Apparent manoeuvre by USA 116

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Tue Nov 25 2008 - 19:05:27 UTC

  • Next message: Russell Eberst: "2008NOV25.OBS"

    USA 116 (95066A / 23728) was last observed by David Brierley, on 2008 Nov 18,
    near 17:18 UTC:
    
    http://satobs.org/seesat/Nov-2008/0112.html
    
    It was in the following orbit:
    
    USA 116         15.0  4.0  0.0  5.1 v
    1 23728U 95066A   08323.69802823  .00000600  00000-0  31670-4 0    02
    2 23728  97.9290 101.5081 0307000 194.3756 165.6243 14.83044340    09
    
    Tony Beresford attempted to observe it in the same orbit, on 2008 Nov 24 near
    18:20 UTC, but did not see it:
    
    http://satobs.org/seesat/Nov-2008/0171.html
    
    I estimate that the object should have reached magnitude 4.2 +/- 1.5, so Tony
    had a reasonable probability of observing it with the unaided eye.
    
    If it has manoeuvred, then based on its history of the past 6 years or so, the
    following search elsets bracket the likely range of mean-motion and
    eccentricity:
    
                                                             400 X 837 km
    1 70001U          08323.73413194  .00000574  00000-0  30000-4 0    02
    2 70001  97.8500 101.5440 0312000 194.2578 358.4000 14.82460000    01
                                                             400 X 847 km
    1 70002U          08323.73413194  .00000569  00000-0  30000-4 0    07
    2 70002  97.8500 101.5440 0319000 194.2578 358.4000 14.81000000    08
    
    Epoch of both is the first perigee after David's observation of Nov 18, so they
    yield worst-case predictions in terms of lateness relative the last known orbit.
    
    If the object were in the 70001 orbit, then it would have passed within the
    period that Tony waited for it. If in the 70002 orbit, it would have passed
    about 5 minutes after Tony stopped waiting.
    
    The object has seldom manoeuvred since it was replaced as the primary eastern KH
    satellite in 2001 Oct, by USA 161 (01044A / 26934), and there was nothing about
    its recent orbit that suggested the need to make a manoeuvre. The object holds
    the record as the longest surviving KH, just shy of 13 years, so the possibility
    that it has been de-orbited cannot be excluded.
    
    Observers interested in attempting to recover the object are advised to first
    check the last known orbit (in case Tony missed it due its having been unusually
    faint); if not seen, then switch to a planar search, using either the 70001 or
    the 70002 elset.
    
    Ted Molczan
    
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