% @(#)responeche.hlq	19.1 (ESO-IPG) 02/25/03 14:18:39 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      responeche.hlq
%.AUTHOR     PB, IPG/ESO
%.KEYWORDS   MIDAS, help files, RESPONSE/ECHELLE
%.PURPOSE    On-line help file for the command: RESPONSE/ECHELLE
%.VERSION    1.0  05-MAR-1991 : Creation, PB
%----------------------------------------------------------------
\se
SECTION./ECHELLE
\es\co
RESPONSE/ECHELLE					25-SEP-1991 PB
\oc\su
RESPONSE/ECHELLE [std] [fluxtab]  [response] 
	compute instrument response 
\us\pu
Purpose:    Compute instrument response by comparing the extracted
            orders of the standard star to a table of fluxes.
            Optional step in the STANDARD reduction of echelle spectra.
            Parameters can be defaulted to the current session values,
            as displayed by SHOW/ECHELLE.
\up\sy
Syntax:     
            RESPONSE/ECHELLE [std] [fluxtab] [response] 
\ys\pa
            std      = standard star raw image
                       Echelle keyword is STD
\ap\pa
            fluxtab  = is the table containing flux reference
                       Echelle keyword is FLUXTAB
\ap\pa
            response = instrument response
                       Echelle keyword is RESPONSE
\ap\no
Note:     
            a) In addition to parameters STD, FLUXTAB, RESPONSE, the
               command uses echelle keywords FILTMED, FILTSMO, PIXNUL
               (see below). Keywords FILTMED and FILTSMO correspond
               to parameter [filter_specs] of MIDAS commands
               FILTER/MEDIAN and FILTER/SMOOTH
  
            b) The background will not be computed if descriptor 
               BACKGROUND/C/1/12 exists in the frame <std>. The background
               is displayed in a graphic window if BKGVISU=YES. Set it
               to NO to avoid the display.

            c) The response function is computed the following way:

                - The background is subtracted from standard star spectrum
                - An optional flat-fielding is performed (keyword FFOPT)
                - Standard star spectrum is extracted and rebinned.
                - Standard star spectrum is filtered, first by a median
                  filter, then by a smoothing filter (keywords FILTMED, 
                  FILTSMO).
                - An image is created from the flux table at the same
                  start and step than the standard star spectrum
                - response is the flux reference divided by the standard 
                  star spectrum.
                - left and right parts of the response function are
                  set to zero (keyword PIXNUL).

            d) See also Section 9. Response of SHOW/ECH
\on\exs
Examples:
\ex
            RESPONSE/ECHELLE feige56.bdf  feige56.tbl  response
\xe \sxe



