Decay watch update: December 18

Alan Pickup (alan@wingar.demon.co.uk)
Fri, 18 Dec 1998 21:56:54 +0000

OIG shows the following decay notices to be in effect:

Object                            Notice issued    Predicted decay
                                       UTC              UTC
#25120 = Orbcomm 9 Pegasus r      Dec 16 10:38     Dec 29 11:40 +-8d
#25499 = C 2350 aux motor         Dec 18 20:14     Dec 19 14:09 +-11h

Current elsets for these are:

Orbc9 Pegasus r  1.3  1.0  0.0  7.0 d            326 x 225 km
1 25120U 97084J   98352.22386277  .00636851  18886-3  86588-3 0  3931
2 25120  44.9516 322.7925 0075907 109.9089 251.0029 15.99808377 55551
C 2350 Prot deb (aux motor)                      2292 x 97 km
1 25499U 98025E   98352.87086016  .99999999  29478-4  24594-2 0  1282
2 25499  47.2036 207.2373 1449266  83.7550 293.2924 13.17565073  5944


I now show decay of the Pegasus on December 28 +-2 days.

For once, I agree with USSPACECOM's decay prediction for the auxiliary
motor. My own calculation puts decay at December 19.58 (14:00 UTC +-5h).
SatEvo predicted elsets:

C 2350 Prot deb (aux motor)                      2023 x 96 km
1 25499U 98025E   98353.02002082 1.28850748  46408+0  27079-2 0 91289
2 25499  47.1888 206.6437 1295219  84.3265 290.2619 13.53492739  5967
C 2350 Prot deb (aux motor)                      1573 x 96 km
1 25499U 98025E   98353.23602318 1.72447654  10014+1  31116-2 0 91289
2 25499  47.1661 205.7186 1023526  85.2181 286.3754 14.17345230  5997
C 2350 Prot deb (aux motor)                      1012 x 96 km
1 25499U 98025E   98353.44089433 2.73188723  33918+1  37865-2 0 91285
2 25499  47.1351 204.7402 0660383  86.1622 281.3579 15.04228758  6027
C 2350 Prot deb (aux motor)                      765 x 96 km
1 25499U 98025E   98353.50611206 3.74004194  89378+1  43944-2 0 91288
2 25499  47.1246 204.3973 0490847  86.4934 279.1059 15.45351312  6031
C 2350 Prot deb (aux motor)                      375 x 90 km
1 25499U 98025E   98353.56899731 9.99999999  50000+2  64667-2 0 91281
2 25499  47.1000 204.0417 0216018  86.8371 275.6320 16.15295303  6042

The final orbit above has perigee (in daylight) over the Bay of Biscay
with the track taking it eastwards over France (14:01 UTC) and
Switzerland towards Bulgaria (14:06 UTC). Given the rapid increase in
mean motion over the coming hours, the along track timing could be
several minutes in error.

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/