RE: Possible Observation of USA 193 Debris

From: Ted Molczan (
Date: Mon Feb 25 2008 - 14:51:57 UTC

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    Christian Kjśrnet has reported an observation of an object that may have been in
    the vicinity of the plane of USA 193.
    I reduced Christian's observation as 18 arc min south in declination of the star
    Monoceros 13:
    99999 99 999A   5059 G 20080224180548000 17 25 0633198+070252 38 S
    Site 5059: 59.6408 N  09.6402 E  Alt 176m
    I have been unable to match the observation to any known object; however, this
    does not mean that Christian observed a fragment of USA 193, nor does it make it
    especially probable. Considering the huge population of orbital debris, not all
    of which is in the public catalogue, he could have seen something totally
    unrelated to USA 193.
    The only way to know whether or not Christian observed a fragment of USA 193, is
    for someone to recover the object he observed, in an orbit consistent with that
    of USA 193; therefore, I have fit rough search elements to Christian's
    observation and a position near the approximate location of the intercept nearly
    4 days earlier.
    1 72001U          08055.74057874  .00465146  00000-0  39831-3 0    06
    2 72001  58.8297   9.4354 0015000  90.0000 270.2828 16.12582003    08
    This solution is based on the assumption that most of the change in velocity
    relative the orbit of USA 193 manifested itself as a small increase in the
    inclination and orbital plane. Fragments would have exited the intercept in all
    directions, at a wide range of velocities, resulting in a wide variety of
    orbits, but this assumption appears to be the most likely that could explain
    Christian's observation.
    Christian's guess that the magnitude of the object was 6 +/- 2, suggests a
    standard visual magnitude of about 9 +/- 2 (1000 km range, 90 deg phase-angle).
    Since the search elements are very rough, large errors in time and track are to
    be expected; therefore, optics with a reasonably wide field of view are
    recommended. 11x80 binoculars offer a good trade-off between sensitivity and
    FOV. 7x50 may be useful on higher elevation passes, but at greater risk of
    missing it should it be fainter than predicted.
    I recommend allowing for at least several minutes prediction time uncertainty,
    with compensation for Earth's rotation during the search period.
    Happy hunting!
    Ted Molczan
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