OPERATION HARDIACK I TATE: TIME: PPG Time 28 Jun 1958 0530 ~ Redwood GMT 27 Jun 1958 Sponsor: 1730 SITE: UCRL PPG - Bikini South of Fox 12° 4i' 165° 2ht ik" N sk" Site elevation: HEIGHT OF BURST: E Sea level 10.79 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water CLOUD TOP HEIGHT: 51,000 ft MSL CLOUD BOTTOM HEIGHT: 28,000 ft MSL REMARKS: Only individual island dose rates are available. These were obtained from Radiological Safety organization helicopter surveys at H+ 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*? decay approximation was used to extrapolate the H+ hour dose-rate readings to H+l hour. 258