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Scintillation-limited photometry with the 20-cm NGTS telescopes at Paranal Observatory

O’Brien, Sean M; Bayliss, Daniel; Osborn, James; Bryant, Edward M; McCormac, James; Wheatley, Peter J; Acton, Jack S; Alves, Douglas R; Anderson, David R; Burleigh, Matthew R; Casewell, Sarah L; Gill, Samuel; Goad, Michael R; Henderson, Beth A; Jackman, James AG; Lendl, Monika; Tilbrook, Rosanna H; Udry, Stéphane; Vines, Jose I; West, Richard G

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Sean M O’Brien

Daniel Bayliss

Edward M Bryant

James McCormac

Peter J Wheatley

Jack S Acton

Douglas R Alves

David R Anderson

Matthew R Burleigh

Sarah L Casewell

Samuel Gill

Michael R Goad

Beth A Henderson

James AG Jackman

Monika Lendl

Rosanna H Tilbrook

Stéphane Udry

Jose I Vines

Richard G West


Ground-based photometry of bright stars is expected to be limited by atmospheric scintillation, although in practice observations are often limited by other sources of systematic noise. We analyse 122 nights of bright star (Gmag ≲ 11.5) photometry using the 20-cm telescopes of the Next-Generation Transit Survey (NGTS) at the Paranal Observatory in Chile. We compare the noise properties to theoretical noise models and we demonstrate that NGTS photometry of bright stars is indeed limited by atmospheric scintillation. We determine a median scintillation coefficient at the Paranal Observatory of CY=1.54⁠, which is in good agreement with previous results derived from turbulence profiling measurements at the observatory. We find that separate NGTS telescopes make consistent measurements of scintillation when simultaneously monitoring the same field. Using contemporaneous meteorological data, we find that higher wind speeds at the tropopause correlate with a decrease in long-exposure (t = 10 s) scintillation. Hence, the winter months between June and August provide the best conditions for high-precision photometry of bright stars at the Paranal Observatory. This work demonstrates that NGTS photometric data, collected for searching for exoplanets, contains within it a record of the scintillation conditions at Paranal.


O’Brien, S. M., Bayliss, D., Osborn, J., Bryant, E. M., McCormac, J., Wheatley, P. J., …West, R. G. (2022). Scintillation-limited photometry with the 20-cm NGTS telescopes at Paranal Observatory. Monthly Notices of the Royal Astronomical Society, 509(4), 6111-6118.

Journal Article Type Article
Acceptance Date Nov 18, 2021
Online Publication Date Nov 26, 2021
Publication Date 2022-02
Deposit Date Dec 17, 2021
Publicly Available Date Jun 16, 2022
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 509
Issue 4
Pages 6111-6118


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Copyright Statement
© The Author(s) 2021.
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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