Differential Comparison of the One-Way Speed of Light in the East-West and West-East Directions on the Rotating Earth

Abstract

A status report is presented for a time transfer experiment which compares the times of flight in the east-west and west-east directions of short pulses of light sent from a laser coupled to the 48-inch telescope at the NASA Goddard Optical Research Facility to the U.S. Naval Observatory and reflected back over the same path. The times t₁ and t₃ when each light pulse leaves GORF and returns are measured with an event timer referenced to a hydrogen maser. The timer t₂ when the pulse is reflected at USNO is measured with a portable event timer and maser combination carried in a heated and air-conditioned truck. Each maser is maintained in a temperature-controlled environment. The portable maser enclosure is supported by pneumatic shock and vibration suppression mounts.