Technical description of the intensive solution opa2015i

1. Origin of input data: databases from IVS data center, version 3 or more.

2. Authentic processing steps after data retrieval: re-calc using Calc 11.0, 
   transform to superfile and treat with BATCH Solve.

3. Origin of meteorological data: use database content.

4. Use numerical weather model: none.

5. Setting of mapping functions: NMF.

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
        plus empirical modeling of the FCN and prominent tidal oscillations
        fitted to the IERS EOP 08 C 04 nutation data.
   
   8.2. Short-period tidal variations in x, y, UT1: IERS 2010.
   
   8.3. Troposphere mapping functions: NMF.
   
   8.4. A priori mean gradients: from VLBI data or DAO weather model.
 
   8.5. Solid Earth tide: IERS 2010.
 
   8.6. Ocean loading displacements: FES 2004.

   8.7. Atmospheric loading displacements: APLO.
   
   8.8. Permanent tide correction: applied.

   8.9. Thermal expansion: Nothnagel (2008).
   
   8.10. A priori station positions and velocities: VTRF 2013d or database
         content for new stations.
   
   8.11. A priori source coordinates: ICRF2 or database content for new
         sources.

9. Parameterization

   9.1. Clock: quadratic.

   9.2. Atmosphere: offset.

   9.3. Gradients: not estimated.
     
   9.4. Earth orientation: UT1.
        
   9.5. Station positions: not estimated.

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

   9.8. Antenna axis offsets: not estimated.
 
10. Outlier elimination: use database settings.

11. Constraints: none.

12. Generation of pre-reduced datum-free normal equations: none.

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 11.0, Solve revision date 2014.02.21.

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