Using Dark Sky Images Captured with a Standard Digital Camera to Quantify Visual Air Quality and the Night Sky Viewing Experience at Bryce Canyon National Park

摘要

A digital SLR camera has been operating in Bryce Canyon National Park since September 2013, capturing night sky images of the light dome (sky region) over the Alton coal mine and St. George, Utah, southwest of the Park. The images capture the direct light from the dome, as well as light scattered by haze and clouds in the dome. Research by the authors into using daytime webcam images from Great Smoky Mountains and Grand Canyon National Parks to determine visual air quality is currently underway using techniques such as equivalent (EQ) and average contrast (CR), Sobel (SOB) and fast Fourier transform (FFT) to develop air quality indexes. Night sky images may also be used to determine visual air quality, but using different techniques to develop air quality indexes. In particular, characterizing the light dome on moonless, cloud free nights and comparing those data to concurrent measures of the atmospheric extinction coefficient demonstrate a relationship between the two. Since most nights are not cloud free, analysis of the entire moonless image set provides a measure of how much light is coming from the dome and affecting the night sky viewing experience.