Planet X: SLOWING Rotation 1
In Article <%OWR6.4337$Ke.firstname.lastname@example.org> David Tholen wrote:
> By the way, the decision of when to insert a leap second
> is made by the International Earth Rotation Service, not
> the U.S. Navy.
The Navy seems to be very much in charge, and wanting to get rid of this
issue lately, too. This way, when the dawn starts coming later and
later, they can shoo people away from their door. Not my problem, etc.
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 0.9s) 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
B. Would you be in favor of such a proposal?
C. Is there anyone else you would recommend
we contact? (feel free to forward this eamil
I would appreciate your assistance, and a response
by January 15 [2,000] to email@example.com.
I am attaching a list of institutions and persons
contacted, except for 931 institutions whose
emails were obtained from the AAS. 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 observatories.
Director, Time Service Department,
U. S. Naval Observatory
Nov 16, 1999