% @(#)definesky.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:50:35
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1994 European Southern Observatory
%.IDENT      definesky.hlq
%.AUTHOR     PB, IPG/ESO
%.KEYWORDS   MIDAS, help files, 
%.PURPOSE    On-line help file for the command: DEFINE/SKY
%.VERSION    1.0  07-OCT-94 : Creation, PB
%----------------------------------------------------------------
\se
SECTION./SKY
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DEFINE/SKY					      07-OCT-94  PB
\oc\su
DEFINE/SKY  ima  [nsky]   [possky]  [half_width] 
	defines limits of the sky windows
\us\pu
Purpose:    
            The limits of the sky window(s) are defined directly
            or interactively. 1 or 2 sky windows can be defined. 
            A cross-order profile is plotted in the graphic window
            and the program expects two position clicked for 1 window
            and four position cliked for two windows. The position
            of the cross-order profile plotted is set automatically
            (POSSKY=AUTO), indicated numerically (POSSKY=order,column)
            or defined interactively by a click in the display window
            (POSSKY=CURSOR). The cross-order profile is plotted over
            1.0 order on each side (parameter half-width).
\up\sy
Syntax:     
            DEFINE/SKY ima  [nsky]   [possky]  [half_width] 
 \\
\ys\pa
            ima    = Name of the original 2D echelle spectrum displayed
                     in the display window.
 \\
\ap\pa
            nsky   = Number of sky windows (1 or 2). Echelle keyword: NSKY
 \\
\ap\pa    
            possky = Position of the plotted cross-order profile.  \\
                     Echelle keyw.: POSSKY \\
                     Possible values are: AUTO (default), CURSOR or order,col \\
                     AUTO : The position corresponds to the central order \\
                            in the central column  \\
                     order,col: The relative order number <order> is plotted \\
                            at the column <col> \\
                     CURSOR: a cursor appears in the display windows which \\
                            allows to point an order. The order number and \\
                            column position are taken from the cursor position. 
 \\
\ap\pa
            half-width = extension of the cross-order profile. Default value
                     is 1.0 order width on each side.
 \\       
\ap\sa
See also: 
            EXTRACT/SKY
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Note:       
            None 
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Examples:
\ex
            DEFINE/SKY  rot0001 2 CURSOR 0.75
\xe \sxe