Re: Decay of 96- 54 B = Centaur r

Alan Pickup (alan@wingar.demon.co.uk)
Sun, 16 Mar 1997 00:23:30 +0000 

It is not just US SpaceCom having difficulty with this object.

Another OIG elset is:
Centaur r                                        4151 x 96 km
1 24316U 96054B   97074.87306863  .80404431 -22561-4  26958-2 0   862
2 24316  25.1748  86.9727 2384668 270.8352  62.4321 11.07570954  9015
showing it 110s (!) late vs the "9075" evolution in my previous posting.

Forcing a SatEvo evolution through three of the four latest elsets (to
0.03s) gives me a residual of 3 seconds on the other one and probably
leads to a better current mean motion than my earlier fits. However,
fractional changes in the drag from rev to rev must be expected and can
build up over a few revs to a respectable time error. Remember also that
errors in drag lead to increasing error in mean motion and, with the
perigee likely to be fairly steady until v close to decay, this will
manifest as an increasing error in apogee distance. Observers shooting
for this near apogee may anticipate increased cross-track uncertainty.
Indeed, if the object is early, expect it be below the predicted track
and if late it should be above the track.

This new "9080" evolution (below) leads to decay at March 17.0:

Centaur r                                        3982 x 96 km
1 24316U 96054B   97074.96284062 1.10435552  23426+0  35393-2 0 90801
2 24316  25.2115  86.6978 2308627 271.2348  62.6505 11.24268528  9027
Centaur r                                        3785 x 96 km
1 24316U 96054B   97075.05112444 1.17115036  27271+0  36111-2 0 90806
2 24316  25.2046  86.3559 2217343 271.8193  63.1245 11.44342860  9032
Centaur r                                        3585 x 96 km
1 24316U 96054B   97075.13784710 1.24770758  32224+0  36935-2 0 90800
2 24316  25.1974  86.0086 2122610 272.4129  63.6280 11.65302252  9040
Centaur r                                        3381 x 96 km
1 24316U 96054B   97075.22299555 1.33656875  37945+0  37925-2 0 90806
2 24316  25.1915  85.6557 2023836 273.0163  64.1650 11.87285176  9055
Centaur r                                        3174 x 96 km
1 24316U 96054B   97075.30655102 1.42896811  38604+0  38741-2 0 90805
2 24316  25.1852  85.2967 1920692 273.6300  64.7371 12.10391013  9062
Centaur r                                        2963 x 96 km
1 24316U 96054B   97075.38849709 1.53451917  48007+0  39637-2 0 90800
2 24316  25.1769  84.9313 1813114 274.2548  65.3454 12.34647280  9077
Centaur r                                        2748 x 96 km
1 24316U 96054B   97075.46881597 1.66211426  59931+0  40762-2 0 90802
2 24316  25.1699  84.5590 1700166 274.8916  65.9990 12.60284953  9084
Centaur r                                        2527 x 96 km
1 24316U 96054B   97075.54747954 1.82020466  77498+0  42161-2 0 90802
2 24316  25.1625  84.1791 1580564 275.5413  66.7082 12.87627215  9093
...remaining evolution clipped.

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