The future of Coordinated Universal Time (UTC) and the leap second (Forwarded)
- From: Andrew Yee <ayee@xxxxxxxxxxxxxxxxxxxxxx>
- Date: Sat, 19 Nov 2005 09:38:01 -0500 (EST)
Radiocommunication Study Groups
International Telecommunication Union
Geneva, Switzerland
11 November 2005
Document 7A/TEMP/16R1-E
Working Party 7A
STATEMENT FOR RELEASE TO THE PRESS
THE FUTURE OF COORDINATED UNIVERSAL TIME (UTC) AND THE LEAP SECOND
A working party of the International Telecommunication Union -
Radiocommunication Sector (ITU-R) has considered a proposed change to UTC
at a meeting in Geneva on 8 -11 November 2005. The proposal is based on
studies done by an ITU-R Special Rapporteur Group (SRG) that was
established due to some evidence of the difficulties experienced by
communication, navigation and other electronic systems caused by leap
seconds and the general proliferation of continuous system "time scales".
The proposed change is intended to make UTC a continuous time scale. This
would however cause UTC to gradually diverge from UT1, the astronomical
time scale based on the irregular rotation of the Earth. At present, leap
seconds are added to UTC to limit its divergence from UT1 by no more than
0.9 seconds. The proposal recommends that the maximum difference allowed
between UTC and UT1 be increased to one hour (an event predicted to occur
only once every several hundred years).
The working party has discussed the proposed change and options, and
decided that more time is required to build consensus. In addition, the
forthcoming leap second just prior to 01 January 2006 00:00:00 h UTC --
the first for seven years -- provides an opportunity to further document
current problems.
UTC has been adopted as the basis of civil time in most of the world. It
is derived from more than 200 atomic clocks operated in some 50 time
standards laboratories around the world. The Bureau International des
Poids et Mesures (BIPM) is responsible for computing UTC on the basis of
data from those laboratories. UT1 is maintained by the International Earth
Rotation and Reference Systems Service (IERS) and it is this body that
decides when leap second adjustments should be applied. The procedures for
maintaining UTC are described by Recommendation ITU-R TF.460-6.
Attention: The information contained in this document is temporary in
nature and does not necessarily represent material that has been agreed by
the group concerned. Since the material may be subject to revision during
the meeting, caution should be exercised in using the document for the
development of any further contribution on the subject.
.
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