PICARD SOL, a new ground-based facility for long-term solar radius measurements: first results

Mustapha Meftah (1) , Thierry Corbard (2, 3) , Abdanour Irbah (1) , Frédéric Morand (2, 3) , Rabah Ikhlef (2, 3, 4, 5) , Catherine Renaud (2, 3) , Alain Hauchecorne (1) , Pierre Assus (2, 3) , Bertrand Chauvineau (2, 3) , Mickael Crepel (6) , Francis Dalaudier (1) , Djelloul Djafer (7) , Mammar Fodil (5) , Francis Laclare (2, 3) , Patrick Lesueur (6) , Marc Lin (1) , Germain Poiet (6)

1 STRATO - LATMOS
2 OCA - Observatoire de la Côte d'Azur
3 LAGRANGE - Joseph Louis LAGRANGE
4 Observatoire d'Alger
5 CRAAG - Centre de Recherche en Astronomie Astrophysique et Géophysique
6 LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
7 URAER - Unité de Recherche Appliquée en Energies Renouvelables

PICARD SOL is the ground component of the PICARD mission and is operational since March 2011. A set of instruments including the replica of the space instrument and several atmospheric monitors was set up at Calern observatory in order to compare solar radius measured in space and on ground and to better understand and calibrate atmospheric effects on ground based measurements. SODISMII provides full disk images of the chromosphere and photosphere of the Sun in five narrow pass bands ranging from the near ultraviolet to the near infrared. Our preliminary results show a very good instrumental stability. After plate scale calibration using star doublet observations and corrections for atmospheric refraction, first estimates of the mean solar radius at the five wavelengths (393.37, 535.7, 607.1, 782.2, and 1025.0nm) are deduced from measurements recorded between May 2011 and December 2012.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]; Physique Atmosphérique et Océanique [physics.ao-ph]

Mustapha Meftah, Thierry Corbard, Abdanour Irbah, Frédéric Morand, Rabah Ikhlef, et al.. PICARD SOL, a new ground-based facility for long-term solar radius measurements: first results. Journal of Physics: Conference Series, 2013, 440, 012003 (6 p.). ⟨10.1088/1742-6596/440/1/012003⟩. ⟨hal-00835418⟩