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)
|Total number of sources
|Number of TGAS* sources
|Number of secondary sources**
|Number of light curves for Cepheids
|Number of light curves for RR Lyrae
Magnitude distribution percentiles (G)
* 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).
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.
Table with variability summary of sources with phot_variable_flag = "VARIABLE" in the gaia_source table.