Revised Lacrosse 4 post-manoeuvre search elements

From: Ted Molczan (molczan@home.com)
Date: Sat Aug 19 2000 - 12:24:16 PDT

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    I have used Paul Gabriel's observations:
    
    http://www2.satellite.eu.org/seesat/Aug-2000/0256.html
    
    to produce the first Lacrosse 4 parking-orbit elements from observations, and
    to revise my post-manoeuvre search elements.
    
    Since there are still too few points to produce a complete orbital analysis, I
    made use of the Titan 2nd stage orbit, for which the official elements were:
    
    Lacrosse 4 r     9.8  3.0  0.0  4.8 v
    1 26474U 00047B   00232.45120305  .00006795  00000-0  83219-3 0    96
    2 26474  68.0033  35.0324 0073427 179.4307 180.6939 14.81793814   222
    
    To produce the Lacrosse elements, I manually adjusted the epoch and mean motion
    to reflect the fact that it trailed its 2nd stage by about 63 s, and I added a
    reasonable rate of decay. Finally, I used Elcor to adjust only the RAAN and
    mean anomaly to fit Paul's points, with this result:
    
    Lacrosse 4      18.0  4.5  0.0  3.6 v
    1 26473U 00047A   00232.45193222  .00002000  00000-0  24527-3 0    06
    2 26473  68.0033  35.0594 0073427 179.4307 180.6777 14.81066426    08
    
    I used the parking orbit to revise my predicted post-manoeuvre elements, with
    this result:
    
    Lacrosse 4      18.0  4.5  0.0  3.6 v
    1 70007U          00232.99197917  .00001500  00000-0  27197-3 0    01
    2 70007  68.0033  33.5777 0005500 178.8486 180.1000 14.66165000    09
    
    This corresponds to a manoeuvre on 2000 Aug 19 at 23:48:47 UTC, at the apogee
    of the parking orbit, over
    1.1 S and 67.4 E, headed northbound.
    
    Of course, there is no guarantee that the manoeuvre will take place when
    predicted, so observers should run predictions for both the parking orbit and
    the post-manoeuvre search orbit.
    
    Ted Molczan
    
    
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