GeomagneticModelData
GeomagneticModelData[] returns the current magnetic field data for the current location.
GeomagneticModelData[locationspec] returns the current magnetic field data for a location.
GeomagneticModelData[datespec] returns the magnetic field data for the specified time for the current location.
GeomagneticModelData[locationspec,datespec] returns the magnetic field data for the specified time and location.
GeomagneticModelData[locationspec,datespec,component] returns the component of the magnetic field for the specified time and location.
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