Dome C coherence time statistics from DIMM data

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Aristidi, E., Agabi, A., Abe, L., Fossat, E., Ziad, A., Mekarnia, D.
• Other Authors: Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Antarc*; Antarctica
• Online Access: https://hal.science/hal-02890504; https://hal.science/hal-02890504/document; https://hal.science/hal-02890504/file/Aris_tau0_arXiv.pdf; https://doi.org/10.1093/mnras/staa1862

International audience We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time τ 0. Statistics and seasonal behaviour of τ 0 are given at two heights above the ground, 3m and 8m, for the wavelength λ = 500nm. We found an annual median value of 2.9ms at the height of 8m. A few measurements could also be obtained at the height of 20m and give a median value of 6ms during the period June-September. For the first time, we provide measurements of τ 0 in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5pm local time. Exceptional values of τ 0 above 10ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system.