11/12/2023 0 Comments Eso lunar cycleUsing nighttime sky observations of scattered moonlight and a set of sky background models is a new method to probe the aerosol content of the atmosphere.īased on observations collected at the European Southern Observatory under ESO programme 491.L-0659. For nearly 30 years GLSEN has been there every step of the way to ensure the rights of LGBTQ youth are. In short, the current sky background model is in fair agreement with the observations, and we have determined better aerosol extinction curves and phase functions for Cerro Paranal. Make an Impact Donate to support LGBTQ+ students. For the three nights of sky observations, the aerosol size distributions differed, most likely reflecting the changes in atmospheric conditions and aerosol content, which is expected. Having more coarse particles affects the phase function by being more peaked at small angular distances. Also, the current model had significantly less coarse particles compared to the favored volume densities from the X-shooter data. While there are some degeneracies in the aerosol scattering properties, the extinction curves tend to flatten towards redder wavelengths and are overall less steep compared to the extrapolated curve used in the current model. Using a set of sky background models with varying aerosol distributions to compare with the observations, we found the most likely aerosol extinction curves, phase functions, and volume densities for the three nights of observations and compare them with the current model. Overall, the current model does reproduce the observations for average conditions quite well. These observations were taken of blank sky, during three different lunar phases, and at six different angular distances from the moon for each lunar phase. To our knowledge, this is the first time that a scattered moonlight model has been used for this purpose. With a set of X-shooter sky observations, we have tested the current sky background model as well as determined the aerosol extinction from the ultra-violet (UV) to near-infrared (NIR). The current, official sky background model for Cerro Paranal uses an extrapolated aerosol extinction curve. The most uncertain component of a scattered moonlight model is the aerosol scattering. In the optical, scattered moonlight dominates the sky background, when the moon is above the horizon. Estimating the sky background is critical for ground-based astronomical research.
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