THE SOLAR X-RAY FLARE OF 7 JULY 1966,

By means of a mica window Geiger-Mueller tube on earth satellite Explorer 33, a major solar x-ray flare was observed with 81.8 sec time resolution on 7 July 1966. The flare had its onset at 0023, its maximum intensity at 0042, and a total duration of 200 minutes. The maximum energy flux was 0.03 ergssq cm sec and the time integrated flux was 97 ergssq cm 2 lambda 12 deg. A. Assuming equal intensity over 2 pi-steradians at the sun, the total emission in this wave length band was 1.4 x 10 to the 29th power ergs and the maximum surface luminosity of the sun was 2.9 x 10 to the 6th power ergssq cm sec or 4.5 x 10 to the -5 power of the whole radiant luminosity of the average solar surface. Charged particles began to arrive at the satellite at 0058, or 35 minutes after the first detection of the x-ray enhancement, and remained in the interplanetary system for at least ten days thereafter. The intensity-time curve of the soft x-rays is compared with those of 2700 MHz solar radio noise flux and of ionospheric absorption at 22 MHz as observed at Pentiction. Author