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Proceedings Paper

In-flight UV and polarized-VL radiometric calibrations of the solar orbiter/METIS imaging coronagraph
Author(s): M. Focardi; G. Capobianco; V. Andretta; C. Sasso; M. Romoli; F. Landini; S. Fineschi; M. Pancrazzi; A. Bemporad; G. Nicolini; S. Pucci; M. Uslenghi; G. Naletto; P. Nicolosi; D. Spadaro; L. Teriaca; U. H. Schühle; E. Antonucci
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Paper Abstract

METIS is an innovative inverted occulted solar coronagraph capable of obtaining for the first time simultaneous imaging of the full corona in linearly polarized visible-light (580-640 nm) and narrow-band (± 10 nm) ultraviolet H I Ly-α (121.6 nm). It has been selected to fly aboard the Solar Orbiter1 spacecraft, whose launch is foreseen in July 2017. Thanks to its own capabilities and exploiting the peculiar opportunities offered by the Solar Orbiter planned orbit, METIS will address some of the still open issues in understanding the physical processes in the corona and inner heliosphere. The Solar Orbiter Nominal Mission Phase (NMP) will be characterized by three scientific observing windows per orbit and METIS will perform at least one in-flight calibration per observing window. The two imaging channels of METIS will be calibrated on ground and periodically checked, verified and re-calibrated in-flight. In particular, radiometric calibration images will be needed to determine the absolute brightness of the solar corona. For UV radiometric calibration a set of targets is represented by continuum-emitting early type bright stars (e.g. A and B spectral types) whose photospheres produce a bright far-ultraviolet continuum spectrum stable over long timescales. These stars represent an important reference standard not only for METIS in-flight calibrations but also for other Solar Orbiter instruments and they will be crucial for instruments cross-calibrations as well. For VL radiometric calibration, a set of linearly polarized stars will be used. These targets shall have a minimum degree of linear polarization (DoLP > 5%) and a detectable magnitude, compatible with the instrument integration times constrained by the desired S/N ratio and the characteristics of the spacecraft orbit dynamics.

Paper Details

Date Published: 24 July 2014
PDF: 15 pages
Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 914409 (24 July 2014); doi: 10.1117/12.2055717
Show Author Affiliations
M. Focardi, INAF - Osservatorio Astrofisico di Arcetri (Italy)
G. Capobianco, INAF - Osservatorio Astronomico di Torino (Italy)
V. Andretta, INAF - Osservatorio Astronomico di Capodimonte (Italy)
C. Sasso, INAF - Osservatorio Astronomico di Capodimonte (Italy)
M. Romoli, Univ. degli Studi di Firenze (Italy)
F. Landini, INAF - Osservatorio Astrofisico di Arcetri (Italy)
S. Fineschi, INAF - Osservatorio Astronomico di Torino (Italy)
M. Pancrazzi, INAF - Osservatorio Astrofisico di Arcetri (Italy)
A. Bemporad, INAF - Osservatorio Astronomico di Torino (Italy)
G. Nicolini, INAF - Osservatorio Astronomico di Torino (Italy)
S. Pucci, Univ. degli Studi di Firenze (Italy)
M. Uslenghi, INAF - IASF Milano (Italy)
G. Naletto, Univ. degli Studi di Padova (Italy)
Istituto di Fotonica e Nanotechnologie, CNR (Italy)
P. Nicolosi, Univ. degli Studi di Padova (Italy)
Istituto di Fotonica e Nanotechnologie, CNR (Italy)
D. Spadaro, INAF - Osservatorio Astrofisico di Catania (Italy)
L. Teriaca, Max-Planck-Institut für Sonnensystemforschung (Germany)
U. H. Schühle, Max-Planck-Institut für Sonnensystemforschung (Germany)
E. Antonucci, INAF - Osservatorio Astronomico di Torino (Italy)


Published in SPIE Proceedings Vol. 9144:
Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Jan-Willem A. den Herder; Mark Bautz, Editor(s)

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