OPERATION CROSSROADS - DATE: TIME: PPG time 25 Jul 1946 0835 TOTAL YIELD: Baker GMT 24 Jul 19h6 2135 Sponsor: SITE: LASL and DOD PPG - Bikini - Near How 11° 37' #10" N 165° 29' 28" E Site elevation: 23 kt HEIGHT OF BURST: Sea level -90 ft TYPE OF BURST AND PLACEMENT: Underwater - cable-supported 90 ft above lagoon floor. Time to lst minimum: Time to 2nd maximum: Radius at 2nd maximum: 223 FIREBALL DATA: Lagoon was 180 ft deep. CLOUD TOP HEIGHT: CRATER DATA: Diameter: Depth: 7,600 ft MSL 3,300 ft maximum 1,800 ft minimum 25 ft REMARKS: The contamination pattern is unreliable. The dose-rate readings used for the pattern were obtained from the total dose measured by film badges collected between D+tlO days and D+15 days. The radioactivity on the target vessels diminished At its greatest extent the base surge extended about 2,000 yd upwind, 3,000 yd crosswind and 4,COO yd downwind. "The contamination resulted from fallout or radioactive rain from the mushroom head reinforced somewhat by condensation of the base surge. Ideally there should have been an annular infinitivedose pattern as a result of fallout from the outer edges of the mushroom head. This ideal pattern was changed because of the intermittent behavior of the rain-out and because of the varying ability of the different target ships to retain the fallout activity."