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I/337               Gaia DR1                          (Gaia Collaboration, 2016)

Gaia DR1 data. Gaia collaboration <Astron. Astrophys., 595, A1-A7, A133 (2016)> =2016A&A...595A...1G =2016yCat.1337....0G
ADC_Keywords: Surveys ; Positional data ; Proper motions ; Parallaxes, trigonometric Mission_Name: Gaia Keywords: catalogs - astrometry - parallaxes - proper motions - surveys Abstract: Gaia Data Release 1 (DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained, essentially by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. For about two million of the brighter stars (down to magnitude ∼11.5) we obtain positions, parallaxes, and proper motions to Hipparcos- type precision or better. For these stars, systematic errors depending for example on position and colour are at a level of ±0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to ∼10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03mas/yr. The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24mas/yr. Description: Gaia DR1 is based on observations collected between 25 July 2014 and 16 September 2015. Gaia DR1 contains positions (RA,DE) 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", Michalik et al., 2015A&A...583A..68M). 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 (paper with detailed description (Michalik et al., 2015A&A...574A.115M); paper describing theory and background (Michalik et al., 2014A&A...571A..85M); paper describing quasar extension (Michalik & Lindegren, 2016A&A...586A..26M)). 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 based on these high-cadence measurements are contained in Gaia DR1. Positions (RA,DE) and G magnitudes for 2152 ICRF quasars (F. Mignard et al., 2016, A&A, in press.). The Gaia Archive DR1 data is available at archives.esac.esa.int/gaia. Tgas and Gaia Sources can be downloaded as VOTables, FITS or CSV at http://1016243957.rsc.cdn77.org/Gaia/ If you use public Gaia DR1 data in your paper, please take note of our guide on how to acknowledge and cite Gaia DR1: http://gaia.esac.esa.int/documentation/GDR1/Miscellaneous/seccreditandcitationinstructions.html File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file gaia.sam 494 1000 Sample of GaiaSource data tgas.dat 513 2057050 TGAS: 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 (TgasSource) tgasptyc.dat 552 2057050 TGAS supplement with BT and VT magnitudes varsum.dat 50 3194 Variability summary of sources with photvariableflag = "VARIABLE" in the GaiaSource table (VariableSummary) cepheid.dat 200 599 Cepheid stars identified in table VariableSummary as classification="CEP" rrlyrae.dat 183 2595 RRLyrae stars identified in table VariableSummary as classification="RRLYR" (Rrlyrae) fovparam.dat 131 3194 *Statistical parameters of field-of-view time series (PhotVariableTimeSeriesGfovStatisticalParameters) fov.dat 87 233181 Photometric variable time series G field-of-view (PhotVariableTimeSeriesGfov) qso.dat 125 2191 *Auxilliary Quasar Solution for the QSOs that were matched to ICRF2 sources (qso_icrf2)
Note on fovparam.dat: from G-band time series, only including observations with rejectedbyvariability_processing=false, as found in table PhotVariableTimeSeriesGfov. Note on qso.dat: 111 sources in this table are not present in the gaia_source table in the Gaia Data Release 1.
See also: I/259 : The Tycho-2 Catalogue (Hog+ 2000) archives.esac.esa.int/gaia : Gaia Home Page http://1016243957.rsc.cdn77.org/Gaia : Download Tgas and Gaia Sources Byte-by-byte Description of file: gaia.sam
Bytes Format Units Label Explanations
1- 14 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 (ra) 16- 29 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0 (dec) 31- 49 I19 --- SolID Solution ID (solution_id) (G1) 51- 69 I19 --- Source Source ID (source_id) (G2) 71- 80 I10 --- RandomI Random index used to select subsets (random_index) (G3) 82- 87 F6.1 yr Epoch [2015.0] Reference epoch in Julian years (ref_epoch) (G4) 89- 94 F6.3 mas e_RAdeg Standard error of right ascension (ra_error) 96-101 F6.3 mas e_DEdeg Standard error of declination (dec_error) 103-108 F6.2 mas Plx ? Absolute barycentric stellar parallax of the source at the reference epoch Epoch (parallax) 110-113 F4.2 mas e_Plx ? Standard error of parallax (parallax_error) 115-123 F9.3 mas/yr pmRA ? Proper motion in right ascension direction (pmRA) (G5) 125-130 F6.3 mas/yr e_pmRA ? Standard error of proper motion in right ascension direction (pmra_error) 132-140 F9.3 mas/yr pmDE ? Proper motion in declination direction (pmdec) (G6) 142-147 F6.3 mas/yr e_pmDE ? Standard error of proper motion in declination direction (pmdec_error) 149-154 F6.3 --- RADEcor Correlation between right ascension and declination (radeccorr) 156-161 F6.3 --- RAPlxcor ? Correlation between right ascension and parallax (raparallaxcorr) 163-168 F6.3 --- RApmRAcor ? Correlation between right