CNES has scheduled the launch of PICARD microsatellite in October (1) SA (F) IRMB (B) PMOD (Ch) OCA Nice University IAS LMD (3) Yale university HAO (2) GSFC JPL NRL Valencia U ILWS THE PICARD MISSION and ITS SYNERGY WITH THE HELIOSEISMIC and MAGNETIC IMAGER Gérard Thuillier 1, Judit Pap 2, and Sabatino Sofia 3

PICARD MISSION MAIN SCIENTIFIC OBJECTIVES (1) Measure the variability of several global solar properties. In particular, the solar diameter with a metrological instrument. (2) Modelling of the solar machine Role of the magnetic field, on surface or deeper in the convective zone. (3) Contribution to solar luminosity reconstruction (4) Long term trend (5) Understanding of the ground based measurements

Key constraints for validating the physics of solar models are simultanously measured by PICARD: - solar diameter, limb shape, asphericity in the photosphere - total solar irradiance - oscillation modes - Temperature variations in the photosphere  HMI and PICARD have a strong synergy

MDI/SoHO images are used to determine the radius variation as a function of time. The recent results show a maximum change of 15 mas per year (Kuhn et al., 2004). MDI is not a metrological instrument, as having no internal means to control the instrument angular scale. Corrections by models were made. Photospheric diameter Measurements From ground observations, there are several optical methods (Mercury transits, eclipses, astrolabes, imaging telescope) showing: - in phase, or anti phase with the 11-year solar cycle, or no variation.  contradictory results

DIAMETER VARIATION FROM STRATOSPHERIC BALLOON OBSERVATIONS Sofia et al. (1994) have built the Solar Disk Sextant (SDS) using an angular reference. Operated on board a stratospheric balloon, several flights were achieved. Results of four stratospheric balloons flights carrying SDS (Egidi et al., 2006) showing a diameter increase of 0.2“ while the solar activity decreases. SDS Calern

Sofia et al, 2005 Sans turbulence, diamètre et activité sont en phase Avec turbulence, diamètre et activité sont en antiphase Depth (Mm) Sofia et al., 2005 With turbulence No turbulence

THE PICARD MISSION MEASUREMENTS In orbit: Diameter, limb shape and asphericity in the continuum (535, 607, 782 nm). Diameter (215 nm) refered to stars doublets Precision: 3 mas per single image TSI: 2 independent radiometers as on SoHO 5 spectral channels (2 in UV relevant of ozone photochemistry) Activity (215 nm, Ca II) Solar oscillations (535 nm) on the ground : - diameter, limb shape and asphericity, - local atmospheric turbulence

NPOESS PICARD SDO PROBA 2 ISS STEREO SOLAR B SORCE SoHO Mission SOHO: TSI, images in visible, UV et EUV, magnetograms, helioseismology. SORCE: TSI and solar spectrum from 12 to 2500 nm. SOLAR B : X-Rays-X and EUV STEREO: CME SOLAR/ISS: TSI and solar spectrum from 17 to 3000 nm. PROBA 2: EUV image, EUV spectral irradiances SDO: EUV, magnetograms, heliosismologie, several wavelengths PICARD: TSI, diameter, asphericity, helioseismology NPOESS: TSI and minor components concentration measurements.

SYNERGY HMI/PICARD PICARD will ensure continuity with SoHO and SORCE for TSI measurements. Diameter, asphericity, limb shape in three photospheric spectral domains Spectral irradiance in UV, visible and near IR Activity in near UV and CaII line Temperature variation Helioseismology measurements (limb, macropixels, and spectral channels).

ThemesMeasurementsInstruments Solar Physics Variability diameter/luminosity, activity, luminosity SODISM I, SOVAP, PREMOS Asphericity, limb shapeSODISM I Differential rotationSODISM I Diameter/ stellar referenceSODISM I HelioseismologySODISM I, PREMOS ClimateDiameter/luminositySODISM I, SOVAP, PREMOS LuminositySOVAP, PREMOS UV VariabilityPREMOS, SODISM I Atmospheric Physics Diameter and limb shape at ground Ozone Ground-based instruments (SODISM II, MISOLFA, …) SODISM I, PREMOS Space 215 and 393 nm (Ca II)SODISM I SODISM I : diameter measurement in orbit. SODISM II, on ground SOVAP and PREMOS : measurement of the Total Solar Irradiance (TSI) PREMOS : measurement in 5 spectral domains