OPERATION HARDIACK I - DATE: TIME: PPG Time 21 May 1958 0630 Holly GMT Sponsor: 20 May 1998 1830 LASL SITE: | PPG - Eniwetok - West of Yvonne, 4,000 f* from the nearest edge of the island 11° 32' 38" WN 1620 21' 22" Site elevation: HEIGHT OF BURST: § Sea level 13.06 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water Water depth: 4O ft CLOUD TOP HEIGHT: 15,000 ft MSL CLOUD BOTTOM HEiGHT: 7,000 ft MSL REMARKS: Only individual island dose rates are available. These were obtained from helicopter surveys made by the Radiological Safety organization at H+ 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+2 decay approximation was used to extrapolate the H+ hour dose rate readings to H+1 hour. 210