DJAFER , Djelloul

Daily observation conditions are needed when observing the Sun at high angular resolution. MISOLFA is a daytime seeing monitor developed for this purpose that allows the estimation of the spatial and temporal parameters of atmospheric turbulence. This information is necessary, for instance, for astrometric measurements of the solar radius...

The PICARD spacecraft was launched on June 15, 2010 with one of its sci- entific objectives the study of the geometry of the Sun. The measure of the solar oblateness remains difficult because images are affected by optical distortions. Rolling the satellite as performed in previous space missions, allows determi- nation of the telescope...

The PICARD spacecraft was launched on June 15, 2010 with one of its sci- entific objectives the study of the geometry of the Sun. The measure of the solar oblateness remains difficult because images are affected by optical distortions. Rolling the satellite as performed in previous space missions, allows determi- nation of the telescope...

Knowledge of the Solar Diameter Imager and Surface Mapper (SODISM) plate scale is a fundamental parameter for obtaining the solar radius. We have determined the plate scale of the telescope on the ground and in flight onboard the Picard spacecraft. The results show significant differences; the main reason is that the conditions of observation...

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...

For the past thirty years, modern ground-based time-series of the solar radius have shown different apparent variations according to different instruments. The origins of these variations may result from the observer, the instrument, the atmosphere, or the Sun. Solar radius measurements have been made for a very long time and in different ways....

For the last thirty years, ground time series of the solar radius have shown different variations according to different instruments. The origin of these variations may be found in the observer, the instrument, the atmosphere and the Sun. These time series show inconsistencies and conflicting results, which likely originate from instrumental...

PICARD is a mission devoted to solar variability observation, through imagery and radiometric measurements, with the goal to provide data for scientific investigation first in the area of solar physics, and second in the assessment of the influence of the solar variability on the Earth climate variability. PICARD contains a double program with...

The Solar Diameter Imager and Surface Mapper (SODISM) on board the PICARD space mission provides wide-field images of the photosphere and chromosphere of the Sun in five narrow pass bands (centered at 215.0, 393.37, 535.7, 607.1, and 782.2 nm). PICARD is a space mission, which was successfully launched on 15 June 2010 into a Sun synchronous...