  Knowledge of the night sky radiance over a large territory may be valuable
informationto identify sites appropriate to astronomical observations or for
assessing the impacts ofartificial light at night on ecosystems. Measuring the
sky radiance can be a complex endeavourdepending on the desired temporal and
spatial resolution. Similarly, modelling of artificialnight sky radiance for
multiple points of a territory can represent a significant amount ofcomputing
time depending on the complexity of the model used. The use of the
convolutionof a point spread function with the light sources geographical
distribution has been suggestedin order to model the sky radiance over large
territories of hundreds of kilometres in size.We determine how the point spread
function is sensitive to the main driving parameters ofthe artificial night sky
radiance such as the wavelength, the ground reflectance, the
obstaclesproperties, the Upward Light Output Ratio and the Aerosol Optical
Depth using the Illuminav2 model. The obtained functions were used to model the
artificial night sky brightness ofthe Mont-M\'egantic International Dark Sky
Reserve for winter and summer conditions. Theresults were compared to the New
world atlas of artificial night sky brightness, the Illuminav2 model and in
situ Sky Quality Camera measurements. We found that the New world
atlasoverestimates the artificial sky brightness by 55% whereas the Illumina
model underestimatesit by 48%. This may be due to varying atmospherical
conditions and the fact that the modelonly accounts for public light sources.
