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A comparison of next-generation turbulence profiling instruments at Paranal

Griffiths, R; Bardou, L; Butterley, T; Osborn, J; Wilson, R; Bustos, E; Tokovinin, A; Le Louarn, M; Otarola, A

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Ryan Griffiths
PGR Student Doctor of Philosophy

E Bustos

A Tokovinin

M Le Louarn

A Otarola


A six-night optical turbulence monitoring campaign has been carried at Cerro Paranal observatory in February and March, 2023 to facilitate the development and characterisation of two novel atmospheric site monitoring instruments - the ring-image next generation scintillation sensor (RINGSS) and 24-hour Shack Hartmann image motion monitor (24hSHIMM) in the context of providing optical turbulence monitoring support for upcoming 20-40m telescopes. Alongside these two instruments, the well-characterised Stereo-SCIDAR and 2016-MASS-DIMM were operated throughout the campaign to provide data for comparison. All instruments obtain estimates of optical turbulence profiles through statistical analysis of intensity and wavefront angle-of-arrival fluctuations from observations of stars. Contemporaneous measurements of the integrated turbulence parameters are compared and the ratios, bias, unbiased root mean square error and correlation of results from each instrument assessed. Strong agreement was observed in measurements of seeing, free atmosphere seeing and coherence time. Less correlation is seen for isoplanatic angle, although the median values agree well. Median turbulence parameters are further compared against long-term monitoring data from Paranal instruments. Profiles from the three small-telescope instruments are compared with the 100-layer profile from the stereo-SCIDAR. It is found that the RINGSS and SHIMM offer improved accuracy in characterisation of the vertical optical turbulence profile over the MASS-DIMM. Finally, the first results of continuous optical turbulence monitoring at Paranal are presented which show a strong diurnal variation and predictable trend in the seeing. A value of 2.65″ is found for the median daytime seeing.


Griffiths, R., Bardou, L., Butterley, T., Osborn, J., Wilson, R., Bustos, E., …Otarola, A. (2024). A comparison of next-generation turbulence profiling instruments at Paranal. Monthly Notices of the Royal Astronomical Society, 529(1), 320 - 330.

Journal Article Type Article
Acceptance Date Feb 8, 2024
Online Publication Date Feb 10, 2024
Publication Date 2024-03
Deposit Date Feb 15, 2024
Publicly Available Date May 22, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 529
Issue 1
Pages 320 - 330
Keywords Space and Planetary Science; Astronomy and Astrophysics
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Copyright Statement
© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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