Subject: [IGLOSMAIL-450] Wk 1120 IGX Orbits Report
From: Weber Robert <[email-masked]>
To: [email-masked] (IGLOS Mail Service)
Cc: [email-masked]
Date: Wed, 14 Nov 2001 14:08:10 MET

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IGLOS Electronic Mail      14 Nov 05:10:41 PST 2001   Message Number 450
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Author:   IGEX AC Coordinator                                                   
                                                                                
IGX Orbit Combination - Week 1120   (Jun 24, 2001 - Jun 30, 2001) 
                                                                                
Contact: Robert Weber      ([email-masked])                           
	 Elisabeth Fragner ([email-masked])                                

COMBINATION STRATEGY                                                            
--------------------                                                            
                                                                                
Ephemeris are combined as weighted averages computed over all centres.          
Each centre and satellite is given a position weight computed from the centers  
absolute deviation to the unweighted average orbit after removing small         
differences in the reference frames. These weights were applied in a            
second iteration to estimate Helmert transformation parameters for each         
center. Finally the transformation parameters with respect to the combined      
solution and the RMS of the fit are reported in Tables 2.1120.
The Earth Orientation Parameters (EOPs) are fixed to the values of the          
final IGS (GPS) combination.                                                    

SOFTWARE:                                                                       
---------                                                                       
                                                                                
The GPS long arc orbit analysis software used here for individual center        
ephemeris evaluation (Table 1) was developed by Beutler et al. at the           
Astronomical Institute of the University of Bern (AIUB).                        
                                                                                
The weighted average (Tables 2. and 3.) software was developed by R.Weber       
according to                                                                    
                                                                                
   Springer T., Beutler G., 1993, Towards an official IGS Orbit by              
   combining the results of IGS processing centers.                             
   Proceedings of the IGS Workshop 1993, pp.242-249.                            
                                                                                
   Beutler G., Kouba J. and T. Springer, 1995, Combining the orbits of the IGS  
   Analysis Centers, Bulletin Geodesique, 69, pp 200-222.                       
                                                                                
   Weber R., 2000, IGS Technical Report 1999                                    

PRODUCTS GENERATED:                                                             
-------------------                                                             
                                                                                
The combined IGEX-ephemerides are written to daily files in the SP3-format.     
The satellite accuracy codes in the header are based on the weighted rms.       
for each satellite. Note, that the result files contain all satellites          
that were analysed by at least one center. We refer to the 'REMARKS' section    
below, in case a satellite or center was excluded from the combination.         
                                                                                
The following naming convention is used for the result files:                   
                                                                                
 igx11200-6.sp3  IGEX Glonass ephemerides files for days 0-6
                 of GPS Week 1120 in the SP3 format.
 igx11207.sum    Combination Report for GPS Week 1120.

REMARKS concerning the IGEX Orbit Combination:                                  
                                                                                
1. The satellite clock values in the combined orbit files are broadcast         
   clock values.                                                                
   The value of 999999.999999 microseconds, according to the sp3 format         
   convention, is used to indicate that no clock solution is available.         

2. The following orbit solutions were excluded from the combination because     
   they were biasing the weighted average (generally indicated by long arc RMS).
                                                                                
                  Day | Centre | SAT list                                       
                 -----+--------+----------                                      
                      |        |                                                
                                                                                
3. Until Wk 1020 the combined orbits refer to the ITRF96.                       
   Since Wk 1021 the combined orbits refer to the ITRF97.                       

ORBIT COMBINATION AND EVALUATION STATISTICS:                                    
--------------------------------------------                                    
                                                                                
Table 1 summarizes the statistics for a long-arc (seven days) analysis.         
It gives for each satellite the position rms. for each individual center        
and for the combined orbit.                                                     
                                                                                
Table 2 contains the transformation parameters w.r.t. the combination for       
each center and each day (Tables 2.1120.0-6).
                                                                                
Table 3 contains the daily RMS for each satellite and center w.r.t. the         
combination together with the computed satellite position RMS values            
for the combined orbits  (Tables 3.1120.0-6).

