A rocket‐borne experiment package containing a vector magnetometer and an array of charged particle detectors was launched over a structured auroral arc from Poker Flat, Alaska, at 0722 UT on February 25, 1972. This paper discusses the results of the magnetometer data which indicate the existence of a pair of oppositely directed Birkeland current sheets with magnitudes of ∼2.7 × 10−5 A/m² and a system of two eastward electrojets. The downward Birkeland current flowed to the south of the upward current which coincided with the location of the peak auroral luminosity and the region of maximum electron precipitation as measured by the on‐board particle detectors. Some changes in the magnetic field profile during the flight are interpreted as being due to movement of the sheet currents in range and azimuth corresponding to the motion of two large folds in the arc as determined from the all‐sky camera pictures.

Auroral electron flux measurements obtained with rocket-borne detectors have been used to model ionospheric effects and resulting optical radiations. The predicted emission rate of N? first negative group (4278 •) is in excellent accord with ground-based observations made from Fort Yukon and Ester Dome, Alaska. This measurement provides a test of the energy deposition computations and the ionization-excitation efficiency used in the model. Predictions and observations of [O I] 5577 •, however, do not agree, and on the basis of the height profile of energy deposition we conclude that we do not, as yet, fully understand the low-altitude excitation or the quenching of O(•S) in the aurora. The electron density profiles derived from the model are used to compute the ionospheric Pedersen and Hall conductivities. Ionospheric currents are deduced from vector magnetometer measurements made on board the rocket, and these are combined with the conductivities to infer the presence of an electric field orthogonal to the magnetic field of about 20 mV m -• directed approximately 17 ø west of north.

A rocket-borne experiment package was launched over a structured auroral arc from Poker Flat, Alaska, at 0722 UT on February 25, 1972. The results of the flight vector magnetometer data have been detailed by Casserly and Cloutier (1975), who report the detection of a pair of oppositely directed Birkeland current sheets associated with the auroral band. This association has now been extensively investigated, and it has been shown that some observed structures in the arc due to the presence of a fold are also evident in the Birkeland current system. In particular, the field-aligned current to the east of the fold is at a higher geomagnetic latitude than the current to the west of the fold. Variations in other model current parameters are also shown to be well correlated with changes in the visual arc system.