This README contains information on writing your own correlation method for
use with the Astro::Correlate Perl module.

The basic infrastructure you need is a correlate() method that accepts two
Astro::Catalog objects as parameters. The two output catalogues are
Astro::Catalog objects that contain Astro::Catalog::Item objects with the same
IDs as the input catalogues. For example, if an object in the first catalogue
with an ID of 1 matches with an object in the second catalogue with an ID of
2, then the first returned catalogue will contain the object with an ID of 1
and the second will contain the object with an ID of 2.

IDs must be maintained between the input and output catalogues. This allows
the user to perform further operations on the matched items after the
correlation takes place.

Be careful not to modify the input catalogues, as they're passed by
reference. It's probably safest to take a deep clone of each catalogue using
the dclose() method in Storable.

Typically, your matching program won't take input data in a format known to
Astro::Catalog, so you will probably need to write a corresponding
Astro::Catalog::IO class.

The best way to go about creating your own correlation method is to look at
the pre-existing methods (FINDOFF and RITMatch), and go from there. Both of
these methods have corresponding Astro::Catalog::IO classes that you can also
examine for writing that class.

Any questions should go to Brad Cavanagh at brad.cavanagh@gmail.com.

Happy correlating!
