XY2SKY (Feb95)               ftools.heasarc               XY2SKY (Feb95)



NAME
    xy2sky - Given the XY in a file, transform to sky  coordinates  (RA,
    DEC)
    
    
USAGE
    xy2sky infile xpix ypix
    
    
DESCRIPTION
    This  tasks takes the input X and Y pixel values and transforms them
    to sky coordinates using the World Coordinate System (WCS)  keywords
    in  the input file.  The input file can either contain an image or 2
    columns.  The results are both printed to the screen and recorded in
    the parameter file.
    
    The  following  information  is written back into XY2SKY's parameter
    file.  The valid flag is set to 'no' at the  beginning  of  the  run
    and reset to 'yes' following successful completion:
    
    (valid = ) Is the following file WCS info valid?
    
    (radecsys = ) File World Coordinate System (WCS)
    
    (ctype1 = ) File X axis coordinate projection type
    
    (ctype2 = ) File Y axis coordinate projection type
    
    (equinox = ) File equinox for this WCS
    
    (crval1 = ) File X axis coord. value at ref pixel (deg)
    
    (crval2 = ) File Y axis coord. value at ref pixel (deg)
    
    (crpix1 = ) File X axis reference pixel location
    
    (crpix2 = ) File Y axis reference pixel location
    
    (cdelt1 = ) File X axis increment at ref pixel (deg/pixel)
    
    (cdelt2 = ) File Y axis increment at ref pixel (deg/pixel)
    
    (rot = ) File coordinate rotation angle (deg)
    
    
PARAMETERS
    
    infile [filename]
        The  name  and extension of the FITS file containing the data to
        transform.  Either an image or a table with  the  appropriate  2
        columns  are acceptable.  The default is an image in the primary
        array.
    
    xpix [double]
        The X coordinate in pixels to be transformed to sky coordinates.
    
    ypix [double]
        The Y coordinate in pixels to be transformed to sky coordinates.
    
    (xcol = X) [string]
        The name of the X column to use if a table is specified.
    
    (ycol = Y) [string]
        The name of the Y column to use if a table is specified.
    
    (valid = ) [boolean]
        The returned true if this data is valid else false.
    
    (radecsys = ) [string]
        The returned WCS for the input file.
    
    (ctype1 = ) [string]
        Returned type of file X coordinate axis (CTYPE keyword).
    
    (ctype2 = ) [string]
        Returned type of file Y coordinate axis (CTYPE keyword).
    
    (equinox = ) [real]
        The returned equinox for WCS used.
    
    (xsky = ) [double]
        Returned value of the X sky coordinate (RA).
    
    (ysky = ) [double]
        Returned value of the Y sky coordinate (DEC).
    
    (crval1 = ) [double]
        The returned file X axis coord. value at reference pixel(deg).
    
    (crval2 = ) [double]
        The returned file Y axis coord. value at reference pixel(deg).
    
    (crpix1 = ) [double]
        The returned file X axis reference pixel location.
    
    (crpix2 = ) [double]
        The returned file Y axis reference pixel location.
    
    (cdelt1 = ) [double]
        The  returned  file  X   axis   coord.   incrementat   reference 
        pixel(deg).
    
    (cdelt2 = ) [double]
        The   returned   file   Y   axis  coord.  incrementat  reference 
        pixel(deg).
    
    (rot = ) [double]
        The returned file coordinate rotation angle (deg).
    
    (sensecase = no) [boolean]
        Whether to be case sensitive about column names.
    
    (tchat = 10) [integer]
        Terminal chattiness value.
    
    (lchat = 0) [integer]
        Log file chattiness  level.   To  initialize  logging,  set  the
        environment  variable  FLOGFILE  to  be  the name of the file to
        contain the logging.  Add a + in the from to append  information
        from each FTOOL.
    
    
EXAMPLES 
    1.  Calculate the sky coordinate of the pixel 126.3 128.4 for the
        image in the primary array of input.fits
    
        ft> xy2sky input.fits+0 126.3 128.4
    
    2.  Calculate the sky coordinates for 1. 1. for the DETX and DETY
        columns of first extension of the file input.fits.
    
        ft> xy2sky input.fits+1 1.0 1.0 xcol=detx ycol=dety sensecase=no
    
    
    
BUGS
    
    
SEE ALSO
    SKY2XY, F2DHISTO