Journal Article

An estimate of the temporal fraction of cloud cover at San Pedro Mártir Observatory

E. Carrasco, A. Carramiñana, L. J. Sánchez, R. Avila and I. Cruz-González

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 420, issue 2, pages 1273-1280
Published in print February 2012 | ISSN: 0035-8711
Published online January 2012 | e-ISSN: 1365-2966 | DOI:
An estimate of the temporal fraction of cloud cover at San Pedro Mártir Observatory

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San Pedro Mártir in the north-west of Mexico is the site of the Observatorio Astronómico Nacional. It was one of the five candidate sites for the Thirty Meter Telescope, whose site-testing team spent four years measuring the atmospheric properties on site with a very complete array of instrumentation. Using the public data base created by this team, we apply a novel method to solar radiation data to estimate the daytime fraction of time when the sky is clear of clouds. We analyse the diurnal, seasonal and annual cycles of cloud cover. We find that 82.4 per cent of the time the sky is clear of clouds. Our results are consistent with those obtained by other authors, using different methods, adding support to this value and proving the potential of the applied method. The clear conditions at the site are particularly good showing that San Pedro Mártir is an excellent site for optical and infrared observations.

Keywords: atmospheric effects; site testing

Journal Article.  4900 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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