atomic time scale | ScienceGate

The long-term instability of the new generation hydrogen masers

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-1-35-38 ◽

2020 ◽

pp. 35-38

Author(s):

S.I. Donchenko ◽

I.Y. Blinov ◽

I.B. Norets ◽

Y.F. Smirnov ◽

A.A. Belyaev ◽

...

Keyword(s):

Time Scale ◽

Frequency Difference ◽

Clock Frequency ◽

Quantum Frequency ◽

Frequency Standards ◽

Quantum Frequency Standards ◽

New Generation ◽

Atomic Time

The latest changes in the algorithm for the formation of the international atomic time scale TAI are reported in terms of estimating the weights of the clocks involved in the formation of TAI. Studies of the characteristics of the long-term instability of new-generation hydrogen masers based on processing the results of the clock frequency difference with respect to TAI are performed. It has been confirmed that at present, new-generation hydrogen masers show significantly less long-term instability in comparison with quantum frequency standards ofsimilar and other types.

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The Role of Occultations in the Improvement of the Lunar Ephemeris

Symposium - International Astronomical Union ◽

10.1017/s0074180900097692 ◽

1972 ◽

Vol 47 ◽

pp. 395-401

Author(s):

L. V. Morrison

Keyword(s):

Time Scale ◽

The Moon ◽

Secular Acceleration ◽

Lunar Ephemeris ◽

Occultation Data ◽

Correction Terms ◽

Empirical Constants ◽

Atomic Time

Analyses of occultation timings show that periodic correction terms with semi-amplitude as great as 0.″18 arise from corrections required to the empirical constants of the Brown/Eckert theory. Using the atomic time-scale, some of the occultation data have been used to determine a correction of – 30 ± 16″/cy2 to Spencer Jones' value for the secular acceleration of the Moon. In the light of this correction, and previous determinations, attention is drawn to the possible weakness of Spencer Jones' value, which is not reflected in his quoted error of ± 1″/cy2. Further analyses of 50000 occultations observed since 1943 promise to reveal more accurately-determined corrections.

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