APT Weather Satellites - Useful Internet Sites
Software for APT
The HF-FAX Site
One of the most comprehensive sources of software for decoding, inter alia, APT Weatherfax (the data transmitted by the NOAA weather satellites), is the software page at Marius Rensen's HF-FAX site. Here you will find links to all the most popular software packages plus many more specialised programs. Additionally, you will find that the site also gives access to a number of computer programs dedicated to satellite tracking, an essential tool for all avid satellite enthusiasts.
David Taylor's Satellite Tools Site
David Taylor has developed a number of popular and inexpensive software packages aimed at the weather satellite enthusiast. Visit his website, not only to try out his software, but to consult the many pages of essential information for every weather satellite enthusiast.
NASA 2-line Element Sets
If you have a satellite tracking program such as Wxtrack or Satscape it is essential to update the NASA 2-line element sets used by these programs to calculate the actual positions of satellites.
The orbits of satellites around the Earth are continually changing by small amounts as a result of disturbing influences. These include the Solar Wind, atmospheric drag, tidal forces from the Moon and perturbations due to small variations in the Earth's gravitational field.
As a result, it is necessary to update your 2-line elements regularly. The most popular site for this purpose is the Celestrak Site where elements for just about every body in Earth orbit are listed. These are generally updated daily.
It is a good idea to update your tracking program once a month for general use. If you are relying on an automatic recording control system (in which case, you must also ensure that your PC internal clock is accurate to within a few seconds), you should update more frequently.