Cross-Comparison Tool

Perform fast positional cross-matches between an input table of up to one million sources and common astronomical source catalogs, which may contain records of over one billion astronomical sources.

(version 1.2)

The analysis and interpretation of multi-wavelength data in astronomy, especially from surveys, demands the comparisons of source properties (flux, morphology) from different bandpasses, instruments and telescopes. The first step in such analysis is to perform a spatial cross-match between source tables. These tables may be on-line catalogs, subsets of them, or may be user-supplied table files.

This service performs cross-comparisons between two tables, one supplied by the user and one an on-line source catalog, for a user-specified match radius. The service does not return cross-identifications, but rather cross-identification candidates; that is, it returns all sources in the on-line catalog that are within the match radius of each input source. The output is a spatially “joined” composite table consisting of records from the first table, joined to all the matching records in the second table, and the angular distance and position angles of the matches. Matches are not unique because there are often multiple sources in the cone of comparison, so the same source (from any of the catalogs) may appear in multiple places in the output, especially for crowded regions of the sky. The service returns a separate output table showing sources in the input that had no matches in the on-line catalog

*This service is recommended for use with the most recent versions of Firefox, Chrome or Safari. Internet Explorer 9, old versions of Firefox (prior to version 8) and Opera are not supported.

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