NATIONAL PARK SERVICE—
Nightscape Measurement System

The 2001 the National Park Service (NPS) designation of pristine “nightscapes” as a natural resource led to a program to document the quality and establish baseline management conditions at national parks across the nation. As no suitable technology existed to accomplish this, NPS scientists developed their own.

The resulting system is the only one in the world capable of accurately documenting levels of artificial light present across the full dome of the sky. Traditional mapping reduces sky quality to a single number that can be plotted on terrestrial map. The NPS system represents the full "spatial diversity" of its data as fish-eye (right) and panoramic projections (below).

This method makes it possible to document the precise amount of artificial light coming from every part of the sky. It accurately documents not only the overall quality, but also the major sources, known as "light domes." Most significantly, the NPS system does so in units of visible light carefully calibrated to the human eye.

The video below shows the system on loan to the Institute, being used to conduct a nightscape survey at an observing site on Mount Desert Island, Maine.

The NPS system’s hardware consists of a robotic camera that scans the sky, taking 104 images over 30 minutes. Custom software searches each image for stars of well-understood brightness. The system automatically identifies such stars and precisely calibrates the brightness of each image. The software then removes all stars from the image, leaving only the glow remaining between the stars—the artificial light.

The result is the world’s most precise measurement of how much artificial light is present in every quadrant of the sky. The results are visually stunning—or alarming, as the case may be—and very accessible to the non-scientist whose understanding of this newly-recognized natural resource is vital to its protection. 
 

The NPS measurement system is currently on loan to the Island Astronomy Institute, in support of Acadia National Park’s Night Sky Initiative. It is available on a limited basis for select light pollution measurement on a cost-of-service basis. The project builds upon the services that the Institute piloted in 2008 for the Acadia All American Road and Friends of Acadia.

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Island Astronomy Institute
P. O. Box 249
Bernard, ME 04612
Ph: 207-244-9477
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