1. Design, pointing control, and on-sky performance of the mid-infrared vortex coronagraph for the VLT/NEAR experiment
- Author
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Anne-Lise Maire, Gérard Zins, Ralf Siebenmorgen, Mikael Karlsson, P. Duhoux, A. J. Eldorado Riggs, Prashant Pathak, Christian Delacroix, Serban Leveratto, Olivier Absil, Garreth Ruane, Johann Kolb, Lorenzo Pettazzi, Elsa Huby, Eric Pantin, M. Kasper, Hans-Ulrich Käufl, G. Orban de Xivry, Dimitri Mawet, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
- Subjects
media_common.quotation_subject ,FOS: Physical sciences ,Context (language use) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Star (graph theory) ,01 natural sciences ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Adaptive optics ,010303 astronomy & astrophysics ,Instrumentation ,Coronagraph ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Astrophysics::Galaxy Astrophysics ,media_common ,Physics ,[PHYS]Physics [physics] ,business.industry ,Mechanical Engineering ,Astrophysics::Instrumentation and Methods for Astrophysics ,Estimator ,Astronomy and Astrophysics ,Electronic, Optical and Magnetic Materials ,Vortex ,Stars ,Space and Planetary Science ,Control and Systems Engineering ,Sky ,Astrophysics::Earth and Planetary Astrophysics ,business ,Astrophysics - Instrumentation and Methods for Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
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 METIS. 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 $\alpha$ Cen Region (NEAR) experiment with the VLT/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 $0.015 \lambda/D$ rms over 4h 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., Comment: Published in JATIS. This version is the manuscript resubmitted before acceptance, 30 pages, 14 figures
- Published
- 2020
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