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Author Hänel, A.; Posch, T.; Ribas, S.J.; Aubé, M.; Duriscoe, D.; Jechow, A.; Kollath, Z.; Lolkema, D.E.; Moore, C.; Schmidt, N.; Spoelstra, H.; Wuchterl, G.; Kyba, C.C.M. url  doi
openurl 
  Title Measuring night sky brightness: methods and challenges Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 205 Issue Pages 278-290  
  Keywords (down) skyglow  
  Abstract Measuring the brightness of the night sky has become an increasingly important topic in recent years, as artificial lights and their scattering by the Earthâ??s atmosphere continue spreading around the globe. Several instruments and techniques have been developed for this task. We give an overview of these, and discuss their strengths and limitations. The different quantities that can and should be derived when measuring the night sky brightness are discussed, as well as the procedures that have been and still need to be defined in this context. We conclude that in many situations, calibrated consumer digital cameras with fisheye lenses provide the best relation between ease-of-use and wealth of obtainable information on the night sky. While they do not obtain full spectral information, they are able to sample the complete sky in a period of minutes, with colour information in three bands. This is important, as given the current global changes in lamp spectra, changes in sky radiance observed only with single band devices may lead to incorrect conclusions regarding long term changes in sky brightness. The acquisition of all-sky information is desirable, as zenith-only information does not provide an adequate characterization of a site. Nevertheless, zenith-only single-band one-channel devices such as the â??Sky Quality Meterâ? continue to be a viable option for long-term studies of night sky brightness and for studies conducted from a moving platform. Accurate interpretation of such data requires some understanding of the colour composition of the sky light. We recommend supplementing long-term time series derived with such devices with periodic all-sky sampling by a calibrated camera system and calibrated luxmeters or luminance meters.  
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  Series Volume Series Issue Edition  
  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ kyba @ Serial 1731  
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Author Posch, T.; Binder, F.; Puschnig, J. url  doi
openurl 
  Title Systematic measurements of the night sky brightness at 26 locations in Eastern Austria Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 211 Issue Pages 144-165  
  Keywords (down) Skyglow  
  Abstract We present an analysis of the zenithal night sky brightness (henceforth: NSB) measurements at 26 locations in Eastern Austria focussing on the years 2015-2016, both during clear and cloudy to overcast nights. All measurements have been performed with ’Sky Quality Meters’ (SQMs). For some of the locations, simultaneous aerosol content measurements are available, such that we were able to find a correlation between light pollution and air pollution at those stations. For all locations, we examined the circalunar periodicity of the NSB, seasonal variations as well as long-term trends in the recorded light pollution. The latter task proved difficult, however, due to varying meteorological conditions, potential detector ’aging’ and other effects. For several remote locations, a darkening of the overcast night sky by up to 1 magnitude is recorded – indicating a very low level of light pollution –, while for the majority of the examined locations, a brightening of the night sky by up to a factor of 15 occurs due to clouds. We present suitable ways to plot and analyze huge long-term NSB datasets, such as mean-NSB histograms, circalunar, annual (’hourglass’) and cumulative (’jellyfish’) plots. We show that five of the examined locations reach sufficiently low levels of light pollution – with NSB values down to 21.8 magSQM/arcsec2 – as to allow the establishment of dark sky reserves, even to the point of reaching the ’gold tier’ defined by the International Dark Sky Association. Based on the ’hourglass’ plots, we find a strong circalunar periodicity of the NSB in small towns and villages ( <  5.000 inhabitants), with amplitudes of of up to 5 magnitudes. Using the ’jellyfish’ plots, on the other hand, we demonstrate that the examined city skies brighten by up to 3 magnitudes under cloudy conditions, which strongly dominate in those cumulative data representations. Nocturnal gradients of the NSB of 0.0–0.14 magSQM/arcsec2/hr are found. The long-term development of the night sky brightness was evaluated based on the 2012-17 data for one of our sites, possibly indicating a slight ( 2%) decrease of the mean zenithal NSB at the Vienna University Observatory.  
