Methods for use in celestial navigation system use multiple star observations from an unknown observer location using an observer camera with an observational field of view along a boresight axis and a focal plane perpendicular to the boresight axis. An observer local ECI coordinate system is determined from the star observations. Then for each of multiple observable objects in orbit around the Earth, multiple optical angular measurements relative to stars are performed over time to estimate its orbital ellipse, and its focus at the center of the Earth. From the multiple focus estimates, a position of the center of the Earth is estimated in the observer local coordinate system without use of object ephemeris data. From the estimated position of the center of the Earth, a radius vector to the observer is determined that represents the estimated observer location in Earth centered Earth fixed coordinates.