Daytime sky quality at El Leoncito, Argentina

IGLESIAS, F. A; FRANCILE, C; LAZARTE-GELMETTI, J; L. A. BALMACEDA; CISTERNA, F. L.

SOLAR PHYSICS

SPRINGER

Lugar: Berlin; Año: 2023

0038-0938

Abstract We characterize the daytime sky quality in terms of its brightness,cloud coverage and main weather variables at the Carlos Ulrico Cesco stationof the Felix Aguilar Astronomical Observatory (OAFA), located in El Leoncitonational park, San Juan, Argentina. We have collected more than 15 years ofdaily observations from the auxiliary sky brightness detectors of the Mirror Coronagraph for Argentina (MICA, in operations from 1997 to 2012), including dailyobserving reports. We additionally present data from two meteorological stationsthat operated at the site from 2000 to 2020. We determine the main statisticalproperties and seasonal variability of daytime sky brightness, clear sky timefraction (CSTF), precipitable water vapor (WV), temperature, humidity andwind speed, which are relevant for solar and particularly coronal observations.Our results confirm that El Leoncito is an excellent place to perform daytimeastronomical observations. We measure a median sky brightness of 15.8 ppm,estimated at 526.0 ± 1 nm and 6 solar radii from the solar disk center; a medianCSTF of 0.7; and a median WV below 6 mm. These values, and those of otherrelevant weather variables, are comparable to the levels found among the best