Astro-Azimuth Using Time Difference

Conventionally, the determination of astronomic azimuth involves the synchronization of the observations with a radio time signal or the measurement of zenith distances which are subject to refraction errors. A mathematical model is developed which is dependent upon time differences (not absolute time) and horizontal angles (nearly refraction-free) between pairs of stars. Error analysis indicates that an optimum star pair includes Polaris and any second star whose azimuth is at least moderately changing. Field tests indicate that the azimuth of Polaris may be determined to within 0.6 seconds of arc. The formation and solution of the necessary equation may be implemented on a programmable calculator.