V.L.F. ionosonde and long-distance propagation anomalies produced by galactic CEN X-4 X-ray burst in May 1979

The galactic X-ray source Cen X-4 produced a large outburst in May 1979, measured by Ariel-5 satellite. Low ionosphere group heights measured daily by a V.L.F. ionosonde indicated anomalous lowering of the effective reflection height in good correlation with Cen X-4 burst, as well as an increase in reflection coefficient, larger for larger frequencies. Diurnal V.L.F. phase variations in a long-distance propagation path presented nighttime 3-4 sigma deviations from average in some days during the Cen X-4 bursting period. These results are a suggested confirmation that galactic transient X-ray sources are capable to produce sufficient ionization effects to be detectable as low ionosphere anomalies.