Here's a few links to echelle reduction documentation and desciptions of echelle instruments:
NIST GUIDE - High-resolution UV and Optical Spectroscopy Facility
Multielemental ICP Spectrochemical Analysis Using Two-Dimensional Echelle Spectrometer Systems.
The program EGRAM: Echelle spectrograph design aid was part of NASA's `Cosmic collection' (!), which was at one time distributed from a centre at the University of Georgia. It's now been transferred to the cosmic collection at the `Open Channel Foundation'; however EGRAM itself appears to have been semi-orphaned, and is in that collection's set of `other projects'. An enquiry to the Open Channel folk revealed that they ``are not currently able to fulfill orders for COSMIC software from non-US customers.'' I don't know if this tells you if it's effectively available or not. In this collection, EGRAM seems to have `NASA case number gsc-13016'.
$Log: echelle_refs.html,v $ Revision 1.4 2003/10/01 16:04:48 norman Update information about EGRAM, after contact from current holders Revision 1.3 2003/10/01 10:20:16 norman Added information on last known whereabouts of EGRAM (this was a gopher link!)