The IDL Astronomy Users Library is a central repository for low-level astronomy software written in the commercial language IDL. The Library is not meant to be an integrated package, but rather is a collection of procedures from which users can pick and choose (and possibly modify) for their own use. Submitted procedures are given a cursory testing, but are basically stored in the Library as submitted. Instrument-specific software is generally not included in the IDL Astronomy Library, but can be found at the Links to Other Astronomy and IDL related sites.
The entire contents of the Library can be downloaded in a tar file or in a .zip file from the the FTP site . Additional software, not included in the tar files, is available in a contrib directory. Individual procedures can be copied by browsing through a list of one-line descriptions. Changes to the contents of the Library are recorded in a news file.
Documentation is available describing the various options for working with FITS data in IDL.
The IDL Astronomy User's Library 
