Ed Cannon's UNID probably is USA 159 r

From: Ted Molczan (molczan@home.com)
Date: Thu Aug 16 2001 - 06:20:18 PDT

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    Ed Cannon reported an unidentified satellite in this post:
    
    http://www2.satellite.eu.org/seesat/Aug-2001/0231.html
    
    I believe that this object probably is USA 159 r (26881 / 01033B), the Titan IV
    2nd stage of the DSP satellite launched on 2001 Aug 06 at 07:28 UTC.
    
    As I write this, U.S. Spacecom has issued only two elsets, both of which have
    flaws:
    
    1 26881U 0133B    01218.36215998  .00000332  00000-0  00000+0 0    18
    2 26881  28.6968 249.1085 0243087  78.4785 282.1509 15.23242448    11
    
    1 26881U 0133B    01226.28993968  .00000349  00000-0  00000+0 0    27
    2 26881  28.6968 195.6121 0243087 165.2938 177.1552 15.22595359  1228
    
    The ndot/2 decay terms are about 100 times too low for the stated orbit. The B*
    decay term required by the SGP4 orbit propagator is set to zero. The
    international designator is incorrect; it should be 01033B.
    
    Note also that second elset's inclination and eccentricity are identical and
    its mean motion has decreased, despite the passage of 8 days, which is
    unrealistic. By all appearances, U.S. Spacecom is struggling with this object's
    orbit, without success.
    
    Ed Cannon and Mike McCants have not been able to find the object in the above
    orbits in circumstances in which it should have been easily visible to the
    unaided eye.
    
    In a recent e-mail, Ed Cannon pointed out that previous Titan IV 2nd stages
    from DSP launches had been in significantly more eccentric orbits than the ones
    that U.S. Spacecom issued for this launch. For example, here is an early elset
    of the Titan IV 2nd stage of DSP 20, launched on 2000 May 08 at 16:01 UTC:
    
    1 26357U 00024B   00131.15084957  .00421046 -54059-5  52085-3 0    94
    2 26357  28.6455 279.7515 0402109  90.4083 274.2447 15.34290365   234
    
    Inspired by Ed Cannon, I decided to check whether or not this would have been a
    more reasonable orbit for the DSP 21 launch, so I changed the Epoch and RAAN to
    match the circumstances of that launch:
    
    1 77001U          01219.79459954  .00421046 -54059-5  52085-3 0    02
    2 77001  28.6455 239.6200 0402109  90.4083 274.2447 15.34290365   232
    
    Next, I tried to use this orbit to predict Ed Cannon's unknown of last night. I
    found that it was about 13 min too early, but near the correct track. When I
    allowed for Earth's rotation during 13 min, I found that Ed Cannon's unknown
    was within 1 min of time and a fraction of 1 deg of the predicted track. Also,
    eclipse followed by about 15 s, as Ed reported.
    
    A 13 min error after 8.3 days amounts to about a 6 s difference in the orbital
    period, which seems reasonable, given that no two launches are identical. More
    likely, the difference is due to small differences in all of the elements.
    
    I suggest the following search orbit, which is the above orbit, propagated to
    the time of Ed's observation
    
    1 77002U          01228.12618056  .00439299  00000-0  52085-3 0    00
    2 77002  28.6455 181.9913 0373000 183.5141 268.1500 15.41279729    05
    
    Predictions should be accurate to within a few minutes of time for the next few
    nights.
    
    Ted Molczan
    
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