Stability of the Nine Sky Quality Meters in the Dutch Night Sky Brightness Monitoring Network

Abstract

In the context of monitoring abundance of artificial light at night, the year-to-year stability of Sky Quality Meters (SQMs) is investigated by analysing intercalibrations derived from two measurement campaigns that were held in 2011 and 2012. An intercalibration comprises a light sensitivity factor and an offset for each SQM. The campaigns were concerned with monitoring measurements, each lasting one month. Nine SQMs, together forming the Night Sky Brightness Monitoring network (MHN) in The Netherlands, were involved in both campaigns. The stability of the intercalibration of these instruments leads to a year-to-year uncertainty (standard deviation) of 5% in the measured median luminance occurring at the MHN monitoring locations. For the 10-percentiles and 90-percentiles, we find 8% and 4%, respectively. This means that, for urban and industrial areas, changes in the sky brightness larger than 5% become detectable. Rural and nature areas require an 8%–9% change of the median luminance to be detectable. The light sensitivety agrees within 8% for the whole group of SQMs.

Imaging and mapping the impact of clouds on skyglow with all-sky photometry

“…A detailed description of dark current subtraction is given in the Stars4All intercomparison campaign report 53 . The device has been used in other intercomparison measurements before 25 , 57 .…”

Monitoring Long-Term Trends in the Anthropogenic Night Sky Brightness

“…Regarding the first possibility, the readings of the SQM detectors have been shown to be stable over long periods of time, with small annual drifts [54]. The glass windows of the GNSBMN detectors are periodically maintained according to the MeteoGalicia operating protocols, much like the remaining optical instruments installed in their stations.…”

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“…They described the measurement error in the instrument, and recommended intercalibration and methods for data collection to reduce error (i.e., reject first few readings, allow the SQM to warm up, rotate the SQM around all 4 cardinal directions while aiming at the zenith etc.). Cinzano (2005Cinzano ( , 2007 provided an early review on the use, precision and accuracy of SQM, and a growing body of literature has built on this work (for example see den Outer et al, 2011Outer et al, , 2015Duriscoe et al, 2015;Sanchez et al, 2017). Stanley et al (2020) used a tripod for pointing, but otherwise did not report following these recommended methods.…”