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gaia data release 3 documentation

Gaia Data Release 3
Documentation release 1.1

European Space Agency (ESA)
Gaia Data Processing and Analysis Consortium (DPAC)
13 June 2022
Executive summary

The third Gaia data release, Gaia DR3, contains the astrometry and broad-band photometry already published as part of Gaia EDR3 and introduces a large variety of new data products:

  • A much expanded radial velocity survey, as well as magnitudes of sources in the GRVS band, and a spectral line broadening parameter vbroad;

  • Mean BP, RP, and RVS spectra for a large subset of sources;

  • A much expanded collection of variable sources, covering 24 variability types;

  • Photometric time series for all variable sources;

  • The Gaia Andromeda Photometric Survey which contains the photometric time series for all sources (variable and non-variable) in a 5.5 radius field around M31;

  • Object classification, including a self-organised map (SOM) of poorly classified sources;

  • Astrophysical parameters (APs) from mean BP/RP spectra, including Markov-Chain Monte Carlo (MCMC) samples;

  • Astrophysical parameters from mean RVS spectra;

  • Chemical abundances from mean RVS spectra;

  • Diffuse interstellar band parameters from mean RVS spectra;

  • Non-single star solutions;

  • QSO and galaxy candidates, including redshifts, QSO host detections, and QSO host and galaxy light profiles;

  • Solar system objects (SSO), including reflectance spectra derived from epoch BP/RP spectra;

  • Total galactic extinction maps at various HEALPix levels;

  • Archived photometric science alerts.

The archive contents are summarized in Table 0.1 and Table 0.2, while Table 0.3 provides a list of all tables available in the Gaia DR3 archive.

Table 0.1: Number of sources of a certain type, or the number of sources for which a given data product is available in Gaia DR3.
Data product or source type Number of sources Comments
Total 1 811 709 771
5-parameter astrometry 585 416 709
6-parameter astrometry 882 328 109
2-parameter astrometry 343 964 953
Gaia-CRF3 sources 1 614 173
ICRF3 sources used for frame orientation 2007
Gaia-CRF3 sources used for frame spin 428 034
G-band, mean magnitude 1 806 254 432
GBP-band, mean magnitude 1 542 033 472
GRP-band, mean magnitude 1 554 997 939
Photometric time series 11 754 237
Gaia Andromeda Photometric Survey 1 257 319 Photometric time series for all sources in a 5.5 radius field around M31
Mean radial velocity 33 812 183 GRVS<14, 3100<Teff<14 500 K
GRVS-band, mean magnitude 32 232 187
vbroad 3 524 677 spectral line broadening parameter
Radial velocity time series 1898 Sample of Cepheids and RR Lyrae
BP/RP mean spectra 219 197 643 G<17.65 with small number of exceptions
RVS mean spectra 999 645 AFGK spectral types with SNR>20, and sample of lower SNR spectra
Variable sources 10 509 536 See Table 0.2
Object classification 1 590 760 469
Self-organised map of poorly classified sources 1 30×30 map and prototype spectra
APs from mean BP/RP spectra 470 759 263 G<19, see Table 0.2
APs from mean RVS spectra 5 591 594
Chemical abundances from mean RVS spectra 2 513 593 Up to 12 elements
DIBs from mean RVS spectra 472 584
Non-single stars 813 687 astrometric, spectroscopic, eclipsing, orbits, trends, see Table 0.2
QSO candidates 6 649 162 High completeness, low purity
QSO redshifts 6 375 063
QSO host galaxy detected 64 498
QSO host galaxy light profile 15 867
Galaxy candidates 4 842 342 High completeness, low purity
Galaxy redshifts 1 367 153
Galaxy light profiles 914 837
Solar system objects (SSOs) 158 152 Epoch astrometry and photometry
SSO BP/RP reflectance spectra 60 518
Total galactic extinction maps 5 HEALPix levels 6–9, and optimum HEALPix level
Photometric science alerts 2612 Triggered in the period 25-07-2014 to 28-05-2017
Table 0.2: Further details on the number of sources of a certain type, or the number of sources for which a given data product is available in Gaia DR3.
Data product or source type Number of sources Comments
Variable sources
Total 10 509 536
Classified with supervised machine learning 9 976 881 24 variability types or type groups
Active galactic nuclei 872 228
Cepheids 15 021
Compact companions 6 306
Eclipsing binaries 2 184 477
Long-period variables 1 720 588
Microlensing events 363
Planetary transits 214
RR Lyrae stars 271 779
Short-timescale variables 471 679
Solar-like rotational modulation variables 474 026
Upper-main-sequence oscillators 54 476
Astrophysical parameters from mean BP/RP spectra
Total 470 759 263 G<19
Spectroscopic parameters 470 759 263
Interstellar extinction and distances 470 759 263
MCMC samples from the BP/RP AP estimation 449 297 716
APs assuming an unresolved binary 348 711 151
MCMC samples from BP/RP unresolved binary AP estimation 348 711 151
Evolutionary parameters 128 611 111 mass, age, evolutionary stage
Stars with emission-line classifications 57 511
Sources with spectral types 217 982 837
Hot stars with spectroscopic parameters 2 382 015
Ultra-cool stars 94 158
Cool stars with activity index 1 349 499
Sources with Hα emission measurements 235 384 119
Non-single stars
Total 813 687
Acceleration solutions 338 215
Orbital astrometric solutions 169 227 including astroSpectroSB1 combined solutions
Orbital spectroscopic solutions (SB1/SB2) 220 372 including astroSpectroSB1 combined solutions
Trend spectroscopic solutions 56 808
Eclipsing binaries 87 073 including eclipsingSpectro combined solutions

