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+SLALIB_Version_2.4-0                                  Expiry 31 December 1999
+
+The latest releases of SLALIB include the following changes:
+
+*  Four new routines have been introduced which transform between the
+   FK5 system and the ICRS (Hipparcos) system.  sla_FK52H and sla_H2FK5
+   transform star positions and proper motions from FK5 coordinates to
+   Hipparcos coordinates and vice versa.  sla_FK5HZ and sla_HFK5Z do the
+   same but for the case where the Hipparcos proper motions are zero.
+
+*  Six new routines have been introduced for dealing with orbital elements.
+   Four of them (sla_EL2UE, sla_PV2UE, sla_UE2EL and sla_UE2PV) provide
+   applications with direct access to the "universal variables" method
+   that was already being used internally.  Compared with using conventional
+   (angular) elements and solving Kepler's equation, the universal variables
+   approach has a number of advantages, including better handling of near-
+   parabolic orbits and greater efficiency.  The remaining two routines
+   (sla_PERTEL and sla_PERTUE) generate updated elements by applying
+   major-planet perturbations.  The new elements can then be used to
+   predict positions that are much more accurate.  For minor planets,
+   sub-arcsecond accuracy over a decade is achievable.
+
+*  Several observatory sites have been added to the sla_OBS routine:  CFHT,
+   Keck 2, Gemini North, FCRAO, IRTF and CSO.  The coordinates for all
+   the Mauna Kea sites have been updated in accordance with recent aerial
+   photography results made available by the Institute for Astronomy,
+   University of Hawaii.
+
+*  A bug in sla_DAT has been corrected.  It used to give incorrect
+   results for dates in the first 54 days of 1972.
+
+*  There are new routines for generating permutations (sla_PERMUT) and
+   combinations (sla_COMBN).
+ 
+ P.T.Wallace
+ 17 August 1999
+
+ ptw@star.rl.ac.uk
+ +44-1235-44-5372
+--------------------------------------------------------------------------