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Updating the Elements


WinOrbit uses a Satellite Database containing data sets called Keplerian Elements. These data sets are publicly available, and are revised frequently to include new satellites, and to reflect the gradual changes of the orbits of old ones. New tables are available from many BBSes, and in the form of bulletins on the Amateur Radio packet networks and in bulletin broadcasts from various Amateur Radio stations, as well as on the Internet.

You have two choices about maintaining the database: simply replace the currently-used file with a new one; or get fancy by merging multiple files, together with manual entries, into the database and then saving the contents as a new file. See the discussion under the File Menu for the Satellite Information Window.

In any event, you must periodically choose Satellite... in each Map Window and select the appropriate new entry from the list. How often you do this depends on the availability of new data, your ambition, and how fast the satellite seems to drift from the program predictions. For some satellites, this may be months or even a year or more, for others, only a few weeks.
The program accepts two basic formats ( NASA 2-line, and AMSAT Kep. Vector format is also acceptable. WinOrbit is not terribly picky about the details of the files - all you need to do is save a bulletin file in ASCII text format with the right sort of filename:
NASA format files should have a filename ending in ".2LI", or ".TLE".
AMSAT format files should end in ".KEP".

Vector format files should end in ".VEC" or ".VIF".

The program can find its way past the header information, so there's no need to edit the files at all in most cases. Currently published element sets have a checksum included to verify that the numbers were transcribed or transmitted correctly. If the checksum is absent or wrong, an error message appears, giving you the option to keep the data anyway or discard it.

Element sets can also be edited or created, by manually typing in the element values.
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