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R. H. Garstang (JILA, Univ. Colo.)
Although previous attempts to observe lines of Hg I in the night sky spectrum had failed, Osterbrock, Waters, Barlow, Slanger and Cosby (PASP 112, 733, 2000) have now identified three Hg I lines on co-added echelle spectra with a total exposure of 132 hours. The mean intensity of the line 5461A is 0.13 R, equivalent to 1.0\times104\rm\,photons/cm2/sec/sterad. I have tried to model this very weak line using slight modifications of my light pollution programs. One model assumed that all the mercury lamps were in the city of Waimea, the nearest significant town to Mauna Kea, at a distance of 29 km. It would require about 60 mercury lamps. I examined the possibility that all the mercury radiation comes from lamps in Honolulu. That seems to be impossible because an unreasonably large number of lamps would be required. Some of the radiation probably comes from the island of Maui. If the mercury lamps are distributed throughout the Big Island in proportion to the population about 130 mercury lamps would be needed. Some mercury radiation may also originate in fluorescent lamps and in metal halide lamps, I am investigating the contributions of lamps of these kinds.