Using all-sky cameras to measure atmospheric transparency at robotic telescope sites

N. Volgenau; E. Manne-Nicholas; S. Foale; M. Bowman; D. Harbeck; M. Daily

doi:10.1117/12.3019079

25 July 2024 Using all-sky cameras to measure atmospheric transparency at robotic telescope sites

N. Volgenau, E. Manne-Nicholas, S. Foale, M. Bowman, D. Harbeck, M. Daily

Proceedings Volume 13098, Observatory Operations: Strategies, Processes, and Systems X; 130980E (2024) https://doi.org/10.1117/12.3019079
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Abstract

The telescopes in Las Cumbres Observatory’s global network (LCO) operate robotically. The enclosures open and shut automatically, based on data provided by LCO’s own weather stations. In 2023, LCO began using images from all-sky cameras to estimate the sky transparency at its sites. For each image, the locations and opacities of clouds are revealed by comparing a smoothed visibility map (based on visible stars) with a catalog (i.e. unattenuated) visibility map. The cloud map is then multiplied by a weighting scheme that favors low airmasses to determine a single all-sky transparency. To calibrate the transparencies at which the enclosures should be opened or closed, LCO staff astronomers reviewed thousands of all-sky images acquired during partly cloudy nights. The reviews were performed independent of the transparency calculations, to avoid biasing the close/open decisions. Since deploying the all-sky transparency calculations to LCO’s sites, we have empirically determined that they provide a more accurate measure than IR cloud sensors of when sky conditions are appropriate for observing, and the time spent attempting to observe through clouds has been reduced.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

N. Volgenau, E. Manne-Nicholas, S. Foale, M. Bowman, D. Harbeck, and M. Daily "Using all-sky cameras to measure atmospheric transparency at robotic telescope sites", Proc. SPIE 13098, Observatory Operations: Strategies, Processes, and Systems X, 130980E (25 July 2024); https://doi.org/10.1117/12.3019079

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