David and/or Peter, if I attempt to load the attached spectrum into SPLAT, I get the following pop-up error: uk.ac.starlink.splat.util.SplatException: uk.ac.starlink.ast.AstException: AST: Error at line 406 in file AstObject.c. astMatch(SpecFrame): Inappropriate units (Hz) specified for a wavelength axis. Unable to accommodate the attribute setting "Digits(1)=17". (AST__BADUN) Naively eyeballing the headers it looks to me like this has frequency in Hz in column 1 which I'd have thought would be OK. However, I know practically nothing about spectrum FITS headers etc, so I expect there's an error of some sort in the data. Can you comment on what's wrong and how it might get fixed? thanks Mark -- Mark Taylor Astronomical Programmer Physics, Bristol University, UK [log in to unmask] +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/