Alert: Lacrosse 4 made a second manoeuvre

From: Ted Molczan (
Date: Tue Aug 22 2000 - 05:52:40 PDT

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    I observed Lacrosse 4 on 2000 Aug 22 at 09:24 UTC, running 2.98 min late
    relative to the epoch 00234.4262 elements that I posted yesterday. I alerted
    Paul Gabriel, who confirmed the late arrival on the next rev, at 10:58 UTC.
    It now appears that the spacecraft made a second manoeuvre about one rev prior
    to Paul's observation on 2000 Aug 21 at 10:20 UTC, which further circularized
    its orbit, and increased its orbital period by about 14 s. This would account
    for most of its approx 16 s late arrival on 21 Aug.
    I was suspicious that there may have been a manoeuvre, but chose to attribute
    it to imperfect obs on 20 Aug, when we were somewhat hampered by bright
    Paul and I have obtained quite a few points this morning, which should yield a
    pretty good orbit. I hope to post it in a few hours.
    In the meantime, observers should expect the object to be running progressively
    later, relative the epoch 00234.4262 elements. I suggest adding 14 s for each
    rev after the epoch to approximate the error.
    Ted Molczan
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