ne nnneeneen eneene neeeeeeeeeeeennneneen nennnnnanneenneeeeeee Butternut OPERATION HARDTIACK I - TATE: TIME: ~~ PPG Time 12 May 1958 0615 GMT Sponsor: 11 May 1953 SITE: 1815 LASL PPG - Eniwetok - SW of Yvonne 4,000 ft from the nearest edge of the island 119 20' 162 21' i" O02" Site elevation: HEIGHT OF BURST: N & Sea level 10.13 ft TYPE OF BURST AND PLACEMENT: Surface burst from barge on water Water depth: 65 ft CLOUD TOP HEIGHT: 35,000 ft MSL CLOUD BOTTOM HEsIGHT: NM REMARKS: Only individual island dose rates are available. These were obtained from helicopter surveys at H+4 hours made by the Radiological Safety Organization. The helicopter survey technique called for the pilot either to land the aircraft at the desired spot, so that a ground reading coula 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. Thet--? decay approximation was used to extrapolate the H+ hour dose-rate readings to H+1 hour. 197