% @(#)extincspec.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:55:40 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      extincspec.hlq
%.AUTHOR     JDP, IPG/ESO
%.KEYWORDS   MIDAS, help files, EXTINCTION/SPECTRUM
%.PURPOSE    On-line help file for the command: EXTINCTION/SPECTRUM
%.VERSION    1.0  13-JUN-1986 : Creation, JDP
%----------------------------------------------------------------
\se
SECTION./SPEC
\es\co
EXTINCTION/SPECTRUM					13-JUN-1986 JDP
\oc\su
EXTINCTION/SPECTRUM inframe outframe scale [table] [col]
	correct spectra for interstellar or atmopsheric extinction
\us\pu
Purpose:      Correct spectra for interstellar or atmopsheric extinction.
\up\sub
Subject:      Spectroscopy, Calibration, Extinction.
\bus\sy
Syntax:       EXTINCTION/SPECTRUM inframe outframe scale [table] [col]
\ys\pa
              inframe  = the frame to be correct for extinction
\ap\pa
              outframe = the frame to hold the corrected data
\ap\pa
              scale    = the scaling factor:
                         a) E(B-V) if interstellar reddening
			 b) AIRMASS if atmospheric extinction.
                         Defaulted to the AIRMASS descriptors from the frame.
\\
\ap\pa
            table    = the table with the wavelength dependence of the
                         reddening or the atmospheric extinction, defaulted
                         to ATMOEXAN (cf. below)
\ap\pa
              col      = the column of the table to be used (defaulted to: 2)
\ap\out
Output:       Outframe
\tuo\no
Note:         The table supported by MIDAS to correct for interstellar
              extinction is:
\\
              1a) INSTEXAN contains in column \#1 the wavelength in Angstroem
              units and in columns 2-8 seven different extinction laws the
              references for which are as follows:
\\
              col. 2: Savage, B.D., Mathis, J.S.,
                      Ann. Rev. Astron. Astrophys. No. 17, 73 (1979): Galaxy
\\
              col. 3: Nandy et al., MNRAS Vol. 196, 955 (1981): LMC
\\
              col. 4: Prevot et al., Astron. Astrophys. Vol. 132, 389 (1984):
                      SMC
\\
              col. 5: Koornneef, J., Code, A.D., ApJ Vol. 247, 860 (1981): LMC
\\
              col. 6: Seaton, M.J., MNRAS Vol. 187, 73P (1979): Galaxy fit
\\
              col. 7: Howarth, I.D., MNRAS Vol. 203, 301 (1983): Galaxy fit
\\
              col. 8: Howarth, I.D., MNRAS Vol. 203, 301 (1983): LMC fit
\\
              All laws are normalized to A/E(B-V) = 3.1 at 5550 A and
              interpolated and rebinned to constant step in wavelength (10 A).
	      Note that the wavelength coverage is very different for the
              various data sets.
\\
	      1b) The contents of INSTEXNM is the same except for use with
              spectra calibrated in nanometers
\\
	      Correction for atmospheric extinction is possible with:
\\
	      2a) ATMOEXAN containing the wavelength in Angstroem units
	      in column \#1 and the extinction law for La Silla as described
              by H. Tug in the ESO Messenger No.11, December 1977, and
              listed in the ESO User's Manual.
\\
	      2b) ATMOSNM which is identical to ATMOEXAN except for
              wavelengths in nm
\\
	      If "scale" is defaulted, descriptor "AIRMASS" is read from
              frame "inframe".
\\
              These tables are stored in
              MID_EXTINCTION:
\on\exs
Examples:
\ex
              EXTINCTION/SPECTRUM OBSERVED CORRECTED
\xe \sxe