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First On-Sky Demonstration of a Scintillation Correction technique using Tomographic Wavefront Sensing

Hartley, Kathryn E; Farley, Oliver JD; Townson, Matthew J; Osborn, James; Wilson, RW

First On-Sky Demonstration of a Scintillation Correction technique using Tomographic Wavefront Sensing Thumbnail


Authors

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Kathryn Hartley kathryn.e.hartley@durham.ac.uk
Post Doctoral Research Associate

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Ollie Farley o.j.d.farley@durham.ac.uk
Post Doctoral Research Associate



Abstract

Scintillation noise significantly limits high precision ground-based photometry of bright stars. In this paper we present the first ever on-sky demonstration of scintillation correction. The technique uses tomographic wavefront sensing to estimate the spatial-temporal intensity fluctuations induced by high altitude optical turbulence. With an estimate of the altitudes and relative strengths of the turbulent layers above the telescope, the wavefront sensor data from multiple guide stars can be combined to estimate the phase aberrations of the wavefront at each altitude through the use of a tomographic algorithm. This 3D model of the phase aberrations can then be used to estimate the intensity fluctuations across the telescope pupil via Fresnel propagation. The measured photometric data for a given target within the field of view can then be corrected for the effects of scintillation using this estimate in post-processing. A simple proof-of-concept experiment using a wavefront sensor and a stereo-SCIDAR turbulence profiler attached to the 2.5m Isaac Newton Telescope was performed for a range of exposure times using the Orion Trapezium cluster as the reference stars. The results from this on-sky demonstration as well as simulations estimating the expected performance for a full tomographic AO system with laser guide stars are presented. On-sky the scintillation index was reduced on average by a factor of 1.9, with a peak of 3.4. For a full tomographic system we expect to achieve a maximum reduction in the scintillation index by a factor of ∼25.

Citation

Hartley, K. E., Farley, O. J., Townson, M. J., Osborn, J., & Wilson, R. (2023). First On-Sky Demonstration of a Scintillation Correction technique using Tomographic Wavefront Sensing. Monthly Notices of the Royal Astronomical Society, 520(3), 4134-4146. https://doi.org/10.1093/mnras/stad420

Journal Article Type Article
Acceptance Date Feb 2, 2023
Online Publication Date Feb 20, 2023
Publication Date 2023-04
Deposit Date Feb 8, 2023
Publicly Available Date Feb 13, 2023
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 520
Issue 3
Pages 4134-4146
DOI https://doi.org/10.1093/mnras/stad420

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© The Author(s) 2023. 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 (http://creativecommons.org/licenses/by/4.0/), which permits
unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.







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