% @(#)astromcomp.hlq	19.1 (ESO-SDAG) 02/25/03 13:23:00
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SECTION./ASTROM
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ASTROMETRY/COMPUTE		 		           17-Oct-1994 OH, RHW
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ASTROMETRY/COMPUTE mes option out trail
	Convert the coordinates from the measured xy ot RA,Dec vice versa
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Purpose:	
	Convert the coordinates from the measured xy ot RA,Dec and
	vice versa, using the transformation transformation parameters 
        computed by ASTROMETRY/TRANSFO.
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Syntax:   
	ASTROMETRY/COMPUTE  mes option out trail
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        mes =    table containing the XY measurements; It must have
                 been previously processed by ASTROMETRY/TRANSFO in
                 order to have the descriptors with the transformation
                 parameters set.
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	option = specifies what should be done with the data:\\
		 1: Calculate (A,D) for plate center (assuming that the
                    first measurements correspond to the plate crosses)
	   	    and several (X,Y)-values from the mes table.\\
  		 2: Calculate (A,D) for several (X,Y)-values from the mes
 		    table. This is the most used option (and the default).\\
		 3: Calculate (A,D) for one (X,Y)-value entered at the
                    keyboard. In this case, mes table is used only to get 
		    the transformation parameters, and is not actually red.\\
   		 4: Calculate (X,Y) for one (A,D)-position entered at the
		    keyboard. In this case, mes table is used only to get
                    the transformation parameters, and is not actually red.\\
		 5: Calculate (X,Y) for several (A,D)s in disc file 
    		    (not implemented in Midas... the input file must be
		    ASCII).
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	out =   output table, where the computed coordinates are
                stored. This table can be used as standard stars table
	        in case a multistep astrometric  calibration is
	        needed.
\ap\pa           
	trail = Flag indicating if the measurements correspond to
                the end of the trails (Y), eg left by a moving object
                or not (N); default is N.
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See also:
	ASTROMETRY/TRANSFO, ASTROMETRY/EDIT, ASTROMETRY/POS1
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Note:  
        ASTROMETRY/COMPUTE computes the A,D from X,Y using directly the
	transformation parameters, while it obtain X,Y from the A,D
	in an iterative manner.\\
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	NOTE THAT THE EQUINOX OF THE COMPUTED COORDINATES IS THE SAME
	AS THE STANDARD STARS CATALOGUE (which is NOT necessarilly
	the same as its epoch). 2000.0 in case the PPM is used.\\
\\
	Option 5 is not fully implemented in MIDAS; it works like in
	the former standalone version, using an ASCII input file.\\
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Examples:
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        ASTROMETRY/COMPUTE mesxy342 2 sec342 
	Convert the measured X,Y from mesxy342 in A,D, and store the
        results in sec342. The objects were not trailed.
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