On Tue 2004/08/24 23:17:53 +0100, "Malcolm J. Currie" wrote in a message to: fitswcs at aoc.nrao.edu >It's interesting that DS9 generates c.180. Paper II, Sect. 6.2, shows that there are two solutions for CROTAn separated by 180 degrees. It's probably chosen the other one. Mark Calabretta ATNF