o 99 shelter occupants at shelters 9,150 meters north, south, and west of ground zero o 144 to 160 officers and enlisted men of the evacuation detachment, located 14 kilometers northwest of ground zero near Guard Post 2 o Five radiological safety monitors assigned to the evacuation detachment to perform offsite monitoring of nearby towns and residences o One radiological safety monitor assigned to Guard Post 4 o Two military policemen at each of the seven guard posts (indicated by photographs such as figures 1-3 and 1-4). 2.2 DETONATION AND POSTSHOT ACTIVITIES Because of bad weather, the Project TRINITY director (Dr. Bainbridge) delayed the detonation, which had been scheduled for 0400 hours. By 0445, however, the forecast was better, and shot-time was set for 0530. This gave the scientists 45 minutes to arm the device and prepare the instruments in the shelters. The final countdown began at 0510, and the device was detonated at 0529:45 Mountain War Time from the Control Point in the south shelter (3; 12). No one was closer than 9,150 meters to ground zero at the time of the detonation. With the exception of a few men holding the ropes of barrage balloons or guiding cameras to follow the fireball as it ascended, all shelter personnel were in or behind the shelters. Some left the shelters after the initial flash to view the fireball. As a precautionary measure, they had been advised to lie on the ground before the blast wave arrived. Project personnel located beyond the shelters, such as at the Base Camp and on Compania Hill, were also instructed to lie on the ground or in a depression until the blast wave had passed (1). However, the blast wave at these locations was not as strong as had been expected. In order to prevent eye damage, Dr. Bainbridge ordered the distribution of welder's filter glass. Because it was not known exactly how the flash might affect eyesight, it was suggested that direct viewing of the fireball not be attempted even with this protection. The recommended procedure was to face away from ground zero and watch the hills or sky until the fireball illuminated the area. Then, after the initial flash had passed, one could turn around and view the fireball through the filter glass. Despite these well-publicized instructions, two participants did not take precautions. They were temporarily blinded by the intense flash but experienced no permanent vision impairment (1; 17). People as far away as Santa Fe and El Paso saw the brilliant light of the detonation. Windows rattled in the areas immediately surrounding the test site, waking sleeping ranchers and townspeople. To dispel any rumors that might compromise the security of Project TRINITY, the Government announced that an Army munitions dump had exploded. However, immediately after the destruction of Hiroshima, the Government revealed to the public what had actually occurred in the New Mexico desert (12; 13).