Photoelectro-Photometric Survey of Night Sky Conditions in the Vicinity of Iowa City

Abstract

During the summer 1962, a systematic survey of night sky conditions in the vicinity of Iowa City was carried out for the purpose of selecting the best site for the proposed research observatory of the State University of Iowa. A photoelectric photometer was attached to the Newtonian focus of an 11-inch reflector whose equatorial mounting was modified to a horizontal system. The equipment was carried by a truck and observations were made at six different sites, ranging in distance from eight to twenty-three miles in all directions from the city. In order to eliminate random errors due to variations in sky conditions from night to night, measurements of scattered city lights and the atmospheric extinctions were taken on at least two different sites during the same night and were repeated for six or seven different moonless nights at each site. As a result, it was concluded that the region about twelve miles south-southwest of the city is least affected by the artificial city light

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