Browsing Images in World Coordinate Space with SAOimage, D.J.Mink(1995),
presented at the Fifth Annual Conference on Astronomical Data Analysis
Software and Systems
Browsing Images in World Coordinate Space with
SAOimage
By Douglas J. Mink
Smithsonian Astrophysical Observatory
Since the advent of astronomical image serving over the World Wide Web,
SAOimage, developed in the late 1980's at the Smithsonian Astrophysical
Observatory, has been used as an image viewer. More and more images,
especially those from large surveys, contain information in their
headers linking spatial coordinates (World Coordinate Systems) to image
pixel coordinates. I added code developed at the National Radio Astronomy
Observatory to SAOimage to implement the most popular projections and
coordinate systems. To decode the Space Telescope Science Institute's
Digitized Sky Survey's WCS, plate projection algorithms were added. I
wrote additional code to efficiently extract WCS information from FITS
headers and track the cursor. The WCS information for the cursor
position can be displayed or passed to an external program for uses
such as source identification. These features were implemented in a
self-contained package which is also being used in SAOtng, a "next
generation" image viewer. The library of C subroutines, as well as
current source and executable binary files for the rest of SAOimage
are available through the SAOimage page on the World Wide Web,
http://tdc-www.harvard.edu/software/saoimage.html.