Gaia Early Data Release 3 (GEDR3)

The third data release is split into two parts: the Early Data Release 3 (Gaia EDR3) was released the 3rd of December 2020. The full Gaia Data Release 3 (Gaia DR3) is scheduled for the first half of 2022.

A description of the contents of Gaia EDR3 is given below.

Content

The Gaia Early Data Release 3 (EDR3) enhances the DR2 catalogs by 118.79 million objects. It includes five-parameter astrometric solutions – positions on the sky, parallaxes, and proper motions – for more than 585 million sources, an additional pseudo-colour parameter for 800 million further sources (called six-parameter solution), and an additional 400 million sources with only positions, for a total of more than 1.8 billion sources with a mean G magnitude. The EDR3 release delivers an overall improvement in sky-coverage (almost complete down to 19 mag) and a great improvement in precision of both astrometric and photometric measurements. It spans 34 month of data collection by the Gaia satellite.

  • The full astrometric solution (5 parameters) – positions on the sky (α, δ), parallaxes, and proper motions – for around 1.468 billion (1.468 109) sources, with a limiting magnitude of about G ≈ 21 and a bright limit of about G ≈ 3. The astrometric solution wil be accompanied with some new quality indicators, like RUWE, and source image descriptors.
  • The full astrometric solution has been done as 5-parameter solution for 585 million sources and as 6-parameter solution for 882 million sources. In the 6-parameter solution, the additional fitted quantity is the so-called pseudo-colour that had to be included for sources without high-quality colour information.
  • In addition, two-parameters solutions – positions on the sky (α, δ) – for around 344 million additional sources. G magnitudes for around 1.806 billion sources. GBP and GRP magnitudes for around 1.542 billion and 1.555 billion sources, respectively.
  • Please be aware that the photometric system for the G, GBP, and GRP bands in Gaia EDR3 is different from the photometric system as used in Gaia DR2 and Gaia DR1.
  • Full passband definitions for G, GBP, and GRP. More information is available here.
  • About 1.614 million celestial reference frame (Gaia-CRF3) sources.
  • Cross-matches between Gaia EDR3 sources on the one hand and Hipparcos-2, Tycho-2 + TDSC merged, SDSS DR13, Pan-STARRS1 DR1, SkyMapper DR2, and URAT-1 data on the other hand.
  • Additionally, a Gaia DR2 to Gaia EDR3 match table.
  • Simulated data from Gaia Object Generator (GOG) and Gaia Universe Model Snapshot (GUMS).
  • The commanded scan law covering the Gaia EDR3 data collection period. Also the major periods where data was not sent to the ground or could not be processed are identified.

[caption id="attachment_1005" align="aligncenter" width="1000"]Gaia early data release - The Gaia Sky in colour. Gaia early data release - The Gaia Sky in colour - Image credit: ESA/Gaia/DPAC Image - license: CC-BY-SA 3.0 IGO - Acknowledgement: created by A. Moitinho, University of Lisbon, Portugal[/caption]

GEDR3 in numbers

The below table gives an overview of Gaia Early Data Release 3 in numbers:

and more...
# sources in Gaia EDR3 # sources in Gaia DR2 # sources in Gaia DR1
Total number of sources 1,811,709,771 1,692,919,135 1,142,679,769
Number of 5-parameter sources 585,416,709 1,331,909,727 2,057,050
Number of 6-parameter sources 882,328,109
Number of 2-parameter sources 343,964,953 361,009,408 1,140,622,719
Sources with mean G magnitude 1,806,254,432 1,692,919,135 1,142,679,769
Sources with mean GBP-band photometry 1,542,033,472 1,381,964,755 -
Sources with mean GRP-band photometry 1,554,997,939 1,383,551,713 -
Gaia-CRF sources 1,614,173 556,869 2,191
Sources with radial velocities 7,209,831 (Gaia DR2) 7,224,631 -
Variable sources expected with Gaia DR3 / see Gaia DR2 550,737 3,194
Known asteroids with epoch data expected with Gaia DR3 / see Gaia DR2 14,099 -
Effective temperatures (Teff) expected with Gaia DR3 / see Gaia DR2 161,497,595 -
Extinction (AG) and reddening (E(GBP-GRP)) expected with Gaia DR3 / see Gaia DR2 87,733,672 -
Sources with radius and luminosity expected with Gaia DR3 / see Gaia DR2 76,956,778 -
expected with Gaia DR3 - -

Background of the data

Gaia EDR3 data is based on data collected between 25 July 2014 and 28 May 2017, spanning a period of 34 months of data collection. As compared to Gaia DR2 which was based on observations collected in the first 22 months of Gaia's routine operational phase.

The reference epoch for Gaia DR3 (both Gaia EDR3 and the full Gaia DR3) is 2016.0. Positions and proper motions are referred to the ICRS. The time coordinate for Gaia EDR3 is the barycentric coordinate time (TCB).

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