Measuring the Evolution of the Most Stable Optical Clock G 117‐B15A
Measuring the Evolution of the Most Stable Optical Clock G 117‐B15A
We report our measurement of the rate of change of period with time dP/dt for the 215 s periodicity in the pulsating white dwarf G 117-B15A, the most stable optical clock known. After 31 years of observations, we have finally obtained a 4 sigma measurement dP/dt_observed = (4.27 +/- 0.80) …