Re: Foton 12 R/B

Alan Pickup (alan@wingar.demon.co.uk)
Sat, 25 Sep 1999 09:50:19 +0100

Mike DiMuzio <mdimuzio@cisnet.com> writes
>       It's still up....wow!!  Reddish in color
>and about 4 minutes early on the following elset,
>
>Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       225 x 172 km
>1 25903U 99048B   99266.76080540  .03694740  85965-5  76763-3 0   445
>2 25903  62.7758 153.1091 0040409 114.2091 247.4341 16.27947582  2256
>
>       No signs of it entering the atmosphere.  Estimated magnitude, 
>-4.  It was only in view for about 30 secs.

The fact that it was so early is mostly due to the elset being 1.3 days
old - in fact it was running 85 seconds _late_ against the SatEvo
prediction I'd based on that elset and posted to by Decay Watch page
late on September 23 UTC. At that time I was predicting decay for
September 25 at 01:30 UTC +-8h which, in retrospect, may have been more
accurate than some of my later ones.

I agree with Ted Molczan that the very fact that you saw this at all
indicates that it was already incandescent with the heat from re-entry.
I am suspicious, though, about the final published elset which does not
fit well with the earlier ones. Here are the final four elsets from OIG:

Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       190 x 155 km
1 25903U 99048B   99267.61830898  .07019031  87145-5  55913-3 0   476
2 25903  62.7720 149.5808 0026365 116.5960 243.8369 16.37418014  2394
Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       176 x 149 km
1 25903U 99048B   99267.80136088  .10806535  88070-5  45206-3 0   487
2 25903  62.7712 148.8182 0020868 109.4121 251.2412 16.41166149  2424
Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       158 x 138 km
1 25903U 99048B   99267.98387238  .15093932  89795-5  25047-3 0   492
2 25903  62.7772 148.0506 0015540  99.3105 261.4998 16.46748638  2451
Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       149 x 145 km
1 25903U 99048B   99268.04447280  .11018540  90653-5  21505-3 0   504
2 25903  62.7985 147.8535 0003029 141.2075 218.9170 16.47203761  2462

The final elset (corresponding to your pass) shows a rather miraculous
rise in the perigee as the orbit became almost circular very quickly.
There is also an implied drop in drag and little increase at all in mean
motion. It suggests to me that SpaceCom was having difficulty
reconciling its observations, perhaps because the rocket was already in
the early stages of re-entry.

According to me Quicksat calculations for your pass, the rocket was some
500 km deep in the Earth's shadow near its closest approach. SpaceCom's
orbit places it 152 km above ground with a peak elevation of 20 deg in
your SW. Several of my SatEvo-predicted orbits (ignoring the final
SpaceCom one) give an altitude of about 135 km and a culmination at
about 17 deg. I would have thought that it would have to be lower still,
perhaps at 80 km, for it to be luminous. This would take its highest
point down to around 10 degrees. Are you able to estimate whether it was
closer to 10 than 20 degrees at its highest?

In any case, many congratulations on your observation :)

Alan
-- 
 Alan Pickup | COSPAR 2707:  55d53m48.7s N  3d11m51.2s W   156m asl
 Edinburgh   | Tel: +44 (0)131 477 9144     Fax: +44 (0)870 0520750
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