IGS 1A and IB elements

From: Ted Molczan (molczan@rogers.com)
Date: Sat Apr 19 2003 - 13:11:23 EDT

  • Next message: Björn Gimle: "Re: Obs Apr 18"

    I have derived the following from observations by David Brierley, Russell
    Eberst and Peter Wakelin received to this moment:
    
    Arc 2003 Apr 15 - 18 UTC:
    
    IGS 1A           0.0  0.0  0.0  5.6 v
    1 27698U 03009A   03108.87390629  .00010094  00000-0  39115-3 0    09
    2 27698  97.4218 181.0049 0009965 273.9134  86.0965 15.26143568    01
    
    WRMS residuals = 0.017 deg
    
    Arc 2003 Apr 16 - 18 UTC:
    
    IGS 1B           0.0  0.0  0.0  3.1 v
    1 27699U 03009B   03108.90051537  .00010869  00000-0  47791-3 0    05
    2 27699  97.4090 180.9367 0000894 165.9909 194.1352 15.21933798    01
    
    WRMS residuals = 0.014 deg
    
    The additional IGS 1B obs reveal that its inclination is a few hundredths of a
    degree greater, and its orbit is more nearly circular, than first thought.
    
    IGS 1A's history may offer a clue as to timing of the next orbit maintenance
    manoeuvre. Its mean motion has not exceeded about 15.2621 rev/d, and its
    latest manoeuvre occurred shortly after mean motion exceeded 15.2617 rev/d:
    
    1 27698U 03009A   03101.49873843  .00013092  00000-0  50877-3 0   676
    2 27698  97.3158 173.6735 0004262 286.6823 260.9584 15.26172631  2200
    
    1 27698U 03009A   03101.61626672 -.00525736  00000-0 -21944-1 0   683
    2 27698  97.4117 173.7898 0005797 286.0429 186.8456 15.25972834  2225
    
    If 15.2617 rev/d is an upper limit, then IGS 1A could manoeuvre within the
    next 24 h.
    
    Ted Molczan
    
    
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