USA 129 manoeuvred at 21:00 UTC, 26 April 2000

From: Ted Molczan (
Date: Thu Apr 27 2000 - 01:44:36 PDT

  • Next message: Tony Beresford: "progress + rocket + MIR"

    Thank you to Walter Nissen, for the first observation report of USA 129 after
    its apogee-raising manoeuvre of 26 April 2000 UTC:
    and to Jari, for the second report, one revolution later, which fully confirmed
    Walter's report:
    I ran findsat against the latest alldat.tle, and found no other candidate
    object within 5 minutes or 5 deg of either observation.
    Through good luck, my theoretical orbit, posted nearly 7 hours before Walter's
    observation, happened to be for the actual manoeuvre time, 21:00:12 UTC, on 26
    1 70000U          00117.87513889  .00033818  00000-0  46276-3 0    09
    2 70000  97.8967 181.7773 0523000 146.1591   1.7000 14.73500000    04
    That was simply the time of the object's next perigee crossing (i.e. next
    manoeuvre opportunity), following Pierre Neirinck observation that it had not
    yet manoeuvred as of 20:34 UTC.
    So the maneouvre occurred just 26 minutes after Pierre's observation. He was
    clouded out on his next pass, otherwise, he might have been the first to report
    its manoeuvre.
    The theoretical orbit predicted Walter's observation to within 3 s in time, and
    0.2 deg; and Jari's to within 0 s time, and 1.3 deg. I expect it to be accurate
    to within about 1 minute after 24 hours.
    These sightings confirm my 18 April prediction of 26 April UTC as one of the
    two most probable manoeuvre dates, depending upon which of USA 116 or USA 129
    was planned to have its perigee near the equator for its manoeuvre:
    USA 129's perigee had reached the equator on 16 April, but the manoeuvre did
    not occur, so I was reasonably certain that it would occur on 26 April, when
    USA 116's perigee would reach the equator. Of course, I had doubts, so I am
    excited to see my prediction confirmed.
    Precise observations over several days are needed to refine the elements of the
    new orbit.
    Ted Molczan
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    This archive was generated by hypermail 2b29 : Thu Apr 27 2000 - 01:46:03 PDT