Cloud Detection and Prediction with All Sky Cameras

Autor: Adam Jan, Buss Jens, Brügge Kai, Nöthe Max, Rhode Wolfgang
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: EPJ Web of Conferences, Vol 144, p 01004 (2017)
Druh dokumentu: article
ISSN: 2100-014X
DOI: 10.1051/epjconf/201714401004
Popis: Atmospheric monitoring is a field of special importance for astroparticle physics, especially for Imaging Atmospheric Cherenkov Telescopes (IACTs) as clouds will absorb and scatter the Cherenkov photons of air showers. Conventional tools used for atmospheric monitoring (e.g. LIDAR) are very expensive and monitor only a small part of the sky at once. Therefore, they are not suitable to perform a wide scan of the sky which is necessary to detect clouds in advance. This article gives a short overview about a method that uses an all sky camera with a 180 ° field of view to identify the cloud distribution by measuring the absorption of star light. It can be used to assign a sky quality rating to single spots, arbitrary regions or the whole sky at once within a 1 min exposure time. A cloud map can be created from the available data that can be used to determine shape and dimension of clouds and to predict their movement. The resulting data can be used by a scheduling algorithm or the operating crew to point the telescope to a different source before the current source gets covered by clouds. The all sky cameras used so far are located on La Palma at the observatory Roque de los Muchachos close to the telescopes FACT and MAGIC and the planned northern CTA site.
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