DS9 is the next version of the popular SAOtng display program. It is a Tk/Tcl application which utilizes the TkSAO widget set. It also incorporates the new X Public Access (XPA) mechanism to allow external processes to access and control its data, GUI functions, and algorithms. DS9 supports the direct display of FITS images and binary tables, multiple frame buffers, region cursor manipulation, many scale algorithms and colormaps, and easy communication with external analysis tasks. It is highly configurable and extensible to meet the evolving needs of the astronomical community.
DS9 supports advanced features such as multiple frame buffers, mosaic images, tiling, blinking, geometric markers, colormap manipulation, scaling, arbitrary zoom, rotation, pan, and a variety of coordinate systems (including Image, Physical, Detector, and WCS). DS9 also supports FTP and HTTP access. The GUI for DS9 is user configurable.