LEAP SECOND TO BE INTRODUCED BY THE END OF THE YEAR & LEAP SECOND TALKS POSTPONED

November 21, 2005

LEAP SECOND TO BE INTRODUCED BY THE END OF THE YEAR

Reprinted below is the U.S. Naval Observatory Time Series Announcement Series 14.


U.S. NAVAL OBSERVATORY WASHINGTON, D.C. 20392-5420

July 27, 2005 No. 69

TIME SERVICE ANNOUNCEMENT SERIES 14

UTC TIME STEP

1. The International Earth Rotation and Reference Systems Service
(IERS) has announced the introduction of a time step to occur at the end of
December, 2005.

2. Coordinated Universal Time (UTC) will be retarded by 1.0s so that
the sequence of dates of the UTC markers will be:

2005 December 31 23h 59m 59s
2005 December 31 23h 59m 60s
2006 January 01 0h 0m 0s

3. The difference between UTC and International Atomic Time (TAI) is:

from 1999 01 Jan, UTC to 2006 01 January, UTC: TAI-UTC= +32s
from 2006 01 Jan, UTC until further notice: TAI-UTC= +33s

4. Information regarding current and predicted values of UT1-UTC is
provided in IERS Bulletin A.

5. UTC and all time scales based on UTC will be affected by this
adjustment. However, Loran-C and GPS will not be adjusted physically. Times of
Coincidence for LORAN-C are available on the Time Service Web Page
( http://tycho.usno.navy.mil/loran.html ). For GPS, the leap second correction
contained within the UTC data of subframe 4, page 18 of the navigation
message transmitted by satellites will change.

Before the leap second
GPS-UTC = +13s (i.e., GPS is ahead of UTC by thirteen seconds)

After the leap second
GPS-UTC = +14s (i.e., GPS will be ahead by fourteen seconds)

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November 21, 2005

LEAP SECOND TALKS POSTPONED

The controversial adjustment of UTC by leap seconds will continue. Scientists
expert on timekeeping have decided to postpone any changes to the current
application of leap seconds until more studies are performed.

Read full press release at:

        http://news.bbc.co.uk/1/hi/sci/tech/4420084.stm