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%.COPYRIGHT  (c)  1993-2011 European Southern Observatory
%.IDENT      initiaemmi.hlq
%.AUTHOR     PB, IPG/ESO
%.KEYWORDS   MIDAS, help files, 
%.PURPOSE    On-line help file for the command: INITIAL/EMMI
%.VERSION    1.0  09-MAR-95 : Creation, PB
%----------------------------------------------------------------
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SECTION./EMMI
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INITIALIZE/EMMI					      09-MAR-95  PB
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INITIALIZE/EMMI  [ref] [grism] 
	Initializes the Echelle context for a given EMMI configuration
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Purpose:    
            The command INIT/EMMI reads header information from
            EMMI Echelle images and initialises the Echelle context
            to the corresponding configuration. The configuration
            can also be set directly.
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Syntax:     
            INITIALIZE/EMMI  [ref] [grism] 
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            ref    = If no value is provided for this parameter, 
                     the displayed image (if it exists) will be used
                     as reference. If an image name is provided, 
                     the header information will be read from this 
                     image. If a number is provided it will be 
                     interpreted as the grating number (9 or 10)
                     and the second parameter is expected.
\ap\pa
            grism  = If a numerical value has been provided as
                     first parameter (grating number), the second
                     parameter must indicate the grism number
                     (3 or 4 for grating 9, 3 to 6 for grating 10).
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See also: 
            UPDATE/ORDER, UPDATE/ECHELLE.
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Note:       
            1) Pre-calibrated EMMI solutions are stored in the 
               MID_EMMI directory. These solutions are defined
               in world coordinates and apply to EMMI images flipped
               with the command FLIP/IMAGE to be set at standard 
               orientation. The command INIT/EMMI will attempt  to 
               read the descriptors _EIG1_ID and _EIO9_ID from the
               image header and will activate the command: 
               INIT/ECHELLE MID_EMMI:echGRgCD where GR and CD stand
               for grating and cross-disperser numbers.
            2) The pre-calibrated solutions apply to images at 
               standard orientation, namely EMMI images flipped with
               the command FLIP/IMAGE.
            3) The solution can be visualized on an image using
               LOAD/ECHELLE. An Offset between the displayed image and
               the pre-calibrated solution is usually present and
               must be corrected with the command UPDATE/ORDER. 
            4) The MID_EMMI directory must be installed in the
               /midas/calib area. The calibration tables are distributed
               on request in complement to the Midas releases. These tables 
               are also available on anonymous ftp at the host 
               ftphost.hq.eso.org (IP number 134.171.40.2). The files 
               to be retrieved are located in the directory 
               /midaspub/calib and are named README.calib and calib.tar.Z. 
               Command SHOW/TABLE can be used to visualize the 
               column name and physical units of the tables. Demonstration 
               data required to execute the tutorial procedure 
               TUTORIAL/ECHELLE are also located on this ftp
               server in the directory /midaspub/demo as echelle.tar.Z. 
               FTP access is also provided on the World Wide Web URL: 
               http://http.hq.eso.org/midas-info/midas.html 
               The calibration directory contains other information 
               such as characteristic curves for ESO filters and CCD 
               detectors, which can be visualized with the Graphical 
               User Interface XFilter (command CREATE/GUI FILTER).
            5) ThAr calibration tables are located in MID_ARC directory.
               A standard ThAr table is provided as thar.tbl and can be
               copied with the system command: 
                  copy  MID_ARC:thar.tbl   thar.tbl      (VMS)  
                  cp    $MID_ARC/thar.tbl  thar.tbl      (UNIX) 
               Other ThAr tables selected for blends at different resolutions
               have been provided by H.Hensberge \& al. (Antwerp University) 
               for the spectral resolutions 25000, 33000, 50000 and 100000
               and are named thar25.tbl, thar33.tbl, thar50.tbl and 
               thar100.tbl.
            6) Spectrophotometric standards are provided in the MID_STANDARD
               directory, usually corresponding to the directory 
               /midas/calib/data/spec/flux. Additional tables are
               available in /midas/calib/data/spec/ctio.
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Examples:
\ex
            INITIALIZE/EMMI  
            Reads header information from the image currently present
            in the display window and initializes the context.
\xe\ex
            INITIALIZE/EMMI ccd0026
            Reads header information from the image ccd0026.bdf and
            initializes the context.
\xe\ex
            INITIALIZE/EMMI 10 4
            Retrieves pre-calibrated solution for grating 10, 
            cross-disperser 4 by issuing the command: 
            INITIALIZE/ECHELLE MID_EMMI:ech10g4.
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