Decay watch: Mar 31 (Ir 11A S/D)

Alan Pickup (alan@wingar.demon.co.uk)
Wed, 31 Mar 1999 20:36:38 +0100

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Object: #25580 = 98- 74 D = Iridium 11A Smart Dispenser

Decay predictions:
Source   Prediction made    Predicted decay at      Latitude Longitude
               UTC                UTC                  deg      deg

SpaceCom   Mar 23 10:26     Apr  2 10:53 +-6d        50.3 S    25.0 W
SpaceCom   Mar 25 22:20     Apr  1 20:34 +-4d         5.8 S     5.8 E
SpaceCom   Mar 29 04:21     Apr  2 02:50 +-2d        78.2 N    70.0 W
SpaceCom   Mar 30 00:40     Apr  1 19:21 +-2d        51.7 N    29.2 E
SpaceCom   Mar 30 18:18     Apr  1 15:55 +-1d        70.1 S    65.9 E
SpaceCom   Mar 31 14:55     Apr  1 14:19 +-14h       75.2 S    65.2 W

SatEvo     Mar 23 20:40     Apr  2 00:00 +-2.5d
SatEvo     Mar 25 23:40     Apr  2 00:00 +-1.5d
SatEvo     Mar 29 21:00     Apr  1 23:26 +-16h       12.1 S    38.7 W
SatEvo     Mar 30 19:25     Apr  1 16:03 +-10h       22.1 S    71.8 E
SatEvo     Mar 31 19:10     Apr  1 15:07 +-6h        71.1 N   103.4 W

Latest elset:
Irid 11A S/D     4.0  2.0  0.0  5.5 d            217 x 154 km
1 25580U 98074D   99090.57481146  .04724076 -15910-5  44814-3 0  2192
2 25580  86.2977 144.3026 0047872 114.4592 246.1672 16.32561562 16041

SatEvo prediction:
Irid 11A S/D     4.0  2.0  0.0  5.5 d            198 x 146 km
1 25580U 98074D   99091.00325591  .07345457  29515-1  33179-3 0 92199
2 25580  86.2960 144.0525 0039779 112.5637 247.8577 16.37632420 16117
Irid 11A S/D     4.0  2.0  0.0  5.5 d            178 x 137 km
1 25580U 98074D   99091.30830582  .12292383  10048+0  25985-3 0 92193
2 25580  86.2939 143.8730 0031337 111.2039 249.1309 16.43322981 16160
Irid 11A S/D     4.0  2.0  0.0  5.5 d            143 x 119 km
1 25580U 98074D   99091.55128918  .39134425  13751+1  25646-3 0 92193
2 25580  86.2908 143.7285 0018270 110.1100 250.0866 16.53082281 16209
Irid 11A S/D     4.0  2.0  0.0  5.5 d            116 x 104 km
1 25580U 98074D   99091.61169375 1.38382132  16778+2  37021-3 0 92195
2 25580  86.2888 143.6921 0009458 109.8345 250.2675 16.61267459 16218

Note: At the epoch of the latest elset, this was running 5 seconds 
early against the prediction I posted yesterday. I predict decay on 
a southbound (daylight) track that passes W of Hudson Bay and across 
the USA at about 97 deg W longitude from Fargo, N Dakota, to Dallas. 
SpaceCom's latest decay warning has it decaying over the Antarctic on
the previous orbit. The uncertainty is still several orbit.
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Alan
-- 
 Alan Pickup | COSPAR 2707:   55d53m48.7s N   3d11m51.2s W   156m asl
 Edinburgh   | Home:   alan@wingar.demon.co.uk    +44 (0)131 477 9144
 Scotland    | SatEvo page:     http://www.wingar.demon.co.uk/satevo/