Sep 21 – 23, 2015
Royal Observatory of Belgium
Europe/Brussels timezone

Projet SOLIMB : métrologie du bord du soleil et détermination de son diamètre pendant les éclipses solaires

Sep 22, 2015, 11:15 AM
Meridian Room (Royal Observatory of Belgium)

Meridian Room

Royal Observatory of Belgium

Avenue Circulaire - 3 - Ringlaan 1180 Brussels
3-Results from recent space missions


Dr Philippe Lamy (LAM)


We report on a novel technique of measuring the solar radius during total solar eclipses that exploits light curves recorded just before and after the second and third contacts. The measurements are performed by pre-programmed photometers deployed over the eclipse paths and operating unattended. The recorded light curves are compared to synthetic ones calculated from high accuracy ephemerides and lunar limb profiles constructed from the topographic model of the Moon provided by the Kaguya lunar space mission. A minimization process between the two sets of curves yields the solar radius. Altogether, seventeen determinations have been obtained at the past four total eclipses with the following averages (at a wavelength of 540 nm and scaled to 1 AU): 959.94±0.02 arcsec on 11 July 2010, 960.02±0.04 arcsec on 13 November 2012, 959.99±0.09 arcsec on 3 November 2013, and 960.01±0.09 arcsec on 20 March 2015. Part of the differences between these four values may be attributed to weather conditions. Averaging the whole set of measurements yield a radius of 959.99±0.06 arcsec (696,246±45 km), in excellent agreement with the most recent data and supporting an upward revision of the standard IAU value as already suggested.

Primary author

Dr Philippe Lamy (LAM)


Dr Guillaume Faury (LAM/AKKA) Dr Jean-Yves Prado (CNES) Dr Olivier Floyd (AKKA) Dr Patrick Rocher (Institut de Mécanique Céleste et de Calcul des Ephémérides) Dr Serge Koutchmy (IAS)

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