OPERATION HARDIACK I - DATE: TIME: PPG Time 2 July 1958 0630 sequoia GMT Sponsor: 1 July 1958 1830 SITE: LASL PPG - Eniwetok - 4 mi west of Yvonne 11° 32' 39" oN 162° 21' Site elevation: HEIGHT OF BURST: 23" E Sea level 6.5 ft TYPE OF BURST AND PLACEMENT: Surface burst from varge on water CLOUD TOP HEIGHT: 17,000 ft MSL CLOUD BOTTOM HEIGHT: NM REMARKS: Only individual island dose rates are available. These were cbtaineda 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 cf 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+4 hour dose-rate readings to H+l hour. 274