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  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 1825  
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Author Ahmed, AK; Sadik, MA url  openurl
  Title Study of sky brightness profiles of Baghdad and Karbala cities in Iraq Type Journal Article
  Year 2018 Publication International Journal of Science and Nature Abbreviated Journal  
  Volume 9 Issue 1 Pages 18-24  
  Keywords (down) Skyglow  
  Abstract This study was used two detectors only i.e., the human eye and photometer of Sky Quality Meter (SQM-LU) during the time of sunrise and sunset. The human eye used to determine the moon's phase. The measurements of sky brightness, by using SQM-LU, performed via two locations that covered Baghdad and Karbala in Iraq from December 2016 through March 2017 intermittently. The research focused only on light perceived by detectors and not how it happens. The aim of research is to find a mathematical formula (i.e . brightness contrast) between the sky brightness against the solar altitude by taking moon illumination as the standard reference. Analytical software based on the Python's PyEphem astrometry library was developed to calculate the solar altitude at the two locations. Finally, the formula of sky brightness obtained from this work is an important key that contributed to finding the simulated sky brightness, when the sun's altitude is known.  
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  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 1851  
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Author Petržala, J. url  doi
openurl 
  Title Feasibility of inverse problem solution for determination of city emission function from night sky radiance measurements Type Journal Article
  Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 213 Issue Pages 86-94  
  Keywords (down) Skyglow  
  Abstract The knowledge of the emission function of a city is crucial for simulation of sky glow in its vicinity. The indirect methods to achieve this function from radiances measured over a part of the sky have been recently developed. In principle, such methods represent an ill-posed inverse problem. This paper deals with the theoretical feasibility study of various approaches to solving of given inverse problem. Particularly, it means testing of fitness of various stabilizing functionals within the Tikhonov’s regularization. Further, the L-curve and generalized cross validation methods were investigated as indicators of an optimal regularization parameter. At first, we created the theoretical model for calculation of a sky spectral radiance in the form of a functional of an emission spectral radiance. Consequently, all the mentioned approaches were examined in numerical experiments with synthetical data generated for the fictitious city and loaded by random errors. The results demonstrate that the second order Tikhonov’s regularization method together with regularization parameter choice by the L-curve maximum curvature criterion provide solutions which are in good agreement with the supposed model emission functions.  
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  Series Editor Series Title Abbreviated Series Title  
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  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 1868  
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Author Aubé, M.; Simoneau, A.; Wainscoat, R.; Nelson, L. url  doi
openurl 
  Title Modeling the effects of phosphor converted LED lighting to the night sky of the Haleakala Observatory, Hawaii Type Journal Article
  Year 2018 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal  
  Volume 478 Issue 2 Pages 1776-1783  
  Keywords (down) Skyglow  
  Abstract The goal of this study is to evaluate the current level of light pollution in the night sky at the Haleakala Observatory on the island of Maui in Hawaii. This is accomplished with a numerical model that was tested in the first International Dark Sky Reserve located in Mont-Mégantic National Park in Canada. The model uses ground data on the artificial light sources present in the region of study, geographical data, and remotely sensed data for: 1) the nightly upward radiance; 2) the terrain elevation; and, 3) the ground spectral reflectance of the region. The results of the model give a measure of the current state of the sky spectral radiance at the Haleakala Observatory. Then, using the current state as a reference point, multiple light conversion plans are elaborated and evaluated using the model. We can thus estimate the expected impact of each conversion plan on the night sky radiance spectrum. A complete conversion to white (LEDs) with (CCT) of 4000K and 3000K are contrasted with a conversion using (PC) amber (LEDs). We include recommendations concerning the street lamps to be used in sensitive areas like the cities of Kahului and Kihei and suggest best lighting practices related to the color of lamps used at night.  
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  Series Volume Series Issue Edition  
  ISSN 0035-8711 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 1907  
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