|   | 
Details
   web
Records
Author Priyatikanto, R.; Mayangsari, L.; Prihandoko, R.A.; Admiranto, A.G.
Title Classification of Continuous Sky Brightness Data Using Random Forest Type Journal Article
Year 2020 Publication Advances in Astronomy Abbreviated Journal Advances in Astronomy
Volume 2020 Issue Pages 1-11
Keywords (down) Skyglow
Abstract Sky brightness measuring and monitoring are required to mitigate the negative effect of light pollution as a byproduct of modern civilization. Good handling of a pile of sky brightness data includes evaluation and classification of the data according to its quality and characteristics such that further analysis and inference can be conducted properly. This study aims to develop a classification model based on Random Forest algorithm and to evaluate its performance. Using sky brightness data from 1250 nights with minute temporal resolution acquired at eight different stations in Indonesia, datasets consisting of 15 features were created to train and test the model. Those features were extracted from the observation time, the global statistics of nightly sky brightness, or the light curve characteristics. Among those features, 10 are considered to be the most important for the classification task. The model was trained to classify the data into six classes (1: peculiar data, 2: overcast, 3: cloudy, 4: clear, 5: moonlit-cloudy, and 6: moonlit-clear) and then tested to achieve high accuracy (92%) and scores (F-score = 84% and G-mean = 84%). Some misclassifications exist, but the classification results are considerably good as indicated by posterior distributions of the sky brightness as a function of classes. Data classified as class-4 have sharp distribution with typical full width at half maximum of 1.5 mag/arcsec2, while distributions of class-2 and -3 are left skewed with the latter having lighter tail. Due to the moonlight, distributions of class-5 and -6 data are more smeared or have larger spread. These results demonstrate that the established classification model is reasonably good and consistent.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1687-7969 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2878
Permanent link to this record
 

 
Author Jechow, A.; Kyba, C.C.M.; Hölker, F.
Title Mapping the brightness and color of urban to rural skyglow with all-sky photometry 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 (down) Skyglow
Abstract Artificial skyglow is a form of light pollution with wide ranging implications on the environment. The extent, intensity and color of skyglow depends on the artificial light sources and weather conditions. Skyglow can be best determined with ground based instruments. We mapped the skyglow of Berlin, Germany, for clear sky and overcast sky conditions inside and outside of the city limits. We conducted observations using a transect from the city center of Berlin towards a rural place more than 58 km south of Berlin using all-sky photometry with a calibrated commercial digital camera and a fisheye lens. From the multispectral imaging data, we processed luminance and correlated color temperature maps. We extracted the night sky brightness and correlated color temperature at zenith, as well as horizontal and scalar illuminance simultaneously. We calculated cloud amplification factors at each site and investigated the changes of brightness and color with distance, particularly showing differences inside and outside of the city limits. We found high values for illuminance above full moon light levels and amplification factors as high as 25 in the city center and a gradient towards the city limit and outside of the city limit. We further observed that clouds decrease the correlated color temperature in almost all cases. We discuss advantages and weaknesses of our method, compare the results with modeled night sky brightness data and provide recommendations for future work.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
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 2895
Permanent link to this record
 

 
Author Wallner, S.; Kocifaj, M.; Komar, L.; Solano-Lamphar, H.A.
Title Night-sky imaging as a potential tool for characterization of total lumen output from small and medium-sized cities Type Journal Article
Year 2020 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume 494 Issue 4 Pages 5008-5017
Keywords (down) Skyglow
Abstract In this article, the asymptotic formula developed in past work and applied to predict skyglow due to distant sources was evolved, with the objective of characterizing small and medium-sized cities in the observer's surroundings. To enable this, a combination of theoretical computations and in situ measurements is needed, aiming to distinguish between dominant and smaller light-emitting sources, with the latter usually being camouflaged when measuring the night sky. Furthermore, for numerical modelling of skyglow, few of the most important parameters, specifically the amount of total lumens installed and radiated to the upward hemisphere, can be derived. Astronomical observatories, in particular, can profit from this concept, since they are usually situated far away from large cities but can still be surrounded by smaller villages and towns. We present a detailed description of how theoretical computations are combined with all-sky photometry in order to obtain the properties mentioned. Results are compared with satellite data, showing that, regarding approximations undertaken for processing, they are comparable, underlining the functionality of our approach. The idea of including in situ observations enables us to quantify the impact of small and medium-sized cities globally and independent of location, as long as measurements were conducted outside light domes. In addition, the presented work may be of major interest to the light-pollution community if conducting long-term observations of cities, since the quality of commonly used satellite data is going to decrease in the future, due to blindness in short wavelengths and upcoming conversions of public lighting systems to blue-enlightened LEDs.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2911
Permanent link to this record
 

 
Author Linares, H.; Masana, E.; Ribas, S.J.; Aubé, M.; Simoneau, A.; Bará, S.
Title Night sky brightness simulation over Montsec protected area Type Journal Article
Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 249 Issue Pages 106990
Keywords (down) Skyglow
Abstract Night sky brightness over Montsec Observatory (north-east of Spain) has been computed and checked against measurements using Illumina numerical model [2]. In a previous publication [20] the methodology was validated and light pollution received in the observatory coming from a unique city was computed. Here we present a simulation that includes all the sources that has a significant impact over the quality of the night sky in this area. The decision of which sources should be included in the simulations was taken following the methodology explained by [6]: using a point spread function (PSF) as a simple approach to estimate which sources are brightening the sky dome over the observer. An ad hoc PSF derived with Illumina was used with the purpose of avoiding to have to rely on already existing empirical PSF. The resulting PSF can be used in any location with similar atmospheric conditions. Differences in the spectrum of the lamps can be accounted easily by adjusting a spectrum scale factor. Illumina simulates the artificial sky brightness received (W/sr/m2) by an observer from any direction. Adding the natural sky brightness allows to compare the simulations to measurements taken with different instrumentation. In our case simulations were checked against ASTMON, SQC and SQM measurements. They show a good agreement both in absolute values and in geographical patterns for the three filters studied, B, V and R. The methodology presented opens many possibilities, such as increasing the reliability of the maps that point out the light pollution main contributors for any location, and reducing the amount of time needed to perform an accurate simulation of the night sky brightness.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
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 2923
Permanent link to this record
 

 
Author Cinzano, P.; Falchi, F.
Title Toward an atlas of the number of visible stars 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 107059
Keywords (down) Skyglow
Abstract Modelling techniques for the propagation of light pollution in the atmosphere allow the computation of maps of artificial night sky brightness in any direction of the sky, involving a large number of details from satellite data. Cinzano et al. (2001a) introduced a method of mapping naked eye star visibility at the zenith from large areas based on satellite radiance measurements and Garstang models of the propagation of light pollution. It takes into account the altitude of each land area from digital elevation data, natural sky brightness in the chosen sky direction based on the Garstang approach, eye capability after Garstang and Schaefer, and atmospheric extinction in the visual photometric band. Here we discuss how to use these methods to obtain maps of the average number of visible stars when looking at the night sky hemisphere, finally answering, site by site, the question of how many stars are visible in the sky. This is not trivial, as the number of stars visible depends on the limiting magnitude in each direction in the sky, and this depends on sky brightness in that direction, atmospheric extinction at that zenith distance and the observer's visual acuity and experience. We present, as an example, a map of the number of visible stars in Italy to an average observer on clear nights with a resolution of approximately 1 km.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
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 2928
Permanent link to this record