ascension and proper motion in right ascension (rapmracorr) 170-175 F6.3 --- RApmDEcor ? Correlation between right ascension and proper motion in declination (rapmdeccorr) 177-182 F6.3 --- DEPlxcor ? Correlation between declination and parallax (decparallaxcorr) 184-189 F6.3 --- DEpmRAcor ? Correlation between declination and proper motion in right ascension (decpmracorr) 191-196 F6.3 --- DEpmDEcor ? Correlation between declination and proper motion in declination (decpmdeccorr) 198-203 F6.3 --- PlxpmRAcor ? Correlation between parallax and proper motion in right ascension (parallaxpmracorr) 205-210 F6.3 --- PlxpmDEcor ? Correlation between parallax and proper motion in declination (parallaxpmdeccorr) 212-217 F6.3 --- pmRApmDEcor ? Correlation between proper motion in right ascension and proper motion in declination (pmrapmdeccorr) 219-222 I4 --- NAL Total number of observations AL (astrometricnobs_al) (G7) 224-227 I4 --- NAC Total number of observations AC (astrometricnobs_ac) (G8) 229-232 I4 --- NgAL Number of good observations AL (astrometricngoodobsal) (G9) 234-237 I4 --- NgAC Number of good observations AC (astrometricngoodobsac) (G9) 239-242 I4 --- NbAL Number of bad observations AL (astrometricnbadobsal) (G10) 244-246 I3 --- NbAC Number of bad observations AC (astrometricnbadobsac) (G10) 248-255 F8.2 --- DQ ?=- Hipparcos/Gaia data discrepancy (Hipparcos subset of TGAS only) (astrometricdeltaq) (G11) 257-261 F5.2 mas epsi Excess noise of the source (astrometricexcessnoise) (G12) 263-272 E10.3 --- sepsi [] Significance of excess noise (astrometricexcessnoise_sig) (G13) 274 I1 --- APF [0/1] Primary or secondary (astrometricprimaryflag) (G14) 276-281 F6.2 --- ARF Relegation factor (astrometricrelegationfactor) 283-289 F7.3 mas-2 WAL Mean astrometric weight of the source in the AL direction (astrometricweightal) 291-299 E9.3 mas-2 WAC ? Mean astrometric weight of the source in the AC direction (astrometricweightac) 301 I1 --- Apr [0/6] Type of prior used in in the astrometric solution (astrometricpriorsused) (G15) 303-305 I3 --- MatchObs Amount of observations matched to this source (matched_observations) (G16) 307 I1 --- Dup [0/1] Source with duplicate sources (duplicated_source) (G17) 309-313 F5.3 --- sK1 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k1) (G18) 315-319 F5.3 --- sK2 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k2) (G18) 321-325 F5.3 --- sK3 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k3) (G18) 327-331 F5.3 --- sK4 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k4) (G18) 333-345 F13.8 deg mK1 Mean position angle of scan directions across the source (scandirectionmean_k1) (G19) 347-358 F12.8 deg mK2 Mean position angle of scan directions across the source (scandirectionmean_k2) (G19) 360-371 F12.8 deg mK3 Mean position angle of scan directions across the source (scandirectionmean_k3) (G19) 373-384 F12.8 deg mK4 Mean position angle of scan directions across the source (scandirectionmean_k4) (G19) 386-389 I4 --- o_<Gmag> Number of observations contributing to G photometry (photgn_obs) 391-401 E11.5 e-/s <FG> G-band mean flux (photgmean_flux) 403-413 E11.5 e-/s e_<FG> Error on G-band mean flux (photgmeanfluxerror) 415-420 F6.3 mag <Gmag> G-band mean magnitude (photgmean_mag) (G20) 422-434 A13 --- Var Photometric variability flag (photvariableflag) (G21) 436-449 F14.10 deg GLON Galactic longitude at epoch 2015.0 (l) 451-464 F14.10 deg GLAT Galactic latitude at epoch 2015.0 (b) 466-479 F14.10 deg ELON Ecliptic longitude at epoch 2015.0 (ecl_lon) 481-494 F14.10 deg ELAT Ecliptic latitude at epoch 2015.0 (ecl_lat)
Byte-by-byte Description of file: tgas.dat
Bytes Format Units Label Explanations
1- 6 I6 --- HIP ?=- Hipparcos identifier (hip) 8- 19 A12 --- TYC2 Tycho 2 identifier (tycho2_id) 21- 39 I19 --- SolID Solution ID (solution_id) (G1) 41- 59 I19 --- Source Source ID (source_id) (G2) 61- 67 I7 --- RandomI Random index used to select subsets (random_index) (G3) 69- 74 F6.1 yr Epoch [2015.0] Reference epoch in Julian years (ref_epoch) (G4) 76- 89 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 (ra) 91- 96 F6.3 mas e_RAdeg Standard error of right ascension (ra_error) 98-111 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0 (dec) 113-118 F6.3 mas e_DEdeg Standard error of declination (dec_error) 120-125 F6.2 mas Plx Absolute barycentric stellar parallax of the source at the reference epoch Epoch (parallax) 127-130 F4.2 mas e_Plx Standard error of parallax (parallax_error) 132-140 F9.3 mas/yr pmRA Proper motion in right ascension direction (pmRA) (G5) 142-147 F6.3 mas/yr e_pmRA Standard error of proper motion in right ascension direction (pmra_error) 149-157 F9.3 mas/yr pmDE Proper motion in declination direction (pmdec) (G6) 159-164 F6.3 mas/yr e_pmDE Standard error of proper motion in declination direction (pmdec_error) 166-171 F6.3 --- RADEcor Correlation between right ascension and