The astrometric data in Gaia DR3 are the same as those of Gaia EDR3, hence there is a global parallax bias, in the sense Gaia - ‘true’, of about -0.017 mas, which has not been ‘corrected’ in the data. Details are provided by (Lindegren et al. 2020), including a proposed recipe for correcting the parallaxes for the bias as a function of sky position, G magnitude and colour GBP-GRP. The broad-band photometric contents (G, GBP, GRP) are also the same as in Gaia EDR3 with the following exception. For Gaia EDR3 a milli-magnitude level correction was applied to the G-band photometry for sources with 6-parameter and 2-parameter astrometric solutions. This correction was provided in the form of Python code and Astronomical Data Query Language (ADQL) recipes. These corrections are included in Gaia DR3 and should thus not be applied when working with broad-band photometry extracted from the Gaia DR3 data tables in the Gaia archive.

The data collected between 25 July 2014 and 28 May 2017 – during the first 34 months of the Gaia mission – have been processed by the Gaia Data Processing and Analysis Consortium (DPAC), resulting in Gaia DR3. A summary of the release properties is provided in Gaia Collaboration et al. (2022k). The overall scientific validation of the data is described in Babusiaux et al. (2022) and Fabricius et al. (2021) (astrometry, broad-band photometry). Background information on the Gaia  mission and the spacecraft can be found in Gaia Collaboration et al. (2016b), with a more detailed presentation of the Radial Velocity Spectrometer (RVS) in Cropper et al. (2018). In addition, Gaia DR3 is accompanied by dedicated papers, all part of a Special Issue of A&A, that describe the processing and validation of the various data products: Lindegren et al. (2021) for the Gaia DR3 astrometry, Riello et al. (2021) for the Gaia DR3 photometry, and Gaia Collaboration et al. (2022g) for the Gaia celestial reference frame.

The processing of the BP/RP spectra for Gaia DR3 is described in De Angeli et al. (2022), with details on the internal calibration model provided in Carrasco et al. (2021). The external flux calibration is described in Montegriffo et al. (2022) and is based on a set of spectro-photometric calibrators described in Pancino et al. (2021) and references therein. The processing of the RVS spectra and the various data products derived from these spectra is described in Katz et al. (2022) (radial velocity processing and validation), Blomme et al. (2022b) (radial velocities of hot stars), Damerdji et al. (2022) (double-lined spectra), Frémat et al. (2022) (determination of vbroad), Sartoretti et al. (2022) (GRVS magnitudes and the RVS pass-band), and Seabroke and et al. (2022) (mean RVS spectra).

