cdsskymatch: Crossmatches table on sky position against VizieR/SIMBAD table
cdsskymatch uses the
CDS X-Match service
to join a local table to one of the tables hosted by the
Centre de Données astronomiques de Strasbourg.
This includes all of the VizieR tables and the SIMBAD database.
The service is very fast, and in most cases it is the best way to
match a local table against a large external table hosted by a service.
It is almost certainly much better than using
though it is less flexible than TAP
for flexible access to TAP services, and
for positional matches).
The local table is uploaded to the X-Match service in chunks, and the matches for each chunk are retrieved in turn and eventually stitched together to form the final result. The tool only uploads sky position and an identifier for each row of the input table, but all columns of the input table are reinstated in the result for reference.
The remote table in most cases contains only a subset of the the columns in the relevant VizieR table, including the most useful ones. The service currently provides no straightforward way to acquire columns which are not returned by default.
Acknowledgement: CDS note that if the use of the X-Match service is useful to your research, they would appreciate the following acknowledgement:
"This research made use of the cross-match service provided by CDS, Strasbourg."