OPERATION CASTLE - DATE: TIME: PPG Lire 1h May 1954 0620 Nectar GMT Sponsor: 13 May 1954 1820 SITE: LASL PPG - Eniwetok - Ivy Mike Crater 21° hot TOTAL YIELD: 162? 1l' 1.69 Mt Site elevation: HEIGHT OF BURST: oak" Wy" oN OR Sea level 7 ft CLOUD TOP HEIGHT: ‘71,000 ft M5I, CLOUD BOTTOM JESIGHT: 40,500 ft MSL TYPE OF BURST AND PLACEMENT: Surface burst from barge on water REMARKS: The on-site fallout pattern was drawn from Radiological Safety orgunization data and by converting the readings obtained from fallout samples to equivalent dose-rate readings over land. Since the fallout went in a northerly direction from ground zero very few of the collecting stations received significant fallout. The fallout collected was primarily upwind fallout. Aerial survey was used for measurements north of the atoll, and two tugs gathered water sampies throughout the fallout area. Anulyses of the water samples, combined with an estimate of the depth of mixing, served to determine the land-equivalent exposure rate at a number of points. The aerial survey served to fill in the contours. 91