Decay watch: April 24/25

Alan Pickup (alan@wingar.demon.co.uk)
Fri, 24 Apr 1998 21:14:08 +0100

The final elset for the Long March rocket was:

Ir 51 CZ-2C r   12.0  3.5  0.0  4.3 d            129 x 110 km
1 25264U 98018C   98114.31817484  .37513683 -14931-5  14791-3 0  1160
2 25264  86.3464 358.1243 0014139 124.9644 235.2815 16.57573902  4674

This shows it surviving long after the time I'd predicted for its decay
(April 24 at ~02:00 UTC). I think decay probably came on this orbit,
possibly around the southbound equator crossing near 159 deg W at 08:22
UTC (April 24.35). Fortunately I have a good set of elsets over the
final day to help with the investigation on how SatEvo went astray.


The latest elset for the Iridium 43 Delta 2 rocket is:
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            215 x 172 km
1 25044U 97069F   98114.64204652  .04163098  00000-0  83913-3 0  2641
2 25044  83.5240 341.5518 0033120  82.6674 277.9100 16.29631344 26045
This shows it 8 seconds late on the "9257" SatEvo evolution I posted
yesterday. Using a modified SatEvo "Q" factor which gives a better fit
for the Long March decay, I now estimate that this will decay at about
April 25.88. Predicted elsets:
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            202 x 165 km
1 25044U 97069F   98115.01005260  .05751003  16738-1  84019-3 0 92640
2 25044  83.5227 341.1785 0027970  81.1182 279.1984 16.33303302 26102
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            184 x 156 km
1 25044U 97069F   98115.37712050  .08722099  43471-1  64791-3 0 92646
2 25044  83.5209 340.8039 0021645  79.5635 280.6803 16.38444707 26160
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            161 x 142 km
1 25044U 97069F   98115.68190306  .15957075  15298+0  34935-3 0 92647
2 25044  83.5186 340.4901 0014421  78.2618 281.9000 16.45501228 26218
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            145 x 132 km
1 25044U 97069F   98115.80336135  .26339151  55019+0  27817-3 0 92640
2 25044  83.5167 340.3639 0010203  77.7385 282.3757 16.50391331 26237
Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            133 x 123 km
1 25044U 97069F   98115.86392392  .43414462  18732+1  26631-3 0 92646
2 25044  83.5153 340.3005 0007232  77.4759 282.6049 16.54412872 26245

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    | SatEvo satellite page: http://www.wingar.demon.co.uk/satevo/