Illumination Levels within aids to Navigation Lanterns at Sunrise and Sunset.
COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CONN
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Cadmium-sulfide photoconductive cells are used as daylight controls for lighted aids to navigation. The purpose of this work was to determine the illumination levels in lanterns and their effect on the operation of daylight controls. An array of standard Coast Guard aids to navigation lanterns was equipped with calibrated illumination meters. Measurements of illumination within the lanterns and in the external horizontal plane, as a function of time before and after sunset and sunrise, were compiled for 23 days. Spectral curves of daylight for various sky conditions were obtained. Transmission factors were calculated for each of the lanterns used. Turn-on and turn-off times and periods of maximum daylight operation were calculated for each type lantern. Average maximum periods of daylight operation vary with lantern type, lens color, and sky condition. In general, they were found to be reasonably small, averaging around fifteen minutes. Author
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