the yield and burst altitude were very close to those desired, but according to most official documents the exact nuclear yield remains classified. It is reported in the open literature as simply being less than 20 kilotons. One report by the U.S. federal government, however, reported the Checkmate test yield as 10 kilotons. It was reported that, "Observers on Johnston Island saw a green and blue circular region surrounded by a blood-red ring formed overhead that faded in less than 1 minute. Blue-green streamers and numerous pink striations formed, the latter lasting for 30 minutes. Observers at Samoa saw a white flash, which faded to orange and disappeared in about 1 minute." Bluegill Triple Prime The fourth attempt at the Bluegill test was launched on a Thor missile on October 25, 1962 (Johnston Island time). It resulted in a successful detonation of a submegaton nuclear warhead at about one minute before midnight, local time (the official Coordinated Universal Time was 0959 on October 26, 1962). It was officially reported as being in the submegaton range (meaning more than 200 kilotons but less than one megaton), and most observers of the U.S. nuclear testing programs believe that the nuclear yield was about 400 kilotons. One report by the U.S. federal government reported the test yield as 200 kilotons. Since all of the Operation Fishbowl tests were planned to occur during the night, the potential for eyeburn, especially for permanent retinal damage, was an important consideration at all levels of planning. Much research went into the potential eyeburn problem. One of the official reports for the project stated that, for the altitudes planned for the Bluegill, Kingfish and Checkmate tests, "the thermal-pulse durations are of the same order of magnitude or shorter than the natural blink period which, for the average person, is about 150 milliseconds. Furthermore, the atmospheric attenuation is normally much less for a given distance than in the case of sea-level or near-sea-level explosions. Consequently, the eye-damage hazard is more severe." Two cases of retinal damage did occur with military personnel on Johnston Island during the Bluegill Triple Prime test. Neither individual had his protective goggles in place at the instant of the detonation. One official report stated, "In the first case, acuity for central vision was 20/400 initially, but returned to 20/25 by six months. The second victim was less fortunate, as central vision did not improve beyond