CU3 - Gaia Astrometry
Channel: Stefan Jordan
Date: 2021-06-22

Gaia is one of the most successful space missions leading to about five scientific papers per day which are based on its fantastic and extremely accurate star catalogues.

Gaia is an astrometric satellite Gaia of the European Space Agency (ESA). The goal of Gaia's astrometry is to determine the positions, proper motions, and distances (parallaxes) of billions of stars.

From April 21-23, 2021, the Coordination Unit 3 (CU3) of the Gaia Data Processing and Analysis Consortium (DPAC) gathered for an online meeting. This coordinate unit is responsible for astrometry.


Dr. Michael Biermann (https://youtu.be/s-jsPiTlfDk?t=270),
Prof. Lennart Lindegren (https://youtu.be/s-jsPiTlfDk?t=802),
José Hernández (https://youtu.be/s-jsPiTlfDk?t=1351),
Dr. Javier Castañeda Pons (https://youtu.be/s-jsPiTlfDk?t=1634),
Prof. Sergei Klioner (https://youtu.be/s-jsPiTlfDk?t=1903),
and Dr. Katja Weingrill (https://youtu.be/s-jsPiTlfDk?t=2555)

are explaining their contributions to this ambitious mission.

One goal of the CU3 meeting was to discuss how the most accurate star catalogue to date, Gaia EDR3, can become even more accurate.

Interviews were conducted by Prof. Stefan Jordan

More than 400 astronomers and software engineers from many European and a few non-European countries contribute to the  Gaia mission.

Experts in Gaia astrometry discuss the Gaia mission, which aims to provide a census of stars and other objects in the Milky Way and beyond. The Astrometric Global Iterative Solution (AGIS) is described as the mathematical basis for determining positions, proper motions, and parallaxes or distances of stars and other celestial bodies from individual Gaia observations. The accuracy of data in the latest Gaia Early Data Release 3 is discussed, with the best accuracy achieved for stars that are not too bright or too faint. The technical manager of AGIS discusses the coordination of activities by a team of scientists and software engineers with a strong background in mathematics and instrument calibration to produce the Gaia Astrometric Solution for each Gaia data release.

The Gaia mission has processed up to 78 billion observations from the first 34 months of data and plans to process twice this amount for their next release, but they need a lot of computing power such as the powerful supercomputer, Mare Nostrum. To reach the desired accuracy for the Gaia catalog, they also need to consider relativistic effects such as aberration and the modeling of light propagation from stars, which involves taking into account the gravitational fields of planets. There are some regions in the sky where Gaia misses stars due to the density of sources, but they plan to fill these gaps with sieve sources in their next release.

Credits are mentioned in the video.

If not mentioned otherwise credits are
ESA/Gaia/DPAC (CC BY-SA 3.0 IGO)

Music: "Space Walk" by Westy Reflector
https://freemusicarchive.org/music/Westy_Reflector
(CC BY-NC-SA 3.0 US)
https://creativecommons.org/licenses/by-nc-sa/3.0/us

Videos were created with 
Gaia Sky (developed by Toni Sagristà)

Gaia Sky can be downloaded from 
www.zah.uni-heidelberg.de/gaia/outreach/gaiasky
Video editing by Stefan Jordan

There is a shortened 22-minute version of this video on https://youtu.be/aQ0iuIT98Pw