Optical observations conjugate to the FAST satellite show good agreement between the widths of auroral structures observed optically and those inferred from the measured electron energy flux. The implication is that these structures are imposed by processes at or above the ∼4000 km altitude of FAST. A variety of widths down to about 2 km were observed, but there were no examples of finer scale structures. A pre-breakup weak discrete arc at the poleward edge of the diffuse aurora showed electron produced optical structures located on either side of upward going ion beams. The optical emission in the equatorward part of the diffuse aurora was caused almost exclusively by precipitating ions. The optical observations were made over northern Alaska between Jan 31 and Feb 16, 1997, from a jet aircraft carrying an all-sky and three narrow-field TV cameras.