Hipparcos2 Neighbourhood (gaiaedr3.hipparcos2_neighbourhood)
The table has 100009 rows, 5 columns.
Table hipparcos2_neighbourhood includes all good neighbours for each matched Hipparcos2 object. A good neighbour for a given Hipparcos2 source is a nearby Gaia object whose position is compatible (within position errors) with the Hipparcos2 target. The cross-match algorithm is not symmetric and searches Hipparcos2 sources counterparts in Gaia. The cross-match algorithm is positional and exploits the full 5 parameter covariance matrix of the Gaia astrometric solution when available and the external catalogue positions and position errors. In addition it takes into account the Gaia environment using the local density. Please note that the cross-match algorithm is a trade-off between multiple requirements, in particular between completeness and correctness. It is thus not limited to a simple cone search. Reference papers: Marrese et al. (2017) Marrese et al. (2019)
If you have used Gaia data in your research, please use the following acknowledgement:
This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
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Unique Gaia source identifier
Original External Catalogue source identifier
Angular Distance between the two sources
Score of neighbours
Cross-match algorithm flag