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Probabilistic Cross-Identification of Astronomical Sources

Project description

nway is a source cross-matching tool for arbitrarily many astronomical catalogues.


  • Bayesian match probabilities based on astronomical sky coordinates (RA, DEC)
  • Works with arbitrarily many catalogues
  • Can handle varying errors
  • Can incorporate additional prior information, such as the magnitude or color distributions of the sources to match
  • Works accurately and fast in small areas and all-sky catalogues


See the manual in the doc/ folder,

A full worked example with demo catalogues is included.


The easiest way to install nway is with pip:

$ pip install nway

Add –user if you do not have admin privileges. Alternatively, download the source code and run “python install”.

nway uses the following python packages:

  • numpy, scipy, matplotlib
  • astropy
  • tqdm
  • joblib
  • healpy
  • pandas

nway works with both Python 3 and Python 2 and various astropy versions.

Reporting issues

Please file an issue on Github if you have any problems.

Citing nway correctly

Please cite Salvato et al (2017). (Get BibTex)


This program is free and open-source software, licensed under AGPLv3 (see LICENSE and COPYING files). Written by Johannes Buchner (C) 2013-2020

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