CFIND

CFIND, short for Cross-Identification Finder, is a software utility used in astronomy to associate sources across different catalogs and wavelengths. The program performs positional cross-matching of sources by comparing their sky coordinates and applying a user-specified search radius. It supports multiple matching algorithms, including nearest-neighbor matching, likelihood-ratio methods, and Bayesian association, allowing users to evaluate the probability that a given pair of sources is the same object. Optional information such as positional uncertainties, magnitudes, colors, or source morphology can be incorporated to improve the reliability of matches. The tool can handle multiple possible counterparts and produces an output catalog that records the original sources, their matched counterparts, the angular separation, and a match probability or score. It can also generate statistics and diagnostic plots to assess match quality.

CFIND accepts common data formats used in astronomy, such as FITS tables, CSV, and VOTables, and produces joinable catalogs suitable for subsequent analysis. It is designed to integrate into data reduction pipelines and can be used interactively in GUI-based environments or scripted workflows (e.g., via Python). Typical applications include combining optical, infrared, and X-ray surveys, matching transient alerts across surveys, and preparing multi-wavelength catalogs for statistical studies. Limitations include sensitivity to crowded fields and reliance on accurate input positions and uncertainties. In practice, CFIND is one component of broader astroinformatics ecosystems that aim to unify heterogeneous data sets for scientific analysis.