Night Skies Data Report: Photometric Assessment of Night Sky Quality at Sunset Crater Volcano National Monument
Olstad TA , Hung LW, Meyer E . 2025. Night Skies Data Report: Photometric Assessment of Night Sky Quality at Sunset Crater Volcano National Monument. Science Report. NPS/SR—2025/337. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2314778
This report characterizes night sky conditions in Sunset Crater Volcano National Monument (SUCR) 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 one site. These ground-based observations were collected on seven nights between June 20, 2004, and March 13, 2012. Satellite data from 2023 were used to create a map of predicted night sky conditions in and around the park. The sky overhead remains fairly dark with an average zenith brightness of 21.67 magnitudes per square arcsecond (mag/arcsec2), close to the darkest level expected for pristine night skies, 22.0 mag/arcsec2. We estimate that 92.4–97.1% of naked eye stars were visible throughout the data collection period, providing a good opportunity to view the natural night sky from the park during a cloudless moonless night. The whole sky over SUCR is 10%–21% (mean = 17%) brighter than average natural levels, indicating very good dark sky conditions on average. In SUCR, 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 6.8–7, which indicates a very dark night sky with excellent viewing conditions. Light pollution is present along the south-southwestern horizon, but the sky zenith is relatively unimpacted. The Milky Way is visible horizon to horizon with a high level of detail. The main impacts on SUCR’s night sky quality are light domes from Flagstaff, Phoenix, and their surrounding communities.
- Type
- Published Report
- Authors
- Olstad, Tyra; Hung, Li; Meyer, Erik
- Date of Issue
- 2025-07
- Publisher
- National Park Service
- DOI
- 10.36967/2314778
- Units
- NRSS , SUCR
- Keywords
- brightness, light pollution, night skies, night sky, photometric assessment, sky quality