OPERATION HARDIACK I - DATE: TIME: PPG Time 31 May 1958 1500 Sycamore Gur Sponsor: 31 May 1955 0300 SITE: UCRL PPG ~ Bikini - SW of Charlie 4,000 ft from the nearest edge of the island 11° 4i't 165° 16' 27" 25" N £E HEIGHT OF BURST: 11.64 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water CLOUD TOP HEIGHT: 46,000 ft MSL CLOUD BOTTOM HEIGHT: NM REMARKS: Only individual island dose rates are available. These were obtained from helicopter surveys made by the Radiological Safety organization at H+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 Ht+4 hour dose rate readings to H+l hour. 230 —— Site elevation: Sea level