Table 1.1120     GPS week : 1120   MJD: 52084.0-52090.0
        Long Arc Evaluation                                                     
        Satellite position RMS for the individual centers' orbits               
        and for the combined orbit (IGX).                                       
        "E" flags eclipsing satellites.                                         
        "*" less than 7 days of data available.                                 
        "--" not (continuously) available in center solution.                   
        Units: cm.                                                              
      ------------------------------                                            
      | SAT  |  BKG  ESA  MCC  IGX |                                            
      ------------------------------                                            
      |   1  |    5   14   34    9 |                                            
      |   7  |    5   12   --    7 |                                            
      |   8  |    8   81   --   42 |                                            
      |  13  |    5   13   --    7 |                                            
      |  15  |   --   31   10   19 |                                            
      |  17  |    5    8   --    5 |                                            
      |  24  |    4   12   54   11 |                                            
      ------------------------------                                            
      |MEDIAN|    5   13   34    9 |
      ------------------------------                                            

                                                                                
Table 2: Daily transformation parameters w.r.t. the combined orbit.             
         Units: meters (DX, DY, DZ, RMS), mas (RX, RY, RZ), ppb (SCL).          

Table 2.1120.0  GPS week: 1120   Day: 0   MJD: 52084                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28| -.01  .01 -.13  -.28  -.03   .90   .1  .33|                      
   | ESA   29|  .01 -.01  .09   .19  -.07  -.19   .2  .24|                      
   | MCC   --|  .00  .00 -.05  -.11   .90 -2.87 -2.5  .80|                      
   |-----------------------------------------------------|                      

Table 2.1120.1  GPS week: 1120   Day: 1   MJD: 52085                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28| -.01  .00 -.11  -.27   .08  -.11  -.1  .31|                      
   | ESA   29|  .00 -.01  .09   .28  -.11   .03   .8  .22|                      
   | MCC   --|  .00  .03 -.05  -.36   .25  -.23 -2.9  .35|                      
   |-----------------------------------------------------|                      

Table 2.1120.2  GPS week: 1120   Day: 2   MJD: 52086                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28|  .02  .00 -.13  -.24   .19   .13   .2  .27|                      
   | ESA   29|  .00 -.01  .13   .36  -.08   .39  1.9  .24|                      
   | MCC   --| -.04  .02 -.08  -.19  -.34 -1.39 -4.1  .21|                      
   |-----------------------------------------------------|                      

Table 2.1120.3  GPS week: 1120   Day: 3   MJD: 52087                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28|  .02  .01 -.14  -.34   .06  1.68  -.1  .34|                      
   | ESA   29|  .01  .00  .14   .48   .08   .19  3.1  .31|                      
   | MCC   --| -.02 -.02 -.10  -.10  -.20 -2.53 -3.9  .18|                      
   |-----------------------------------------------------|                      

Table 2.1120.4  GPS week: 1120   Day: 4   MJD: 52088                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28| -.01  .01 -.16  -.27  -.34  1.81  -.9  .35|                      
   | ESA   29|  .00  .01  .13   .28   .26  -.06  2.2  .30|                      
   | MCC   --|  .00 -.04 -.08  -.35   .08 -5.67 -6.1  .54|                      
   |-----------------------------------------------------|                      

Table 2.1120.5  GPS week: 1120   Day: 5   MJD: 52089                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28| -.02  .00 -.17   .06  -.30  1.25  -.6  .34|                      
   | ESA   29|  .01  .00  .15   .03   .20  -.04  1.4  .35|                      
   | MCC   --|  .07  .00  .04  -.56   .36 -8.77 -7.1 1.12|                      
   |-----------------------------------------------------|                      

Table 2.1120.6  GPS week: 1120   Day: 6   MJD: 52090                            
   |-----------------------------------------------------|                      
   | CENT STA|   DX   DY   DZ    RX    RY    RZ  SCL  RMS|                      
   |-----------------------------------------------------|                      
   | BKG   28|  .00 -.01 -.15  -.12  -.04   .91  -.8  .33|                      
   | ESA   29| -.01  .00  .15   .08  -.02  -.27  2.4  .30|                      
   | MCC   --|  .01  .01 -.07   .05   .12  -.72 -3.8  .18|                      
   |-----------------------------------------------------|                      