declination (radeccorr) 173-178 F6.3 --- RAPlxcor Correlation between right ascension and parallax (raparallaxcorr) 180-185 F6.3 --- RApmRAcor Correlation between right ascension and proper motion in right ascension (rapmracorr) 187-192 F6.3 --- RApmDEcor Correlation between right ascension and proper motion in declination (rapmdeccorr) 194-199 F6.3 --- DEPlxcor Correlation between declination and parallax (decparallaxcorr) 201-206 F6.3 --- DEpmRAcor Correlation between declination and proper motion in right ascension (decpmracorr) 208-213 F6.3 --- DEpmDEcor Correlation between declination and proper motion in declination (decpmdeccorr) 215-220 F6.3 --- PlxpmRAcor Correlation between parallax and proper motion in right ascension (parallaxpmracorr) 222-227 F6.3 --- PlxpmDEcor Correlation between parallax and proper motion in declination (parallaxpmdeccorr) 229-234 F6.3 --- pmRApmDEcor Correlation between proper motion in right ascension and proper motion in declination (pmrapmdeccorr) 236-239 I4 --- NAL Total number of observations AL (astrometricnobs_al) (G7) 241-244 I4 --- NAC Total number of observations AC (astrometricnobs_ac) (G8) 246-249 I4 --- NgAL Number of good observations AL (astrometricngoodobsal) (G9) 251-254 I4 --- NgAC Number of good observations AC (astrometricngoodobsac) (G9) 256-257 I2 --- NbAL Number of bad observations AL (astrometricnbadobsal) (G10) 259-261 I3 --- NbAC Number of bad observations AC (astrometricnbadobsac) (G10) 263-270 F8.2 --- DQ ?=- Hipparcos/Gaia data discrepancy (Hipparcos subset of TGAS only) (astrometricdeltaq) (G11) 272-276 F5.2 mas epsi Excess noise of the source (astrometricexcessnoise) (G12) 278-286 E9.2 --- sepsi Significance of excess noise (astrometricexcessnoise_sig) (G13) 288 I1 --- APF [1] Primary or secondary (astrometricprimaryflag) (G14) 290-295 F6.2 --- ARF Relegation factor (astrometricrelegationfactor) 297-303 F7.3 mas-2 WAL Mean astrometric weight of the source in the AL direction (astrometricweightal) 305-312 E8.3 mas-2 WAC ? Mean astrometric weight of the source in the AC direction (astrometricweightac) 314 I1 --- Apr [3/5] Type of prior used in in the astrometric solution (astrometricpriorsused) (G15) 316-318 I3 --- MatchObs Amount of observations matched to this source (matched_observations) (G16) 320 I1 --- Dup [0/1] Source with duplicate sources (duplicated_source) (G17) 322-326 F5.3 --- sK1 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k1) (G18) 328-332 F5.3 --- sK2 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k2) (G18) 334-338 F5.3 --- sK3 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k3) (G18) 340-344 F5.3 --- sK4 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k4) (G18) 346-358 F13.8 deg mK1 Mean position angle of scan directions across the source (scandirectionmean_k1) (G19) 360-371 F12.8 deg mK2 Mean position angle of scan directions across the source (scandirectionmean_k2) (G19) 373-384 F12.8 deg mK3 Mean position angle of scan directions across the source (scandirectionmean_k3) (G19) 386-397 F12.8 deg mK4 Mean position angle of scan directions across the source (scandirectionmean_k4) (G19) 399-402 I4 --- o_<Gmag> Number of observations contributing to G photometry (photgn_obs) 404-418 F15.5 e-/s <FG> G-band mean flux (photgmean_flux) 420-432 F13.5 e-/s e_<FG> Error on G-band mean flux (photgmeanfluxerror) 434-439 F6.3 mag <Gmag> G-band mean magnitude (photgmean_mag) (G20) 441-453 A13 --- Var Photometric variability flag (photvariableflag) (G21) 455-468 F14.10 deg GLON Galactic longitude at epoch 2015.0 (l) 470-483 F14.10 deg GLAT Galactic latitude at epoch 2015.0 (b) 485-498 F14.10 deg ELON Ecliptic longitude at epoch 2015.0 (ecl_lon) 500-513 F14.10 deg ELAT Ecliptic latitude at epoch 2015.0 (ecl_lat)
Byte-by-byte Description of file: tgasptyc.dat
Bytes Format Units Label Explanations
1- 6 I6 --- HIP ?=- Hipparcos identifier (hip) 8- 19 A12 --- TYC2 Tycho 2 identifier (tycho2_id) 21- 39 I19 --- SolID Solution ID (solution_id) (G1) 41- 59 I19 --- Source Source ID (source_id) (G2) 61- 67 I7 --- RandomI Random index used to select subsets (random_index) (G3) 69- 74 F6.1 yr Epoch [2015.0] Reference epoch in Julian years (ref_epoch) (G4) 76- 89 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 (ra) 91- 96 F6.3 mas e_RAdeg Standard error of right ascension (ra_error) 98-111 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0 (dec) 113-118 F6.3 mas e_DEdeg Standard error of declination (dec_error) 120-125 F6.2 mas Plx Absolute barycentric stellar parallax of the source at the reference epoch Epoch (parallax) 127-130 F4.2 mas e_Plx Standard error of parallax (parallax_error) 132-140 F9.3 mas/yr pmRA Proper motion in right ascension direction (pmRA) (G5) 142-147 F6.3 mas/yr e_pmRA Standard error of proper motion in right ascension direction (pmra_error) 149-157 F9.3 mas/yr pmDE Proper motion in declination direction (pmdec) (G6) 159-164 F6.3 