Quantitative estimates of the brightness of the terrestrial halo at specific distances from within the shadow cone of the earth have been obtained by a method that combines refraction and multiple scattering theory with observed twilight phenomena. Results are presented for a range of radial altitudes from 10,000 km to 250,000 km. Both the luminance, or surface brightness, of the atmospheric halo and the total brightness, or illumination, received by an observer within this altitude range are given. 27 pp. Bibliog.
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