USA 129 search elements - in case it manoeuvred

From: Ted Molczan (
Date: Wed Apr 19 2000 - 09:26:22 PDT

  • Next message: Mark A. Hanning-Lee: "Bright 23502 Cosmos 2306 r"

    In case Jim Nix's non-sightings on two passes last night were due to the
    manoeuvre we have been awaiting, I have produced a search orbit; however, since
    we are not certain that a manoeuvre did occur, observers should first look for
    the object in its most recent known orbit:
    1 24680U 96072A   00109.89468950  .00044307  00000-0  55741-3 0    09
    2 24680  97.8675 173.7963 0479240 171.8283 189.1141 14.84373412    08
    If it manoeuvred, then it will be late, but on a similar path. Below is the
    approximate orbit the object would have entered, had it manoeuvred at the first
    perigee following the last reported on-time sighting (by Pierre Neirinck, at
    21:34 UTC on 18 April 2000):
    1 70000U          00109.92660880  .00042112  00000-0  55741-3 0    04
    2 70000  97.8675 173.8279 0526000 171.7236   0.0000 14.73500000    08
    This should be a reasonably accurate search orbit.
    The period of the search orbit would be about 43 s longer than the old one, so
    after one day (i.e. 15 revs), the object would be nearly 11 minutes late,
    relative the old orbit. The higher altitude would also change its path across
    the sky.
    I recommend plotting the search orbit's ephemeris in addition to that of the
    last known orbit, as a guide for searching, in the event the object does not
    appear at the expected time.
    Ted Molczan
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