Restitution of the K and F Components of the Solar Corona from LASCO-C2 Images over 24 Years [1996–2019]. (arXiv:2011.12920v1 [astro-ph.SR])

Restitution of the K and F Components of the Solar Corona from LASCO-C2 Images over 24 Years [1996–2019]. (arXiv:2011.12920v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Llebaria_A/0/1/0/all/0/1">Antoine Llebaria</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Lamy_P/0/1/0/all/0/1">Philippe Lamy</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Gilardy_H/0/1/0/all/0/1">Hugo Gilardy</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Boclet_B/0/1/0/all/0/1">Brice Boclet</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Loirat_J/0/1/0/all/0/1">Jean Loirat</a> (1) ((1) Laboratoire d&#x27;Astrophysique de Marseille, (2) Laboratoire Atmospheres, Milieux et Observations Spatiales)

We present a photometrically accurate restitution of the K and F coronae from
white-light images obtained over 24 Years [1996–2019] by the Large-Angle
Spectrometric COronagraph “LASCO-C2” onboard the Solar and Heliospheric
Observatory (SOHO). The procedure starts with the data set coming from the
polarimetric separation of images of 512 x 512 pixels in which the F-corona and
the instrumental stray light are entangled. Disentangling these components
proceeds in three stages, each composed of several steps. Stage 1 establishes
the distinct variations of the radiance of these components with the Sun–SOHO
distance and generate a new data set of median images calculated for each
Carrington rotation. Stage 2 achieves the restitution of a set of 36 stray
light images reflecting its temporal variation and the periodic rolls of SOHO
which started in 2003. Stage 3 achieves the restitution of the F-corona and a
time series of daily images is generated. These results allowed us processing
the whole set of routine LASCO-C2 images of 1024 x 1024 pixels (approximately
626000 images) and producing calibrated, high resolution images of the
K-corona. We extend our past conclusions that the temporal variation of the
integrated radiance of the K-corona tracks the solar activity over two solar
cycles 23 and 24 and that it is highly correlated with the temporal variation
of the total magnetic field. The behaviours of the integrated radiance during
the last few years of the declining phases of solar cycles 23 and 24 are
remarkably similar, reaching the same floor level and leading to a duration of
11.0 year for the latter cycle, in agreement with the sunspot determination.

We present a photometrically accurate restitution of the K and F coronae from
white-light images obtained over 24 Years [1996–2019] by the Large-Angle
Spectrometric COronagraph “LASCO-C2” onboard the Solar and Heliospheric
Observatory (SOHO). The procedure starts with the data set coming from the
polarimetric separation of images of 512 x 512 pixels in which the F-corona and
the instrumental stray light are entangled. Disentangling these components
proceeds in three stages, each composed of several steps. Stage 1 establishes
the distinct variations of the radiance of these components with the Sun–SOHO
distance and generate a new data set of median images calculated for each
Carrington rotation. Stage 2 achieves the restitution of a set of 36 stray
light images reflecting its temporal variation and the periodic rolls of SOHO
which started in 2003. Stage 3 achieves the restitution of the F-corona and a
time series of daily images is generated. These results allowed us processing
the whole set of routine LASCO-C2 images of 1024 x 1024 pixels (approximately
626000 images) and producing calibrated, high resolution images of the
K-corona. We extend our past conclusions that the temporal variation of the
integrated radiance of the K-corona tracks the solar activity over two solar
cycles 23 and 24 and that it is highly correlated with the temporal variation
of the total magnetic field. The behaviours of the integrated radiance during
the last few years of the declining phases of solar cycles 23 and 24 are
remarkably similar, reaching the same floor level and leading to a duration of
11.0 year for the latter cycle, in agreement with the sunspot determination.

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