The total solar eclipse of 23 October 1976 observed at VLF

VLF transmissions at 13.6 and 22.3 kHz from Omega Reunion, Omega Japan and NWC, were monitored at Melbourne during the total solar eclipse of 23 October 1976. The solar obscuration function for each path was calculated and compared with the phase deviation observed experimentally. The phase response was found to be a non-linear function of solar obscuration with a maximum phase deviation which was less than expected when compared with the normal diurnal phase variation. A differential equation was developed to model the observations. The effective time constant of ionospheric response was found to be four minutes and independent of reflection height.