Gaia Data Release 1 (GDR1)

Content

  • 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).

Source: http://www.cosmos.esa.int/web/gaia/dr1

GDR1 Tables

This table has an entry for every Gaia observed source as listed in the Main Database accumulating catalogue version from which the catalogue release has been generated. It contains the basic source parameters, that is only final data (no epoch data) and no spectra (neither final nor epoch).

This table is a subset of GaiaSource comprising those stars in the Hipparcos and Tycho-2 Catalogues for which a full 5-parameter astrometric solution has been possible in Gaia Data Release 1. This is possible because the early Hipparcos epoch positions break some degeneracies due to the limited Gaia time coverage. The table contains a substantial fraction of the around 2.5 million stars in the Hipparcos and Tycho-2 catalogue. Many stars have been excluded due to several reasons, such as saturation, cross-match errors or bad astrometric solution.

This table describes the Cepheid stars identified in the table variable_summary as "CEP".

This table describes the Cepheid stars identified in the table variable_summary as "RRLYR".

Field-of-view time series of sources that have phot_variable_flag = "VARIABLE" in the gaia_source table.

Statistical parameters of field-of-view time series, only including observations with rejected_by_variability_processing=false as found in the phot_variable_time_series_gfov table. Note that only sources that have phot_variable_flag = "VARIABLE" in the gaia_source table are included.

  • GDR1.variable_summary

    Table with variability summary of sources with phot_variable_flag = "VARIABLE" in the gaia_source table.

Auxiliary cross match databases and tables

For the auxiliary cross match tables, please look up

    • TYCHO2 (Crossmatch TYCHO2 and TGAS)

The Tycho-2 Catalogue is an astrometric reference catalog containing positions and proper motions as well as two-colour photometric data for the 2.5 million brightest stars in the sky. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1; see CDS Cat. I/239) collected by the star mapper of the ESA Hipparcos satellite, but Tycho-2 is much bigger and slightly more precise, owing to a more advanced reduction technique. Components of double stars with separations down to 0.8 arcsec are included. Proper motions precise to about 2.5 mas/yr are given as derived from a comparison with the Astrographic Catalogue and 143 other ground-based astrometric catalogs, all reduced to the Hipparcos celestial coordinate system. Tycho-2 supersedes in most applications Tycho-1, as well as the ACT (CDS Cat. I/246) and the TRC (CDS Cat. I/250) catalogs based on Tycho-1.

    • RAVE DR5 (Crossmatch RAVE DR5 and TGAS)

Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9< I < 12) survey of stars randomly selected in the southern hemisphere. The RAVE medium-resolution spectra (R~7500) covering the Ca-triplet region (8410-8795 A) span the complete time frame from the start of RAVE observations in 2003 to their completion in 2013. Radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 218,846 unique stars have have parallaxes and proper motions from the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from high-resolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalogue of red giant stars in the dereddened color (J-Ks)_0 interval (0.50,0.85) for which the gravities were calibrated based only on seismology. Further data products for sub-samples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the Vizier database. From https://arxiv.org/abs/1609.03210

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