Updated elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Thu Apr 23 2009 - 17:57:15 UTC

  • Next message: GERHARD GROENEWALD: "DSP 19"

    Greg Roberts and Peter Wakelin contributed observations used to determine one or
    more of the following element sets.
    
    Peter recovered DSP 19 last night, 9.4 months after it was last observed,
    running about 75 minutes early relative the last known orbit. Recovering lost
    objects is a fine test of skill and patience.
    
    http://satobs.org/seesat/Apr-2009/0266.html
    
    I propagated the epoch day 08192 elements using int2, then adjusted the mean
    motion and rate of decay separately by trial and error, and finally used my
    differential corrector to adjust the elements to the observed arc, varying all
    but the mean motion and decay. The resulting RAAN is ~3 deg less, and the
    argument of perigee is ~4 deg greater, than those of the int2 propagation.
    
    DSP F19                                                634 X 34705 km
    1 25669U 99017A   09112.66353415  .00000079  00000-0  13000-2 0    05
    2 25669  29.0595  65.0110 7084240 271.8615  15.7626  2.32857989    08
    Arc 20090422.91-0422.99 WRMS resid 0.009 deg
    
    USA 202                                              35730 X 35889 km
    1 33490U 09001A   09112.22945190  .00000000  00000-0  00000-0 0    07
    2 33490   2.8857 339.2414 0018859  91.1742 268.6372  1.00194084    03
    Arc 20090415.73-0422.92 WRMS resid 0.005 deg
    
    On Apr 20 UTC USA 202 passed through 46 E, drifting west 0.286 deg/d. If its
    destination is near 44 E, then I estimate that the manoeuvre to synchronize its
    mean motion with Earth's rotation would occur around Apr 28-30, near perigee,
    which is within a few minutes of 11:18 UTC.
    
    I may have additional updates later.
    
    Ted Molczan
    
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