## 2 Precise MGEX Orbit and Clock Products
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Institutions** & **ID** & **Constellations 9** & **Orbit** & **Clock** & **Remarks** \\ \hline CODE 1  & COD0 MGXFIN & GRECJ & 5 min & 30 s & GEOs excluded[ENDFOOTNOTE] \\ ESA 2  & ESM & 5 min & 30 s & BDS-3 included; GEOs excluded[ENDFOOTNOTE] \\ GFZ 3  & GFZ0 MGXRAP & GRECJ & 5 min & 30 s & BDS-3 included; GEOs excluded[ENDFOOTNOTE] \\ CNES/CLS 4  & GRG0 MGXFIN & GREC & 15 min & 30 s & \\ JAXA 5  & JAXA 5  & GJ & 5 min & 30 s & J02, J03 and J07 excluded \\ THUM 7  & TIMOM & MGXRAP & ECJ & 5 min & / \\ WHU 8  & WUM0 MGXFIN & GRECJ & 15 min & 30 s & BDS-3 included \\ \hline \hline \end{tabular}  
* CODE stands for Center for Orbit Determination in Europe. 2 ESA stands for European Space Agency. 3 GFZ stands for GeoForschungsZentrum. 4 CNES/CLS stands for Centre National d’Etudes Spatiales and Collecte Localisation[ENDFOOTNOTE] & SATellites. 5 JAXA stands for Japan Aerospace Exploration Agency. 6 SHAO stands for Shanghai Observatory. 7 TUM stands for Technische Universität München. 8 WHU stands for Wuhan University. 9 The letters G, R, E, C and I denote Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), Galileo, BDS and QZSS, respectively.  
\end{table} 
Table 1: Overview of the precise MGEX orbit and clock products as of November 2019. The five-parameter Extended CODE Orbit Model (ECOM) [34] was adopted by GFZ for the new BDS, Galileo and QZSS satellites [3]. According to the IGS Technical Report 2018 [8], GFZ switched the SRP model from ECOM to ECOM2 [35] for IGS final, rapid and ultra-rapid processing in November 2018. However, it is uncertain whether ECOM2 was also applied by GFZ to generate MGEX products. CODE and CNES/CLS used the ECOM2 model. Please note that CODE adopted a so-called terminator reference frame since DOY198 2018 to describe the SRP accelerations for QZSS and BDS-2 satellites during orbit normal (ON) mode [36]. ESA adopted an a priori box-wing model to enhance the ECOM model, and estimated box-wing parameters were used for BDS and QZSS. In addition, one constant and two first-order harmonic terms were also estimated in along-track ([[http://navigation-office.esa.int/products/gnss-products/esm.acn](http://navigation-office.esa.int/products/gnss-products/esm.acn)]([http://navigation-office.esa.int/products/gnss-products/esm.acn](http://navigation-office.esa.int/products/gnss-products/esm.acn))). TUM also improved SRP models for Galileo and QZSS by using the a priori box-wing models, while ECOM is still used for BDS POD [4]. WHU has been applied for different SRP models for different satellites. The ECOM model has been used for the BDS-3, QZSS J02, J03 and J07 satellites. The cuboid model proposed by [PERSON] et al. [37] has been used for QZSS J01 POD. For BDS-2 IGSO and MEO satellites, a tightly constrained acceleration bias in the along-track direction has been added to the ECOM model [5]. For BDS-2 GEO satellites, an improved a priori model has been adopted to reduce the perturbation caused by the communication antenna [17]. As for JAXA, it has utilized a more complicated ECOM model with 13 parameters for QZSS POD [7].