Technical decriptions of the files Combo_*.*
Created 18-Jun-2019 by Maria Karbon (maria.karbon@obspm.fr)
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Combo_*.cat

File contains the combination product of the catalogs referenced in the name in the IERS-format, 
the description of the individual columns is given in the respective file.

* Combo_KX.cat:   combination of the S/X and the K-band catalog
* Combo_KXKa.cat: combination of the S/X, the K-band and the X/Ka catalog

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*.Qxx

Combo_KX.Qxx and Combo_KXKa.Qxx contain the co-variance matrices of the combination Combo_KX.cat and 
Combo_KXKa.cat, respectively. Unit is [mas^2].

It is given as a decomposed lower trinagle matrix in the format:

Row__ Col__  Matrix_Estim_Value    Matrix_Estim_Valu2    Matrix_Estim_Valu3
1     1    4.1343103500256e-03
2     1   -8.2211190916641e-04    1.3755605057912e-02
3     1    1.3340803079570e-05    7.2010288497463e-06    1.4517259569855e-02
4     1    1.5558503124551e-05    4.2292165263673e-05   -1.2927525391321e-02
4     4    8.1510233758259e-02
5     1    1.3181123124379e-05    6.2589404995755e-06    5.8125526068192e-04
...

Row runs from 1:numSources*2, Col from 1:Row. Odd Row-numbers correspond to the right ascension, even to the 
declination of the respective source. The order of the sources corresponds to the order given in *.cat.