; NAME:
;      OHLINES
;
; PURPOSE: 
;      This function makes OH lines from a database
;
; CALLING SEQUENCE:
;      Result = OHLINES(wavl)
;
; INPUTS:
;      Wavl = The array of wavelength locations (in meters) 
;             (range 0.5 microns to 2.0)
;      OHLoc = The location of the oh line database
;
; OUTPUT:
;      A spectrum with lines from the OH database
;      (in photons*s-1*m-2*arcsec-2)
;      
; PROCEDURE:
;      Calculate the range, make a list from the database.
;
; MODIFICATION HISTORY:
;      created June 22 2003 by John Dermody

function OHLINES, wavl, ohloc=ohloc

; initialize variables. 
if not keyword_defined(ohloc) then begin
  ohloc = file_which('ohsky/database.txt')
endif

nwavl = n_elements(wavl)	; number of wavelengths
wavla = wavl * 1.e10		; conver wavl to angstroms
swavela = wavla[0]		; start wavelength (A)
ewavela = wavla[nwavl-1]	; end wavelegth (A)

; set up the data to be read
if not file_test(ohloc) then message, 'OH Database missing; ' + ohloc
ohdatafile = parsetab(rdasctab(ohloc))
i = where (    ohdatafile[0,*] eq 'OH' $
           and ohdatafile[1,*] eq 'Skylines') 
dashloc = where(ohdatafile eq '-')  ; change missing data to 0s
ohdatafile[dashloc] = '0'
ohdata = float(ohdatafile[3 : 5, i + 1 : *])

; make a list of all lines with positions between swavela and ewavela
lineloc = where((ohdata[0,*] gt swavela) and (ohdata[0,*] lt ewavela))
if (lineloc eq [-1]) then return, 0
ohdata = ohdata[*,lineloc]

; limit it to lines with height and width greater than 0.
lineloc = where((finite(ohdata[2,*]) ge 0.) and (finite(ohdata[1,*]) ge 0.))
if (lineloc eq [-1]) then return, 0
ohdata = ohdata[*,lineloc]

; convert wavelengths to subscripts
cnvt = (nwavl - 1) / (ewavela - swavela)
ohdata[0,*] = (ohdata[0,*] - swavela) * cnvt
ohdata[1,*] = ohdata[1,*] * cnvt

return, ohdata
end