Night skies data report: Photometric assessment of night sky quality at Lassen Volcanic National Park
Meyer EW . 2025. Night skies data report: Photometric assessment of night sky quality at Lassen Volcanic National Park. Science Report. NPS/SR—2025/250. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2308837
This report characterizes night sky conditions in Lassen Volcanic National Park (LAVO) using measurements made in the park unit and models of regional conditions based on satellite data. Calibrated night sky imagery was obtained to characterize the night sky at 2 sites. These ground-based observations were collected on 3 nights from 2004-07-16 to 2008-05-29. Satellite data from 2022 was used to create a map of predicted night sky conditions in and around the park. The sky overhead remains pristine with the average zenith brightness of 21.62 mag/arcsec2. We estimate more than 97% of stars were still visible for most of the time, providing an outstanding opportunity to observe the natural night sky from the park. The whole sky over LAVO is 6%-21% (mean=15%) brighter than average natural levels, indicating excellent dark sky conditions on average. In LAVO, we classified the sky as Bortle Class 3: rural sky, based on the visibility of astronomical objects. The average naked eye limiting magnitude (NELM) is 7.25, which is approaching excellent, just about the faintest attainable. Some indication of light pollution is evident along the horizon. Clouds may appear faintly illuminated in the brightest parts of the sky near the horizon but are dark overhead. The Milky Way still appears complex. The main impacts on LAVO’s night sky quality were the light domes from Redding, Chico, Sacramento, Reno, Shingletown, Chester, Susanville, Red Bluff, Anderson, and Roseville. These light domes were observed along the horizon, with a few nearing the natural brightness of the Milky Way.
- Type
- Published Report
- Authors
- Meyer, Erik
- Date of Issue
- 2025-03
- Publisher
- National Park Service
- DOI
- 10.36967/2308837
- Units
- LAVO , NRSS , NSNSD
- Keywords
- brightness, light pollution, night skies, night sky, photometric assessment, sky quality