Two ?negative bursts? with moving filaments, 19 May 1969

Abstract

The event of 1969 May 19, 1430 UT included a flare, radio burst, and an active dark flocculus (ADF) or moving filament described by Vorpahl (1973) and a microwave negative burst superposed on a gradual rise and fall, described by Covington (1973). He found the interpretation of a second decrease at 2010 UT to be ambiguous in the absence of complete information. The second decrease is found here to be part of a series of events that parallels that of the earlier negative burst. Each decrease is superposed on a long-enduring burst that begins simultaneously with the eruption of a prominence near the equator at east limb and each is preceded by an ADF seen in Hα in a nearby active region. The similarity of these sequences strengthens the interpretation of the second event as a negative burst. The prominence eruptions, while not directly related to the negative bursts, add to a number of other signs of rapid changes in the large-scale structure of magnetic fields in the complex of active regions where the events took place.