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arXiv · 2302.07308

In-flight validation of Metis Visible-light Polarimeter Coronagraph on board Solar Orbiter

A. Liberatore·S. Fineschi·M. Casti·G. Capobianco·L. Abbo·V. Andretta·V. Da Deppo·M. Fabi·F. Frassati·G. Jerse·F. Landini·D. Moses·G. Naletto·G. Nicolini·M. Pancrazzi·M. Romoli·G. Russano·C. Sasso·D. Spadaro·M. Stangalini·R. Susino·D. Telloni·L. Teriaca·M. Uslenghi
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Abstract

Context. The Metis coronagraph is one of the remote-sensing instruments of the ESA/NASA Solar Orbiter mission. Metis is aimed at the study of the solar atmosphere and solar wind by simultaneously acquiring images of the solar corona at two different wavelengths; visible-light (VL) within a band ranging from 580 nm to 640 nm, and in the HI Ly-alpha 121.6 +/- 10 nm ultraviolet (UV) light. The visible-light channel includes a polarimeter with electro-optically modulating Liquid Crystal Variable Retarders (LCVRs) to measure the linearly polarized brightness of the K-corona to derive the electron density. Aims. In this paper, we present the first in-flight validation results of the Metis polarimetric channel together with a comparison to the on-ground calibrations. It is the validation of the first use in deep space (with hard radiation environment) of an electro-optical device: a liquid crystal-based polarimeter. Methods. We used the orientation of the K-corona's linear polarization vector during the spacecraft roll maneuvers for the in-flight calibration. Results. The first in-flight validation of the Metis coronagraph on-board Solar Orbiter shows a good agreement with the on-ground measurements. It confirms the expected visible-light channel polarimetric performance. A final comparison between the first pB obtained by Metis with the polarized brightness (pB) obtained by the space-based coronagraph LASCO and the ground-based coronagraph KCor shows the consistency of the Metis calibrated results.

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A. Liberatore, S. Fineschi, M. Casti, G. Capobianco, L. Abbo, V. Andretta, V. Da Deppo, M. Fabi, F. Frassati, G. Jerse, F. Landini, D. Moses, G. Naletto, G. Nicolini, M. Pancrazzi, M. Romoli, G. Russano, C. Sasso, D. Spadaro, M. Stangalini, R. Susino, D. Telloni, L. Teriaca, M. Uslenghi. 2023-02-14. In-flight validation of Metis Visible-light Polarimeter Coronagraph on board Solar Orbiter. https://doi.org/10.1051/0004-6361/202244069

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