OPERATION HARDIACK I= PATE: TIME: PPG Time 18 July 1958 1100 Pisonia GMT Sponsor: 17 July 1958 2300 SITE: LASL PPG - Eniwetok - 11,000 ft W of Yvonne 11° 33' 162° 19' N 43" Site elevation: HEIGHT OF BURST: &£ Sea level 6.5 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water CLOUD TOP HEIGHT: 55,000 ft MSL CLOUD BOTTOM HETGa?: 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 <5 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-}+* decay approximation was used to extrapolate the H+ hour dose-rate readings to H+l hour. 291