Observed particle effects of an interplanetary shock wave on July 8, 1966

At 2106 UT on July 8, 1966, a distinctive, discontinuous drop in the intensities of solar protons Ep ∼ 0.5 Mev was observed by Explorer 33 in interplanetary space at 187,000 km in the antisolar direction from the earth. The protons had been emitted by the sun in a flare whose onset time was 0027 UT on July 7. The intensity drop is attributed to the effects of an interplanetary shock wave whose detailed structure was observed by a triaxial flux gate magnetometer on the same satellite.