Gil and Harro,
It is just as well that you, Gil, asked for emailed elsets since the one
for 00049.48035817 has yet to become available via OIG. OIG has also
failed to post any decay warnings since the one issued at 09:46 UTC so
it is good that we had the alternative route for these too.
I don't know whether to expect any further elsets, but I guess not. I
had posted a prediction at 08:20 UTC this morning, predicting the decay
for 15:04. Since then, we have received three more elsets showing it,
respectively, 0.1 sec early, 3.4 sec early and (for the 00049.48 elset)
7.2 sec early against my prediction
A new set of calculations suggest that Starshine may have decayed on a
northbound pass over the Atlantic and Africa, perhaps near Lagos,
Nigeria, at 14:28 UTC. This is more than one hour before SpaceCom and
Harro, but I have difficulty in keeping Starshine in orbit to reach even
the southbound equator crossing at 15:12 UTC. For what its worth, here
is an elset for the equator crossing at which I claim, or rather
"guess", it was close to decay...
Starshine 1.0 0.0 0.0 9.0 d 0.30 119 x 118 km
1 25769U 99030B 00049.60136312 2.59942209 50000+2 89468-3 0 93422
2 25769 51.5790 5.5397 0000738 270.0144 89.9772 16.57999085 42112
I remain suspicious of the drag (ndot) and Bstar terms in SpaceCom's
TLEs and I wonder whether your iterations/computations, Harro, use these
values from the elset. If I recalculate the ndot terms using the mean
motion over a range of elsets close to decay, I usually find a higher
value for ndot than the one in the TLE. For example...
Elset epoch Elset ndot Computed ndot...using mean motion
from elsets at...
00049.23746154 0.06695398 0.08463523 00049.11/.35
00049.35901652 0.09446491 0.11981190 00049.23/.48
In both cases, the computed ndot is >25% higher than the one quoted in
the elset. In my analyses, I (almost always) derive my own values for
ndot and mean motion by carrying an orbital evolution through the
satellite positions described by the elsets over the past day or so.
Cheers,
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
Scotland | SatEvo page: http://www.wingar.demon.co.uk/satevo/
-----------------------------------------------------------------
Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org
http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Fri Feb 18 2000 - 08:58:03 PST