Whistler observations in connection with nuclear explosions

During part of the ‘Plumbbob’ series of nuclear explosions at the Nevada testing grounds in September 1957, whistler recording equipment was installed and operated by NRL personnel near Fallon, Nevada, about 260 miles north of the explosion area. Whistlers were obtained that proved to be two-hop whistlers originating in electromagnetic pulses associated with the explosions. It is shown that the probability of a naturally-excited whistler (from lightning) occurring at the exactly correct times in each case is extremely small. The electromagnetic pulse from the explosion was recorded simultaneously on the whistler recorder in Nevada and on the AWS sferic direction-finding equipment at Andrews AFB near Washington, D. C.