring auroral precipitation and processes with high spatial and temporal resolution. We present initial auroral electron observations from one of the TRACERS spacecraft on October 7, 2025. We observe both discrete and diffuse electron precipitation in two orbits in the northern hemisphere. TRACERS-2 observes numerous inverted-V structures indicative of discrete aurora within the auroral oval and polar cap, as well as within the northern cusp. Hours later, TRACERS-2 observes broadband, diffuse electron precipitation spanning tens of eV to tens of keV across the northern polar cap, indicative of polar rain. We discuss the upstream solar wind conditions during each observation utilizing Wind data, as well as the characteristic energies, pitch angle distributions, and fluxes of each electron population observed by TRACERS-2 during these two observations.