Sub-millimeter Atmospheric Opacity over 'El Leoncito' Site

Espinoza D.C.; Raulin J.-P.; Valle Silva J.F.; Gimenez De Castro C.G.; Cassiano M.M.

Sub-millimeter Atmospheric Opacity over 'El Leoncito' Site

Tipo

Artigo de evento

Data de publicação

2020

Periódico

2020 33rd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2020

Citações (Scopus)

2

Autores

Espinoza D.C.
Raulin J.-P.
Valle Silva J.F.
Gimenez De Castro C.G.
Cassiano M.M.

Resumo

© 2020 URSI.Ground-based radio telescopes observing at millimeter/submillimeter wavelengths need information on atmospheric attenuation to recover the corrected brightness temperature of astrophysical objects. To determine the zenital opacity, several methods have been used. In comparison with other techniques, the solar brightness method allows determining the atmospheric opacity up to high values and only depends on estimating, as accurately as possible, the product P=η T_{bigodot} where η is the beam efficiency and T_{bigodot} is the Sun brightness temperature at the observation frequencies. Although T_{bigodot} and η are not known individually, we assume that P must be constant. In this work, we reported the measured the zenith opacity at 212 GHz, τ{212}, and 405 GHz,τ{405} using the solar brightness method, over 'El Leoncito' site (2550 m altitude above sea level) for the period 2006-2014. We found a linear correlation betweenτ{212} andτ{405} with R=0.90, the resulting relationτ{405}=0.07+6.90tau_{212}, allows to estimate the opacity at 405 GHz. Our result also shows that the ration of opacities (tau_{405}/tau_{212})is 7, which indicates an excellent agreement with the value of model prediction (approx 7). As expected, a clear seasonal pattern of opacity measurements is observed along the years. Finally, we also confirm that there is a significance correlation between the opacities obtained and the precipitable water vapor content (PWV) over 'El Leoncito' site, between 2011 and 2014.

Assuntos Scopus

Astrophysical objects , Atmospheric attenuation , Atmospheric opacity , Brightness temperatures , Linear correlation , Observation frequencies , Precipitable water vapor , Seasonal patterns