Abstract
WE wish to point out that the random fluctuations in the rotation rate of the Earth1–4 are occasionally large enough significantly to affect the measured values of ΔP/P for pulsars. Recent measurements of ΔP/P (P is the pulse repetition period) reported by P. E. Reichley, G. S. Downs and G. A. Morris to a meeting of the US National Committee for URSI (Washington, April 22, 1969) have attained a precision of 1 part in 1016 or better. Such observations are usually corrected for effects due to the annual and diurnal motions of the Earth, the long term variation in the relationship between Universal Time and Atomic Time, and so on, in order to reduce them to the heliocentric frame or even that of the solar system bary-centre. One then examines the reduced data for possible second-order terms in the pulsar slow-down process, such as the 1 per cent increase in ΔP/P that occurred after an abrupt change in the period of PSR 0833–45 (ref. 5). As we will show, however, it is necessary to analyse the data carefully in order to exclude effects due to the random variations in the length of the day (l.o.d.).
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MARAN, S., ÖGELMAN, H. Pulsar Periods and Rapid Changes in the Terrestrial Rotation Rate. Nature 224, 349 (1969). https://doi.org/10.1038/224349a0
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DOI: https://doi.org/10.1038/224349a0
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