Astronomy & Astrophysics has the great pleasure of publishing a special issue on the early installment of the third data release (EDR3) of the Gaia space mission which has been obtaining exquisite astrometric and photometric measurements since July 2014. Similar to the full third data release planned for 2022, Gaia EDR3 is based on the analysis on the first 34 months of the mission. It provides parallaxes, proper motions, and three-color photometry for 1.5 billion sources, which will all be unchanged in the full third release that will only add information to EDR3.

The articles in this special issue describe the complex data processing of the Gaia observations, provide extensive validation checks, and quantify both the very significant improvements over DR2 and some important caveats on the known remaining shortcomings of the EDR3 data. They demonstrate that both the precision and the systematic errors are improved, compared to DR2, by one-third for the parallaxes and by over a factor of two for the proper motions, that a single passband for each photometric band describes the photometry to better than 1%, and that the fraction of catastrophic outliers is dramatically reduced. The articles provide spectacular illustrations of the scientific potential of the new data, and demonstrate that it will no doubt form the basis for excellent science over the coming years.

© ESO 2021