Interplanetary magnetic effects of solar flares: Explorer 18 and Pioneer 5

Abstract

Ness [1965] has recently called attention to a portion of the Explorer 18 magnetometer record characterized by higher than usual field magnitude, variable field direction, and relatively high variances. This magnetic event extended from 0130 December 14 to 0900 December 15, 1963, during which interval the field magnitude reached the ‘anomalously large value of about 15 gammas for more than three hours, from 1800 to 2100, December 14.’ According to the Central Radio Propagation Laboratory [1964] tables of Hα flare reports, solar activity during December 1963 was confined to subflares only (importance 1−) except on December 1, 6, 9, 10, 11, 12, 13, 24, and 27, when larger events (importance 1) were seen, including the month's only flare designated 1+ by any observatory, on December 13, recorded by seven stations, and reported as 3.2 square degrees corrected area by Swedish Capri. This flare began around 0922 UT, 16 hours before onset of the disturbed interval noted by Ness and 33 hours before the 3 hours of sustained high field magnitude in the quotation of the paragraph above. No other event that month was so widely reported. Table 1 summarizes the flare reports associated by CRPL with this event; discrepancies among various estimates of the flare's features are typical of flare reportage.