For purposes of WinOrbit, an observer is just a location on the ground, with a Latitude, Longitude, and Altitude. A real observer, of course, might look visually or with a telescope for a satellite, or might have a ground station consisting of some radios and antennas with which to attempt communication to or through the satellite. In Amateur Radio jargon, the observer's location is referred to as QTH, using an old Morse code symbol.

In addition to the principal observer (generally you), always displayed in the main window, for whom the various calculations are performed, there may be other observers of interest - those with whom you might share a Mutual Visiblity Window. These stations may be called DX, or distant stations, in Amateur Radio jargon. You can get a list of all stations, including yourself, having mutual visibility with a particular satellite by choosing Show DX in the Map Window.

Observer data are contained in the Observer Database