Convenience table to be used to join 2MASS PSC+XSC catalogue with the cross-match results. The table links the external catalogue original source_id (original_ext_source_id) to the corresponding additional numerical identifier (clean_tmass_psc_xsc_oid).
Both original_ext_source_id and clean_tmass_psc_xsc_oid are present in the cross-match output tables (tmass_psc_xsc_best_neighbour and tmass_psc_xsc_neighbourhood). However, in case there are suspected duplicates in the external catalogue, different original_ext_source_id will correspond to the same clean_tmass_psc_xsc_oid.
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 clean_tmass_psc_xsc_oid in the join with the cross-match result tables.
See Chapter 15 for more details on the duplicates in the external catalogues and their treatment in the cross-match computations.
The unique source identifier in 2MASS PSC.
The unique source identifier in 2MASS XSC.
The additional numeric source identifier of the external catalogue, increasing with Declination.