The present invention relates to a method for determining a position of an object having a Global Navigation Satellite System (GNSS) receiver. According to the invention, the method comprises the steps of: receiving signals by the GNSS receiver which are transmitted by GNSS transmitters positioned on board of satellites which are positioned in a view of the object; updating service data in the object, the service data including satellite clock data indicating internal clocks of the satellites, satellite orbit data indicating positions of the satellites, satellite delay code bias data relating to delay code biases of the GNSS transmitters and ionospheric model data indicating a state of an ionosphere; determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of the signals through the ionosphere between transmission of the signals from the GNSS transmitters and reception of the signals by the GNSS receiver; and determining a position of the object based on the signals, the satellite clock data, the satellite orbit data, the satellite delay code bias data and the determined ionospheric delay data.