As part of Operation Periquito, two sounding rockets were launched into regions of particle precipitation at invariant latitude 76¿N and magnetic local time 13 hours from Cape Parry, Northwest Territories, Canada, in November 1975. On one of the flights, which did not cross any well-defined auroral arcs, the electron spectra were always soft, the thermal ion drift velocity was variable but generally westward at 500m/s, and energetic particles ($70 keV) were always well above cosmic ray background, indicating a region of closed magnetic field lines. The other flight crossed two auroral arcs. Electrons with soft (mean energy of 200 eV) power law spectra were observed on the equatorward and poleward sides, whereas intense 1-keV precipitation was measured within the arcs. The mean drift velocity of thermal ions was seen to change from 1500 m/s westward, parallel to the boundary, on the equatorward side to ~200 m/s southward on the poleward side of the arcs. Energetic (E>70 keV) particle measurements showed that the high-latitude boundary was well poleward of the auroral arcs (Heikkila and Winningham's 'cleft' precipitation and ion convection velocity reversals), which indicates that the entire region was on closed magnetic field lines. Comparison of these features with those from midnight aurora shows that the two are qualitatively similar, strongly suggesting that dayside and nightside arcs are different aspects of the same process. No support was seen for the idea that direct penetration of magnetosheath particles is responsible for the dayside aurora.