title: Intercomparisons of nine sky brightness detectors.
abstract: Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across The Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from -16% to +20%. Intercalibration reduces this to 0.5%, and -7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m(2) on 12 April, and the largest value was 5.94 ± 0.03 mcd/m(2) on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.
authors.affiliation: National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3720 BA Bilthoven, The Netherlands. peter.den.outer@rivm.nl
authors.forename: Peter
authors.initials: P
authors.lastname: den Outer
authors.forename: Dorien
authors.initials: D
authors.lastname: Lolkema
authors.forename: Marty
authors.initials: M
authors.lastname: Haaima
authors.forename: Rene
authors.initials: R
authors.lastname: van der Hoff
authors.forename: Henk
authors.initials: H
authors.lastname: Spoelstra
authors.forename: Wim
authors.initials: W
authors.lastname: Schmidt
mesh_terms: D002138:Calibration; D003624:Darkness; D005118:Extraterrestrial Environment; D006801:Humans; D008027:Light; D008163:Luminescent Measurements; D009426:Netherlands; D055620:Optical Phenomena; D055095:Optics and Photonics / Q000295:instrumentation* / Q000379:methods*