Technical description of the SINEX solution opa2012a

1. Origin of input data: databases from IVS Data Center, version 4 or more.

2. Authentic processing steps after data retrieval: re-Calc, transform to 
   superfile, and put into BATCH Solve.

3. Origin of meteorological data: use database content.

4. Use numerical weather model: ECMWF for computing VMF1.

5. Setting of mapping functions: VMF1.

6. Origin of cable cal data: use database content.

7. Application of cable cal flags: use database settings.

8. Selection/settings of geophysical models: replace database settings.

   8.1. Nutation/precession: IAU 2000A nutation and IAU 2006 precession.
   
   8.2. Short-period tidal variations in x, y, UT1: IERS 2003.
   
   8.3. Troposphere mapping functions: VMF1.
   
   8.4. A priori mean gradients: from VLBI data or DAO weather model.
 
   8.5. Solid Earth tide: IERS Conventions 1996, pp. 56--65, step 1 and step 2,
        anelasticity variant, including tides of the 3-rd order.
 
   8.6. Ocean loading displacements: FES 2004.

   8.7. Atmospheric loading displacements: APLO (Petrov & Boy 2004).
   
   8.8. Permanent tide correction: applied.

   8.9. Thermal expansion: Nothnagel (2008).
   
   8.10. A priori station positions and velocities: opa2012a or blokq.dat
         file content or database content for new stations.
   
   8.11. A priori source coordinates: opa2012a or database content for new sources.

9. Parameterization

   9.1. Clock: quadratic + continuous piece-wise linear with 60-mn interval.

   9.2. Atmosphere: continuous piece-wise linear 20-mn interval.

   9.3. Gradients: estimated at 6-hr interval at all sites.
     
   9.4. Earth orientation: polar motion and rate, UT1 and rate, nutation 
        offsets.
        
   9.5. Station positions: estimated.

   9.6. Station velocities: not estimated.
     
   9.7. Source coordinates: estimated.

     0014+813 0235+164 0637-752 0738+313 1308+326 1448+762 2145+067 3C120    \
     1610-771 0208-512 0438-436 0451-282 0919-260 0607-157 2243-123 NGC1052  \
     2128-123 3C279    0106+013 2134+00  1021-006 3C273B   0528+134 2121+053 \
     0202+149 3C454.3  1611+343 OQ208    2201+315 2234+282 OK290    4C39.25  \
     3C345    0711+356 3C84     1739+522 1044+719 0212+735 3C309.1
   
   9.8. Antenna axis offsets: not estimated.
      
10. Outlier elimination: use database settings.

11. Constraints (only of interest for direct EOP estimates)

   11.1. Sources: loose no-net rotation is uniformly applied to all sources
         except the "special handling" sources:
     
     0014+813 0235+164 0637-752 0738+313 1308+326 1448+762 2145+067 3C120    \
     1610-771 0208-512 0438-436 0451-282 0919-260 0607-157 2243-123 NGC1052  \
     2128-123 3C279    0106+013 2134+00  1021-006 3C273B   0528+134 2121+053 \
     0202+149 3C454.3  1611+343 OQ208    2201+315 2234+282 OK290    4C39.25  \
     3C345    0711+356 3C84     1739+522 1044+719 0212+735 3C309.1

   11.2. Stations: loose no-net rotation/translation on positions and velocities
         applied to all stations.
   
12. Generation of pre-reduced datum-free normal equations: yes.

13. Further details

   13.1. Data type: group delays.

   13.2. Data editing: 5 degree elevation cutoff.

   13.3. Data weighting: weights are defined as follows: 1/sqrt ( f**2 + a**2 ) 
         where "f" is the formal uncertainty of the ionosphere free linear
         combination of group delays at X- and S-band obtained by fringe fitting
         on the base of achieved signal to noise ratio. Station-dependent 
         parameter "a" was computed for each session by an iterative procedure 
         such that the ratio of the sum of squares of the weighted residuals to 
         the estimate of their mathematical expectation is about unity.
 
   13.4. Standard errors reported: all errors are derived from least-squares 
         estimation propagated from the data weights and the constraints applied 
         to the troposphere, clock and EOP parameters.
         
   13.5. Software: CALC 10.0, SOLVE revision date 2010.05.21.

   13.6. Other informations about the solution are reported at
         http://ivsopar.obspm.fr.