Title: PICARD ground-based and space observatories: a joint venture to study the Sun

Abstract:
The PICARD project involves not only a space mission but also a ground-based observatory at 
Calern (France) dedicated to the study of the Sun. Thus, measurements are taken in orbit by 
the PICARD mission satellite in order to avoid the impact of atmospheric effects. Nevertheless, 
it is important to understand and interpret the ground-based measurements, which actually 
constitute the longest series of currently available measurements. This is why an important 
ground-based measurement programme (“PICARD SOL”) is associated with the space 
operation before, during, and after the PICARD space mission.

Space observations are a priori most favourable, however, space entails also technical 
challenges, a harsh environment, and a finite mission lifetime. The PICARD spacecraft, 
launched on June 15, 2010 was retired in April 2014. On ground, the instruments are less 
affected by in-space degradation and maintenance is easily provided, so, if the atmosphere is 
properly monitored and taken into account, they still represent an opportunity to generate the 
needed long-term time-series. That is why ground measurements have been carried out since 
May 2011, and will be pursued after the space program.

In this talk, we will describe both sets of instruments, and then will present our current results. 
We will highlight the importance of ground-based and space measurements. Indeed, our 
measurements show the benefit of simultaneous measurements obtained from ground and 
space observatories. As a result, these two means are complementary from each other and 
represent a feedback for planetary science.