Hipparcos2 Best Neighbour (gaiaedr3.hipparcos2_best_neighbour)
The table has 99524 rows, 5 columns.
Table hipparcos2_best_neighbour lists each matched external catalogue object with its best neighbour in Gaia. The cross-match algorithm is not symmetric and searches Hipparcos2 sources counterparts in Gaia. The best neighbour is chosen among good neighbours as the one with the highest value of the figure of merit, which evaluates the ratio between two opposite models/hypotheses: the counterpart candidate is a match or it is found by chance. Good neighbours are nearby objects in Gaia whose position is compatible within position errors with the external catalogue target. 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.
More information can be found on the credit and citation instructions page.
Unique Gaia source identifier
Original External Catalogue source identifier
Angular Distance between the two sources
Number of neighbours in Gaia Catalogue
Cross-match algorithm flag