Optical, electromagnetic, and satellite observations of high-altitude nuclear detonations: Part II

The radio effects of the Argus detonations were measured using (1) 30-Mc radars designed to obtain echoes from the aurora or from the earth's surface mirrored in an enhanced ionospheric layer, (2) VLF receivers for monitoring distant transmitters or atmospheric noise sources in search of changes in signal strength, (3) riometers for recording cosmic noise absorption or VHF shot-created noise at 30, 60, and 120 Mc. Results included (1) auroral echoes in the vicinity of the launch point after all three shots and near the conjugate points after the first and third shot, (2) sudden depressions of 6 to 12 db of the signal from England (19.6 kc) at Madrid and the Azores, (3) no ionospheric absorption at the conjugate location.