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   58769.         4.960         7.336        -5.697
 aji   58770.         5.227        12.069        -5.778
 aji   58771.         4.990        18.267        -5.642
 aji   58772.         5.336        26.690        -5.704
Ajisai ITT - JAX    
 aji   58769.        -5.059        -7.342         5.758
 aji   58770.        -5.327       -12.170         5.845
 aji   58771.        -5.103       -18.432         5.704
Ajisai JAX - SGF    
 aji   58769.         0.100         0.007        -0.061
 aji   58770.         0.100         0.101        -0.067
 aji   58771.         0.113         0.164        -0.062
Beacon-C SGF - ITT  
 bec   58769.         3.256        -7.365        -1.480
 bec   58770.         3.901       -15.094        -0.627
 bec   58771.         9.213       -19.306         0.047
 bec   58772.         5.373       -22.561         4.270
Cyrosat-2 ESA - ITT 
Etalon-1 SGF - ITT  
Etalon-2 SGF - ITT  
Jason-2 SGF - ITT   
Jason-2 ITT - CNES  
Jason-2 CNES - SGF  
Larets SGF - ITT    
 lar   58769.         5.456        -6.277        -5.803
 lar   58770.         6.386        -8.611        -6.780
 lar   58771.         6.721       -11.341        -8.386
 lar   58772.         8.654       -14.055        -9.332
LARES SGF - ITT     
LAGEOS-1 SGF - ITT  
 lga   58769.         7.508         2.372        -0.767
 lga   58770.         8.110         1.886        -0.717
 lga   58771.         8.260         1.527        -0.202
 lga   58772.         7.957         0.299         0.680
LAGEOS-1 ITT - JAX  
 lga   58769.        -7.501        -2.375         0.675
 lga   58770.        -8.094        -1.910         0.601
 lga   58771.        -8.645        -1.850         0.736
LAGEOS-1 JAX - SGF  
 lga   58769.        -0.007         0.002         0.092
 lga   58770.        -0.016         0.023         0.117
 lga   58771.        -0.034         0.044         0.148
LAGEOS-2 SGF - ITT  
 lgb   58769.         5.209         0.819        -5.079
 lgb   58770.         7.051        -0.705        -5.931
 lgb   58771.         4.615        -1.873        -5.025
 lgb   58772.         6.587        -4.320        -7.980
LAGEOS-2 ITT - JAX  
 lgb   58769.        -5.157        -0.656         5.032
 lgb   58770.        -7.093         0.985         5.872
 lgb   58771.        -4.846         2.143         4.088
LAGEOS-2 JAX - SGF  
 lgb   58769.        -0.052        -0.163         0.047
 lgb   58770.         0.041        -0.280         0.059
 lgb   58771.        -0.093        -0.368         0.166
Stella SGF - ITT    
 ste   58769.         5.947         5.411        -2.074
 ste   58770.         5.952         7.626        -1.863
 ste   58771.         6.000        10.629        -2.078
 ste   58772.         6.133        14.527        -2.088
Starlette SGF - ITT 
 str   58769.         5.685         0.701         0.186
 str   58770.         6.151        -0.433         2.293
 str   58771.         7.126        -2.249         4.844
 str   58772.         7.013        -2.018         6.196