Home » Quality Checks » CPF Comparison

Satellite CPF Predictions

The ILRS network uses CPF orbit predictions provided by mission operators and analysis centres.


The SGF calculates precise satellite orbit predictions daily for most of the ILRS targets and makes these orbits available to other SLR stations internationally. These predictions can be compared in advance to those from other CPF providers so that stations and providers can be confident in their accuracy.

The Consolidated Prediction Format (CPF) is the official format used by the ILRS. It consists of geocentric X, Y, and Z positions at different epochs that can be interpolated for very accurate predictions. Accurate prediction of the positions of the full range of laser-tracked satellites is possible in a single, simple format.

The plots below compare the CPFs when there is more than one provider by taking the differences in metres between the orbital X, Y and Z values at zero hours for today and for the next three or four days.

Full residual plot comparisons are plotted here.
           Difference between CPF Providers
        JD            X             Y             Z
Ajisai SGF - ITT    
 aji   58941.         1.236         2.295        -0.856
 aji   58942.         1.121         4.323        -0.817
 aji   58943.         1.038         7.028        -0.829
 aji   58944.         1.423         9.644        -1.052
Ajisai ITT - JAX    
 aji   58941.        -1.165        -1.716         0.965
 aji   58942.        -1.081        -3.061         0.986
 aji   58943.        -1.024        -5.031         1.051
Ajisai JAX - SGF    
 aji   58941.        -0.070        -0.579        -0.109
 aji   58942.        -0.041        -1.262        -0.170
 aji   58943.        -0.015        -1.996        -0.222
Beacon-C SGF - ITT  
 bec   58941.         1.309       -16.254        -5.533
 bec   58942.         0.769       -16.374        -8.530
 bec   58943.         0.724        -7.442       -13.847
 bec   58944.         0.623        12.347       -22.183
Cyrosat-2 ESA - ITT 
Etalon-1 SGF - ITT  
 eta   58941.        18.438       -16.610         5.246
 eta   58942.        19.717        29.673       -23.322
 eta   58943.        10.381        46.137       -28.408
 eta   58944.        -2.905        45.492       -29.118
Etalon-2 SGF - ITT  
 etb   58941.        19.434        10.859       -75.490
 etb   58942.        29.402         9.374       -89.275
 etb   58943.        39.976        25.501       -96.946
 etb   58944.        32.296        46.415       -85.444
Jason-2 SGF - ITT   
Jason-2 ITT - CNES  
Jason-2 CNES - SGF  
Larets SGF - ITT    
 lar   58941.        -7.395        -0.797        -0.106
 lar   58942.        -8.079        -4.483        -1.800
 lar   58943.        -8.651       -12.510        -3.210
 lar   58944.       -11.896       -13.115        -4.264
LARES SGF - ITT     
 las   58941.         1.722        -0.022        -0.818
 las   58942.         1.866        -0.032        -1.220
 las   58943.         1.933        -0.283        -1.457
 las   58944.         2.061        -0.626        -1.913
LAGEOS-1 SGF - ITT  
 lga   58941.         2.711         1.898         0.283
 lga   58942.         2.850         2.849         0.407
 lga   58943.         4.281         2.956         0.074
 lga   58944.         2.442         7.204         0.925
LAGEOS-1 ITT - JAX  
 lga   58941.        -2.727        -1.778        -0.331
 lga   58942.        -2.854        -2.739        -0.466
 lga   58943.        -4.277        -2.835        -0.139
LAGEOS-1 JAX - SGF  
 lga   58941.         0.015        -0.120         0.048
 lga   58942.         0.004        -0.110         0.059
 lga   58943.        -0.004        -0.121         0.064
LAGEOS-2 SGF - ITT  
 lgb   58941.         2.519         2.969        -1.824
 lgb   58942.         1.672         4.985        -1.831
 lgb   58943.         2.733         6.152        -2.184
 lgb   58944.         1.975         9.906        -2.489
LAGEOS-2 ITT - JAX  
 lgb   58941.        -2.736        -4.344         2.139
 lgb   58942.        -1.625        -6.913         2.005
 lgb   58943.        -2.946        -8.270         2.550
LAGEOS-2 JAX - SGF  
 lgb   58941.         0.216         1.375        -0.315
 lgb   58942.        -0.048         1.928        -0.174
 lgb   58943.         0.213         2.118        -0.365
Stella SGF - ITT    
 ste   58941.         1.235        -0.072         0.004
 ste   58942.         1.008        -1.167         0.343
 ste   58943.         0.789        -3.328         0.671
 ste   58944.         1.132        -4.930         0.447
Starlette SGF - ITT 
 str   58941.         0.975         3.529        -2.266
 str   58942.         1.115         6.037        -2.013
 str   58943.         0.189        10.752        -1.707
 str   58944.         1.386        16.447        -2.052