mas/yr e_pmDE Standard error of proper motion in declination direction (pmdec_error) 166-171 F6.3 --- RADEcor Correlation between right ascension and declination (radeccorr) 173-178 F6.3 --- RAPlxcor Correlation between right ascension and parallax (raparallaxcorr) 180-185 F6.3 --- RApmRAcor Correlation between right ascension and proper motion in right ascension (rapmracorr) 187-192 F6.3 --- RApmDEcor Correlation between right ascension and proper motion in declination (rapmdeccorr) 194-199 F6.3 --- DEPlxcor Correlation between declination and parallax (decparallaxcorr) 201-206 F6.3 --- DEpmRAcor Correlation between declination and proper motion in right ascension (decpmracorr) 208-213 F6.3 --- DEpmDEcor Correlation between declination and proper motion in declination (decpmdeccorr) 215-220 F6.3 --- PlxpmRAcor Correlation between parallax and proper motion in right ascension (parallaxpmracorr) 222-227 F6.3 --- PlxpmDEcor Correlation between parallax and proper motion in declination (parallaxpmdeccorr) 229-234 F6.3 --- pmRApmDEcor Correlation between proper motion in right ascension and proper motion in declination (pmrapmdeccorr) 236-239 I4 --- NAL Total number of observations AL (astrometricnobs_al) (G7) 241-244 I4 --- NAC Total number of observations AC (astrometricnobs_ac) (G8) 246-249 I4 --- NgAL Number of good observations AL (astrometricngoodobsal) (G9) 251-254 I4 --- NgAC Number of good observations AC (astrometricngoodobsac) (G9) 256-257 I2 --- NbAL Number of bad observations AL (astrometricnbadobsal) (G10) 259-261 I3 --- NbAC Number of bad observations AC (astrometricnbadobsac) (G10) 263-270 F8.2 --- DQ ?=- Hipparcos/Gaia data discrepancy (Hipparcos subset of TGAS only) (astrometricdeltaq) (G11) 272-276 F5.2 mas epsi Excess noise of the source (astrometricexcessnoise) (G12) 278-286 E9.2 --- sepsi Significance of excess noise (astrometricexcessnoise_sig) (G13) 288 I1 --- APF [1] Primary or secondary (astrometricprimaryflag) (G14) 290-295 F6.2 --- ARF Relegation factor (astrometricrelegationfactor) 297-303 F7.3 mas-2 WAL Mean astrometric weight of the source in the AL direction (astrometricweightal) 305-312 E8.3 mas-2 WAC ? Mean astrometric weight of the source in the AC direction (astrometricweightac) 314 I1 --- Apr [3/5] Type of prior used in in the astrometric solution (astrometricpriorsused) (G15) 316-318 I3 --- MatchObs Amount of observations matched to this source (matched_observations) (G16) 320 I1 --- Dup [0/1] Source with duplicate sources (duplicated_source) (G17) 322-326 F5.3 --- sK1 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k1) (G18) 328-332 F5.3 --- sK2 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k2) (G18) 334-338 F5.3 --- sK3 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k3) (G18) 340-344 F5.3 --- sK4 [0/1] Degree of concentration of scan directions across the source (scandirectionstrength_k4) (G18) 346-358 F13.8 deg mK1 Mean position angle of scan directions across the source (scandirectionmean_k1) (G19) 360-371 F12.8 deg mK2 Mean position angle of scan directions across the source (scandirectionmean_k2) (G19) 373-384 F12.8 deg mK3 Mean position angle of scan directions across the source (scandirectionmean_k3) (G19) 386-397 F12.8 deg mK4 Mean position angle of scan directions across the source (scandirectionmean_k4) (G19) 399-402 I4 --- o_<Gmag> Number of observations contributing to G photometry (photgn_obs) 404-418 F15.5 e-/s <FG> G-band mean flux (photgmean_flux) 420-432 F13.5 e-/s e_<FG> Error on G-band mean flux (photgmeanfluxerror) 434-439 F6.3 mag <Gmag> G-band mean magnitude (photgmean_mag) (G20) 441-453 A13 --- Var Photometric variability flag (photvariableflag) (G21) 455-468 F14.10 deg GLON Galactic longitude at epoch 2015.0 (l) 470-483 F14.10 deg GLAT Galactic latitude at epoch 2015.0 (b) 485-498 F14.10 deg ELON Ecliptic longitude at epoch 2015.0 (ecl_lon) 500-513 F14.10 deg ELAT Ecliptic latitude at epoch 2015.0 (ecl_lat) 515-526 A12 --- TYC TYC2 or TYC1 designation 528-533 F6.3 mag BTmag ? Tycho-2 or HIP BT magnitude 535-539 F5.3 mag e_BTmag ? rms uncertainty on BTmag 541-546 F6.3 mag VTmag ? Tycho-2 or HIP VT magnitude 548-552 F5.3 mag e_VTmag ? rms uncertainty on VTmag
Byte-by-byte Description of file: varsum.dat
Bytes Format Units Label Explanations
1- 18 I18 --- SolID Solution ID (solution_id) (G1) 20- 38 I19 --- Source Source ID (source_id) (G2) 40- 44 F5.3 d-1 F1 Fundamental frequency 1 (photvariablefundam_freq1) (1) 46- 50 A5 --- Class Photometric variability classification (classification) (2)
Note (1): Identified 1st fundamental frequencies in the photometric G band, copied from either the cepheid,dat or rrlyrae.dat table depending on the value of classification. Note (2): Photometric variability classification for the types included in this data release: "RRLYR" (RR Lyrae) or "CEP" (Cepheid). The tables cepheid.dat and rrlyrae.dat contain detailed results for each type.