Table 3: Daily RMS difference w.r.t. combination per satellite and center.      
         The IGX column gives the weighted RMS of the combination               
         according to the accuracy codes in the SP3-file.                       
         "E" marks eclipsing satellites.                                        
         Units: cm.                                                             

Table 3.1120.0  GPS week: 1120   Day: 0   MJD: 52084                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |  26  16 128   26 |
    |  07  |  10   8  --   13 |
    |  08  |  57  45  --   51 |
    |  13  |   9   7  --    6 |
    |  15  |  --   4  16   13 |
    |  17  |  10   8  --    6 |
    |  24  |  11   7  17   13 |
    ---------------------------                                                 
    |Median|  11   8  17      |
    ---------------------------                                                 

Table 3.1120.1  GPS week: 1120   Day: 1   MJD: 52085                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |  11  10  21   13 |
    |  07  |   9   7  --    6 |
    |  08  |  52  43  --   51 |
    |  13  |   9   7  --    6 |
    |  15  |  --   7  10    6 |
    |  17  |   8   6  --    6 |
    |  24  |  29  13  52   26 |
    ---------------------------                                                 
    |Median|  10   7  21      |
    ---------------------------                                                 

Table 3.1120.2  GPS week: 1120   Day: 2   MJD: 52086                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |   7   9   8    6 |
    |  07  |   7   7  --    6 |
    |  08  |  47  44  --   51 |
    |  13  |   5   5  --    6 |
    |  15  |  --   9   8    6 |
    |  17  |   5   4  --    6 |
    |  24  |  23  17  32   26 |
    ---------------------------                                                 
    |Median|   7   9   8      |
    ---------------------------                                                 

Table 3.1120.3  GPS week: 1120   Day: 3   MJD: 52087                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |  14  11  11   13 |
    |  07  |   8   8  --    6 |
    |  08  |  57  54  --   51 |
    |  13  |   7   7  --    6 |
    |  15  |  --  19  10   13 |
    |  17  |   4   4  --    3 |
    |  24  |  22  17  20   13 |
    ---------------------------                                                 
    |Median|  11  11  11      |
    ---------------------------                                                 

Table 3.1120.4  GPS week: 1120   Day: 4   MJD: 52088                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |  12  12  31   13 |
    |  07  |   7   6  --    6 |
    |  08  |  55  49  --   51 |
    |  13  |   8   7  --    6 |
    |  15  |  --   7  12   13 |
    |  17  |   7   6  --    6 |
    |  24  |  26  18  70   26 |
    ---------------------------                                                 
    |Median|  10   7  31      |
    ---------------------------                                                 

Table 3.1120.5  GPS week: 1120   Day: 5   MJD: 52089                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |   6  10  34   13 |
    |  07  |   8   8  --    6 |
    |  08  |  56  58  --   51 |
    |  13  |   6   6  --    6 |
    |  15  |  --   5  18   13 |
    |  17  |   9  10  --   13 |
    |  24  |  23  23 158   26 |
    ---------------------------                                                 
    |Median|   9  10  34      |
    ---------------------------                                                 

Table 3.1120.6  GPS week: 1120   Day: 6   MJD: 52090                            
                                                                                
          Weighted Average                                                      
    ---------------------------                                                 
    | SAT  | BKG ESA MCC  IGX |                                                 
    ---------------------------                                                 
    |  01  |  11  15  21   13 |
    |  07  |   7   7  --    6 |
    |  08  |  63  58  --   51 |
    |  13  |   5   5  --    6 |
    |  15  |  --   9   8    6 |
    |  17  |   8   8  --    6 |
    |  24  |   7   7   7    6 |
    ---------------------------                                                 
    |Median|   8   8   8      |
    ---------------------------                                                 

   End of Report: Week 1120
--
___________________________________________________________________________
Robert Weber                           Tel:    ++43-1-58801-12865               
Department of Advanced Geodesy         Fax:    ++43-1-58801-12896              
University of Technology, Vienna       E-Mail: [email-masked]
Gusshausstrasse 27-29                          [email-masked]
A-1040 Vienna, Austria                         
___________________________________________________________________________