[LEAPSECS] QB213 .R4 2013

[Rob Seaman]

Our librarian has assigned the Library of Congress classification QB213 .R4 2013 to the proceedings of “Requirements for UTC and Civil Timekeeping on Earth” (ISBN 978-0-87703-603-6, http://futureofutc.org/preprints/).  Looking on the shelf, this is next to the proceedings for IAU Symposium 11, “The Rotation of the Earth and Atomic Time Standards", held in Moscow in August 1958.

Both volumes contain transcriptions of discussions during the meetings.  On p. 35 of the IAU #11 volume we have this harbinger of things to come (following G. M. Clemence’s contribution, “Ephemeris Time”):

	“Prof. PAVLOV mentioned that in recent years the time service is experiencing a great change.  The function of the International Time Service is turning more and more into a service for checking the rotation of the earth; at the same time, the determination of uniform time is becoming in greater degree dependent on the atomic standards of frequency.”

Following L. Essen’s “Report on the Precision of Atomic Standards of Frequency” there’s another portending discussion, including:

	“Dr. STOYKO commented that even though the atomic standard is not a clock, it can still be used as a time-keeper through the intermediary of quartz clocks.”  […]

	“Since the conventional frequency of the atomic standard does not correspond to the exact second with the provisional Uniform Universal Time (UT2) which is the basis of time services, the correction of the atomic clock must be represented as calculated by a linear function which is of a sufficient precision for an interval of the order of two months.”  […]

	“The frequency of 9,192,631,770 c/sec will be used as the standard but the service will operate with an error of about +160 parts in 10^10 so as to bring the frequency and time pulses in close accord with the time scale of UT2.  Corrections published by the Royal Greenwich Observatory will give the errors from UT2.  Corrections published by the National Physical Laboratory will give the errors from the cesium frequency of 9,192,631,770 c/sec to +1 part in 10^10.  This will also be the error from ephemeris time with the lower precision of +/- 20 parts in 10^10.  All possible time and frequency information will thus be given by the service.”

We have sought similar clarity in our two volumes, and to pay due homage to those who have come before:

	• The “atomic standard is not a clock”.

	• “Universal Time […] is the basis of time services”.

	• “All possible time and frequency information [should continue to] be given by the service."

Rob

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