Geomagnetic models at low earth orbit and their use in attitude determination

In this study, three geomagnetic field models, T89, CHAOS-6 and IGRF-12 models are compared at LEO orbit altitudes with the satellite observations. Comparisons between the models and with the observations are made using the total magnetic field and the components during the geomagnetically disturbed and quiet times. Main interest is to see how the angle between the modelled and observed magnetic field vectors changes. The differences are important since satellite's attitude determination system strongly depends on the angle. Effects of geomagnetic activity on the angle is investigated using geomagnetic activity index and the position of the satellite which are inputs to the models. Comparisons are made between the models using root mean square error analysis. Differences between the model magnetic fields and those of observed are seen to increase when the geomagnetic activity occurs. We discuss the implications of these differences on the satellite attitude determination system.