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arXiv · 2004.03918

Sky Quality Meter and satellite correlation for the night cloud cover analysis at astronomical sites

S. Cavazzani·S. Ortolani·A. Bertolo·R. Binotto·P. Fiorentin·G. Carraro·I. Saviane·V. Zitelli
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Abstract

The analysis of the night cloud cover is very important for astronomical observation in real time, considering a typical observation time of about 15 minutes, and to have a statistics of the night cloud cover. In this paper we use the SQM (Sky Quality Meter) for high resolution temporal analysis of the La Silla and Asiago (Ekar observatory) sky: 3 and 5 minutes respectively. We investigate the annual temporal evolution of the natural contributions of the sky in a site not influenced by artificial light at night (ALAN) and one highly influenced respectively. We also make a correlation between GOES and AQUA satellites data and ground-based SQM data to confirm a relationship between the SQM data and cloud cover. We develop an algorithm that allows the use of the SQM for night cloud detection and we reach a correlation of 97.2\% at La Silla and 94.6\% at Asiago with the nighttime cloud cover detected by the GOES and AQUA satellites. Our algorithm also classifies the photometric (PN) and spectroscopic nights (SN). We measure 59.1\% PN and 21.7\% SN for a total percentage of clear nights of 80.8\% at La Silla in 2018. The respective Ekar observatory values are 31.1\% PN, 24.0\% SN and 55.1\% of total clear nights time. Application to the SQM network would involve the development of long-term statistics and big data forecasting models, for site testing and real-time astronomical observation.

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S. Cavazzani, S. Ortolani, A. Bertolo, R. Binotto, P. Fiorentin, G. Carraro, I. Saviane, V. Zitelli. 2020-04-08. Sky Quality Meter and satellite correlation for the night cloud cover analysis at astronomical sites. https://doi.org/10.1093/mnras/staa416

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