BOUQUILLON , Sébastien

The first data release of star astrometry by Gaia (Sept. 2016) has given an anticipation of the mission capabilities. By providing positions with uncertainties at the level of few milli-arcsec (mas) a new frame to calibrate ground-based observations has immediately become available, thus disclosing a new possibility of exploitation for archive...

Gaia's unprecedented ambitions regarding astrometric accuracy and precision require a level of knowledge of the position and velocity vector of the satellite itself not required in other satellite mission. Thus the usual methods of determining these quantities do not suffice and new approaches must be invoked. One of these is the Ground Based...

Gaia's unprecedented ambitions regarding astrometric accuracy and precision require a level of knowledge of the position and velocity vector of the satellite itself not required in other satellite mission. Thus the usual methods of determining these quantities do not suffice and new approaches must be invoked. One of these is the Ground Based...

POLAC (Paris Observatory Lunar Analysis Center) is an ILRS analysis center founded by J. Chapront, M. Chapront-Touzé and G. Francou in 1996. They developed in the 80's a semi-analytical solution of the lunar motion named ELP (Ephémérides lunaires Parisienne). Thus, the original purpose of POLAC was the adjustment of ELP to the lunar laser...

Based on a fully passive space segment, the Lunar Laser Ranging experiment is the last of the Apollo Lunar Surface Experiments Package to operate. Observations from Grasse Lunar Laser Ranging station have been realized on a daily basis since the first echoes obtained in 1981. We will give a brief summary of the progress made at Grasse Laser...

The Ground Based Optical Tracking group (GBOT) consists of about ten scientists involved in the Gaia mission by ESA. Its main task is the optical tracking of the Gaia satellite itself [1]. This novel tracking method in addition to radiometric standard ones is necessary to ensure that the Gaia mission goal in terms of astrometric precision level...