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Bará, S. (2019). Black-body luminance and magnitudes per square arcsecond in the Johnson-Cousins BVR photometric bands. Photon. Lett. Pl., 11(3), 63.
Abstract: A relevant amount of light pollution studies deal with the unwanted visual effects of artificial light at night, including the anthropogenic luminance of the sky that hinders the observation of the celestial bodies which are a main target of ground-based astrophysical research, and a key asset of the intangible heritage of humankind. Most quantitative measurements and numerical models, however, evaluate the anthropogenic sky radiance in any of the standard Johnson-Cousins UBVRI photometric bands, generally in the V one. Since the Johnson-Cousins V band is not identical with the visual CIE V-lambda used to assess luminance, the conversion between these two photometric systems turns out to be spectrum-dependent. Given its interest for practical applications, in this Letter we provide the framework to perform this conversion and the transformation constants for black-body spectra of different absolute temperatures.
Keywords: Skyglow; night sky brightness; luminance; photometric
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Barentine, J. C. (2016). Going for the Gold : Quantifying and Ranking Visual Night Sky Quality in International Dark Sky Places. IJSL, 18, 9–15.
Abstract: Since the invention of electric lighting in the nineteenth century, the steadily increasing use of artificial light at night in outdoor spaces has grown to threaten the integrity of dark night skies and nocturnal terrestrial spaces. The conservation community has gradually come to accept the need to protect natural nighttime darkness, which finds expression in dark sky parks and similar protected areas. As these places begin to reap tangible economic benefits in the form of sustainable ‘astrotourism,’ the movement to actively protect them gains strength. The International Dark-Sky Association designates Dark Sky Parks and Reserves under a comparative ranking scheme that assigns night sky quality tiers according to a combination of objective and subjective characteristics, but shortcomings in the consistency of these ratings exist that undermine the consistency and reputation of the designation program. Here we consider potential changes to the qualification regime to make the ratings system more robust for the benefit of future designations.
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C-Sanchez, E., Sanchez-Medina, A. J., Alonso-Hernandez, J. B., & Voltes-Dorta, A. (2019). Astrotourism and Night Sky Brightness Forecast: First Probabilistic Model Approach. Sensors (Basel), 19(13), 2840.
Abstract: Celestial tourism, also known as astrotourism, astronomical tourism or, less frequently, star tourism, refers to people's interest in visiting places where celestial phenomena can be clearly observed. Stars, skygazing, meteor showers or comets, among other phenomena, arouse people's interest, however, good night sky conditions are required to observe such phenomena. From an environmental point of view, several organisations have surfaced in defence of the protection of dark night skies against light pollution, while from an economic point of view; the idea also opens new possibilities for development in associated areas. The quality of dark skies for celestial tourism can be measured by night sky brightness (NSB), which is used to quantify the visual perception of the sky, including several light sources at a specific point on earth. The aim of this research is to model the nocturnal sky brightness by training and testing a probabilistic model using real NSB data. ARIMA and artificial neural network models have been applied to open NSB data provided by the Globe at Night international programme, with the results of this first model approach being promising and opening up new possibilities for astrotourism. To the best of the authors' knowledge, probabilistic models have not been applied to NSB forecasting.
Keywords: Society; Astrotourism; Skyglow; night sky brightness; artificial neural networks
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Caruana, J., Vella, R., Spiteri, D., Nolle, M., Fenech, S., & Aquilina, N. J. (2020). A photometric mapping of the night sky brightness of the Maltese islands. J Environ Manage, 261, 110196.
Abstract: Over the years, the Maltese Islands have seen a marked rise in the prevalence of artificial lighting at night. The most evident type of light pollution arising from this evolution in anthropogenic night-time lighting is artificial skyglow via partial back-scattering in the atmosphere, leading to an increase in the Night Sky Brightness (NSB). The importance of understanding and quantifying the geographical distribution of the NSB is underscored by the adverse impact of light pollution on various spheres, from astronomical observation to ecology and human health. For the first time, we present a detailed map of the NSB over the Maltese archipelago carried out with Unihedron Sky Quality Meters. We show that the vast majority of the area of the Maltese Islands is heavily light polluted, with 87% of the area registering a NSB < 20.39magSQM/arcsec(2) (Bortle Class 5 or higher) and 37.3% < 19.09magSQM/arcsec(2) (Bortle Class 6 or higher), with the Milky Way being visible for only 12.8% of the area (adopting a visibility threshold > 20.4 – 21.29magSQM/arcsec(2); Bortle Class 4). Coastal Dark Sky Heritage Areas on the island of Gozo retain generally darker skies than the rest of the islands, but light pollution originating further inland is encroaching upon and adversely affecting these sites. The methodology presented in this study can be adopted for continued future studies in Malta as well as for other regions.
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Cinzano, P. (2005). Night Sky Photometry with Sky Quality Meter. Technical Report 9, ISTIL. V1.4., .
Abstract: Sky Quality Meter, a low cost and pocket size night sky brightness photometer, opens to the general public the possibility to quantify the quality of the night sky. Expecting a large diffusion of measurements taken with this instrument, I tested and characterized it. I analyzed with synthetic photometry and laboratory measurements the relationship between the SQM photometrical system and the main systems used in light pollution studies. I evaluated the conversion factors to Johnson’s B and V bands, CIE photopic and CIE scotopic responses for typical spectra and the spectral mismatch correction factors when specific filters are added.
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Cinzano, P., & Falchi, F. (2014). Quantifying light pollution. Journal of Quantitative Spectroscopy and Radiative Transfer, 139, 13–20.