The Gaia Andromeda Photometric Survey consists of broad-band photometric time series for all sources (variable and non-variable) located in a 5.5 radius region centred on M31. This survey is described in Evans et al. (2022) and is based on the photometry presented in Riello et al. (2021).

An overview of the variable source processing and analysis can be found in Eyer et al. (2022). Specific aspects of the variable source processing are described in: Gavras et al. (2022) (cross-match of Gaia DR3 sources with variable sources from the literature); Rimoldini et al. (2022) (machine learning classification of variable sources); Clementini et al. (2022) and Ripepi et al. (2022) (Cepheids and RR Lyrae stars, including radial velocity time series); Lebzelter et al. (2022) (long period variables); Distefano et al. (2022) (solar-like variability and rotational modulation); Marton (2022) (young stellar objects); Wyrzykowski et al. (2022) (microlensing events); Mowlavi et al. (2022) (eclipsing binaries); Gomel et al. (2022) (ellipsoidal variables with possible compact object secondaries); Panahi et al. (2022) (candidate transiting exoplanets); and Carnerero et al. (2022) (active galactic nuclei).

Non-single star solutions are provided for the first time in Gaia DR3, including astrometric (Halbwachs et al. 2022), spectroscopic (Gosset 2022), and eclipsing binaries (Siopis 2022) (where solutions from the combinations of astrometry and radial velocities, or eclipsing binary light curves and radial velocities are also provided). Details on the astrometric determination for systems with sub-stellar companions are provided in Holl et al. (2022b). Relevant to both non-single stars and variable sources, Holl et al. (2022a) discuss how the Gaia scanning law can introduce spurious periods in the analysis of photometric, astrometric, or radial velocity time series.

The extragalactic content of Gaia DR3 is described in Gaia Collaboration et al. (2022b). The process of estimating light profiles of extended objects (resolved galaxies and QSO host galaxies) is detailed in Ducourant et al. (2022), and Delchambre et al. (2022) describe the classification of QSOs and unresolved galaxies and how redshifts are derived for these objects.

The processing and validation of the solar system objects in Gaia DR3 is described in Tanga et al. (2022) (astrometry, photometry, orbits) and in Gaia Collaboration et al. (2022f) (BP/RP reflectance spectra).

Gaia DR3 presents a classification of the majority of sources in the Gaia source list and a large collection of astrophysical data. This data is derived from the combination of basic Gaia observational data, the parallaxes, BP/RP and RVS spectra, and the broad-band photometry. An overview of the processing modules that classify sources and derive astrophysical parameters is provided in Creevey et al. (2022). Fouesneau et al. (2022b) and Delchambre et al. (2022) provide more details on the quality and validation of the stellar and non-stellar parameters, respectively. The latter include total galactic extinction maps and an analysis of outliers in the space of BP/RP spectra in addition to the extragalactic content mentioned above. Details on the extraction of the main astrophysical parameters from the BP/RP spectra is given in Andrae et al. (2022). From the RVS spectra stellar atmospheric parameters and detailed abundances are derived, as well as the parameters of the diffuse interstellar bands present in these spectra. The details are provided by Recio-Blanco and et al. (2022). From the Calcium infrared triplet in the RVS spectra one can also derive a chromospheric activity index. This process is described in Lanzafame et al. (2022).

