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.