Byte-by-byte Description of file: cepheid.dat
Bytes Format Units Label Explanations
1- 5 A5 --- TBest Best type classification (typebestclassification) (1) 7- 12 A6 --- TBest2 Best subclassification estimate (type2bestsub_classification) (2) 14- 27 A14 --- Mbest Best mode classification estimate (modebestclassification) (3) 29- 46 A18 --- SolID Solution ID (solution_id) (G1) 48- 66 A19 --- Source Source ID (source_id) (G2) 68- 78 F11.8 d P1 Period (p1) (G22) 80- 90 F11.8 d e_P1 rms uncertainty on P1 (e_p1) (G23) 92-104 F13.8 d EpG Epoch of the maximum of the light curve in the G band (epoch_g) (G24) 106-118 F13.8 d e_EpG Uncertainty on the epoch parameter EpG (epochgerror) (G25) 120-126 F7.4 mag <Gmag> Intensity-averaged magnitude in the G band (intaverageg) (G26) 128-132 F5.3 mag e_<Gmag> Uncertainty on <Gmag> (intaverageg_error) (G27) 134-138 F5.3 mag AmpG Peak-to-peak amplitude of the G band light curve (peaktopeak_g) (G28) 140-144 F5.3 mag e_AmpG Uncertainty on AmpG (peaktopeakgerror) (G29) 146 I1 --- NHP1 Number of harmonics used to model P1 of the light curve (numharmonicsforp1) (G30) 148-152 F5.3 --- R21G ?=- Fourier decomposition parameter R21=A2/A1 (for G band) (r21_g) (G31) 154-158 F5.3 --- e_R21G ?=- Uncertainty on R21G (r21gerror) (G32) 160-164 F5.3 --- phi21G ?=- Fourier decomposition parameter phi21=phi2-2*phi1 (for G band) (G33) 166-170 F5.3 --- e_phi21G ?=- Uncertainty on phi21G (phi21gerror) 172-185 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 187-200 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0
Note (1): Best type classification estimate out of: "DCEP", "T2CEP", "ACEP" (type best classification): Classification of a Cepheid into DCEP, T2CEP or ACEP using the period-luminosity relations, which are different for the three different types of Cepheids. Note (2): Best subclassification estimate for type best classification="T2CEP" out of: "BL HER", "W VIR","RV TAU" (type2 best sub classification): Sub-classification of a T2CEP Cepheids into BL Herculis, W Virginis or RV Tauris sub-types depending on the source periodicity. Note (3): Best mode classification estimate as follows: FUNDAMENTAL = fundamental mode for type best classification="DCEP" or "ACEP" FIRST OVERTONE = first overtone for type best classification="DCEP" or "ACEP" SECOND OVERTONE = second overtone for type best classification="DCEP" or "ACEP" UNDEFINED = if mode could not be clearly determined for type best classification="DCEP" or "ACEP" NOT APPLICABLE = when type best classification="T2CEP" Cepheid pulsation mode is assigned using the period-luminosity relations, which are different for the various pulsation modes, and the plot of the Fourier parameter R21 vs P1.
Byte-by-byte Description of file: rrlyrae.dat
Bytes Format Units Label Explanations
1- 4 A4 --- TBest Best RR Lyrae classification estimate (best_classification) (1) 6- 23 I18 --- SolID Solution ID (solution_id) (G1) 25- 43 I19 --- Source Source ID (source_id) (G2) 45- 54 F10.8 d P1 Period (p1) (G22) 56- 65 F10.8 d e_P1 rms uncertainty on P1 (e_p1) (G23) 67- 79 F13.8 d EpG Epoch of the maximum of the light curve in the G band (epoch_g) (G24) 81- 90 F10.8 d e_EpG Uncertainty on the epoch parameter EpG (epochgerror) (G25) 92- 97 F6.3 mag <Gmag> Intensity-averaged magnitude in the G band (intaverageg) (G26) 99-103 F5.3 mag e_<Gmag> Uncertainty on <Gmag> (intaverageg_error) (G27) 105-109 F5.3 mag AmpG Peak-to-peak amplitude of the G band light curve (peaktopeak_g) (G28) 111-115 F5.3 mag e_AmpG Uncertainty on AmpG (peaktopeakgerror) (G29) 117 I1 --- NHP1 [1/8] Number of harmonics used to model P1 of the light curve (numharmonicsforp1) (G30) 119-126 F8.6 --- R21G ?=- Fourier decomposition parameter R21=A2/A1 (for G band) (r21_g) (G31) 128-135 F8.6 --- e_R21G ?=- Uncertainty on R21G (r21gerror) (G32) 137-144 F8.6 --- phi21G ?=- Fourier decomposition parameter phi21=phi2-2*phi1 (for G band) (G33) 146-153 F8.6 --- e_phi21G ?=- Uncertainty on phi21G (phi21gerror) 155-168 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 170-183 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0
Note (1): Classification of an RR Lyrae star according to the pulsation mode: RRc for first overtone and RRab for fundamental mode, obtained using the period-amplitude diagram in the G-band and the plots of the Fourier parameters R21 and Phi2 vs period.
Byte-by-byte Description of file: fovparam.dat
Bytes Format Units Label Explanations
1- 18 I18 --- SolID Solution ID (solution_id) (G1) 20- 38 I19 --- Source Source ID (source_id) (G2) 40- 42 I3 --- Nobs Number of processed G-band observations for variability analyses (numobservationsprocessed) (1) 44- 50 F7.2 d ObsTime Mean observation time (with respect to T0) of G-band time series (meanobstime) (2) 52- 57 F6.3 mag b_Gmag Minimum magnitude of the G-band time series (minimum) 59- 64 F6.3 mag B_Gmag Maximum magnitude of the G-band time series (maximum) 68- 73 F6.3 mag <Gmag> Mean magnitude of the G-band time series (mean) 75- 80 F6.3 mag GmagMed Median magnitude of the G-band time series (median) 82- 86 F5.3 mag Range Difference between the highest and lowest magnitude of the G-band time series (range) 88- 92 F5.3 mag stddev Square root of the unweighted variance of the G-band time series values (std_dev) 94- 99 F6.3 --- Ske Standardized unweighted skewness of the G-band time series values (skewness) 101-106 F6.3 --- Kur Standardized unweighted kurtosis of the G-band time series values (kurtosis) 108-113 F6.2 d Dur Time duration of the G-band time series (time_duration) 115-119 F5.3 mag MAD Median Absolute Deviation of the G-band time series values (medianabsolutedeviation) 121-125 F5.3 --- Abbe Abbe value of the G-band time series values (3) 127-131 F5.3 mag IQR Interquartile range of the time series values (4)
Note (1): The number of processed observations for variability analyses of this source. Note (2): Gaia barycentric light-travel time corrected FOV observation times with respect to reference time T0=2455197.5days (=J2010.0=2010-01-01T00:00:00). Note (3): Let {ti, yi} be a time-sorted time series of size N, such that ti<ti+1 for all i<N. The Abbe value A is defined as A=[N/2(N-1)]/[Σ{i=1,N-1}((yi+1-yi)2/[Σ{i=1,N-}{yi-<y>)] where <y> is the unweighted mean. Note (4): The difference between the (unweighted) 75th and 25th percentile values: IQR=P75-P25.
