Astronomy and sodium lighting

Abstract : In the last decade, lighting in the City of San Diego and its suburbs has increased substantially. Astronomers at Palomar Observatory are concerned that the encroaching light will make many of their measurements impossible. San Diego will soon convert its street lights to one of the more efficient sodium systems. Astronomers prefer low-pressure sodium lights because they do not interfere with the detection of distant stars. Other groups prefer high-pressure sodium lights because they have fair color rendition. Many of the issues surrounding this choice have become controversial. The function of this Note is to identify and analyze some of the important factors in this public policy question. The first purpose of the research is to assess the significance of light pollution to astronomers. The second purpose is to focus on methods of mitigating the effects of light pollution. The third purpose is to compare the costs and efficiency of low- and high-pressure sodium lighting. Our findings reveal that light pollution indeed presents a problem for many types of astronomical measurements. Although a number of methods of reducing the impacts of lighting might be adopted, the most promising is conversion to low-pressure sodium lights. Costs of the low- and high-pressure systems in San Diego are comparable, and the final decision on the type of lighting should be based on other factors. (Author).