Satellite Tracking and Keplerian Elements

What is Satellite Tracking?

Satellite Tracking software provides the exact time and location to find a satellite and follow its path through the sky. Amateur radio operators use these programs to know when they can access a satellite with their radio equipment, and there are also special provisions with some programs to provide automatic control of antennas so they constantly track the satellite when it is above the horizon.

Not just amateur radio operators, but everyone can benefit from these programs for visually sighting a satellite. The International Space Station (ISS) is already one of the brightest objects in the night sky, and it will become even brighter in the years ahead as more modules are added and the station grows in size. Also watch for it to be brighter when a shuttle or Soyuz capsule is docked. When conditions are right, the ISS can be seen to "flare," which is a sudden increase in brightness by an order of several magnitudes. This can be quite spectacular to watch or capture on film.

Three things are needed to use a Satellite Tracking program. First, Keplerian Elements (see below). Second, your latitude and longitude. You can get your lat/lon info by entering in your zip code at MapBlast. And third, your time zone and the difference from GMT.

Links to Tracking Software

What are Keplerian Elements?

Named for Johannes Kepler, who created the Three Laws of Planetary Motion, these number sets represent a mathematical "snapshot in time" for each satellite, allowing the Satellite Tracking programs listed above to show real-time movements of any satellite, or project future times that a satellite will pass overhead. There are two main variations in the way these element sets are distributed, NASA format or AMSAT format, and you will need to ensure that you get the correct type for the tracking program that you use (some programs accept both). Keplerian elements are often referred to as keps, kep sets, elsets (for element sets), and TLE's (for Two Line Elements).

Sources for Keplerian Elements


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Site last updated October 2002
Page author: Stan Vandiver, W4SV

(2001) MAREX-MG