GDR1.tgas_source

Description

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.

Columns

ColumnTypeUCDUnitDescription
hipintmeta.id.crossHipparcos identifier
tycho2_idvarcharmeta.id.crossTycho 2 identifier
solution_idbigintmeta.id
meta.version
Solution Identifier
source_idbigintmeta.id
meta.main
Unique source identifier
random_indexbigintmeta.codeRandom index used to select subsets
ref_epochdoublemeta.ref
time.epoch
Time[Julian Years]Reference epoch
radoublepos.eq.ra
meta.main
Angle[deg]Right ascension
ra_errordoublestat.error
pos.eq.ra
Angle[mas]Standard error of right ascension
decdoublepos.eq.dec
meta.main
Angle[deg]Declination
dec_errordoublestat.error
pos.eq.dec
Angle[mas]Standard error of declination
parallaxdoublepos.parallaxAngle[mas]Parallax
parallax_errordoublestat.error
pos.parallax
Angle[mas]Standard error of parallax
pmradoublepos.pm
pos.eq.ra
Angular Velocity[mas/year]Proper motion in right ascension direction
pmra_errordoublestat.error
pos.pm
pos.eq.ra
Angular Velocity[mas/year]Standard error of proper motion in right ascension direction
pmdecdoublepos.pm
pos.eq.dec
Angular Velocity[mas/year]Proper motion in declination direction
pmdec_errordoublestat.error
pos.pm
pos.eq.dec
Angular Velocity[mas/year]Standard error of proper motion in declination direction
ra_dec_corrfloatstat.correlationCorrelation between right ascension and declination
ra_parallax_corrfloatstat.correlationCorrelation between right ascension and parallax
ra_pmra_corrfloatstat.correlationCorrelation between right ascension and proper motion in right ascension
ra_pmdec_corrfloatstat.correlationCorrelation between right ascension and proper motion in declination
dec_parallax_corrfloatstat.correlationCorrelation between declination and parallax
dec_pmra_corrfloatstat.correlationCorrelation between declination and proper motion in right ascension
dec_pmdec_corrfloatstat.correlationCorrelation between declination and proper motion in declination
parallax_pmra_corrfloatstat.correlationCorrelation between parallax and proper motion in right ascension
parallax_pmdec_corrfloatstat.correlationCorrelation between parallax and proper motion in declination
pmra_pmdec_corrfloatstat.correlationCorrelation between proper motion in right ascension and proper motion in declination
astrometric_n_obs_alintmeta.numberTotal number of observations AL
astrometric_n_obs_acintmeta.numberTotal number of observations AC
astrometric_n_good_obs_alintmeta.numberNumber of good observations AL
astrometric_n_good_obs_acintmeta.numberNumber of good observations AC
astrometric_n_bad_obs_alintmeta.numberNumber of bad observations AL
astrometric_n_bad_obs_acintmeta.numberNumber of bad observations AC
astrometric_delta_qfloatstat.valueHipparcos/Gaia data discrepancy (Hipparcos subset of TGAS only)
astrometric_excess_noisedoublestat.valueAngle[mas]Excess noise of the source
astrometric_excess_noise_sigdoublestat.valueSignificance of excess noise
astrometric_primary_flagtinyintmeta.codePrimary or seconday
astrometric_relegation_factorfloatarith.factorRelegation factor
astrometric_weight_alfloatstat.weight
stat.mean
Angle[mas^-2]Mean astrometric weight of the source
astrometric_weight_acfloatstat.weight
stat.mean
Angle[mas^-2]Mean astrometric weight of the source
astrometric_priors_usedintType of prior used in the astrometric solution
matched_observationssmallintmeta.numberAmount of observations matched to this source
duplicated_sourcetinyintSource with duplicate sources
scan_direction_strength_k1floatDegree of concentration of scan directions across the source
scan_direction_strength_k2floatDegree of concentration of scan directions across the source
scan_direction_strength_k3floatDegree of concentration of scan directions across the source
scan_direction_strength_k4floatDegree of concentration of scan directions across the source
scan_direction_mean_k1floatAngle[deg]Mean position angle of scan directions across the source
scan_direction_mean_k2floatAngle[deg]Mean position angle of scan directions across the source
scan_direction_mean_k3floatAngle[deg]Mean position angle of scan directions across the source
scan_direction_mean_k4floatAngle[deg]Mean position angle of scan directions across the source
phot_g_n_obsintmeta.numberNumber of observations contributing to G photometry
phot_g_mean_fluxdoublephot.flux
stat.mean
em.opt
Flux[e-/s]G-band mean flux
phot_g_mean_flux_errordoublestat.error
phot.flux
stat.mean
em.opt
Flux[e-/s]Error on G-band mean flux
phot_g_mean_magdoublephot.mag
stat.mean
em.opt
Magnitude[mag]G-band mean magnitude
phot_variable_flagvarcharmeta.code
src.var
Photometric variability flag
ldoublepos.galactic.lonAngle[deg]Galactic longitude
bdoublepos.galactic.latAngle[deg]Galactic latitude
ecl_londoublepos.ecliptic.lonAngle[deg]Ecliptic longitude
ecl_latdoublepos.ecliptic.latAngle[deg]Ecliptic latitude

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