African VLBI Network Training Site


Invited Talk: Wednesday 25 April - Prof Patrick Charlot

25 April 2018 14:00 - 15:00

Title: The Gaia Space Mission: The Second Data Release: 25 April 2018

Author: Prof Patrick Charlot 
              Astrophysique de Bordeaux
              Université de Bordeaux

The Gaia space mission of the European Space Agency, launched on 19 December 2013, has been in full operational mode since July 2014 after completion of commissioning. Gaia is surveying the entire sky, measuring positions, parallaxes and proper motions of more than a billion stars down to magnitude 20-21. In the eye of Gaia are also a few million galaxies, half a million QSOs and a few hundred thousand moving objects in the Solar System (asteroids). Photometric and spectroscopic information is collected jointly with the astrometric data. The scientific objectives of Gaia cover a wide range of topics in galactic and stellar astrophysics, reference frames and fundamental physics, exoplanet and Solar System science. The lecture will give an overview of the mission, review the scientific objectives and present highlights of the Data Release 1 (released on 14 September 2016) and Data Release 2, to be released on 25 April 2018 at 12:00 (European time).

More about the author:

PCharlot 240917

Patrick Charlot has worked in the field of geodetic, astrometric and astrophysical VLBI for more than 30 years, originally at Paris Observatory (where he obtained a Ph. D. in 1989) and since 1998 at the University of Bordeaux in the southwest of France. He also stayed as a postdoc fellow at the Jet Propulsion Laboratory (USA) in 1989-1990.

Patrick pioneered studies of radio source structure from geodetic and astrometric VLBI data, including the effect of such structures on the VLBI observables and the celestial reference frame. Following up on his early work, he introduced the now widely-used structure index, an indicator of source quality, and pushed imaging of the reference frame sources. This led to the Bordeaux VLBI Image Database, which now incorporates more than 6000 images from extragalactic radio sources. Additional contributions are concerned with studies of the Earth’s precession and nutation, the estimation of the link between the dynamical and extragalactic frames, and astrophysics of active galactic nuclei, in particular from VLBI observations.

Patrick currently chairs the ICRF3 Working Group, in charge of building the next generation celestial reference frame. He has also long been connected to European VLBI, e.g. as chair of the European VLBI Network Program Committee from 2003 to 2008 or at present through the project JUMPING JIVE. Patrick is a member of the JIVE council, representing France, and a member of the IVS Directing Board, representing the International Astronomical Union. His interest also extends to the Gaia space mission for linking the radio and optical frames and understanding the underlying source physics. He is a member of the Data Processing and Analysis Consortium for Gaia. Patrick was Director of the Laboratoire d’Astrophysique de Bordeaux (formerly Bordeaux Observatory) from 2008 to 2015.