Gravity and precisE ORBit determination system

GEORB is a software for Precise Orbit Determination (POD) of Low Earth Orbiters (LEOs), gravity field recovery based on satellite gravity missions and orbit design of future space missions.

GEORB has been used in orbit determination of Gravity Recovery And Climate Experiment (GRACE), and Gravity Field and Steady-State Ocean Circulation (GOCE) missions. The latest release focuses on the POD and accelerometer calibration of the GRACE Follow-On mission. 

GEORB has been released as open source in 2022 while it has been developed by Thomas since 2007. Details are provided through the repository website on GitHub.
Source code Repository:  Download on Github 

Cite GEORB: 

Thomas Loudis Papanikolaou (2023). GEORB: Release for precise orbit determination of low Earth orbiters and satellite gravity missions, Software Impacts, doi:


Papanikolaou T. (2012). Dynamic modelling of satellite orbits in the frame of contemporary satellite geodesy missions, Ph.D. Dissertation, Aristotle University of Thessaloniki (AUTH), Greece.

Papanikolaou T., Tsoulis D. (2016). Assessment of numerical integration methods in the context of low Earth orbits and inter-satellite observation analysis, Acta Geodetica et Geophysica, Vol. 51, No. 4, pp. 619-641,

Papanikolaou T., Tsoulis D. (2018). Assessment of Earth gravity field models in the medium to high frequency spectrum based on GRACE and GOCE dynamic orbit analysis, Geosciences, 8(12): 441,  (Download)

Papanikolaou, T. (2022). Precise orbit determination and accelerometer data modelling of the GRACE Follow-On mission, GRACE/GRACE-FO Science Team Meeting 2022, Potsdam, Germany, 18–20 Oct 2022, GSTM2022-90,, 2022.


Open Source software for gravity field functionals and Earth tides effects

GSynth is a software for gravity field functionals (gravity anomalies, geoid heights) and Earth tides effects considering solid Earth tides and Ocean tides.

GSynth has been released as open source in 2022 and has been developed by Thomas since 2013. The software is being used in gravity data analysis and tides modelling.

Source Code repository:  Download via github.


Papanikolaou T., Papadopoulos N.  (2015). High-frequency analysis of Earth gravity field models based on terrestrial gravity and GPS/levelling data: A case study in Greece, Journal of Geodetic Science, Vol. 5, No. 1, pp. 67-79 doi: 10.1515/jogs-2015-0008 .

Papanikolaou T. (2013). GRAVsynth and GRAVtide software' User guide, Dept. of Gravimetry, HMGS, Greece.







Designed by tp

TPThomas Papanikolaou