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Author Kocifaj, M.
Title A numerical experiment on light pollution from distant sources: Light pollution from distant sources Type Journal Article
Year 2011 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS
Volume (down) 415 Issue 4 Pages 3609-3615
Keywords scattering; atmospheric effects; light pollution; methods: numerical; skyglow; modeling
Abstract To predict the light pollution of the night-time sky realistically over any location or measuring point on the ground presents quite a difficult calculation task. Light pollution of the local atmosphere is caused by stray light, light loss or reflection of artificially illuminated ground objects or surfaces such as streets, advertisement boards or building interiors. Thus it depends on the size, shape, spatial distribution, radiative pattern and spectral characteristics of many neighbouring light sources. The actual state of the atmospheric environment and the orography of the surrounding terrain are also relevant. All of these factors together influence the spectral sky radiance/luminance in a complex manner. Knowledge of the directional behaviour of light pollution is especially important for the correct interpretation of astronomical observations. From a mathematical point of view, the light noise or veil luminance of a specific sky element is given by a superposition of scattered light beams. Theoretical models that simulate light pollution typically take into account all ground-based light sources, thus imposing great requirements on CPU and MEM. As shown in this paper, a contribution of distant sources to the light pollution might be essential under specific conditions of low turbidity and/or Garstang-like radiative patterns. To evaluate the convergence of the theoretical model, numerical experiments are made for different light sources, spectral bands and atmospheric conditions. It is shown that in the worst case the integration limit is approximately 100 km, but it can be significantly shortened for light sources with cosine-like radiative patterns.
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ISSN 0035-8711 ISBN Medium
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Call Number IDA @ john @ Serial 267
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Author Falchi, F.
Title Campaign of sky brightness and extinction measurements using a portable CCD camera: Sky brightness and extinction measurements Type Journal Article
Year 2011 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 412 Issue 1 Pages 33-48
Keywords sky brightness; monitoring; light pollution; skyglow
Abstract In this paper, we present the results of a 12-yr campaign devoted to monitoring the sky brightness affected by different levels of light pollution. Different sites characterized by different altitudes and atmospheric transparency have been considered. The standard photometric Johnson B and V bands were used. An extinction measurement was performed for each site and each night, along with a calibration of the instrument. These measurements have allowed us to build sky brightness maps of the hemisphere above each observing site; each map contains up to 200 data points spread around the sky. We have found a stop in zenith sky brightness growth at the two sites where a time series exists. Using zenith sky brightness measurements taken with and without extensive snow coverage, we weighted the importance of direct versus indirect flux in producing sky glow at several sites.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 190
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Author Kocifaj, M.; Aubé, M.; Kohút, I.
Title The effect of spatial and spectral heterogeneity of ground-based light sources on night-sky radiances: Light pollution for heterogeneous sources Type Journal Article
Year 2010 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 409 Issue 3 Pages 1203-1212
Keywords light pollution; scattering; atmospheric effects; methods: numerical
Abstract Nowadays, light pollution is a permanent problem at many observatories around the world. Elimination of excessive lighting during the night is not only about reduction of the total luminous power of ground-based light sources, but also involves experimenting with the spectral features of single lamps. Astronomical photometry is typically made at specific wavelengths, and thus the analysis of the spectral effects of light pollution is highly important. Nevertheless, studies on the spectral behaviour of night light are quite rare. Instead, broad-band or integral quantities (such as sky luminance) are preferentially measured and modelled. The knowledge of night-light spectra is necessary for the proper interpretation of narrow-band photometry data. In this paper, the night-sky radiances in the nominal spectral lines of the B (445 nm) and V (551 nm) filters are determined numerically under clear-sky conditions. Simultaneously, the corresponding sky-luminance patterns are computed and compared against the spectral radiances. It is shown that spectra, patterns and distances of the most important light sources (towns) surrounding an observatory are essential for determining the light pollution levels. In addition, the optical characteristics of the local atmosphere can change the angular behaviour of the sky radiance or luminance. All these effects are evaluated for two Slovakian observatories: Stará Lesná and Vartovka.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 259
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Author Kocifaj, M.
Title Modelling the spectral behaviour of night skylight close to artificial light sources Type Journal Article
Year 2010 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS
Volume (down) 403 Issue 4 Pages 2105-2110
Keywords scattering; atmospheric effects; light pollution; methods: numerical; Modeling
Abstract Spectral features of the night sky are simulated under cloudless conditions. Numerical runs show that spectral composition of the diffuse light changes over the whole sky and sky radiances quickly respond to altering aerosol characteristics, such as the asymmetry parameter, single scattering albedo and total optical thickness. The general trend is a steep decrease of diffuse irradiance with a distance from the city centre. Powerstar HQI-NDL lamps produce more light at short wavelengths, thus implying the higher levels of light pollution. The red light may markedly contribute to the obtrusive light if Vialox NAV-4Y lamps are considered as a prevailing source of light in the model town. In a non-turbid atmosphere, the minimum radiance is notoriously observed close to the zenith. As aerosol loading increases, the minimum radiance is shifted to larger zenith angles at the opposite side of the light source. Obtained results may serve as corrections to spectrophotometry data, as the light pollution can be easily calculated for any sky element and for any spectral band.
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Call Number IDA @ john @ Serial 276
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Author Skibba, R. A.; Bamford, S. P.; Nichol, R. C.; Lintott, C. J.; Andreescu, D.; Edmondson, E. M.; et al.
Title Skibba, R. A., Bamford, S. P., Nichol, R. C., Lintott, C. J., Andreescu, D., Edmondson, E. M., … others. (2009). Galaxy Zoo: disentangling the environmental dependence of morphology and colour. Type Journal Article
Year 2009 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 399 Issue 2 Pages 966–982
Keywords Remote Sensing
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Call Number LoNNe @ kagoburian @ Serial 971
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