In-flight radiometric calibration of the Metis Visible Light channel using stars and comparison with STEREO-A/COR2 data
Journal
Date Issued
2023
Author(s)
De Leo, Y.
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Burtovoi, A.
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Teriaca, L.
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Romoli, M.
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Chioetto, P.
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Capuano, G. E.
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Casini, C.
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Casti, M.
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Corso, A. J.
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Da Deppo, V.
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Fabi, M.
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Frassetto, F.
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Grimani, C.
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Heinzel, P.
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Liberatore, A.
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Magli, E.
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Moses, J. D.
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Naletto, G.
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NICOLINI, Gianalfredo
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Pelizzo, M. G.
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ROMANO, Paolo
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RUSSANO, Giuliana
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Schühle, U.
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Zuppella, P.
Description
Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. The Metis programme is supported by the Italian Space Agency (ASI) under the contracts to the cofinancing National Institute of Astrophysics (INAF): Accordi ASI-INAF N. I-043-10-0 and Addendum N. I-013-12-0/1, Accordo ASI-INAF N.2018-30-HH.0 and under the contracts to the industrial partners OHB Italia SpA, Thales Alenia Space Italia SpA and ALTEC: ASI-TASI N. I-037-11-0 and ASI-ATI N. 2013-057-I.0. Metis was built with hardware contributions from Germany (Bundesministerium für Wirtschaft und Energie (BMWi) through the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)), from the Academy of Sciences of the Czech Republic (Czech PRODEX) and from ESA. Metis team thanks the former PI, Ester Antonucci, for leading the development of Metis until the final delivery to ESA. In this work we made use of the following open source and community-developed Python packages: Matplotlib (Hunter 2007), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020), Astropy (Astropy Collaboration 2013); astropy:2018; astropy:2022 and SunPy (The SunPy Community 2020). The SECCHI/COR2 data used here were produced by an international consortium of the Naval Research Laboratory (USA), Lockheed Martin Solar and Astrophysics Lab (USA), NASA Goddard Space Flight Center (USA), Rutherford Appleton Laboratory (UK), University of Birmingham (UK), Max-Planck-Institut for Solar System Research (Germany), Centre Spatiale de Liège (Belgium), Institut d’Optique Theorique et Appliquée (France), and Institut d’Astrophysique Spatiale (France). Y.D.L.acknowledges support by Max-Planck-Institut für Sonnensystemforschung in Göttingen (Germany), the Università degli Studi di Catania (PIA.CE.RI. 2020–2022 Linea 2) and by the Italian MIUR-PRIN grant 2017APKP7T on “Circumterrestrial Environment: Impact of Sun-Earth Interaction”. P.H. was partially supported by the grant of the Czech Funding Agency No.22-34841S and by the program “Excellence Initiative – Research University” for University of Wrocław, BPIDUB.4610.96.2021.KG.
Abstract
Context. We present the results for the in-flight radiometric calibration performed for the Visible Light (VL) channel of the Metis coronagraph on board Solar Orbiter. Aims. The radiometric calibration is a fundamental step in building the official pipeline of the instrument, devoted to producing the calibrated data in physical units (L2 data). Methods. To obtain the radiometric calibration factor (ÏμVL), we used stellar targets transiting the Metis field of view. We derived ÏμVLby determining the signal of each calibration star by means of the aperture photometry and calculating its expected flux in the Metis band pass. The analyzed data set covers the time range from the beginning of the Cruise Phase of the mission (June 2020) until March 2021. Results. Considering the uncertainties, the estimated factor ÏμVLis in a good agreement with that obtained during the on-ground calibration campaign. This implies that up to March 2021 there was no measurable reduction in the VL channel throughput. Finally, we compared the total and polarized brightness visible light images of the solar corona acquired with Metis and STEREO-A/COR2 during the November 2020 superior conjunction of these instruments. A general good agreement was obtained between the images of these instruments for both the total and polarized brightness.
Volume
676
Start page
A45
Issn Identifier
0004-6361
Ads BibCode
2023A&A...676A..45D
Rights
open.access
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