Name

       xy2sky - Compute RA Dec from X Y using WCS in FITS and IRAF image files

Synopsis

       xy2sky [-vbjg] [-n ndec] file.fts x1 y1 ... xn yn
       or
       xy2sky [-bdjgv] [-n ndec] file.fts @listfile

Description

       xy2sky  (pronounced  X-Y-to-sky)  is  a  utility  for  getting  the  world  coordinates of a set of image
       coordinates in a FITS or IRAF image. World coordinate  system  (WCS)  information  in  the  image  header
       describes, in a standard way, the relationship between sky coordinates and image pixels. This information
       is  used  by the program to transform image coordinate (X,Y) pairs to right ascension and declination sky
       coordinate pairs. The current version of the program prints the coordinates at the  same  equinox  as  is
       given  in  the  image  header, but future versions will allow transformations to B1950/FK4, J2000/FK5, or
       galactic coordinates. Input and output files in the Starbase format will eventually be allowed.

Options

       -a     Append input line after output position

       -b     B1950 (FK4) output

       -d     RA and Dec output in degrees

       -e     Output in ecliptic longitude and latitude in degrees.

       -f <number>
              Set third dimension for 3-D projections such as CSC

       -g     Galactic longitude and latitude output

       -i     First column is star id; 2nd, 3rd are x,y position

       -j     J2000 (FK5) output

       -m <number>
              Set mode for output of LINEAR WCS coordinates:  0: x y linear 1: x units y units  2:  x  y  linear
              units units

       -n <number>
              Number of decimal places in output RA seconds

       -q <year>
              Output equinox if not 2000 (-j) or 1950 (-b)

       -t     Output as tab-separated table

       -v     More descriptive output -z Use AIPS classic projections instead of WCSLIB

See Also

       sky2xy(1)

Author

       Jessica Mink, SAO (jmink@cfa.harvard.edu)

6 July 2001                                         WCSTools                                           xy2sky(1)