OPERATION HARDTACK I TATE: TIME: PPG Time 27 May 1958 O600 Magnolia GMT 26 May 1958 1800 Sponsor: SITE: LASL PPG -~ Eniwetok - SW of Yvonne, 3,000 ft from the nearest edge of the island 11° 321 162° 21' 3h" 14" Site elevation: HEIGHT OF BURST: N &§E Sea level 13.88 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge cn water CLOUD TOP HEIGHT: 44,00C ft MSL CLOUD BOTICM HEIGHT: 15,0CC ft” 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 e 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-1-4 decay approximation was used to extrapolate the H+4 hour dose-rate readings to H+l hour. 222