Abstract: In this paper we review new available indicators useful to quantify and monitor light pollution, defined as the alteration of the natural quantity of light in the night environment due to introduction of manmade light. With the introduction of recent radiative transfer methods for the computation of light pollution propagation, several new indicators become available. These indicators represent a primary step in light pollution quantification, beyond the bare evaluation of the night sky brightness, which is an observational effect integrated along the line of sight and thus lacking the three-dimensional information.
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den Outer, P., Lolkema, D., Haaima, M., van der Hoff, R., Spoelstra, H., & Schmidt, W. (2011). Intercomparisons of nine sky brightness detectors. Sensors (Basel), 11(10), 9603–9612.
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.
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Grauer, A. D., Grauer, P. A., Davies, N., & Davies, G. (2019). Impact of Space Weather on the Natural Night Sky. PASP, 131(1005), 114508.
Abstract: In 2018, Solar Cycle 24 entered a deep solar minimum. During this period, we collected night sky brightness data at Cosmic Campground International Dark Sky Sanctuary (CCIDSS) in the USA (2018 September 4–2019 January 4) and at Aotea/Great Barrier Island International Dark Sky Sanctuary (AGBIIDSS) in New Zealand (2018 March 26–August 31. These sites have artificial-light-pollution-free natural night skies. The equipment employed are identical Unihedron SQM-LU-DL meters, used as single-channel differential photometers, to scan the sky as Earth rotates on its axis. We have developed new analysis techniques which select those data points which are uninfluenced by Sun, Moon, or clouds to follow brightness changes at selected points on the celestial sphere and to measure the brightness of the airglow above its quiescent level. The 2018 natural night sky was measured to change in brightness by approximately 0.9 mag arcsec−2 at both locations. Preliminary results indicate the modulations of the light curves (brightness versus R.A.) we observed are related in complex ways to elements of space weather conditions in the near-Earth environment. In particular, episodes of increased night sky brightness are observed to be contemporaneous with geomagnetic activity, increases in mean solar wind speed, and some solar proton/electron fluence events. Charged particles in the solar wind take days to reach near-Earth environment after a coronal hole is observed to be facing in our direction. Use of this information could make it possible to predict increases in Earth’s natural night sky brightness several days in advance. What we have learned during this solar minimum leads us to search for other solar driven changes in night sky brightness as the Sun begins to move into solar maximum conditions.
Keywords: Darkness; night sky brightness; United States; New Zealand; Sun; space weather; solar wind
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Masana, E., Carrasco, J. M., Bará, S., & Ribas, S. J. (2021). A multiband map of the natural night sky brightness including Gaia and Hipparcos integrated starlight. Monthly Notices of the Royal Astronomical Society, 501(4), 5443–5456.
Abstract: The natural night sky brightness is a relevant input for monitoring the light pollution evolution at observatory sites, by subtracting it from the overall sky brightness determined by direct measurements. It is also instrumental for assessing the expected darkness of the pristine night skies. The natural brightness of the night sky is determined by the sum of the spectral radiances coming from astrophysical sources, including zodiacal light, and the atmospheric airglow. The resulting radiance is modified by absorption and scattering before it reaches the observer. Therefore, the natural night sky brightness is a function of the location, time, and atmospheric conditions. We present in this work the GAia Map of the Brightness Of the Natural Sky (GAMBONS), a model to map the natural night brightness of the sky in cloudless and moonless nights. Unlike previous maps, GAMBONS is based on the extra-atmospheric star radiance obtained from the Gaia catalogue. The Gaia-Data Release 2 (DR2) archive compiles astrometric and photometric information for more than 1.6 billion stars up to G = 21 mag. For the brightest stars, not included in Gaia-DR2, we have used the Hipparcos catalogue instead. After adding up to the star radiance the contributions of the diffuse galactic and extragalactic light, zodiacal light and airglow, and taking into account the effects of atmospheric attenuation and scattering, the radiance detected by ground-based observers can be estimated. This methodology can be applied to any photometric band, if appropriate transformations from the Gaia bands are available. In particular, we present the expected sky brightness for V (Johnson), and visual photopic and scotopic passbands.
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Pun, C. S. J., So, C. W., Leung, W. Y., & Wong, C. F. (2014). Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring network. Journal of Quantitative Spectroscopy and Radiative Transfer, 139, 90–108.
Abstract: Light pollution is a form of environmental degradation in which excessive artificial outdoor lighting, such as street lamps, neon signs, and illuminated signboards, affects the natural environment and the ecosystem. Poorly designed outdoor lighting not only wastes energy, money, and valuable Earth resources, but also robs us of our beautiful night sky. Effects of light pollution on the night sky can be evaluated by the skyglow caused by these artificial lighting sources, through measurements of the night sky brightness (NSB). The Hong Kong Night Sky Brightness Monitoring Network (NSN) was established to monitor in detail the conditions of light pollution in Hong Kong. Monitoring stations were set up throughout the city covering a wide range of urban and rural settings to continuously measure the variations of the NSB. Over 4.6 million night sky measurements were collected from 18 distinct locations between May 2010 and March 2013. This huge dataset, over two thousand times larger than our previous survey [1], forms the backbone for studies of the temporal and geographical variations of this environmental parameter and its correlation with various natural and artificial factors. The concepts and methodology of the NSN were presented here, together with an analysis of the overall night sky conditions in Hong Kong. The average NSB in Hong Kong, excluding data affected by the Moon, was 16.8 mag arcsec−2, or 82 times brighter than the dark site standard established by the International Astronomical Union (IAU) [2]. The urban night sky was on average 15 times brighter than that in a rural location, firmly establishing the effects of artificial lighting sources on the night sky.
Keywords: Light pollution; Night sky brightness; Skyglow; Moon radiation; Urban lighting; Hong Kong
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