sci The Smithsonian Astrophysical Observatory Image Deep Space 9 is an astronomical imaging and data visualization application. It is the new generation of the SAOImage software. DS9 supports FITS images and binary tables, multiple frame buffers, region manipulation, many scale algorithms and colormaps. It provides communication with external analysis tasks and is configurable and extensible. DS9 supports multiple frame buffers, mosaic images, tiling, blinking, geometric markers, colormap manipulation, scaling, arbitrary zoom, rotation, pan, and a variety of coordinate systems. DS9 also supports FTP and HTTP data access. DS9 is a Tk/Tcl application which utilizes the SAOTk widget set. It also incorporates the X Public Access (XPA) mechanism to allow external processes to access and control its data, GUI functions, and algorithms.