On 23 May 1967 energetic (10-50 kcV) solar flare X-rays were observed by the OGO-III ion chamber during the period 1808-2100 UT. The time-intensity profile for the X-ray event showed three distinct pcaks at ~: 1810, 1841 and 1942 UT. The second peak, which is eqtfivalent to ~-: 2.9 β’ 10 -8 ergscm-esec ~ above 20 keV, is the largest X-ray burst observed so far by the OGO-1 and OGO-III ion chambers. The soft (2.-12 ,&) X-ray obscrvations reported by VAN AI-LEN (1968) also show similar peaks, roughly proportional in magnitude to the energetic X-ray peaks. However, the intensity of energetic X-rays peaked in each case 5-10 rain earlier than the soft X-ray intensity indicating a relatively hard photon energy spectrum near the peak of the energetic X-ray emission. The corresponding time-intensity profile for the solar radio emission also showed three peaks in the microwave region nearly coincident with the energetic X-ray peaks. Thc third radio peak was relatively rich in the metric ernission. Beyond this peak both the encrgetic X-rays and the microwav'e emission decayed with a time constant of ~-8 rain while the corresponding time constant for the soft X-rays was ~ 43 min. ln view of the earlier findings about the energetic X-rays it is indicated that the 23 May solar X-ray event ~,as similar to those observed earlier. During the 23 May event the integral energy flux spectrum at the limc of peak intensity is found to be consistcnt with the form ~e ~,,"~o. E0 being about 3.4 and 3.7 kcV for the peaks at 1841 and 1942 UT, respectivcly. Assumption of a similar spectrum during the decay phase indicatcs that the spectral index E0 decreascd nearly exponentially with time.
The OGO-III ion chamber, which is also sensitive to protons ~> 12 McV, observed a solar particle event starting at ~2100 UT on 23 May. It could not be determined uniquely which of the two principal X-ray peaks was associated with the particle event, and in fact both may have contributed. The particle intensity reached its maximum value at ,~ 1003 UT on 25 May 1967. The equivalent peak radiation dosage was :~ 24 R/hour behind the 0.22 g cm ~ thick aluminum wall of the chamber. This peak radiation dosage was considerably smaller than the maximum dosage (~ 60 R/hour) during the 2 September 1966 solar particle event, the largest event observed so far by the OGO-[ and OGO-III satellites. The temporal rclationship between the solar X-ray and particle events on