Byte-by-byte Description of file: fov.dat
Bytes Format Units Label Explanations
1- 18 I18 --- SolID Solution ID (solution_id) (G1) 20- 38 I19 --- Source Source ID (source_id) (G2) 40- 46 F7.2 d ObsTime Barycentric light-travel time corrected timestamp for each FOV observation (observation_time) (1) 48- 62 F15.5 e-/s FG G-band flux for each FOV observation (g_flux) 66- 78 F13.5 e-/s e_FG Estimated G-band flux uncertainty for each FOV observation (gfluxerror) 80- 85 F6.3 mag Gmag G-band magnitude for each FOV observation (g_magnitude) (2) 87 I1 --- Rej [0/1] 1 (true) when this FOV observation was excluded from variability analyses (rejectedbyvariability_processing) (3)
Note (1): Field-of-view transit averaged observation time in units of Barycentric JD (in TCB) in days -2455197.5, computed as follows. First the observation time is converted from On-board Mission Time (OBMT) into Julian date in TCB (Temps Coordonnee Barycentrique). Next a correction is applied for the light-travel time to the Solar system barycentre, resulting in Barycentric Julian Date (BJD). Finally, an offset of 2455197.5 days is applied (corresponding to a reference time T_0 at 2010-01-01T00:00:00) to have a conveniently small numerical value. Although the centroiding time accuracy of the individual CCD observations is (much) below 1 ms, this per-FoV observation time is averaged over typically 9 CCD observations taken in a time range of about 44 sec. Note (2): G-band magnitude for the field-of-view transit observation, computed from the FG field using magnitude zero-point defined in ExtPhotZeroPoint. Note (3): Observations with this flag true (1) have been excluded from the variability result in tables varsum.dat, cepheid.dat, rrlyrae.dat, and fovparam.dat.
Byte-by-byte Description of file: qso.dat
Bytes Format Units Label Explanations
1- 19 I19 --- SolID Solution ID (solution_id) (G1) 21- 39 I19 --- Source Source ID (source_id) (G2) (1) 41- 46 F6.1 yr Epoch [2015.0] Reference epoch in Julian years (ref_epoch) (G4) 48- 61 F14.10 deg RAdeg Right ascension (ICRS) at epoch 2015.0 (ra) (1) 63- 68 F6.3 mas e_RAdeg Standard error of right ascension (ra_error) 70- 83 F14.10 deg DEdeg Declination (ICRS) at epoch 2015.0 (dec) (2) 85- 90 F6.3 mas e_DEdeg Standard error of declination (dec_error) 92- 97 F6.3 --- RADEcor Correlation between right ascension and declination (radeccorr) 99-104 F6.3 mag <Gmag> ? G-band mean magnitude (photgmean_mag) (G20) (3) 106 I1 --- Apr [3/6] Type of prior used in in the astrometric solution (astrometricpriorsused) (G15) 108-123 A16 --- ICRF2 ICRF2 designation of the source matched to this Gaia source (HHMMSS.s+DDMMSS) (icrf2_match) 125 I1 --- Frot [0/3] Rotation flag (rot_flag) (4)
Note (1): 111 sources in this table are not present in the gaia_source table in the Gaia Data Release 1. Note (2): RA and DE does not match exactly for the same source between this dataset and the gaia source table in the Gaia Data Release 1. Although both datasets are based on the same original data, they have been generated from two separate astrometric solutions. Note (3): null values for 39 sources for which CU5 photometry is not available. Note (4): Flag indicating how this source was used to fix the orientation of the reference frame of the Gaia DR1 solution as follows: 0 = Not used 1 = Only right ascention is used 2 = Only declination is used 3 = Both right ascention and declination are used
Global notes: Note (G1): The data in the MDB will be described by means of a "Solution identifier" parameter. This will be a numeric field attached to each table row that can be used to unequivocally identify the version of all the subsystems that where used in the generation of the data as well as the input data used. Each DPC generating the data will have the freedom to choose the Solution identifier number, but they must ensure that given the Solution identifier they can provide detailed information about the "conditions" used to generate the data: versions of the software, version of the data used... Note (G2): For the contents of Gaia DR1, which does not include Solar System objects, the source ID consists consists of a 64-bit integer, least significant bit = 1 and most significant bit = 64. - a HEALPix index number (sky pixel) in bits 36 - 63; by definition the smallest HEALPix index number is zero. - a 2-bit Data Processing Centre code in bits 34 - 35; for example MOD(sourceId / 4294967296, 8) can be used to distinguish between sources initialised via the Initial Gaia Source List by the Torino DPC (code = 0) and sources otherwise detected and assigned by Gaia observations (code >0) - a 25-bit plus 7 bit sequence number within the HEALPix pixel in bits 1 - 32 split into: - a 25 bit running number in bits 8 - 32; the running numbers are defined to be positive, i.e. never zero (except in the case of forced empty windows) - a 7-bit component number in bits 1 - 7 - one spare bit in bit 33 This means that the HEALpix index level 12 of a given source is contained in the most significant bits. HEALpix index of 12 and lower levels can thus be retrieved as follows: - HEALpix level 12 = source_id / 34359738368 - HEALpix level 11 = source_id / 137438953472 - HEALpix level 10 = source_id / 549755813888 - HEALpix level n = source_id / 235 * 4(12-level). Note (G3): Random index which can be used to select smaller subsets of the data that are still representative. The column contains a random permutation of the numbers from 0 to N-1, where N is the number of rows. The random index can be useful for validation (testing on 10 different random subsets), visualization (displaying 1% of the data), and statistical exploration of the data, without the need to download all the data. Note (G4): Reference epoch to which the astrometic source parameters are referred, expressed as a Julian Year in TCB. Note (G5): Proper motion in right ascension µ_α* of the source in ICRS at the reference epoch Epoch. This is the projection of the proper motion vector in the direction of increasing right ascension. Note (G6): Proper motion in declination µ_δ of the source in ICRS at the reference epoch Epoch. This is the projection of the proper motion vector in the direction of increasing declination. Note (G7): Total number of ALong scan direction (AL) observations (= CCD transits) used in the astrometric solution of the source, independent of their weight. Note that some observations