Nine papers accompanying Gaia DR3 provide an impression on the immense scientific potential of this release. Gaia Collaboration et al. (2022c) presents clean samples of high quality astrophysical parameters of several specific types of stars. Gaia Collaboration et al. (2022i) uses Gaia astrometry, radial velocities and element abundances derived from RVS mean spectra to conduct a chemo-dynamical analysis of Milky Way disc and halo populations. Gaia Collaboration et al. (2022j) discusses the distribution of the diffuse interstellar band at 862 nm in the context of interstellar extinction within a few kpc from the Sun. Gaia Collaboration et al. (2022e) explores non-axisymmetric features in the disc of the Milky Way, spiral arms and the bar, in both configuration and velocity space. Gaia Collaboration et al. (2022a) presents a clean catalogue of binary stars, discussing its completeness and some statistical features of the orbital elements in comparison with external catalogues. In addition, a catalogue of tens of thousands of masses of binary components is provided. Gaia Collaboration et al. (2022f) presents reflectance spectra, derived from BP/RP spectra, for solar system objects, discussing the scientific potential of the combination of accurate orbital data and composition information derived from the reflectance spectra. Gaia Collaboration et al. (2022h) shows how synthetic photometry can be obtained from flux calibrated BP/RP spectra for any pass-bands fully enclosed in the Gaia wavelength range. Applications employing synthetic photometry for a number of well known photometric systems are discussed. Gaia Collaboration et al. (2022d) investigates the properties of high-mass main sequence pulsators, showing that Gaia DR3 data are suitable for the identification of nearby OBAF-type pulsators. Finally, Gaia Collaboration et al. (2022b) summarises the Gaia processing of extragalactic sources, describing the statistical properties of two high purity samples of galaxies and QSOs available in Gaia DR3. For several of the above papers there are accompanying data that are also included in Gaia DR3: a subset of the samples defined in Gaia Collaboration et al. (2022c) (archive tables gaiadr3.gold_sample_*), the synthetic photometry from Gaia Collaboration et al. (2022h) (archive table gaiadr3.synthetic_photometry_gspc), binary component masses from Gaia Collaboration et al. (2022a) (archive table gaiadr3.binary_masses), as well as solar system object osculating orbital elements from Tanga et al. (2022) (archive table gaiadr3.sso_orbits).

Data from Gaia DR3, as well as from Gaia DR1, Gaia DR2, and Gaia EDR3, can be retrieved from the Gaia ESA Archive (GEA), which is accessible from The archive also provides various tutorials on data access and data queries plus an integrated data model (i.e., description of the various fields in the data tables). In addition, Luri et al. (2018) provide concrete advice on how to deal with Gaia astrometry, with recommendations on how best to estimate distances from parallaxes. The Gaia archive features a visualisation service which can be used for quick initial explorations of the entire Gaia DR3 data set. Carefully validated, pre-computed cross matches between Gaia DR3 and a selected set of large surveys is provided, with details described in Marrese et al. (2019, 2022). Finally, Gaia DR3 contains the (intended) pointing of the Gaia telescopes as a function of time (commanded_scan_law table) and simulated Gaia catalogues (gaia_universe_model and gaia_source_simulation tables).

Gaia DR3 includes large amounts of data which are not easily stored in standard tabular form. This concerns the mean BP/RP/RVS spectra, photometric time series, and Markov-Chain Monte Carlo samples. Instead, these products are hosted by a dedicated service designed to handle massive data requests that is accessible via the DataLink protocol. How to discover and access the DataLink products in Gaia DR3 is described here.

Through the Gaia DR3 web pages several supplementary sets of information will be provided:

Summary of miscellaneous links:

Table 0.3: Summary of all the tables available in the Gaia DR3 archive. For an extensive description of these tables and their contents see Chapter 20.
Table name Short description

