OPERATION HARDTACK I TATE: PPG Time 9 June 1956 TIME: 1115 - Umbrella Sponsor: GMT 6 June LYdo SITE: 2315 DOD PPG - Eniwetok - NNE of Henry 11° 22' 162° 13' 51" o9" N E Site elevation: Sea level Water depth: 150 ft HEIGHT OF BURST: 150 ft underwater TYPE OF BURST AND PLACEMENT: Sub-surface burst on lagoon bottom REMARKS: The pattern was obtained from a total of about 80 points which is really too few to place much reliance on the rather pronounced lobing of the downwind contours. "Nearly all of the total gamma dose oceurred within 25 minutes after zero time and was due to the passage of airborne radioactive material. Gamma doses in excess of l00r occurred within the first 15 minutes at downwind distances less than 14,000 feet. The residual field due to deposited radioactive material was relatively insignificant, although radioactive foam may represent a radiological hazard." 238