RE: MAR18.OBS

From: Ted Molczan (molczan@rogers.com)
Date: Fri Mar 19 2004 - 10:36:49 EST

  • Next message: David Brierley: "96-72A manoeuvre?"

    Russell Eberst wrote:
    
    > Note: Difficulties with 9607201: Observation does not fit 
    > nicely with published previous orbits. I may have made an 
    > error, but can't find anything wrong. Has it manoeuvred? 
    
    Apparently so. 
    
    According to your obs, USA 129 (96072A / 24680) was about 9.1 s late and 0.52
    deg below the track predicted by day-old elements.
    
    The object's perigee was within a few degrees of the equator, which is optimal
    for certain kinds of manoeuvres, especially inclination adjustments, which is
    what I suspect it has done.
    
    Its pre-manoeuvre inclination was about 97.8 deg, resulting in precession of the
    ascending node of 0.9661 deg/d, quite a bit off the exact sun-synchronous rate
    of 0.9856 deg/d. 
    
    Increasing the inclination of the day-old elements to 98.0 deg would increase
    the rate of precession to about 0.99 deg/d, and account for the object's 0.52
    deg low track.
    
    Another possibility is reducing the wrong pair of stars. I note that the mag 6.2
    star at 05:40, +23:11, and the mag 8 star at 05:39, +22:51 (both 1950.0), when
    substituted for the pair that you reduced, result in reasonable agreement with
    the day-old elset, contradicting the manoeuvre theory.
    
    Pierre reports receiving obs from David, which I gather support the manoeuvre
    theory, but which appear somewhat inconsistent with yours. It would be
    interesting to see whether or not a higher inclination would resolve the
    apparent inconsistency.
    
    Ted Molczan
     
    
    
    
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