ISS TLE's

Bruno Tilgner (Bruno_Tilgner@compuserve.com)
Thu, 26 Nov 1998 18:14:56 -0500

Hello,

just a warning for those making predictions of ISS passes. The
orbital elements appear to be very unstable, leading to vastly
different results even over the relatively short time span of
one week. I suspect the culprit is the drag term, as exemplified
by the following elsets which are no more than one day and a half
apart:


ISS
1 25544U 98067A   98328.09922526  .00025237  00000-0  15999-3 0   328
2 25544  51.5893 148.2555 0056731  63.3832 297.2474 15.74087737   611
ISS
1 25544U 98067A   98329.57169160 -.00146458  00000-0 -18619-2 0   398
2 25544  51.5964 140.8358 0009347 223.7905 136.2350 15.59090576   841
ISS
1 25544U 98067A   98330.46900289  .00025679  00000-0  32606-3 0   430
2 25544  51.5971 136.3246 0009593 221.8519 138.1711 15.59190118   988


Bruno Tilgner
Paris, France