Source: First peak of bomb light watts radiated in region in which photocell is sensitive Ay = 0.5 108 Distance 600 kdlometers Irradiance at receiving station by inverse aquare attenuation 1 A. ——= C4e DI ~ 0-5% 10" watts = 50 watts/m? , 4(6x105)? m* Assume that various absorption phenomena cause the difference between the meas- ured irradiance and that calculated by inverse square attenuations; then the absorption is the ratio between these two values: Absorption = irradiance by inverse square measured irradiance 00 watts/m? eae " 337 x 10 watta/m =1.4x 108 For the one successful record the following may be added to data as presented in Table 3.1 of Reference 3: Skot King; Radiant flux emitted(approximate flux emitted in visible band); 2,000 A wide centered for red cell at 8,000 A: 0.5 x 10" watts. Observing station and distance aircraft, 600 km, altitude 12,000 feet (3.7 km). . Detector photocell sensitivity and polarization data; red (no polarizer used). Signal amplitude; output voltage at cathode follower of plietohead, measured to top of first peak 0.415. volts. LIrradi~ ance; by inverse distance calculated by Equation 1, 60 watts/m*. Ratio of irradiance by inverse square to that measured (absorption factor); 1.4 x 10°. Signal-to-noise ratio; ~13. Figure 3 is a reproduction of Figure 3.1, Reference 3, with the additional point added. About all that can be stated fs that it is in general agreement with previous data. The light fash was not visible to observers at any of tHe stations for either shot, al- though Mike was beard at Kwajalein as three distinct rumbles about 35 to 40 minutes after the shot. During the analysis of the records, ull wore examined independently by two people accustomed to evaluating bhangmeter film recordings. Line-of-sight to the horizon 1rom 12,000 feet is about 220 km. It fe apparext that the light is dispersed around the earth’s surface for reception at 600 km. A word should be eald regarding the feasibility of an airborne station for long distances. During the Tumbler-Snapper series, sn experiment was performed to determine the noise level in a C-47 plane flying around sunrise in the viciaity of Flagstaff, Arizona. The noise level recorded was between 18 and 42 m‘llivolta using « system similar to that of the Ivy tests. This is but one or two orders of magnitude less than the pezk shown in Figure 2. Present data indicate that a signal would be at noise level at a distance of approximately 800 to 1,000 lan in the early morning. Since the Kwajalein station did not produce data on either shot, if is no: poesible to make a comparison between the light flux received at the ground and at a point in the air above. CCNCLUSIONS AND RECOMMENDATIONS Considering the results to date, it can be stated that with the type of equipment used, 16 es en veeoe we ee - em se - wep eee ee te ne crane at oe