Abstract: A navigational initialization system that includes a reference oscillator, altitude reference system, a celestial navigation system (CNS), and a controller is provided. The reference oscillator is used to generate timing signals. The altitude reference system is used to generate altitude information. The CNS includes a star tracker and inertial sensor assembly (ISA). The star tracker is configured to determine orientation of the star tracker with respect to an earth centered inertial frame. The ISA is used to determine at least an attitude with respect to a local vertical frame. The controller is configured to generate an initialization signal using the timing signals generated by the reference oscillator, the altitude information generated from the altitude reference system, and at least one output of the CNS. The initialization signal is configured to initialize a navigation system.