Gaia DR1 (gaiadr1)



In order to be consistent with the naming of the ESAC Archive the name of the schema (database) holding the data of Gaia data release 1 has been modified on the 3rd of December 2020 from gdr1 to gaiadr1.

Content of DR1

  • Positions (α, δ) and G magnitudes for all sources with acceptable formal standard errors on positions. Positions and individual uncertainties are computed using a generic prior and Bayes" rule (detailed description in "Gaia astrometry for stars with too few observations. A Bayesian approach").
  • The five-parameter astrometric solution - positions, parallaxes, and proper motions - for stars in common between the Tycho-2 Catalogue and Gaia is contained in Gaia DR1. This part of Gaia DR1 is based on the Tycho-Gaia Astrometric Solution (Image of the Week with short TGAS description; paper with a more detailed description; paper describing theory and background; paper describing quasar extension).
  • At the beginning of the routine phase, for a period of 4 weeks, a special scanning mode repeatedly covering the ecliptic poles on every spin was executed for calibration purposes. Photometric data of selected RR Lyrae and Cepheid variable stars including these high-cadence measurements are contained in Gaia DR1.
  • Positions (α, δ) and G magnitudes for 2152 ICRF quasars (F. Mignard et al., 2016). Cross-matches will be provided between Gaia sources on the one hand and Hipparcos-2, Tycho-2, 2MASS PSC, GSC2.3, PPM-XL, UCAC-4, SDSS DR10 / DR12, AllWISE, and URAT-1 data on the other hand.

Gaia DR1 is based on observations collected between 25 July 2014 and 16 September 2015.

Density map for gaiadr1.gaia_source (number of sources per square degree). Healpix based (nside 512, 3.14Mpixels)

Density map for gaiadr1.gaia_source (number of sources per square degree). Healpix based (nside 512, 3.14Mpixels)

Source numbers

Total number of sources 1,142,679,769
Number of TGAS* sources 2,057,050
- Hipparcos 93,635
- Tycho-2 1,963,415
Number of secondary sources** 1,140,622,719
Number of light curves for Cepheids 599
Number of light curves for RR Lyrae 2595

Magnitude distribution percentiles (G)

0.135% 11.2
2.275% 14.5
15.866% 17.1
50% 19.0
84.134% 20.1
97.725% 20.7
99.865% 21.0

* TGAS = Tycho-Gaia Astrometric Solution, also referred to as primary solution for primary sources.

** The astrometric solution of secondary sources (non-TGAS sources) is derived using the calibrations of the spacecraft attitude and the geometry of the instrument as `fixed" input, as derived from the astrometric solution of primary sources (i.e., the TGAS solution).



If you have used Gaia data in your research, please use the following acknowledgement:

This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

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