Proposal to eliminate leap seconds

Eric Ulevik eau at
Tue Nov 16 23:54:44 UTC 1999

Probably off-topic, but anyway:


Dear Project Manager or Scientist,

 It is being proposed to change the definition of Coordinated Universal
 Time (UTC) regarding the insertion of leap-seconds, possibly even
 eliminating their use.  Leap seconds are introduced so as to keep UTC
 synchronized (within 0.9 s) to the time scale determined from the
 Earth's rotation, however many practical problems result from their

 Should no new leap seconds be inserted, solar time will diverge from
 atomic time at the rate of about 2 seconds every 3 years, and after
 about a century |UT1-UTC| would exceed 1 minute.  Although no
 fundamental problems are anticipated, it is very likely that Y2K-like
 problems may result in software that assumes UT1=UTC, or |UT1-UTC|< some
 value, or whose input/output records use a field size that can only
 accommodate |UT1-UTC| values up to one second.

 To gather information, an URSI Commission J Working Group was formed,
 consisting of Don Backer, Wim. N. Brouw, Barry Clark, Irwin Shapiro,
 Ir. E. Van Lil, and myself.

 We would like to ask you to consult with the members of your institute
 who currently deal with UT1-UTC, and give us a considered response to
 the following two questions:

 A. If the appropriate international bodies decide to eliminate the
 insertion of new leap seconds, would you foresee any practical problems
 for your institution/instrument/observations?

     no  ____

  *  yes ___

  *  possibly ____

     (* please explain any known or possible problems)

 B. Would you be in favor of such a proposal?

     yes ____

     no  ____

     indifferent ___

     have better idea ___

     (feel free to comment)

 C. Is there anyone else you would recommend we contact?
    (feel free to forward this eamil directly)

 I would appreciate your assistance, and a response by January 15 to
 dnm at



 Demetrios Matsakis
 Dr. Demetrios N. Matsakis            Director, Time Service Department
 (202) 762-1587  DSN 762-1587         U. S. Naval Observatory
 FAX (202) 762-1511                   3450 Massachusetts Avenue NW
 dnm at              Washington DC, USA  20392-5420

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