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A Re-Evaluation of the Relativistic Redshift on Frequency Standards at NIST, Boulder



Marc A. Weiss, Nikolaos K. Pavlis


We re-evaluated the relativistic redshift correction applicable to the frequency standards at the National Institute of Standards and Technology (NIST) in Boulder, Colorado, USA, based on a precise GPS survey of three benchmarks on the roof of the building where these standards were housed, and on global and regional geoid models supported by data from the GRACE and GOCE missions, including EGM2008, USGG2009, and USGG2012. We also evaluated the redshift offset based on the published NAVD88 geopotential number of the leveling benchmark Q407 located on the side of a building at NIST, Boulder, after estimating the bias of the NAVD88 datum at our specific location. Based on these results, our current best estimate of the relativistic redshift correction on frequency standards located at the second floor of Building 1, NIST, Boulder, Colorado, USA is equal to (-1798.50 ± 0.06)×10-16 , compared to the value of (-1798.70 ± 0.30) ×10-16, estimated by Pavlis and Weiss in 2003. The minus sign implies that clocks run faster in the laboratory in Boulder than a corresponding clock located on the geoid.


Frequency standard, general relativity, relativistic frequency redshift


Weiss, M. and Pavlis, N. (2017), A Re-Evaluation of the Relativistic Redshift on Frequency Standards at NIST, Boulder, Metrologia (Accessed February 29, 2024)
Created July 18, 2017, Updated July 19, 2017