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the radiance L by solving the standard photographic equation, corrected for the effects of atmospheric attenuation:
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where
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H is the film exposure level in J/cm2 and t is the shutter time in seconds. L is the radiance of the object in the direction of the camera in W/sr/cm2, E is the irradiance on the focal plane of the camera in W/cm2, and f is the ratio of the focal length to the diameter, as set by the operator of the camera. The factor exp[(b-a)/cos theta] corrects for atmospheric attenuation, b being the optical thickness of the atmosphere from the ground to the altitude of the plane, a the optical thickness to the altitude of the object and theta the zenith angle of the slant path from the plane to the object. T is the transmission of the optics (aircraft window and lens) and f is the angle between the optic axis of the camera and the optical path from the lens to the image.
We refer the reader to Maccabee's analysis for an excellent discussion of the range of values of these parameters. He finds a value between 1.09 and 1.34 for the attenuation correction factor, a value of 0.7 for T, shutter time of 1/125 at f/8 and a value of 0.95 for cos4phi. The average density over much of the image is estimated at 0.12, leading to a value of H = 10-4 J/cm2.
Inserting these values into (eq. 1) and (eq. 2) gives estimates of radiance of 1.7 to 2.0 W/sr/cm2 if the object was at distances of 6 or 20 kilometers, respectively. Assuming that the object was a Lambertian emitter with constant emittance over its surface, Maccabee finds a range of 2.5 X 109 W (2,500 megawatts) to 3 X 1010 W (30,000 megawatts) for the power output within the spectral range of the film. As he rightly points out, however, "the total power emitted over all frequencies might be much greater."
Case no. 2: September 1965. Fort-de-France (Martinique) --
Classification: MA-1
On July 1, 1965, two French submarines, the Junon and the Daphné, escorted by the logistic support vessel Rhône, left the Toulon navy base in the Mediterranean and sailed toward Gibraltar. The ships traveled first to La Horta in the Azores, then to Norfolk, Virginia, to conduct a series of joint operations with the U.S. Navy, which was engaged at the time in the recovery of a Gemini capsule near Bermuda; the French submarines escorted the aircraft carrier Wasp. Later the ships went through Hurricane Betsy, whose effects they avoided by diving to three hundred meters. On the way back to France they stopped for ten days at Pointe-à-Pitre, Guadeloupe, and for one day at Saintes before reaching the island of Martinique, where they anchored in late September 1965.
It was during their layover in Fort-de-France one evening, by a dark sky and
