Visual Observations of the Night Sky

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Session 27 -- Celestial Visibility
Oral presentation, Wednesday, January 12, 10:15-11:45, Salons A/B Room (Crystal City Marriott)

[27.06] Visual Observations of the Night Sky

A.R. Upgren (Van Vleck Obs.)

Visual observations carefully made, can duplicate at lower precision much of the information gained from photoelectric reductions. Using two sites of greatly differing sky brightness, the author has been able, by means of extensive visual observation, to separate the effects of normal sky extinction, light pollution, the contamination caused by Mount Pinatubo and the effects of cataracts, and their correction by surgical means. The visual observations yield extinctions that agree with those found from photoelectric and photographic sky brightness measures. The limiting magnitude of the faintest stars visible to the naked eye at the two sites is not in agreement with the other ways to determine sky brightness and pollution. This may be due to a crossover from scotopic to photopic vision (from dependence upon the rods to the cones) occurring in observations made between the two sites.

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