VLF and ELF waves were measured on two rocket payloads launched into the dayside auroral oval on December 18, 1974, and on January 11, 1975. The correlation of the VLF hiss intensity with the fluxes of precipitating electrons above 500 eV on short spatial and time scales was often poor, even when a positive slope existed in the electron phase space density. During the flight of January 11, 1975, distinct features were observed at the lower hybrid frequency. The frequency of this emission was used together with an independent density measurement to determine the relative concentration of O+ to the heavier ions NO+ and O2+. It was found that the density of NO+ or O2+, which could not be distinguished, is enhanced over expected values between 150 and 400 km altitude. This may be due to conversion of O+ to NO+ by large dc electric fields as observed in the experiments. Broadband electrostatic and electromagnetic waves were observed shortly after the barium-shaped charged explosion in January 11, 1975. The observed lowering of the auroral VLF hiss cutoff due to the barium is consistent with either ducting of VLF hiss emissions along the enhanced density duct produced by the barium or with local generation VLF hiss during the barium injection. ELF hiss observations were consistent with previous results, indicating that it is limited to latitudes equatorward of the dayside auroral oval. |