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 ABLE, the F6F pilots used earphones connected to Geiger counters to monitor radioactivity.

Early reports from radiological reconnaissance PBMs and drone boats indicated that the lagoon and surrounding atmosphere were intensely radioactive. A drone boat recorded about 730 R/24 hours near the center of the target array. The three PBMs made several passes over the lagoon on 25 July, starting at 4,000 feet (1.22 km), then at 3,000, 2,000, 1,000 and 500 feet (914, 610, 305, and 152 meters); the first pass was made at 0915 and the last at 1615. The preshot radex sector bearings of 360° clockwise to 220° were modified slightly at 0940 to 360° to 270°. The Red Arc was set at 9 nmi (17 km) from surface zero and the Blue Arc at 11 nmi (20 km) from surface zero (Reference C.9.206, Part VII, p. C-19).

Reentry into the lagoon commenced at 0916 when the PGM and LCPL radiological patrol boats with monitors aboard entered. They were closely followed by TU 1.2.8 and ''Kenneth Whiting. Fall River'' took up its position at the lagoon entrance at 0947 to control entry and exit. The Salvage Unit (TU 1.2.7) entered the lagoon at 1015 and began checking and boarding target vessels. A total of 49 support ships with 14,920 personnel entered the lagoon by the end of 25 July.

For BAKER, ten initial boarding teams were established, a total of 86 men, including one monitor for each team. These teams were the first groups to return to the target vessels, although five of the firefighting officers may not have actually reboarded unless there was a fire to fight (Reference B.0.1, pp. X-X-1 through X-X-17). In addition, representatives of the groups responsible for the scientific experiments and tests of military equipment returned to retrieve data and materials when given permission by the monitors. Film and other data were recovered from Bikini and Eneu islands during the afternoon. Twelve target ships were temporarily boarded, ten of which were declared radiologically safe (no radiation measured above 0.1 R/24 hours) before nightfall on 25 July (Reference C.9.206, p. VII-C-53). The remaining target ships were too radioactive to board and the water near the detonation site remained radioactive as well (Reference C.9.206, p. VII-C-54).

The radioactive cloud had apparently moved north of the burst. Radiological reconnaissance F-13s discovered weak radioactivity while flying 43 nmi (80 km) north of the lagoon at 1318 and a highly radioactive cloud at 80 nmi (148 km) almost directly north of Eneu Channel at 1610 (Reference C.9.206, Part VI, p. D13). An F-13 due west of Bikini at 50 nmi (93 km) made no contact with radioactivity by 1415. Apparently based on this information, the alert at Enewetak Atoll west of Bikini was dropped at 1418 and clearance was given to return evacuees there (Reference C.9.206, Part VI, p. D13).

At about 1608 Saratoga sank (Figure 31). Until that time it had been the oldest U.S. aircraft carrier afloat. Saratoga was laid down as a battle cruiser in 1920, but was completed as an aircraft carrier. Radiological conditions prevented any attempt to save the ship.

The radioactivity persisted through 26 July. Films from cameras on Aomen Island were recovered using helicopters. An oil slick with radioactive debris

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