may be strongly downweighted (see NbAL). Note (G8): Total number of ACross scan direction (AC) observations (= CCD transits) used in the astrometric solution of the source, independent of their weight. Note that some observations may be strongly downweighted (see NbAc). Nearly all sources having G<13 will have AC observations from 2d windows, while fainter than that limit only ∼1% of stars (the so-called 'calibration faint stars') are assigned 2d windows resulting in AC observations. Note (G9): Number of AL or AC observations (= CCD transits) that were not strongly downweighted in the astrometric solution of the source. Strongly downweighted observations (with downweighting factor ω<0.2) are instead counted in NbAL or NbAC. Note (G10): Number of AL or AC observations (= CCD transits) that were strongly downweighted in the astrometric solution of the source, and therefore contributed little to the determination of the astrometric parameters. An observation is considered to be strongly downweighted if its downweighting factor ω<0.2, which means that the absolute value of the astrometric residual exceeds 4.83 times the total uncertainty of the observation, calculated as the quadratic sum of the centroiding uncertainty, excess source noise, and excess attitude noise. Note (G11): In the TGAS solution, DQ (ΔQ) indicates the discrepancy between the Hipparcos proper motion and the TGAS proper motion. A large value of ΔQ could indicate non-linear motion (e.g. in a binary). Note (G12): This is the excess noise ε_i of the source. It measures the disagreement, expressed as an angle, between the observations of a source and the best-fitting standard astrometric model (using five astrometric parameters). The assumed observational noise in each observation is quadratically increased by ε_i in order to statistically match the residuals in the astrometric solution. A value of 0 signifies that the source is astrometrically well-behaved, i.e. that the residuals of the fit statistically agree with the assumed observational noise. A positive value signifies that the residuals are statistically larger than expected. Note (G13): A dimensionless measure (D) of the significance of the calculated astrometric excess noise (epsi). A value D>2 indicates that the given epsi probably significant. For good fits in the limit of a large number of observations, D should be zero in half of the cases and approximately follow the positive half of a normal distribution with zero mean and unit standard deviation for the other half. Consequently, D is expected to be greater than 2 for only a few percent of the sources with well-behaved astrometric solutions. Note (G14): Flag indicating if this source was used as a primary source (1) or secondary source (0). Only primary sources contribute to the estimation of attitude, calibration, and global parameters. The estimation of source parameters is otherwise done in exactly the same way for primary and secondary sources. Note (G15): Type of prior used in the astrometric solution as follows: 0 = No prior used 1 = Galaxy Bayesian Prior for parallax and proper motion 2 = Galaxy Bayesian Prior for parallax and proper motion relaxed by factor 10 3 = Hipparcos prior for position 4 = Hipparcos prior for position and proper motion 5 = Tycho2 prior for position 6 = Quasar prior for proper motion For Gaia DR1 the only types of priors used are 2 (for the secondary data set), 3 (for the Hipparcos subset of the primary data set), or 5 (for the non-Hipparcos subset of the primary data set). Type 6 was used for internal calibration purposes and alignment of the reference frame, but the corresponding astrometric results are in general not published. Note (G16): This field indicates the number of observations (detection transits) that have been matched to a given source during the last internal crossmatch revision. Note (G17): During data processing, this source happened to been duplicated and one source only has been kept. This may indicate observational, cross-matching or processing problems, or stellar multiplicity, and probable astrometric or photometric problems in all cases. In DR1, for close doubles with separations below some 2 arcsec, truncated windows have not been processed, neither in astrometry and photometry. The transmitted window is centred on the brighter part of the acquired window, so the brighter component has a better chance to be selected, even when processing the fainter transit. If more than two images are contained in a window, the result of the image parameter determination is un-predictable in the sense that it might refer to either (or neither) image, and no consistency is assured. Note (G18): The scanDirectionStrength (sK) and scanDirectionMean (mK) quantify the distribution of AL scan directions across the source. scanDirectionStrength[k-1] (k = 1, 2, 3, 4) is the absolute value of the trigonometric moments m_k=<ecp(ikθ)>. where θ is the position angle of the scan and the mean value is taken over the nObs[0] AL observations contributing to the astrometric parameters of the source. θ is defined in the usual astronomical sense: θ=0 when the FoV is moving towards local North, and θ=90° towards local East. The scanDirectionStrength is a number between 0 and 1, where 0 means that the scan directions are well spread out in different directions, while 1 mean sthat they are concentrated in a single direction (given by scanAngleMean). The different orders k are statistics of the scan directions modulo 360°/k. For example, at first order (k=1), θ=10° and θ=190° count as different directions, but at second order (k=2) they are the same. Thus, scanDirectionStrength[0] is the degree of concentration when the sense of direction is taken into account, while scanDirectionStrength[1] is the degree of concentration without regard to the sense of direction. A large value of scanDirectionStrength[3] indicates that the scans are concentrated in two nearly orthogonal directions. Note (G19):The scanDirectionStrength and scanDirectionMean quantify the distribution of AL scan directions across the source. scanDirectionMean [k-1](k = 1, 2, 3, 4) is 1=k times the argument of the trigonometric moments m_k=<exp(ikθ)>, where θ is the position angle of the scan and the mean value is taken over the nObs[0] AL observations contributing to the astrometric parameters of the source. θ is defined in the usual astronomical