[WCSTools programs]

Sky Coordinates from Image Coordinates

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. By default, output coordinates are at the same equinox as is given in the image header, they may be transformed to B1950/FK4, J2000/FK5, galactic, or ecliptic coordinates. Input and output files in the Starbase format will eventually be allowed.

The inverse program, sky2xy, computes image pixel coordinates from world coordinates.

Command Line Arguments


Last updated 10 November 2009 by Doug Mink

Telescope Data Center