GaiaEarly Data Release 3

Abstract

Context.We present the early installment of the thirdGaiadata release,GaiaEDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities fromGaiaDR2.Aims.A summary of the contents ofGaiaEDR3 is presented, accompanied by a discussion on the differences with respect toGaiaDR2 and an overview of the main limitations which are present in the survey. Recommendations are made on the responsible use ofGaiaEDR3 results.Methods.The raw data collected with theGaiainstruments during the first 34 months of the mission have been processed by theGaiaData Processing and Analysis Consortium and turned into this early third data release, which represents a major advance with respect toGaiaDR2 in terms of astrometric and photometric precision, accuracy, and homogeneity.Results. GaiaEDR3 contains celestial positions and the apparent brightness inGfor approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (GBP−GRP) colour are also available. The passbands forG,GBP, andGRPare provided as part of the release. For ease of use, the 7 million radial velocities fromGaiaDR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part ofGaiaDR3. Finally,GaiaEDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, theGaia-CRF3, which is based solely on extragalactic sources. The creation of the source list forGaiaEDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that forGaiaDR2, but it does feature new sources and there are some notable changes. The source list will not change forGaiaDR3.Conclusions. GaiaEDR3 represents a significant advance overGaiaDR2, with parallax precisions increased by 30 per cent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30–40% for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband forG,GBP, andGRPis valid over the entire magnitude and colour range, with no systematics above the 1% level