Testing sky brightness models against radial dependency: A dense two dimensional survey around the city of Madrid, Spain - Zamorano J; Sánchez de Miguel A; Ocaña F; Pila-Díez B; Gómez Castaño J; Pascual S; Tapia C; Gallego J; Fernández A; Nievas M (Journal Of Quantitative Spectroscopy & Radiative Transfer, 2016)