gdr2.dr1_neighbourhood

Description

Users wishing to look up the DR2 record for an astrophysical source identified in DR1 must {} simply extract the record from DR2 having the same source identifier.

As described in the detailed description of attribute {designation} in GaiaSource it is not guaranteed that the same astronomical source will always have the same source identifier in different Data Releases. Hence the only safe way to compare source records between different Data Releases in general is to check the records of proximal source(s) in the same small part of the sky. This table provides the means to do this via a precomputed crossmatch of such sources, taking into account the proper motions available at DR2.

Within the neighbourhood of a given DR2 source there may be none, one or (rarely) several possible counterparts in DR1 indicated by rows in this table. This occasional source confusion was introduced during the DR1 processing which used an earlier version of the software for matching of transit observations to unique astrophysical sources. The subsequent merging, splitting and deletion of identifiers introduced at DR1 during the DR2 processing means there is no guaranteed one--to--one correspondence in source identifiers between the releases.

For more details of the procedure used to create this crossmatch, see Section~ in the online documentation.

Attribution

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 (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://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.

Columns

Name Type UCD Unit Description
dr1_source_id long meta.id.cross Source identifier in Gaia DR1
dr2_source_id long meta.id.cross
meta.main
Source identifier in Gaia DR2
angular_distance float pos.angDistance Angle[arcsec] Angular distance between the two sources
magnitude_difference float arith.diff
phot.mag
Magnitude[mag] G band magnitude difference between the sources
rank float stat.probability Rank metric indicating relative probability of a good match