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, published in Astronomical Data Analysis Software and Systems V, A.S.P. Conference Series, Vol. 101, 1996, George H. Jacoby and Jeannette Barnes, eds., p. 96.

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.

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