Whereas in 1958 the altitudes chosen for Teak and Orange were such that the detonations could not be seen from the nearest inhabited islands, namely, Hawaii. The DOD desired moderately large yield shots and altitudes therin from 100 kil- ometers to 400 kilometers. It was quickly recognized that these altitudes would allow the detonations to be seen from Hawaii. Two sets of studies were thus initiated and continued throughout the operation. The first study targely conducted by Group J-I0 in Los Alamos attempted to predict the brightness, size & duration of the fireball as a function of the altitude of detonation and the yield of the detonation. The second study largely conducted by to look that up), a Dr. Hamm as | (we'll have remember, a DOD contractor, concerned itself with the characteristics of the human eye from the point of view of the likelihood of burning the retina from such a flash. This study had to take into account the probable size of the pupil at time of detonation, the likelihood of the person having the detonation in his field of view, the size of the focused spot on the retina, heat conduction characteristics of the retina etc. Dr. Hamm had previously conducted experiments on monkeys using laboratory sources and had some initial information on the subject. Both of these problems had some previous history of effort as a result of the difficulty encountered with Teak and Orange during Hardtack, and for that matter, as a result of earlier comparatively low altitude detonations in Nevada, where some of thedetonations could be seen from local highways and other inhabited spots. (eS 0 Atamos Laboratory had been studying the eye burn problem since the early detonations in Nevada and was of great assistance in these considerations. Also to be taken into account in the problem was the air transmission characteristics between the point of bursts retrac tied in Hawaii and the effects of retraction because of the changing atmospheric density with altitude. Los Alamos. That work was largely carried on again by Group J-10 of