The note below is from Sardi Parthasarathy (sardi@nssdca.gsfc.nasa.gov) 12/2/96 Bill, as you see below, there are 3 predicts for ddd=349, based on elements(FDF provided, not 2-lines) of epoch 311,318, and 334. Focussing on the time 23:56, for example, the older the prediction the more the deviation of Lat (and Long); several degrees, scary! But the s/c reaches the SAME lat/long by a mismatch of only a minute or two. For planning things, including rocketeering, a progressively updated auspicious time would be fair enough?? ( You and I had known this for many years, since DE-1!) If the convergenece turns out to be systemmatic, it is possible to play with the cross-section to mitigate the differences in lat/long AT ANY INSTANT. ------------------------------------------------ FAST **** WITH AN EPOCH OF 96 311 0.0 ***** fast Time GEO Radius yyyy ddd hh:mm Lat Long (km) 1996 349 23:50 -23.0 40.3 6801.01 1996 349 23:51 -18.8 40.6 6833.62 1996 349 23:52 -14.7 40.9 6872.44 1996 349 23:53 -10.6 41.2 6917.21 1996 349 23:54 -6.5 41.4 6967.60 1996 349 23:55 -2.5 41.7 7023.28 1996 349 23:56 1.4 41.9 7083.89 1996 349 23:57 5.3 42.1 7149.08 1996 349 23:58 9.1 42.4 7218.45 1996 349 23:59 12.8 42.6 7291.62 1996 350 00:00 16.4 42.8 7368.22 **** WITH AN EPOCH OF 96 318 0.0 ***** 1996 349 23:50 -28.5 39.4 6768.33 1996 349 23:51 -24.3 39.8 6792.52 1996 349 23:52 -20.1 40.2 6823.24 1996 349 23:53 -15.9 40.5 6860.24 1996 349 23:54 -11.8 40.8 6903.26 1996 349 23:55 -7.7 41.0 6952.01 1996 349 23:56 -3.7 41.3 7006.15 1996 349 23:57 0.3 41.5 7065.33 1996 349 23:58 4.1 41.8 7129.19 1996 349 23:59 7.9 42.0 7197.36 1996 350 00:00 11.7 42.2 7269.44 **** WITH AN EPOCH OF 96 334 0.0 **** 1996 349 23:50 -35.9 38.1 6742.45 1996 349 23:51 -31.6 38.7 6755.01 1996 349 23:52 -27.3 39.1 6774.37 1996 349 23:53 -23.1 39.5 6800.39 1996 349 23:54 -18.9 39.8 6832.87 1996 349 23:55 -14.7 40.1 6871.56 1996 349 23:56 -10.6 40.4 6916.20 1996 349 23:57 -6.6 40.7 6966.48 1996 349 23:58 -2.6 40.9 7022.05 1996 349 23:59 1.3 41.2 7082.57 1996 350 00:00 5.2 41.4 7147.67