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Detailed Description of J/MNRAS/482/4570 :
Gaia DR2 white dwarf candidates (Gentile Fusillo+, 2019)

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Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.
J/MNRAS/482/4570   Gaia DR2 white dwarf candidates      (Gentile Fusillo+, 2019)
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A Gaia Data Release 2 catalogue of white dwarfs and a comparison with SDSS.
    Gentile Fusillo N.P., Tremblay P-E,  Gaensicke B.T., Manser C.J.,
    Cunningham T., Cukanovaite E., Hollands M., Marsh T., Raddi R.,
    Jordan S., Toonen S., Geier S., Barstow M., Cummings J.D.
    <Mon. Not. R. Astron. Soc. 482, 4570-4591 (2019)>
    =2019MNRAS.482.4570G        (SIMBAD/NED BibCode)
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ADC_Keywords: Surveys ; Stars, white dwarf ; Parallaxes, trigonometric;
              Photometry
Keywords: catalogues - surveys - white dwarfs


Abstract:
    We present a catalogue of white dwarf candidates selected from the
    second data release of Gaia (DR2). We used a sample of
    spectroscopically confirmed white dwarfs from the Sloan Digital Sky
    Survey (SDSS) to map the entire space spanned by these objects in the
    Gaia Hertzsprung-Russell diagram.

    We then defined a set of cuts in absolute magnitude, colour, and a
    number of Gaia quality flags to remove the majority of contaminating
    objects. Finally, we adopt a method analogous to the one presented in
    our earlier SDSS photometric catalogues to calculate a probability of
    being a white dwarf (PWD) for all Gaia sources which passed the
    initial selection. The final catalogue is composed of 486641 stars
    with calculated PWD from which it is possible to select a sample
    of~260000 high-confidence white dwarf candidates in the magnitude
    range 8<G<21. By comparing this catalogue with a sample of SDSS white
    dwarf candidates we estimate an upper limit in completeness of 85 per
    cent for white dwarfs with G<=20mag and Teff>7000K, at high
    Galactic latitudes (|b|>20deg). However, the completeness drops at
    low Galactic latitudes, and the magnitude limit of the catalogue
    varies significantly across the sky as a function of Gaia's scanning
    law. We also provide the list of objects within our sample with
    available SDSS spectroscopy.

Description:
    The main catalogue provides 486,641 stars selected from Gaia DR2 with
    calculated probabilities of being a white dwarf (PWD). The PWD values
    can used to reliably select high-confidence white dwarf candidates
    with a flexible compromise between completeness and level of potential
    contamination. As a generic guideline selecting objects with PWD>0.75
    recovers 96 per cent of the spectroscopically confirmed white dwarfs
    from SDSS and only 1 per cent of the contaminant (non white dwarfs)
    objects.

    All Gaia sources in the catalogue have also been cross matched with
    SDSS DR14 taking into account the difference in epoch of observation
    and proper motions. Whether available we include SDSS ugriz
    photometry. In a separate table we provide informations on all the
    available SDSS spectra for the Gaia sources in the main catalogue.

File Summary:

