Observation of terrestrial orbital motion using the cosmic-ray Compton-Getting effect

Using underground observations, the authors have found a small diurnal amplitude modulation of the cosmic-ray muon intensity which agrees in amplitude and phase with a first-order relativistic effect due to the Earth's motion, as discussed by Compton and Getting :1935, Phys. Rev., 47, 817:. Analysis of the arrival times of 5x108 muons during a period of 5.4 yr yields a fractional amplitude variation of 2.5sub(-0.6) sup(+0.7) x 10-4, with a maximum near dawn, at 08:18+-1.0 h local mean solar time (LT). The expected amplitude is 3.40 x 10-4, with the maximum at 06:00LT. (author)