# 4.2 igsl_source

The Initial Gaia Source List (IGSL) was commissioned by DPAC to fulfil the following broad requirements: all-sky positions, proper motions, and magnitudes for objects to a limit of Gaia magnitude $G$ = 21 where possible, e.g., where there are large ($>$10000 square degrees) catalogs that reach that limit. The proper motions and magnitudes are provided on a best effort basis, nominally with precisions of 10 mas yr${}^{-1}$ and 0.3 magnitudes, respectively, but obviously limited by the currently available large catalogs. The DPAC Quasar and the Ecliptic Pole catalogs are included with no selection on magnitudes. HIPPARCOS objects were also included with no selection on magnitudes. The IGSL has been used as the starting point for the Initial Data Treatment (IDT) cross-matching routines (see Smart, R.L. and Nicastro, L., A&A, 570, A87 (2014) for further details).

Columns description:

solution_id : Solution Identifier (long)

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…

source_id : source identifier (long)

A unique single numerical identifier of the source (for a detailed description see gaia_source.source_id)

ra : Right Ascension at catalogue epoch (double, Angle[deg])

The right ascension at epoch and equinox J2000

dec : Declination at catalogue epoch (double, Angle[deg])

The declination at epoch and equinox J2000

ra_error : Error in Right Ascension (float, Angle[mas])

The mean error in the right ascension at mean epoch

dec_error : Error in Declination (float, Angle[mas])

The mean error in the declination at mean epoch

ra_epoch : Mean Epoch of Right Ascension (float, Time[GaiaTime] )

The mean epoch of the right ascension Julian Year in TCB. Note if there are proper motions the actual position will be at J2000 to have a consistent catalog and this is provided if the user wishes to add new information or find the best position.

dec_epoch : Mean Epoch of Declination (float, Time[GaiaTime] )

The mean epoch of the declination Julian Year in TCB. Note if there are proper motions the actual position will be at J2000 to have a consistent catalog and this is provided if the user wishes to add new information or find the best position.

source_position : Source of the position estimate (byte)

The code that appears in the IgslReferences that describes where the positional information comes from.

pm_ra : Proper motion in RA * at catalogue epoch (float, Angular Velocity[mas/year])

Proper motion in right ascension multiplied by cos(declination).

pm_dec : Proper motion in DEC at catalogue epoch (float, Angular Velocity[mas/year])

Proper motion in declination

pm_ra_error : Error in Proper motion in RA (float, Angular Velocity[mas/year])

Mean error of proper motion in RA * cos(declination)

pm_dec_error : Error in proper motion in DEC (float, Angular Velocity[mas/year])

Mean error of proper motion in declination

source_mu : Source of the proper motions (byte)

The code that appears in the IgslReferences that describes where this data point comes from.

galactic_lon : Galactic Longditude (float, Angle[deg] )

Galactic Longditude calculated in float to use for indexing

galactic_lat : Galactic Latitude (float, Angle[deg] )

Galactic Latitude calculated in float to use for indexing

ecliptic_lon : Ecliptic Longditude (float, Angle[deg] )

Ecliptic Longditude calculated in float to use for indexing

ecliptic_lat : Ecliptic Latitude (float, Angle[deg] )

Ecliptic Latitude calculated in float to use for indexing

mag_bj : B mag measure, GSC23 system (float, Magnitude[mag])

The $B_{J}$ magnitude from the GSC23 when present or estimated from transformations when not present in the GSC23 or too bright to be reliable from GSC23. Very similar to B Johnson.

mag_bj_error : Error in B mag measure (float, Magnitude[mag])

Error in the $B_{J}$ magnitude

source_mag_bj : source B mag (byte)

Code in IgslReferences that describes where this magnitude comes from.

mag_rf : R mag measure, GSC23 system (float, Magnitude[mag])

The $R_{F}$ magnitude from the GSC23 when present or estimated from transformations when not present in the GSC23 or too bright to be reliable from GSC23. Very similar to R cousins.

mag_rf_error : Error in R mag measure (float, Magnitude[mag])

Error in $R_{F}$

source_mag_rf : source of R mag (byte)

Code in IgslReferences that describes where this magnitude comes from.

mag_g : G mag estimate (float, Magnitude[mag])

Estimated $G$ magnitude based on transformations in livelink document RLS 001

mag_g_error : Error in G mag estimate (float, Magnitude[mag])

Estimated of error on G magnitude

source_mag_g : Source G mag (byte)

Code in IgslReferences that describes which transformation used.

mag_grvs : Grvs mag estimate (float, Magnitude[mag])

Estimated $G_{r}vs$ magnitude based on transformations in livelink document RLS 004

mag_grvs_error : Error in Grvs mag estimate (float, Magnitude[mag])

Estimated of error on $G_{r}vs$ magnitude

source_mag_grvs : Source Grvs mag (byte)

Code in SourceCatalogIDs that describes where base magnitudes came from

classification : Classification (boolean)

Classification, simply a 0=star and 1=nonstar taken from different sources as given in the souceClass field

source_classification : source of Classification (byte)

Code in IgslReferences that describes where this datapoint comes from.

toggle_asc : Toggle for Atittude Star Catalog (boolean)

A boolean that indicates if the objects is to be used for the Atittude Star Catalog.

aux_gsc23 : Present in the GSC2.3 catalog (boolean)

A boolean that indicates if the objects is present in the GSC2.3 cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the GSC2.3 id is in the SourceCatalogIDs as idGSC23.

aux_sdss : Present in the SDSS catalog (boolean)

A boolean that indicates if the objects is present in the SDSS cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idSDSS

aux_ucac : Present in the UCAC3 catalog (boolean)

A boolean that indicates if the objects is present in the UCAC cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the iSourceCatalogIDs as idUCAC.

aux_lqrf : Present in the LQRF QSO aux catalog (boolean)

A boolean that indicates if the objects is present in the CU3 QSO Aux cat GIQC, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idLQRF.

aux_tycho : Present in the TYCHO2 catalog (boolean)

A boolean that indicates if the objects is present in theTYCHO2 cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idTYCHO

aux_hip : Present in the Hipparcos catalog (boolean)

A boolean that indicates if the objects is present in the Hipparcos catalog, 0=no, 1=yes=true.

aux_ppmxl : Present in the PPMXL catalog (boolean)

A boolean that indicates if the objects is present in the PPMXL cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idPPMXL

aux_ogle : Present in the OGLE catalog (boolean)

A boolean that indicates if the objects is present in the OGLE cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idOGLE

aux_tmass : Present in the Two MASS PSC catalog (boolean)

A boolean that indicates if the objects is present in the Two-MASS cat, 0=no, 1=yes. Version and catalog details in the SourceCatalogReferences table. If yes the ID is in the the SourceCatalogIDs as idTMASS.

aux_epc : Present in the Ecliptic Poles Catalog (boolean)

A boolean that indicates if the objects is present in the EPC, false=no, true=yes. Version and catalog details in the SourceCatalogReference table. If yes, the number in the SourceCatalogIDs table is the number in EPC.