FileName Lrecl Records Explanations
× 80 . This file × ReadMe 80 . This file × gaia2wd.dat 1008 486641 DR2 white dwarf candidates, corrected version (gaiadr2whitedwarfcandidates.dat) × gaiasdss.dat 344 37259 Available SDSS spectra of candidates, corrected version (gaia-sdsswhitedwarf_catalogue.dat)
See also: B/wd : Spectroscopically identified white dwarfs (McCook+, 2014) I/345 : Gaia DR2 (Gaia Collaboration, 2018) V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) J/MNRAS/465/2849 : Gaia DR1 mass-radius relation of WD (Tremblay+ 2017) Byte-by-byte Description of file: gaia2wd.dat
Bytes Format Units Label Explanations
1- 23 A23 --- WD WD name (WDJHHMMSS.ss+DDMMSS.ss, J2000) (whitedwarfname) 25- 52 A28 --- DR2Name Unique Gaia source designation (designation) 54- 72 I19 --- Source Unique Gaia source identifier (source_id) 74- 96 F23.19 deg RAdeg Gaia DR2 barycentric right ascension (ICRS) at epoch J2015.5 (ra) 98-117 F20.18 mas e_RAdeg Standard error of right ascension (ra_error) 119-140 E22.18 deg DEdeg Gaia DR2 barycentric declination (ICRS) at epoch J2015.5 (dec) 142-161 F20.18 mas e_DEdeg Standard error of declination (dec_error) 163-183 F21.17 mas Plx Absolute stellar parallax of the source at J2015.5 (parallax) 185-204 F20.18 mas e_Plx Standard error of parallax (parallax_error) 206-227 E22.19 mas/yr pmRA Proper motion in right ascension (pmRAxcosDE) (pmra) 229-248 F20.18 mas/yr e_pmRA Standard error of proper motion in right ascension (pmra_error) 250-271 E22.19 mas/yr pmDE Proper motion in declination (pmdec) 273-292 F20.18 mas/yr e_pmDE Standard error of proper motion in declination (pmdec_error) 294-315 F22.19 mas epsi Measure of the residuals in the astrometric solution for the source (astrometricexcessnoise) 317-327 F11.9 mas amax Five-dimensional equivalent to the semi-major axis of the Gaia position error ellipse (astrometricsigma5dmax) 329-350 F22.14 e-/s FG Gaia G-band mean flux (photgmean_flux) 352-374 F23.17 e-/s e_FG Error on G-band mean flux (photgmeanfluxerror) 376-385 F10.7 mag Gmag Gaia G-band mean magnitude (Vega scale) (photgmean_mag) 387-409 F23.15 e-/s FBP Integrated GBP mean flux (photbpmean_flux) 411-435 F25.18 e-/s e_FBP Error on GBP-band mean flux (photbpmeanfluxerror) 437-446 F10.7 mag BPmag Gaia GBP-band mean magnitude (Vega scale) (photbpmean_mag) 448-470 F23.15 e-/s FRP Integrated GRP mean flux (photrpmean_flux) 472-497 F26.19 e-/s e_FRP Error on GRP-band mean flux (photrpmeanfluxerror) 499-508 F10.7 mag RPmag Gaia GRP-band mean magnitude (Vega scale) (photrpmean_mag) 510-520 F11.9 --- E(BR/RP) GBP/GRP excess factor estimated from the comparison of the sum of integrated GBP and GRP fluxes with respect to the flux in the G-band (photbprpexcessfactor) 522-542 E21.19 deg GLON Galactic longitude (l) 544-565 E22.19 deg GLAT Galactic latitude (b) 567-578 F12.4 --- Density The number of Gaia sources per square degree around this object (density) 580-602 F23.19 mag AG Extinction in the Gaia G-band band derived from E(B-V) values from Schlafly and Finkbeiner (2011ApJ...737..103S) (AG) 604-622 A19 --- SDSS SDSS object name if available (JHHMMSS,.ss+DDMMSS.s, J2000) (SDSS_name) 624-641 F18.15 mag umag ? SDSS u band magnitude (umag) 643-664 F22.18 mag e_umag ? SDSS u band magnitude uncertainty (e_umag) 666-683 F18.15 mag gmag ? SDSS g band magnitude (gmag) 685-706 F22.19 mag e_gmag ? SDSS g band magnitude uncertainty (e_gmag) 708-725 F18.15 mag rmag ? SDSS r band magnitude (rmag) 727-747 F21.18 mag e_rmag ? SDSS r band magnitude uncertainty (e_rmag) 749-766 F18.15 mag imag ? SDSS i band magnitude (imag) 768-789 F22.19 mag e_imag ? SDSS i band magnitude uncertainty (e_imag) 791-808 F18.15 mag zmag ? SDSS z band magnitude (zmag) 810-830 F21.18 mag e_zmag ? SDSS z band magnitude uncertainty (e_zmag) 832-852 E21.19 --- Pwd [0/1]? The probability of being a white dwarf (Pwd) 854 I1 --- f_Pwd [0/1] If 1 it indicates the PWD value could be unreliable (Pwd_flag) 856-868 F13.6 K TeffH ? Effective temperature from fitting the dereddened G,GBP, and GRP absolute fluxes with pure-H model atmospheres (Teff_H) 870-882 F13.6 K e_TeffH ? Uncertainty on Teff_H (eTeff_H) 884-891 