In message <V3W7nCAeq21yEw5D@wingar.demon.co.uk>, which took an inordinately long time to be reflected on SeeSat-L, Alan Pickup <alan@wingar.demon.co.uk> writes >... it was running all of 40 seconds earlier than my >prediction of a few hours ago; the uncertainty must have been greater >than I thought and the decay will be sooner. Taken alone, this elset >evolves to decay at January 11.8, but yet another analysis (using elsets >since January 10.58) suggests that decay may occur at January 12.66 >(~15.20 UT). >... Oh dear, I meant January 11.66 as my SatEvo output made clear (I hope!). Mike McCants has posted later elsets but not this one, released after his posting: Molniya 3-48 r 7.5 2.6 0.0 5.3 d 145 x 130 km 1 24641U 96060B 97011.68079513 .28457703 90213-5 26505-3 0 1815 2 24641 62.7758 213.2859 0011962 112.6382 247.5773 16.50697726 12553 I believe it decayed on this rev, possibly near or shortly after the perigee at January 11.70. The question arises as to what went wrong with my prediction late on the 10th that this would "decay at about January 12.02 but this is still uncertain by one or two orbits". That prediction had been based on elsets from Jan 9.84 to Jan 10.70. What I didn't appreciate until later was that there had been the strongest geomagnetic storm since October 23 between Jan 10.25 and Jan 10.5. There are good reasons to believe that the atmospheric density (and therefore drag) at low altitudes increased substantially as a result of this event. For example, OIG's ndot/2 for both #23852 = MSX Delta r (perigee at 190 km) and #24702 = Bion 11 SL-4 r (210 km) increased by about 60% during the hours following Jan 10.5 (and is still elevated) as compared with the (pretty stable) average over the previous 3 days. Though both objects are approaching decay in the next month, I'd expect to see their ndot/2 increasing at only 3.5%/day or so, much less than that observed. I suspect the increased density as a result of the storm is what brought #24641 down early. Of course, SatEvo does not (yet!) predict geomagnetic storms :-( Alan -- Alan Pickup | COSPAR site 2707: 55d53m48.7s N 3d11m51.2s W 156m asl Edinburgh | Home: alan@wingar.demon.co.uk +44 (0)131 477 9144 Scotland | Royal Observatory: A.Pickup@roe.ac.uk +44 (0)131 668 8224