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Author Pravettoni, M.; Strepparava, D.; Cereghetti, N.; Klett, S.; Andretta, M.; Steiger, M. url  doi
openurl 
  Title (up) Indoor calibration of Sky Quality Meters: linearity, spectral responsivity and uncertainty analysis Type Journal Article
  Year 2016 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 181 Issue in press Pages 74-86  
  Keywords Instrumentation  
  Abstract The indoor calibration of brightness sensors requires extremely low values of irradiance in the most accurate and reproducible way. In this work the testing equipment of an ISO 17025 accredited laboratory for electrical testing, qualification and type approval of solar photovoltaic modules was modified in order to test the linearity of the instruments from few mW/cm2 down to fractions of nW/cm2, corresponding to levels of simulated brightness from 6 to 19 mag/arcsec2. Sixteen Sky Quality Meter (SQM) produced by Unihedron, a Canadian manufacturer, were tested, also assessing the impact of the ageing of their protective glasses on the calibration coefficients and the drift of the instruments. The instruments are in operation on measurement points and observatories at different sites and altitudes in Southern Switzerland, within the framework of OASI, the Environmental Observatory of Southern Switzerland. The authors present the results of the calibration campaign: linearity; brightness calibration, with and without protective glasses; transmittance measurement of the glasses; and spectral responsivity of the devices. A detailed uncertainty analysis is also provided, according to the ISO 17025 standard.  
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  ISSN 0022-4073 ISBN Medium  
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  Notes Approved no  
  Call Number LoNNe @ kyba @ Serial 1399  
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Author Li, X.; Li, D.; Xu, H.; Wu, C. url  doi
openurl 
  Title (up) Intercalibration between DMSP/OLS and VIIRS night-time light images to evaluate city light dynamics of Syria’s major human settlement during Syrian Civil War Type Journal Article
  Year 2017 Publication International Journal of Remote Sensing Abbreviated Journal International Journal of Remote Sensing  
  Volume 38 Issue 21 Pages 5934-5951  
  Keywords Remote Sensing; Instrumentation; Society  
  Abstract Monthly composites of night-time light acquired from the Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) had been used to evaluate socio-economic dynamics and human rights during the Syrian Civil War, which started in March 2011. However, DMSP/OLS monthly composites are not available subsequent to February 2014, and the only available night-time light composites for that period were acquired from the Suomi National Polar-orbiting Partnership satellite’s Visible Infrared Imaging Radiometer Suite (Suomi NPP/VIIRS). This article proposes an intercalibration model to simulate DMSP/OLS composites from the VIIRS day-and-night band (DNB) composites, by using a power function for radiometric degradation and a Gaussian low pass filter for spatial degradation. The DMSP/OLS data and the simulated DMSP/OLS data were combined to estimate the city light dynamics in Syria’s major human settlement between March 2011 and January 2017. Our analysis shows that Syria’s major human settlement lost about 79% of its city light by January 2017, with Aleppo, Daraa, Deir ez-Zor, and Idlib provinces losing 89%, 90%, 96%, and 99% of their light, respectively, indicating that these four provinces were most affected by the war. We also found that the city light in Syria and 12 provinces rebounded from early 2016 to January 2017, possibly as a result of the peace negotiation signed in Geneva.  
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  ISSN 0143-1161 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 1873  
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Author Wilson, T., & Xiong, X. url  doi
openurl 
  Title (up) Intercomparison of the SNPP and NOAA-20 VIIRS DNB High-Gain Stage Using Observations of Bright Stars Type Journal Article
  Year 2020 Publication IEEE Transactions on Geoscience and Remote Sensing Abbreviated Journal  
  Volume Issue Pages 1-8  
  Keywords Remote Sensing; Instrumentation  
  Abstract The Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi-NPP (SNPP) and NOAA-20 (N20) spacecrafts is a multispectral Earth-observing instrument with bands covering wavelengths from visible to long-wave infrared. Among these bands is a panchromatic day/night band (DNB) with a broad spectral response ranging from 500 to 900 nm, and a high dynamic range spanning over seven orders of magnitude, allowing for observations to take place during both daytime and nighttime. The DNB operates at three gain levels, with low- and mid-gain stages and two high-gain stages (HGSs). The HGS is capable of detecting dim city lights during Earth-view observations at night as well as bright stars through the instrument space-view port. Since SNPP and N20 are at opposite points of the same orbit, each VIIRS instrument is able to observe the same stars with the DNB in successive orbits. This will allow us to make a direct comparison of the relative calibration of each instrument using stars over a range of spectral classes. In this article, we develop methodology for accurately identifying target stars in order to make proper comparisons between the DNB HGS of each instrument. We then take observations from multiple stars in order to compute the ratio in the measured irradiance for each instrument as a function of spectral class. For K-type stars, which have the least spectral change over the DNB wavelength range, we measure a calibration bias between the SNPP and N20 DNB HGS of approximately 4%, which is stable over the duration of the N20 mission.  
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  Notes Approved no  
  Call Number IDA @ intern @ Serial 2959  
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Author den Outer, P.; Lolkema, D.; Haaima, M.; van der Hoff, R.; Spoelstra, H.; Schmidt, W. url  doi
openurl 
  Title (up) Intercomparisons of nine sky brightness detectors Type Journal Article
  Year 2011 Publication Sensors (Basel, Switzerland) Abbreviated Journal Sensors (Basel)  
  Volume 11 Issue 10 Pages 9603-9612  
  Keywords Calibration; Darkness; *Extraterrestrial Environment; Humans; Light; Luminescent Measurements; Netherlands; *Optical Phenomena; Optics and Photonics/*instrumentation/*methods; Sky Quality Meter; artificial lighting; intercalibration; intercomparison; light pollution; night sky brightness  
  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.  
  Address National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3720 BA Bilthoven, The Netherlands. peter.den.outer@rivm.nl  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1424-8220 ISBN Medium  
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  Notes PMID:22163715; PMCID:PMC3231263 Approved no  
  Call Number IDA @ john @ Serial 196  
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Author Kolláth, Z.; Cool, A.; Jechow, A.; Kolláth, K.; Száz, D.; Tong, K.P. url  doi
openurl 
  Title (up) Introducing the Dark Sky Unit for multi-spectral measurement of the night sky quality with commercial digital cameras Type Journal Article
  Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume in press Issue Pages in press  
  Keywords Skyglow; Instrumentation  
  Abstract Multi-spectral imaging radiometry of the night sky provides essential information on light pollution (skyglow) and sky quality. However, due to the different spectral sensitivity of the devices used for light pollution measurement, the comparison of different surveys is not always trivial. In addition to the differences between measurement approaches, there is a strong variation in natural sky radiance due to the changes of airglow. Thus, especially at dark locations, the classical measurement methods (such as Sky Quality Meters) fail to provide consistent results. In this paper, we show how to make better use of the multi-spectral capabilities of commercial digital cameras and show their application for airglow analysis. We further recommend a novel sky quality metric the ”Dark Sky Unit”, based on an easily usable and SI traceable unit. This unit is a natural choice for consistent, digital camera-based measurements. We also present our camera system calibration methodology for use with the introduced metrics.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2993  
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