Author: Demetrios Matsakis
Subject: UTC Questionnaire

Dear Colleague,

It has been 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.

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?

     yes ___

  *  no  ____

  *  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

I would like to apologize to anyone contacted twice, but also appreciate it if
you would forward this email to anyone we have missed.  Also, if you are an
URSI Commission J national chair, we would appreciate your forwarding this
email to your complete membership and in particular to the directors of


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              Washington DC, USA  20392-5420