sense: θ=0 when the FoV is moving towards local North, and θ=90° towards local East. scanDirectionMean[k-1] is an angle between -180°/k and +180°/k, giving the mean position angle of the scans at order k. The different orders k are statistics of the scan directions modulo 360°/k. For example, at first order (k=1), θ=10° and θ=190° count as different directions, but at second order (k=2) they are the same. Thus, scanDirectionMean[0] is the mean direction when the sense of direction is taken into account, while scan-DirectionMean[1] is the mean direction without regard to the sense of the direction. For example, scanDirectionMean[0]=0 means that the scans preferentially go towards North, while scanDirectionMean[1]=0 means that they preferentially go in the North-South direction, and scanDirectionMean[4]=0 that they preferentially go either in the North-South or in the East-West direction. Note (G20): Mean magnitude in the G band. This is computed from the G-band mean flux applying the magnitude zero-point in the Vega scale. Note (G21): Flag indicating if variability was identified in the photometric G band as follows: NOT_AVAILABLE = source not processed and/or exported to catalogue CONSTANT = Source not identified as variable VARIABLE = source identified and processed as variable, see tables varsum.dat, fov.dat, fovparam.dat, and cepheid.dat or rrlyrae.dat for more details. Note that for this data release only a small subset of (variable) sources was processed and/or exported, so for many (known) variable sources this flag is set to "NOT AVAILABLE". No "CONSTANT" sources were exported either. Pour Cepheid et RR Lyrae Note (G22): Period corresponding to the maximum power peak in the periodogram of G band time series (P1): This parameter is filled with the period of the maximum power peak in the frequencygram obtained from the modeling of the time series. The light curve of the target P star is modeled with a truncated Fourier series (mag(tj)=zp+Σ[Aisin(ix2πνmaxtj+φi)]). Zero-point (zp), period (1/ν_max), number of harmonics (i), amplitudes (A_i), and phases (φ_i) of the harmonics, for the Gband light curve are determined using the Levenberg-Marquardt non linear fitting algorithm. Note (G23): This parameter is filled with the uncertainty value of the P1 parameter. Its value is derived with Monte Carlo simulations that generate several (100) time series with the same time path as the data points but with magnitudes generated randomly around the corresponding data value. For each of these time series the period is derived from the non linear modeling with a truncated Fourier series of the light curve. The mean of all the periods found and its standard deviation are then computed, and the latter value is kept as value to fill the P1 error parameter Note (G24): The epoch of maximum light for the Gaia integrated G band. It corresponds to the Baricentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations -3xP1. The mentioned BJD is offset by the Gaia default of JD 2455197.5 (= J2010.0). Note (G25): Its value is three times the error on the P1. Note (G26): The intensity-averaged magnitude in the G-band. The intensity-averaged magnitude is obtained by computing the average flux and then converting the average flux to magnitude Note (G27): The uncertainty is computed as the error(zp), where zp is the zero point obtained by the non linear Fourier modeling of the light curve. Note (G28): This parameter is filled with the peak-to-peak amplitude value of the G band light curve. The peak-to-peak amplitude is calculated as the (maximum)-(minimum) of the folded modeled light curve in the G band. The light curve of the target star is modeled with a truncated Fourier series (mag(tj)=zp+Σ[Aisin(ix2πνmaxtj+φ_i)]). Zero-point (zp), period (1/ν_max), number of harmonics (i), amplitudes (A_i), and phases (φ_i) of the harmonics, for the G-band light curve are determined using the Levenberg-Marquardt non linear fitting algorithm. Note (G29): This parameter is filled with the uncertainty value of the peak to peak g parameter. The uncertainty is computed as the sqrt(2)xerror(zp), where zp is the zero point obtained by the non linear Fourier modeling of the light curve. Note (G30): This parameter is filled with the number of harmonics used to model P1 of the light curve. The light curve of the target star is modeled with a truncated Fourier series (mag(tj)=zp+Σ[Aisin(ix2πνmaxtj +φ_i)]). Zero-point (zp), period (1/ν_max), number of harmonics (i), amplitudes (A_i), and phases (φ_i) of the harmonics are determined using the Levenberg-Marquardt non linear fitting algorithm. Note (G31): This parameter is filled with the Fourier decomposition parameter R21=A2/A1, where A2 is the amplitude of the 2nd harmonic and A1 is the amplitude of the fundamental harmonic of the truncated Fourier series defined hereafter. The light curve of the target star is modeled with a truncated Fourier series (mag(tj)=zp+Σ[Aisin(ix2πνmaxtj+φ_i)]). Zero-point (zp), period (1/ν_max), number of harmonics (i), amplitudes (A_i), and phases (φ_i) of the harmonics, are determined using the Levenberg-Marquardt non linear fitting algorithm. Note (G32): This parameter is filled with the uncertainty value on the r21G parameter. Its value is derived from Monte Carlo simulations that generate several (100) time series with the same time path as the data points but with magnitudes generated randomly around the corresponding data value. For each of these time series the r21 values are computed. The mean for each of these values and their standard deviations are then computed, and the latter values are kept as value to fill the uncertainty. Note (G33): This parameter is filled with the Fourier decomposition parameter φ21=φ2-2φ_1 value. The light curve of the target star is modeled with a truncated Fourier series (mag(tj)=zp+Σ[Aisin(ix2πνmaxtj+φ_i)]). Zero-point (zp), period (1/ν_max), number of harmonics (i), amplitudes (A_i), and phases (φ_i) of the harmonics, for the G-band light curve are determined using the Levenberg-Marquardt non linear fitting algorithm.
History: Data received from ESAC * 16-Sep-2016: First on-line version * 07-Jul-2017: catalog tgasptyc.dat corrected * 20-Sep-2017: catalog tgasptyc.dat corrected References: A&A special feature : Gaia Data Release 1
(End) Thomas Boch, Patricia Vannier [CDS] 28-Jun-2016
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