OPERATION HARDPACK I TATE: TIME: PPG Time 12 May 1958 0550 Fir Sponsor: GMT 11 May 19538 1750 SITE: UCRL PPG - Bikini - SW of Charlie 4,000 ft from nearest edge of the island 11° kl! 165° 16' a7" 25" Site elevation: HEIGHT OF BURST: N FE Sea ievel 9.88 ++ TYPE OF BURST AND PIACEMENT: Surface burst trom burge on water CLOUD TOP HEIGHT: 9C,0CO ft MSL CLOUD BOTTOM HEIGH?: NM REMARKS: Only individual island dose rates are available. These were obtained from Radiological Safety organization helicopter surveys at Ht4 hours. The helicopter survey technique called for the pilot either to land the aircraft at the desired spot, so that a ground reading could be obtained, or to make a slow pass over the desired spot at an elevation of 25 feet. Readings taken at 25 feet were multiplied by a factor of 2 in order to obtain a reasonable approximation of the true ground reading. The basic instrument used in the aerial surveys was the AN/PDR-39 survey meter modified to read up to 500 r/hr. The t-1:2 decay approximation was used to extrapolate the Ht hour dose rate readings to H+tl hour. 193