**Estimation** |

Filter | Extended Kalman filter |

Estimation parameters | Epoch state vector, empirical accelerations, epoch-wise residual phase offset and fractional frequency offset, inter-system bias, phase ambiguities |

Stochastic models | White observation noise, elevation-independent weighting, zero a-priori values, and configurable standard deviation of empirical accelerations |

Ambiguity | Float |

**GNSS Measurements** |

GNSS Observations | Undifferenced GPS L1 C/A / L2C, L1/L2 P(Y), and Galileo E1/E5a pseudorange and carrier phase (Table 4) |

Sampling rate | 30 s |

GNSS data arc | Continuous from January 17 to January 30, 2021; telemetry data gap on January 25 between 02:29 and 02:46 |

GNSS satellite biases | GPS C1C/C2L timing group delay (TGD) and inter-signal corrections from CNAV; Galileo C1C/C5Q neglected |

Phase windup | Neglected |

S6A GNSS antenna | Constant antenna offset in satellite body frame; zero antenna phase center offset |

S6A attitude | Quaternions (measured) |

Reference frame | GPS: WGS84(1762’) (Malys et al., 2016); Galileo: GTRF19v01 |

**Orbit Model** |

Earth gravity field | GOCO03S (Tapley et al., 2004) up to order and degree 50, rate terms *Ċ*_{20}, *Ċ*_{21}, *Ṡ*_{21} |

Third-body gravity | Point-mass model; truncated analytical series of luni-solar coordinates (Montenbruck & Gill, 2000) |

Solid Earth tides | *K*_{2} tides (Rizos & Stolz, 1985) |

Ocean tides | Neglected |

Relativity | Neglected |

Solar radiation pressure | Cannonball model |

Earth radiation pressure | Neglected |

Atmospheric forces | Cannonball model; Harris-Priester model for medium-solar flux (Harris & Priester, 1962) |

Empirical acceleration | Epoch-wise approximation; three components in radial, tangential, normal direction; constant during propagation step |

Reference frame | ITRF |

Earth orientation | GPS CNAV Earth Orientation Parameters (EOP; GPS ICD, 2020) |

Numerical integration | 4th-order Runge-Kutta |