F8.6 --- loggH ? Surface gravity from fitting the dereddened G,GBP,and GRP absolute fluxes with pure-H model atmospheres (loggH) 893-900 E8.6 --- e_loggH ? Uncertainty on loggH (eloggH) 902-909 F8.6 Msun MassH ? Stellar mass resulting from the adopted mass-radius relation (mass_H) 911-919 E9.6 Msun e_MassH ? Uncertainty on the mass (emass_H) 921-931 E11.6 --- chi2H ? chi2 value of the fit (pure-H) (chi2_H) 933-944 F12.6 K TeffHe ? Effective temperature from fitting the dereddened G,GBP, and GRP absolute fluxes with pure-He model atmospheres (Teff_He) 946-959 F14.6 K e_TeffHe ? Uncertainty on Teff_He (eTeff_He) 961-968 F8.6 --- loggHe ? Surface gravity from fitting the dereddened G,GBP,and GRP absolute fluxes with pure-He model atmospheres (loggHe) 970-977 E8.6 --- e_loggHe ? Uncertainty on loggHe (eloggHe) 979-986 F8.6 Msun MassHe ? Stellar mass resulting from the adopted mass-radius relation (mass_He) 988-996 E9.6 Msun e_MassHe ? Uncertainty on the mass (emass_He) 998-1008 E11.6 --- chisqHe ? chi2 value of the fit (pure-H) (chisq_He)
Byte-by-byte Description of file: gaiasdss.dat
Bytes Format Units Label Explanations
1- 22 A22 --- WD WD name (WDJHHMMSS.ss+DDMMSS.ss, J2000) (whitedwarfname) 23 A1 --- n_WD [a] Multiplicity index on WD 24- 42 I19 --- Source Unique Gaia source identifier (source_id) 44- 62 A19 --- SDSS SDSS object name (JHHMMSS,.ss+DDMMSS.s, J2000) (SDSS_name) 64- 83 F20.16 deg RAdeg Right ascension (J2000) of the spectrum source from SDSS DR14 (SDSS_ra) 85- 98 E14.10 deg DEdeg Declination (J2000) of the spectrum source from SDSS DR14 (SDSS_dec) 100-117 F18.15 mag umag ? SDSS u band magnitude (umag) 119-139 F21.18 mag e_umag ? SDSS u band magnitude uncertainty (e_umag) 141-158 F18.15 mag gmag ? SDSS g band magnitude (gmag) 160-179 F20.18 mag e_gmag ? SDSS g band magnitude uncertainty (e_gmag) 181-198 F18.15 mag rmag ? SDSS r band magnitude (rmag) 200-219 F20.18 mag e_rmag ? SDSS r band magnitude uncertainty (e_rmag) 221-238 F18.15 mag imag ? SDSS i band magnitude (imag) 240-260 F21.18 mag e_imag ? SDSS i band magnitude uncertainty (e_imag) 262-279 F18.15 mag zmag ? SDSS z band magnitude (zmag) 281-301 F21.18 mag e_zmag ? SDSS z band magnitude uncertainty (e_zmag) 303-306 I4 --- Plate Identifier of the plate used in the observation of the spectrum (Plate) 308-312 I5 --- MJD Modified Julian date of the observation of the spectrum (mjd) 314-317 I4 --- Fiber Identifier of the fiber used in the observation of the spectrum (fiberID) 319-333 F15.11 --- S/N Signal-to-noise ratio of the spectrum calculated in the range 4500-5500 A (S/N) 335-344 A10 --- SpClass Classification of the object based on a visual inspection of the SDSS spectrum (spectral_class) (1)
Note (1): spectral classes are as follows: CV = Cataclysmic Variable star DA = white dwarfs with H lines only DAB/DAB = white dwarfs with H lines and neutral He lines DABZ/DBAZ/DZAB/DZBA = white dwarfs with H lines, neutral He lines and Ca H & K lines DAO/DO = white dwarfs with H lines and He II lines DAZ/DZA = white dwarfs with H lines and Ca H & K lines DB = white dwarfs with neutral He lines only DBZ/DZB = white dwarfs with neutral He lines and Ca H & K lines DC = white dwarfs with feature-less spectra DQ = white dwarfs with molecular C absorptions hotDQ = white dwarfs with atomic C absorption DQpec = Peculiar white dwarfs with molecular C absorptions DZ = white dwarfs with Ca H & K lines DAH = white dwarfs with Zeeman split H lines DBH = white dwarfs with Zeeman split He lines DZH = white dwarfs with Zeeman split Ca H & K lines MWD = Magnetic white dwarfs with unidentified absorption lines WDPec = Peculiar magnetic white dwarf PG1159 = Pre-white dwarf star DB+MS/DA+MS/DC+M = White Dwarf - Main Sequence binary STAR = non white dwarf stellar object QSO = Quasar UNK = Spectra which we were unable to classify Unreliable = Unreliable spectra
Acknowledgements: Nicola Gentile Fusillo, n.gentile-fusillo(at)warwick.ac.uk History: * 01-Feb-2019: on-line version * 01-Apr-2019: corrected version (from author) ================================================================================ (End) Patricia Vannier [CDS] 31-Jan-2019