Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Why there is no noon-midnight red shift in the GPS

Published

Author(s)

Neil Ashby, Marc A. Weiss

Abstract

Although the effects of solar and lunar gravitational potentials on the frequencies of orbiting GPS clocks are actually negligible, a naive calculation appears to show that such effects are significant, depending on whether the SV clock is between the earth and the sun, or on the side of the earth opposite to the sun. Consequently questions about whether such effects have been properly accounted for in GPS continue to arise. This issue has been discussed in a misleading way in the literature for almost 50 years. The purpose of this article is to provide simple arguments, so that one may understand in a simple way why the effects of the sun's and moon's gravitational potentials on orbiting or earth-bound clocks in the GPS are negligible.
Citation
Journal of Navigation

Keywords

GPS, relativity, gravitational potential, solar potential, GPS clock frequencies

Citation

Ashby, N. and Weiss, M. (2013), Why there is no noon-midnight red shift in the GPS, Journal of Navigation (Accessed April 19, 2024)
Created July 23, 2013, Updated October 12, 2021