SKY2XY (Feb95)               ftools.heasarc               SKY2XY (Feb95)



NAME
    sky2xy - Given sky coordinates and a file, transform to X Y
    
    
USAGE
    sky2xy infile xsky ysky
    
    
DESCRIPTION
    This  tasks  takes  the input sky coordinates and transforms them to
    pixel X and Y 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 SKY2XY'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.
        Either an image or a table with the appropriate  2  columns  are
        acceptable.  The default is an image in the primary array.
    
    xsky =  [double]
        The input value of the X sky coordinate (RA).
    
    ysky =  [double]
        The input value of the Y sky coordinate (DEC).
    
    (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.
    
    (xpix = ) [double]
        The returned X coordinate in pixels.
    
    (ypix = ) [double]
        The returned Y coordinate in pixels.
    
    (valid = ) [boolean]
        The returned true if this data is valid else false.
    
    (radecsys = ) [string]
        The returned WCS for the input file.
    
    (ctype1 = ) [string]
        The returned file X axis coordinate projection type
    
    (ctype2 = ) [string]
        The returned file Y axis coordinate projection type
    
    (equinox = ) [real]
        The returned equinox for WCS used.
    
    (crval1 = ) [double]
        The returned X axis coord. value at reference pixel(deg).
    
    (crval2 = ) [double]
        The returned Y axis coord. value at reference pixel(deg).
    
    (crpix1 = ) [double]
        The returned X axis reference pixel location.
    
    (crpix2 = ) [double]
        The returned Y axis reference pixel location.
    
    (cdelt1 = ) [double]
        The returned X axis coord. incrementat reference pixel(deg).
    
    (cdelt2 = ) [double]
        The returned Y axis coord. incrementat reference pixel(deg).
    
    (rot = ) [double]
        The returned Celestial coord. 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 pixel values for RA=126.3 DEC=23.5 for the 
        image in the primary array of input.fits
    
        ft> sky2xy input.fits+0 126.3 23.5
    
    2.  Calculate the pixel value for 123.4 5.3 using the DETX and DETY
        columns of first extension of the file input.fits.
    
        ft> sky2xy input.fits+1 123.4 5.3 xcol=detx ycol=dety sensecase=no
    
    
    
BUGS
    
    
SEE ALSO
    XY2SKY, F2DHISTO