Optical turbulence profiling with Stereo-SCIDAR for VLT and ELT
| Autor: | Elena Masciadri, Matthew J. Townson, Frederic Derie, Richard Wilson, A. Chacon, Julien Milli, James Osborn, Timothy Butterley, Marc Sarazin, Julio Navarrete, Xavier Haubois, M. Lelouarn, Douglas J. Laidlaw, O. J. D. Farley |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Very Large Telescope Coherence time Turbulence Instrumentation FOS: Physical sciences Astronomy and Astrophysics Effects of high altitude on humans 01 natural sciences 010309 optics Altitude 13. Climate action Space and Planetary Science 0103 physical sciences Extremely Large Telescope Astrophysics - Instrumentation and Methods for Astrophysics Adaptive optics Instrumentation and Methods for Astrophysics (astro-ph.IM) 010303 astronomy & astrophysics Remote sensing |
| Zdroj: | Monthly notices of the Royal Astronomical Society, 2018, Vol.478(1), pp.825-834 [Peer Reviewed Journal] Monthly Notices of the Royal Astronomical Society |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | Knowledge of the Earth's atmospheric optical turbulence is critical for astronomical instrumentation. Not only does it enable performance verification and optimization of the existing systems, but it is required for the design of future instruments. As a minimum this includes integrated astro-atmospheric parameters such as seeing, coherence time, and isoplanatic angle, but for more sophisticated systems such as wide-field adaptive optics enabled instrumentation the vertical structure of the turbulence is also required. Stereo-SCIDAR (Scintillation Detection and Ranging) is a technique specifically designed to characterize the Earth's atmospheric turbulence with high-altitude resolution and high sensitivity. Together with ESO (European Southern Observatory), Durham University has commissioned a Stereo-SCIDAR instrument at Cerro Paranal, Chile, the site of the Very Large Telescope (VLT), and only 20 km from the site of the future Extremely Large Telescope (ELT). Here we provide results from the first 18 months of operation at ESO Paranal including instrument comparisons and atmospheric statistics. Based on a sample of 83 nights spread over 22 months covering all seasons, we find the median seeing to be 0.64″ with 50 per cent of the turbulence confined to an altitude below 2 km and 40 per cent below 600 m. The median coherence time and isoplanatic angle are found as 4.18 ms and 1.75″, respectively. A substantial campaign of inter-instrument comparison was also undertaken to assure the validity of the data. The Stereo-SCIDAR profiles (optical turbulence strength and velocity as a function of altitude) have been compared with the Surface-Layer Slope Detection And Ranging, Multi-Aperture Scintillation Sensor-Differential Image Motion Monitor, and the European Centre for Medium Range Weather Forecasts model. The correlation coefficients are between 0.61 (isoplanatic angle) and 0.84 (seeing). |
| Databáze: | OpenAIRE |
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