The latest version of WinOrbit (3.6) is now available on ftp.amsat.org. This version includes Y2K fixes. An overview of the program follows: WinOrbit is a program for computing artificial Earth-satellite position and visibility, with the Amateur Radio satellite operator in mind. It was written for the Microsoft Windows 3.1 operating system. WinOrbit is free (not shareware). The latest version is 3.6. It will run on Windows 95, NT 4, and 98 (although Win98 has some video compatibility problems on some brands of PC). WinOrbit has 4 basic functions: * Graphical display of satellite positions in real-time, simulation, and manual modes. * Tabular display of satellite information in the same modes. * Generation of tables (ephemerides ) of past or future satellite information for planning or analysis of satellite orbits. * Output of current tracking information (az, el, doppler, etc.) to a client program for control of tracking hardware such as antennas, radios, or telescopes. Features: The principal feature of WinOrbit is a series of Map Windows, which display the current position of satellites and observers on a simple world map, together with information such as bearing (azimuth), distance, and elevation above the observer's horizon. The maps can be updated in real time, or in simulated time, or manually set to show the situation at any time past or future. An additional Table Window displays much more-detailed information about one or more satellites in a tabular form. The tabulated items can be selected and rearranged to fit the screen. This information likewise can be updated in real-time, manual, or simulation modes. Additional noteworthy features include: * Simultaneous tracking of up to 20 satellites. * Choice of 4 tracking algorithms. * A "view from space" map presentation showing what a particular satellite actually sees. * Computation of Doppler shift and path loss for communications satellites. * Utility functions for modifying and comparing published element sets, including post-launch updating of pre-launch elements, and saving composite data files compiled from various sources. * Built-in tracking of Sun and Moon. * Support for tracking other astronomical objects (given Right Ascension and Declination). * DDE server interface to tracking-antenna or doppler-shift correction hardware controllers, compatible with the Full Doppler Tuning standard. WinOrbit can run in a "server only" or "mapless" mode to conserve memory when needed. * Tracking data (Keplerian element sets) read from standard, off-the-air bulletins in three different formats (unlimited number of satellites). No pre-processing is needed, just select a bulletin file. Auto Update is also possible. * Observer (QTH) data (latitude, longitude) may be imported from a simple text database (unlimited number of observers). * Printing of tables of tracking data (Ephemerides) in several formats. Table printing does not interrupt tracking. Table output may be directed to a disk file, for later analysis in a spreadsheet, for example. * On-line help including direct access to text information about each satellite from the map windows, and "context- sensitive" help accessible directly from various windows. * Standard Windows interface for all functions - no commands to memorize. Both mouse and keyboard can be used for most functions. * Many more features described in comprehensive Help file. WinOrbit is distributed as a single file, WINORBxx.ZIP (xx = version). VBRUN300.DLL is also required (you may already have it - if not, you can get it as described in the WinOrbit documentation). Two accessory program packages are also available: announ12.exe - the WinOrbit Announcer A DDE client which gives audio indication of satellite Az/El for visual observers. Self-extracting archive, with source code in VB3. wprair21.zip - version 2.1 of WinPrairie A DDE client which controls radios, and antennas using the Prairie Digital board. With source code in VB3.