Swept?Frequency Radio Observations at the Time of the Nuclear Explosion over Johnston Island on July 9, 1962

Abstract

The sudden ionospheric disturbance (SID) which occurred at the moment of detonation of the 1·4 megaton nuclear device 400 km above Johnston Island on July 9, 1962 (New Zealand Journal of Geology and Geophysics 1962, Journal of Geophysical Research 1963) was recorded with the 5-210 Mc/s solar radio spectrograph (Sheridan 1963) at Dapto, N.S.W. (latitude _34° 28:3, longitude -150° 45:5, geomagnetic latitude about 42° 30' S.). The reported increase in radio noise due to synchrotron emission (Dyce and Horowitz 1963; Ochs, Farley, and Bowles 1963) from high energy electrons generated by the explosion was not observed.