;+
; NAME: os_getfilter 
;
; 	Given a header (or array of headers)
;
; INPUTS:
; KEYWORDS:
; OUTPUTS:
;
; HISTORY:
; 	Began 2006-04-06 14:44:54 by Marshall Perrin 
;-

function os_getfilter,hdrs


instr = strc(sxpararr(hdrs,"INSTR",/silent))

	; handle IMAG headers. This is a little tricky since
	; there are two filter wheels
    if1 = strc(sxpararr(hdrs,"IF1NAME",/silent))
    if2 = strc(sxpararr(hdrs,"IF2NAME",/silent))
    wo = where(if1 eq "Opn",woct)
    if woct gt 0 then if1[wo] = ""
    wo = where(if2 eq "Opn",woct)
    if woct gt 0 then if2[wo] = ""
    filters=if1+if2

	; handle SPEC headers
	wspec = where(instr eq 'spec',nspec)
	if nspec gt 0 then begin
    	sf = strc(sxpararr(hdrs,"SFWNAME",/silent))
		filters[wspec] = sf[wspec]
	endif
   

return,filters

end