GSC2.3 Join

The table links the external catalogue original sourceId (originalExtSourceId) to the corresponding additional numerical identifier (cleanGsc23Oid). Both originalExtSourceId and cleanGsc23Oid are present in the cross-match output tables (Gsc23BestNeighbour and Gsc23Neighbourhood).However, in case there are suspected duplicates in the external catalogue, different originalExtSourceId will correspond to the same cleanGsc23Oid.

In the cross-match output table only the originalExtSourceId of the source with the best astrometry among the suspected duplicates will be listed.In practice, users may use the originalExtSourceId 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 cleanGsc23Oid in the join with the cross-match result tables.See Chapter [chap:crossmatch] for more details on the duplicates in the external catalogues and their treatment in the cross-match computations.