Noninertial Coordinate Time: A New Concept Affecting Time Standards, Time Transfers, and Clock Synchronization

Relativity compensations must be made in precise and accurate measurements whenever an observer is accelerated. Although many believe the Earth-centered frame is sufficiently inertial, accelerations of the Earth, as evidenced by the tides, prove that it is technically a noninertial system for even an Earth-based observer. Using the constant speed of light, a set of fixed remote clocks in an inertial frame can be synchronized to a fixed master clock transmitting its time in that frame. The time on the remote clock defines the coordinate time at that coordinate position. However, the synchronization procedure for an accelerated frame is affected, because the distance between the master and remote clocks is altered due to the acceleration of the remote clock toward or away from the master clock during the transmission interval.

An exact metric that converts observations from noninertial frames to inertial frames was recently derived. Using this metric with other physical relationships, a new concept of noninertial coordinate time is defined. This noninertial coordinate time includes all relativity compensations. This new issue raises several timekeeping issues, such as proper time standards, time transfer process, and clock synchronization, all in a noninertial frame such as Earth.