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 timee 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.