Re: "Unusal event" (fireball)

Alan Pickup (alan@wingar.demon.co.uk)
Mon, 7 Dec 1998 21:05:19 +0000

Harro.Zimmer <Harro.Zimmer@t-online.de> writes
>The "unusual event" that Ed Cannon mentioned - observed on Sept 24, 04:16:16 
>UTC 
>by an Canadian network - could be under some special circumstances the decay
>of 1989 -89BL (23065) COBE Debris on a southbound pass.
>The last ELSET was a few days old. SSC gave for the decay Sept 24, 1998.
>The object itself was small and not heavier then 1 or 2 kg. An extrapolation 
>with 
>MPM and other decay programs is difficult. I worked with the variation of some 
>parameters and there is a small possibility that the unusual "fireball" was the
>reentry of the COBE debris.
>
>Look also the original canadian source at;
>http://astrowww.phys.uvic.ca/~balam/UV980924.hmtl 
                                              ^^^^ should be html

The final published elset for #23065 was:
COBE deb                                         505 x 441 km
1 23065U 89089BL  98260.94469695  .02639513  00000-0  76879-1 0  8825
2 23065  99.4389  41.8009 0046764 295.4019 176.0110 15.30963008225537

This is more than six days prior to the event and USSPACECOM's declared
decay date for this object. SatEvo evolves this elset to decay on
September 21 which is the date I gave (as "September 21?", to indicate
my uncertainty) in my SatEvo decay list #63.

I can force SatEvo to decay it on September 24.2 by decreasing the
initial drag term from 0.02639513 to 0.01377079. The final elset from
that evolution is then:
COBE deb                                         275 x 269 km
1 23065U 89089BL  98267.13533134 1.00057108  51740+1  18716+0 0 98826
2 23065  99.4118  49.8574 0004754 274.1233  85.8223 16.00901396226495
This orbit takes it southbound over the Bering Sea and Aleutian Is at
~03:46 UTC, then towards an equator crossing at 167 deg E longitude at
~04:00 UTC. The times could be very much in error, but not the orbital
plane which lies far to the W of the reported track.

In other words, I don't think the fireball could be the decay of #23065.

Alan
-- 
 Alan Pickup | COSPAR 2707:   55d53m48.7s N   3d11m51.2s W   156m asl
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