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			      AF
				
		 Conversion to 'absolute' flux

	Option ABSFLX takes the final (averaged ?) calibration curve
 (from OK) and applies it to the rest of the data, [which has  been
 prepared (flat-fielding, coincidence correction, scrunching, etc.) in
 exactly the same way as the flux standard(s)].
 a) AIRMAS is calculated from header info - extinction coefs should
 be as used in OKECAL.
 For 2D data there are 2 observational possibilities:
   i)   use CD to produce a mask from the calib star and then use
   this mask to extract (XT) individual line spectra to be calibrated.
   The std may be masked, used in OK to -> calibration and then
   Either the entire 2Dmap calibrated and the "line" spectra extracted
   later OR the extraction may be done first.  (The opp is commutative.)

   or ii)	Do the objects at a fixed slit position, then sum constant
   object rows and subtract constant sky rows to produce '1 row'
   data. This is obviously unsatisfactory for extended objects.

	See FLUXCAL.DOC in the DOCUMENT area for more detailes.

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 Uses the K(LAMBDA) array from OKECAL to convert observed (SCR UNCHED)
 spectra into absolute flux F(lambda) vs lambda.

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			    EXAMPLE

 TYPE OPTIE                              25-SEP-1981 05:24:23.11
 >>>AF                                                                              
 OPTION AF
 OPEN THE FILE TO BE CONVERTED TO ABSOLUTE FLUX
 TYPE FILENAME (<CR> FOR DEFAULT)
 FILI=LLINE
 There are  11 maps in the file       
 Reading from the file
    1 rows of 2040 pixels in R4 format
 TYPE INPUT MAPNUMBERS TO BE CONVERTED (Def = ALL)
 MAPI=1
 TYPE OUTPUT MAPNUMBERS (Def = MAPI)
 MAPO=1
 DO YOU WISH TO STORE THE EXTINCTION COEF ? (Y or N)
 ___ extinction as fn. wavelength can be stored to use in weighting data !
 EXT=Y
 OPEN A FILE TO STORE THE EXT COEF
 Number of rows in the file can be anything > 1
 Number of pixels must be:    2040
 TYPE FILENAME (<CR> FOR DEFAULT)
 FILO=EXTN
 Writing to an existing file
   15 rows of 2040 pixels in R4 format
 TYPE OUTPUT MAP
 MAPEO=1
 TRANSFER FITS MAP HEADER TO THE COEF FILE ?
 SAME=N
 TYPE OUTPUT ROW
 ROWEO=1
 OPEN THE FLUX CALIBRATION FILE
 TYPE FILENAME (<CR> FOR DEFAULT)
 FILC=SCALIB
 There are   2 maps in the file       
 Reading from the file
    1 rows of 2040 pixels in R4 format
 TYPE MAPNUMBER OF CALIBRATION ARRAY
 MAPC=2
 SPECIFY 3 COEFS FOR EXTINC = A/X**4 + B/X**1.3 + C   where X = LAM/10000
 DEFAULTS ARE :
 	RAYLEIGH	A = 0.0092
 	DUST		B = 0.0
 	CONSTANT	C = 0.06
  
 EXTCO=
  0.920000E-02
  0.000000E+00
  0.600000E-01
 SELECT OUTPUT DATA UNIT
 	1	F(Lambda) vs lambda (DEF)
 	2	F(nu)     vs lambda
 TYPE OUTPUT OPTION
 OPT=1
 The dwell times are read from the map headers
 Do you want to specify the dwells yourself  ?
 CHECK=
 F
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