A Terrier-Malemute rocket was launched from Poker Flat, Alaska, on March 9, 1978, over a stable premidnight auroral arc. It carried instrumentation to measure electric and magnetic fields and particle fluxes. The electron intensity in 13 fixed energy intervals from 0.04 to 40 keV was measured over 180¿ of pitch angle every half spin at ~2.5 rps. The intensity was generally isotropic over the upper hemisphere with the total energy flux and the spectral hardness greater in the visible arc than elsewhere. Field alignment of low-energy electrons occurred at the edges of the arc, with higher energies involved toward the center, and in two bursts within the arc. The interaction of the measured downward intensity with the neutral atmosphere (below apogee altitude ~320 km) was modeled by transport theory, including inelastic and multiple-elastic scattering of electrons by neutrals. The upcoming intensity calculated therefrom agrees with the measured upcoming intensity so that no collective effects, including parallel electric fields, need be postulated. The downward intensity at high energy within the discrete arc was fit to a thermal plasma accelerated (at some high altitude) through a parallel potential drop Vo (Evans, 1974). Electrons with energy E<‖eVo‖?6 keV are produced, in this model, by scattering on neutrals and specular reflection from the potential barrier above. The calculated downward intensity of electrons with E?‖eVo‖ fits the measured intensity well enough, in the arc, that no other interactions need by postulated. We infer that in this type of aurora the interaction of electrons with the atmosphere and ionosphere below several hundreds of kilometers is satisfactorily described by collisional scattering.