Main source catalogue
Astrophysical parameter tables
astrophysical_parameters main table with astrophysical parameters
astrophysical_parameters_supp additional astrophysical parameters
total_galactic_extinction_map extinction map at 4 HEALPix levels
total_galactic_extinction_map_opt extinction map at optimum resolution
oa_neuron_information content of the self-organized map of poorly classified sources
oa_neuron_xp_spectra prototype BP/RP spectra for neuron of the above SOM
mcmc_samples_gsp_phot MCMC samples from BP/RP AP estimation
mcmc_samples_msc MCMC samples from BP/RP unresolved binary AP estimation
Auxiliary tables
commanded_scan_law commanded attitude of the Gaia spacecraft
dr2_neighbourhood Gaia DR2 to Gaia DR3 match table
allwise_best_neighbour AllWISE: best neighbour for each matched Gaia source
allwise_neighbourhood AllWISE: all good neighbours for each matched Gaia source
apassdr9_best_neighbour APASS DR9
apassdr9_join Convenience table for joining APASS DR9 with cross-match results
gsc23_best_neighbour GSC2.3
hipparcos2_best_neighbour Hipparcos2
panstarrs1_best_neighbour Pan-STARRS DR1
ravedr5_best_neighbour RAVE DR5
ravedr6_best_neighbour RAVE DR6
sdssdr13_best_neighbour SDSS DR13
skymapperdr2_best_neighbour SkyMapper DR2
tmass_psc_xsc_best_neighbour 2MASS
tycho2tdsc_merge_best_neighbour Tycho-2 merged with TDSC
urat1_best_neighbour URAT-1
Extra–galactic tables
galaxy_candidates classification/characterisation parameters of galaxy candidates
galaxy_catalogue_name catalogues used to select galaxies for morphological parameterization
qso_candidates classification/characterisation parameters of QSO candidates
qso_catalogue_name catalogues used to select QSOs for morphological parameterization
Non-single stars tables
nss_two_body_orbit non-single-star orbital models
nss_acceleration_astro non-single-star astrometric models for sources with non-linear proper motions
nss_non_linear_spectro non-single-star orbital models for spectroscopic binaries
nss_vim_fl non-single-star models for Variability Induced Mover solutions
Epoch photometry
epoch_photometry light curves in G, GBP, and GRP
Reference frame
gaia_crf3_xm cross-match information for the Gaia-CRF3 sources
agn_cross_id sources whose positions and proper motions define Gaia-CRF3
frame_rotator_source sources used to compute the Gaia-CRF3
Science alerts tables
science_alerts Photometric Science Alerts from 25-07-2014 to 28-05-2017
alerts_mixedin_sourceids identifier for sources linked to transits from primary and other sources
Simulation tables
gaia_source_simulation outputs from the Gaia Object Generator
gaia_universe_model simulated galactic stars from the Gaia Universal Model Simulation
Solar system object tables
sso_source data related to Solar System objects observed by Gaia
sso_observation Solar System object observations
sso_reflectance_spectrum mean BP/RP reflectance spectra of asteroids
Spectroscopic tables
rvs_mean_spectrum RVS mean sampled spectra
xp_summary auxiliary information about the mean BP/RP spectra
xp_continuous_mean_spectrum mean BP/RP spectra in continuous basis function representation
xp_sampled_mean_spectrum BP/RP externally calibrated sampled mean spectrum
Variability tables
vari_summary source_id to vari* table link; statistical parameters of time series
vari_classifier_result variability classification results of all variable source classifiers
vari_classifier_definition descriptions of classifiers used in table vari_classifier_result
vari_classifier_class_definition descriptions of published classes for each classifier
vari_agn information on AGN properties
vari_cepheid information on Cepheid stars
vari_compact_companion information on compact companion candidates
vari_eclipsing_binary properties of eclipsing binaries resulting from the variability analysis
vari_epoch_radial_velocity epoch radial velocity data points for a sub-set of variable stars
vari_rad_vel_statistics statistical parameters of radial velocity time series
vari_long_period_variable information on Long Period Variable stars
vari_microlensing information on microlensing events
vari_ms_oscillator information on main-sequence oscillators
vari_planetary_transit candidate planetary transit events
vari_rotation_modulation information on solar-like stars with rotational modulation
vari_rrlyrae information on RR Lyrae stars
vari_short_timescale information on short-timescale variable sources
Performance verification
binary_masses binary component masses
gold_sample_carbon_stars information on carbon stars golden sample
gold_sample_fgkm_stars information on FGKM stars golden sample
gold_sample_oba_stars information on OBA young disk stars golden sample
gold_sample_solar_analogues information on solar analogues golden sample
gold_sample_spss information on spectrophotometric standard stars golden sample
gold_sample_ucd information on ultra-cool dwarfs golden sample
synthetic_photometry_gspc synthetic photometry based in BP/RP spectra
sso_orbits solar system object osculating orbital elements
List of Figures:
List of Tables: