Journal Article

Clear sky fraction above Indonesia: an analysis for astronomical site selection

T. Hidayat, P. Mahasena, B. Dermawan, T. W. Hadi, P. W. Premadi and D. Herdiwijaya

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 427, issue 3, pages 1903-1917
Published in print December 2012 | ISSN: 0035-8711
Published online December 2012 | e-ISSN: 1365-2966 | DOI:
Clear sky fraction above Indonesia: an analysis for astronomical site selection

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We report a study of cloud cover over Indonesia based on meteorological satellite data spanning 15 years (from 1996 to 2010) to aid in the selection of a new astronomical site capable of hosting a multi-wavelength astronomical observatory. High-spatial-resolution meteorological satellite data acquired from Geostationary Meteorological Satellite 5 (GMS 5), Geostationary Operational Environmental Satellite 9 (GOES 9) and Multi-functional Transport Satellite-1R (MTSAT-1R) are used to derive yearly average clear fractions over various regions of Indonesia. This parameter is determined from temperature measurements in the IR3 channel (water vapour, 6.7 μm) for high-altitude clouds (cirrus), and from the IR1 channel (10.7 μm) for lower-altitude clouds. An algorithm is developed to detect the corresponding clouds. The results of this study were used to select the best possible sites in Indonesia, which will be analysed further by performing in situ measurements in the future. The results suggest that regions of East Nusa Tenggara, located in southeastern Indonesia, are the most promising candidates for such an astronomical site. The yearly clear sky fraction of this region may reach better than 70 per cent, with an uncertainty of 10 per cent.

Keywords: atmospheric effects; methods: statistical; site testing

Journal Article.  8404 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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