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Design, pointing control, and on-sky performance of the mid-infrared vortex coronagraph for the VLT/NEAR experiment

Maire, Anne-Lise and Huby, Elsa and Absil, Olivier and Zins, Gérard and Kasper, Markus and Delacroix, Christian and Leveratto, Serban and Karlsson, Mikael and Ruane, Garreth and Käufl, Hans-Ulrich and Orban de Xivry, Gilles and Pathak, Prashant and Pettazzi, Lorenzo and Duhoux, Philippe and Kolb, Johann and Pantin, Éric and Riggs, A. J. Eldorado and Siebenmorgen, Ralf and Mawet, Dimitri (2020) Design, pointing control, and on-sky performance of the mid-infrared vortex coronagraph for the VLT/NEAR experiment. Journal of Astronomical Telescopes, Instruments, and Systems, 6 (3). Art. No. 035003. ISSN 2329-4124. doi:10.1117/1.jatis.6.3.035003.

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Vortex coronagraphs have been shown to be a promising avenue for high-contrast imaging in the close-in environment of stars at thermal infrared (IR) wavelengths. They are included in the baseline design of the mid-infrared extremely large telescope imager and spectrograph. To ensure good performance of these coronagraphs, a precise control of the centering of the star image in real time is needed. We previously developed and validated the quadrant analysis of coronagraphic images for tip-tilt sensing estimator (QACITS) pointing estimator to address this issue. While this approach is not wavelength-dependent in theory, it was never implemented for mid-IR observations, which leads to specific challenges and limitations. Here, we present the design of the mid-IR vortex coronagraph for the “new Earths in the α Cen Region (NEAR) experiment with the Very Large Telescope (VLT)/Very Large Telescope imager and spectrometer for the mid-infrared (VISIR) instrument and assess the performance of the QACITS estimator for the centering control of the star image onto the vortex coronagraph. We use simulated data and on-sky data obtained with VLT/VISIR, which was recently upgraded for observations assisted by adaptive optics in the context of the NEAR experiment. We demonstrate that the QACITS-based correction loop is able to control the centering of the star image onto the NEAR vortex coronagraph with a stability down to 0.015 λ  /  D rms over 4 h in good conditions. These results show that QACITS is a robust approach for precisely controlling in real time the centering of vortex coronagraphs for mid-IR observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Maire, Anne-Lise0000-0002-2591-4138
Huby, Elsa0000-0002-1342-2822
Absil, Olivier0000-0002-4006-6237
Zins, Gérard0000-0002-2935-7404
Kasper, Markus0000-0002-8425-6606
Delacroix, Christian0000-0003-0150-4430
Karlsson, Mikael0000-0002-2011-0851
Ruane, Garreth0000-0003-4769-1665
Käufl, Hans-Ulrich0000-0002-8806-9795
Orban de Xivry, Gilles0000-0002-4790-415X
Pathak, Prashant0000-0003-3991-6107
Pantin, Éric0000-0001-6472-2844
Riggs, A. J. Eldorado0000-0002-0863-6228
Mawet, Dimitri0000-0002-8895-4735
Additional Information:© 2020 The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. Paper 20036 received Apr. 15, 2020; accepted for publication Sep. 1, 2020; published online Sep. 16, 2020. The authors thank the ESO Paranal Staff for support in conducting the observations. A.L.M. acknowledges the financial support of the F.R.S.-FNRS through a postdoctoral researcher grant. O.A. acknowledges the financial support of the F.R.S.-FNRS through a research associate mandate. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 819155) and under the European Union’s seventh framework program (Grant Agreement No. 337569). The research was supported by the Wallonia-Brussels Federation (grant for Concerted Research Actions). The authors have no relevant financial interests and no other potential conflicts of interest to disclose. This work was based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 60.A-9106 and 2102.C-5011.
Group:Astronomy Department
Funding AgencyGrant Number
Fonds de la Recherche Scientifique (FNRS)UNSPECIFIED
European Research Council (ERC)819155
European Research Council (ERC)337569
Wallonia-Brussels FederationUNSPECIFIED
Subject Keywords:adaptive optics; infrared imaging; data processing; simulations
Issue or Number:3
Record Number:CaltechAUTHORS:20210202-104752114
Persistent URL:
Official Citation:Anne-Lise K. Maire, Elsa Huby, Olivier Absil, Gérard Zins, Markus Kasper, Christian Delacroix, Serban Leveratto, Mikael Karlsson, Garreth J. Ruane, Hans-Ulrich Käufl, Gilles Orban de Xivry, Prashant Pathak, Lorenzo Pettazzi, Philippe R. Duhoux, Johann Kolb, Éric J. Pantin, A. J. Eldorado Riggs, Ralf Siebenmorgen, and Dimitri P. Mawet "Design, pointing control, and on-sky performance of the mid-infrared vortex coronagraph for the VLT/NEAR experiment," Journal of Astronomical Telescopes, Instruments, and Systems 6(3), 035003 (16 September 2020).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107871
Deposited By: Tony Diaz
Deposited On:02 Feb 2021 19:03
Last Modified:16 Nov 2021 19:07

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