RE: Obs 24 August 2006 Part 1

From: Ted Molczan (seesat-list@rogers.com)
Date: Fri Aug 25 2006 - 14:49:20 EDT

  • Next message: astro: "obs 8305 26aug 06238"

    Greg Roberts wrote:
    
    > (2) #91080 is a very interesting unknown as it was flying formation
    >     with #21798. I had a second pass and the unknown was still in the
    >     same position relative to #21798 so the orbits must be very similar.
    >     I have no match in my element database. The unknown was variable
    >     but easy for 90% of the pass. #21798 produced some very bright flashes.
    >     The second pass was difficult as the elevation was 11 degrees.
    
    Nice catch, Greg!
    
    I confirm the apparent formation: the unknown companion of DMSP B5D2-6 (91082A /
    21798) preceded it by about 1.09 s on both passes. Based on the orbital velocity
    of the DMSP, the companion was leading by about 8.0 km.
    
    I suspect the companion may be XSS-11 (28636 / 05011A). Greg, on 2006 Jul 18
    UTC, you were the last to observe both, which resulted in the most recent
    hobbyist elements:
    
    DMSP B5D2-6      6.4  1.7  0.0  6.6 v 5.43
    1 21798U 91082A   06199.68681329  .00000050  00000-0  25530-4 0    02
    2 21798  98.6393 208.9319 0012500 163.2370 196.7629 14.15652861    08
    
    XSS-11           1.0  0.6  0.0  7.9 v 1.20
    1 28636U 05011A   06199.66503589  .00000120  00000-0  39812-4 0    02
    2 28636  99.1780 206.5354 0012000 341.9670  18.0329 14.37843992    02
    
    At that time, XSS-11's plane was about 2.4 deg west (206.5354 - 208.9319) of the
    DMSP, but its rate of eastward precession was about 0.097 deg/d greater than
    that of the DMSP, so they should have become coplanar late on Aug 11 UTC, which
    would have been the date of the rendezvous.
    
    Let's see what is revealed by further observations.
    
    Ted Molczan
    
    
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