D. B. Sarrazin

Abstract: The burning of an Atlas-Centaur rocket in the ionospheric F–region was used to determine the extent of HF propagation anomalies associated with the resultant drop in ionospheric electron content. This "ionospheric hole" grew to encompass the control points of many Caribbean to North American high frequency paths soon after the 0528 GMT launch from Kennedy Space Center, Cape Canaveral, Florida, on September 20, 1979. Short-wave listeners, who collectively monitored 86 paths after launch, volunteered signal strength and fade quality data concerning special broadcasts on 15295 kHz from Bonaire and on 17815 kHz from Antigua. Although these frequencies were closer to the predicted maximum usable frequency than what were normally used, the expected blackout of radio circuits did not occur; in fact, computer analysis revealed that the large number of minor fadeouts that followed the launch were not related to the location of the control points. The burning thus appeared to have negligible effect on HF signals that crossed the rocket path.

Keywords: ionospheric depletions; propagation blackout; short-wave broadcasting

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