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Coronal Photopolarimetry with the LASCO-C2. Coronagraph over 24 Years [1996–2019]

Abstract : We present an in-depth characterization of the polarimetric channel of the Large- Angle Spectrometric COronagraph “LASCO-C2” onboard the Solar and Helio- spheric Observatory (SoHO). The polarimetric analysis of the white-light images makes use of polarized sequences composed of three images obtained though three polarizers oriented at +60◦, 0◦ and −60◦, complemented by a neighboring unpolarized image, and relies on the formalism of Mueller. The Mueller matrix characterizing the C2 instrument was obtained through extensive ground-based calibrations of the optical components and global laboratory tests. Additional critical corrections were derived from in-flight tests relying prominently on roll sequences and on consistency criteria (e.g. the “tangential” direction of polar- ization). Our final results encompass the characterization of the polarization of the white-light corona, of its polarized radiance, of the two-dimensional elec- tron density, and of the K-corona over two solar cycles. They are in excellent agreement with measurements obtained at several solar eclipses except for slight discrepancies affecting the innermost part of the C2 field of view .
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Submitted on : Thursday, April 16, 2020 - 10:24:56 AM
Last modification on : Saturday, April 18, 2020 - 1:04:38 AM

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  • HAL Id : insu-02544213, version 1
  • ARXIV : 2001.05925


Philippe Lamy, Antoine Llebaria, Brice Boclet, Hugo Gilardy, Michael Burtin, et al.. Coronal Photopolarimetry with the LASCO-C2. Coronagraph over 24 Years [1996–2019]. Solar Physics, Springer Verlag, 2020, (in press). ⟨insu-02544213⟩



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