The additional numeric unique source identifier of the External catalogue, increasing with Declination.
source_id : Unique Gaia source identifier (long)
Unique identifier of the Gaia source, the attribute corresponds to gaia_source.source_id
original_ext_source_id : Original External Catalogue source identifier (string)
The unique source identifier in the original External catalogue.
angular_distance : Angular Distance between the two sources (double, Angle[arcsec])
Angular distance between a Gaia source and its nearest neighbour in the External Catalogue
score : Score of neighbours (double)
Score of a given neighbour.
For the first Gaia release the score will be a likelihood ratio based on geometric distance and local density of the external catalogue: the higher the score, the most probable the match is.
proper_motion_flag : Use of Gaia proper motions (short)
This flag is set to 0 if Gaia proper motions were not available and were thus not used in the XMatch.
This flag is set to 1 if Gaia proper motions were available and were thus used in the XMatch (for the First Gaia release the TGASS sub-sample.