Auroral‐height measurements were made during a 5‐month period of the IQSY using meridian scanning photometers at three stations spanning the auroral zone on the same dipole meridian. The measurements were restricted to stable homogeneous auroral arcs, which usually occur during quiet times between substorms. They refer to the height of maximum volume emission rate of λ5577 [O I] that in these arcs was found to coincide with that of λ4278 (N2+ first negative). The height of maximum emission of λ4278 is directly related to the characteristic energy of the precipitated auroral electrons. Sufficient triangulation data were obtained (1152 points) to allow a separation of the effects of local time and latitude, which are normally related through the diurnal motion of the auroral oval. Interpreted in terms of the precipitated electrons, the photometric data reveal that the distribution of characteristic electron energy has two components: (1) at any local time during the night the electron energy increases with decreasing latitude, and (2) at every latitude the electron energy increases with increasing time throughout the night. The flux of the precipitated electrons generally increases with time and decreasing latitude. It appears that stable homogeneous auroral arcs observed during quiet times between substorms are manifestations of convective particle motion in the magnetosphere and not of local acceleration mechanisms. This study suggests several extensions or improvements of current theories of magnetospheric convection that would allow a more quantitative comparison between the theoretical models and experimental results.

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A Nike‐Tomahawk rocket was launched into a system of auroral arcs northward of Poker Flat Research Range, Fairbanks, Alaska, at 0815 UT on March 20, 1971. The pitch angle distribution of electrons was measured at 2.5, 5, and 10 keV and also at 10 keV on a separating forward section of the payload. The auroral activity appeared to be the extension of substorm activity centered to the east. The rocket crossed a westward propagating fold in the brightest band. The electron spectrum was relatively hard through most of the flight, showing a peak in the range 2.5 < E < 10 keV in the weaker aurora and E < 5 keV in the brightest arc. The detailed structure of the pitch angle distribution suggested that, at times, a very selective process was accelerating some electrons in the direction of B, so that a narrow field‐aligned component appeared superimposed on a more isotropic distribution. It is concluded that this process could not be a near‐ionosphere field‐aligned potential drop, although the more isotropic component may have been produced by a parallel electric field extending several thousand kilometers along the field line above the ionosphere.