Since 28-Aug-13 the IDL Astronomy Library has required IDL V6.4 or later. This directory contains frozen versions of the Astronomy Library compatible with earlier versions of IDL. Note, however, that these procedures do not include enhancements or bug fixes since the frozen date IDL Version Freeze date Tar file name V4 May 2002 astron_v4.tar.gz V5.1 Jan 2003 astron.dir_v51.tar.gz V5.2 Feb 2004 astron.dir_v52.tar.gz V5.3 Apr 2006 astron_v53.tar.gz V5.4 Sep 2006 astron_v54.tar.gz V5.5 Sep 2007 astron_v55.tar.gz V5.6 Jul 2009 astron_v56.tar.gz V6.1 Aug 2013 astron_V61.tar.gz Also stored as .zip files are snapshots of the Astronomy library at certain times.