OPERATION HARDIACK I - DATE: TIME: PPG Time Hickory GMT Sponsor: 29 June 1958 29 June 1958 1200 2400 SITE: UCRL PPG - Bikini - Off west end of Tare 11° 29' 165° 22' 46" 15" Site elevation: HEIGHT OF BURST: CLOUD TOP HEIGHT: Sea level 12.11 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on 2,000 ft MSL CLOUD BOTTOM HEIGHT: N E water 12,000 ft MSL CRATER TATA: Not available 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 reasonaole 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+4 hour dose-rate readings to H+l hour. 270