A method and apparatus are presented for providing a compact extended ephemeris package for GNSS processing. An extended ephemeris service provides orbit trajectories and clock corrections which are predicted into the future for navigation satellites. The extended ephemeris package format used allows the ephemeris information to be sent quickly and efficiently, even when using a low bandwidth communication network. Client GNSS receiver devices obtain the extended ephemeris package and extract the satellite ephemeris information for later use. This allows a client device to operate for many days or weeks without needing to decode or receive new satellite ephemeris information.