This is an HTML version of an attachment to the Freedom of Information request 'UK policy on Leap Seconds'.


Radiocommunication Study Groups 
 
 
 
 
 
Received:  20 March 2008 
Document 7A/6-E 
25 March 2008 
Subject:  Recommendation ITU-R TF.460 
English only 
United Kingdom 
THE FUTURE OF THE UTC TIMESCALE 
 

The United Kingdom government has considered further the proposals submitted to 
Working Party 7A for the revision of Recommendation ITU-R TF.460-6. The essential part of these 
proposals is that Coordinated Universal Time (UTC) would be re-defined by ceasing the addition of 
leap seconds, thereby causing UTC to differ from UT1, a timescale based on the Earth’s rotation, by 
more than the current limit of 0.9 second. 

The UK continues to oppose strongly the proposed change to UTC. The following matters 
have been taken in to account in coming to this view: 
2.1 
The UK has considered the discussions about the proposed change within Working 
Party 7A, including the evidence presented to the Working Party of technical problems arising from 
the implementation of the leap second on 31 December 2005. It has concluded that the problems 
reported are minor and amenable to technical solutions, and that they do not provide sufficient 
justification for the proposed change. 
2.2 
British astronomers and navigators have strongly recommended that civil time should 
remain closely linked to mean solar time as is done with the current definition of UTC. 
2.3 
No British organisations have supported the proposed change. 
2.4 
In the UK no evidence has been found of serious difficulties arising from the introduction 
of a leap second. 
3. 
In summary UK strongly oppose the proposed changes to the Recommendation ITU-R 
TF.460-6 as the technical issues and concerns we raised regarding the proposal are still unresolved. 
 
 
 
 
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