C. W. F. Everitt

C. W. F. Everitt led the Gravity Probe B experiment, which tested general relativity using four cryogenic gyroscopes in Earth orbit. The instrument measured slow changes in spin-axis direction relative to a stellar reference, separating the geodetic effect from frame dragging.

The 2011 final-results paper reported a geodetic drift of $-6601.8\pm 18.3$ milliarcseconds per year and a frame dragging drift of $-37.2\pm 7.2$ milliarcseconds per year, compatible with the predicted values within the reported uncertainties. The latter effect was much smaller, illustrating why identifying and modelling instrument drifts was central to the test.^[ref]