Convenience table to be used to join SDSS DR13 catalogue with the cross-match results. The table links the external catalogue original source_id (original_ext_source_id) to the corresponding the additional numerical identifier (sdssdr13Oid).
Both original_ext_source_id and sdssdr13Oid are present in the cross-match output tables (sdssdr13BestNeighbour and sdssdr13Neighbourhood). However, in case there are suspected duplicates in the external catalogue, different original_ext_source_id will correspond to the same sdssdr13Oid.
In the cross-match output table only the original_ext_source_id of the source with the best astrometry among the suspected duplicates will be listed.
In practice, users may use the original_ext_source_id in the original catalogue to find the matching source with the best astrometry. Users interested to find all matching suspected duplicates should instead use the sdssdr13Oid in the join with the cross-match result tables.
See Documentation 8, for more details on the duplicates in the external catalogues and their treatment in the cross-match computations.
The unique source identifier in the original External catalogue.
The additional numeric source identifier of the External catalogue, increasing with Declination.