OPERATION HARDTACK I TATE: TIME: PPG Time 3 June 1958 O645 Rose CMT Sponsor: _ 2 June 1958 1845 SITE: LASL PPG - Eniwetok - SW of Yvonne 4,000 ft from the nearest edge of the island Site elevation: Sea level HEIGHT OF BURST: 15.43 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water CLOUD TOP HEIGHT: 17,000 ft MSL CLOUD BOTTOM H&IGHT: 5,000 ft MSL REMARKS: Only individual island dose rates are available. These were obtained from helicopter surveys made by the Radiological Safety organization at H+4 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 extrapolete the H+4 hour dose-rate readings to H+l hour. 234