Towards the final Gaia catalogue
Producing this final catalogue is a complicated endeavour that requires the entire mission dataset and a complex processing chain devised and tested by hundreds of scientists and software experts in the Gaia Data Processing and Analysis Consortium (DPAC).
Even before the first data release special subsets of Gaia data were made public to facilitate timely follow-up observations by the wider astronomical community. For example, Science Alerts – announcements to the scientific community about detected transient events such as supernovae and outbursting stars – were, and continue to be, regularly issued.
Following the first data release in September 2016 based on Gaia's first 14 months of observations, new datasets are released based on longer time intervals and with additional data products. The second data release was in April 2018, based on 22 months of observations. The third data release is based on 34 months of observations and will be split in two parts: an early data release in December 2020 and the full data release in 2022.
These subsequent data sets are characterised by increasingly improving precision and additional parameters for the surveyed stars, as well as for other celestial objects – from Solar System bodies to galaxies beyond our Milky Way.
Eventually, the final catalogue will contain full astrometric (position, distance and motion) and photometric (brightness and colour) parameters for over one billion stars as well as extensive additional information including a classification of the sources and lists of variable stars, multiple stellar systems and exoplanet-hosting stars. For more than 150 million stars there will be measurements of the radial-velocity – the speed at which the star is travelling towards or away from us.
The final Gaia catalogue will be a census of our Galaxy of such superb precision and detail that it will redefine the fundamental reference frame used for all astronomical coordinate systems. This will truly mark a new era of astrometry.