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Aubé, M., Fortin, N., Turcotte, S., García, B., Mancilla, A., & Maya, J. (2014). Evaluation of the Sky Brightness at Two Argentinian Astronomical Sites. Publications of the Astronomical Society of the Pacific, , 000.
Abstract: Light pollution is a growing concern at many levels, especially for the astronomical community. Indeed, not only does artificial lighting veil celestial objects, it disturbs the measurement of many atmospheric phenomena. The sky brightness is one of the most relevant parameters for astronomical site selection. Our goal is to evaluate the sky brightness of two Argentinian observation sites: LEO ++ and El Leoncito. Both sites were preselected to host the Cherenkov Telescope Array. This project consists of an arrangement of many telescopes that can measure high-energy gamma ray emissions via their Cherenkov radiation produced when entering the earthâ€™s atmosphere. In this paper, we describe the measurement methods used to determine whether those sites are valuable or not. We compared our results with the sky radiance of different renowned astronomical sites (Kitt Peak, Arizona, and Mont-Mégantic, Québec, Canada). Among our results, we found that LEO ++ is a good site, however the presence of a low layer of local aerosol can introduce uncertainties in the measurements. Consequently, El Leoncito would be a better option for such an installation. This latter site shows very low sky brightness levels, which are optimal for low light detection.
Aubé, M. (2007). Light pollution modeling and detection in a heterogeneous environment. Proceedings of Starlight 2007 conference. La Palma, Spain., .
Abstract: Few attempts have been made to measure aerosol optical depth (AOD) behaviour
during the night. One such method uses spectrally calibrated stars as reference targets
but the available number of stars is limited. This is especially true for urban sites where
artificial lighting hide most of these stars. In our research we attempt to provide an
alternate method one which exploits the artificial sky glow generated by light pollution.
To achieve that goal, we designed a new methodology which links a 3D light
pollution model with in situ light pollution spectral measurements obtained with our
detector called Spectrometer for aerosol night detection (SAND). The basic idea was to
adjust an AOD value into the model in order to fit the measured artificial sky brightness.
This method requires an accurate model that includes spatial heterogeneity in lighting
angular geometry, in lighting spectral dependence, in ground spectral reflectance and
in topography along with a detailed definition of the vertical atmospheric profile. This
model, named ILLUMINA, computes 1st and 2nd order molecular and aerosol scattering
as well as aerosol absorption. A correction for sub grid obstacles is also included.
These model features represent major improvements to previous light pollution models.
Therefore, new possibilities for light pollution studies will arise, many of which are of
particular interest to the astronomical community. In this paper we will present model
and detector features and some of the first results derived from ILLUMINA model. We
will also present our web based spatio-temporal Sky spectral luminance measurements
Aubé, M. (2015). Physical behaviour of anthropogenic light propagation into the nocturnal environment. Philos Trans R Soc Lond B Biol Sci, 370, 20140117.
Abstract: Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005: Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane.