;The code was written and debugged by Bish Ishibashi at MIT
; (copyright 2005).  You are free to distribute this source
; as long as this notice remains in tact.  End users of this 
; code agree to take responsibility for how this code is used 
; and Bish Ishibashi, MIT, and the University of Minnesota bear 
; no liability.

function eta_wave, file
                                                                                
tmpf=mrdfits(file,1,h)
                                                                                
w0 = sxpar(h,"CRVAL1")
wc = sxpar(h,"CRPIX1")
dw = sxpar(h,"CD1_1")
dm = sxpar(h,"NAXIS1")
                                                                                
wave = w0 + ((findgen(dm)+1-wc))*dw
                                                                                
return, wave
end