UTC might be redefined without Leap Seconds

Three pictures that show the situation

A brief and pictorial page showing how our clocks are affected by leap seconds, and why there is no schedule for them.

Elapsed time

A javascript program showing the international problem that POSIX is not currently capable of providing an interface that properly describes time, and that international agreements confound the process of fixing that problem.

How the problems could be solved now

A prescription that shows how existing deployed and tested code could allow computing and telecommunications systems to handle leap seconds without difficulty, but only if the ITU-R changes the name of the broadcast time scale.

Differences between time scales

Plots showing how time keeping got the way it is, and suggesting a way to reduce the issues associated with leap seconds which is compatible with human history as well as modern systems for navigation, telecomms, and POSIX.

A bibliographic gathering of references

This document gives a picture of how the ITU-R has spent over ten years on redefining UTC without coming to a conclusion. It includes hundreds of links to almost all on-line material pertaining to the future of leap seconds. This is the document which was originally visible at this URL.

Figures and tables showing the reasons for leap seconds

This includes some material on the proposed changes.

A brief history of time scales

During the past century or so the concept of time has changed considerably. The results of struggling with ever more refined notions of time have been some two dozen new ways of expressing time.

What could happen if civil time becomes atomic time?

This question will be treated again at the meeting Requirements for UTC and Civil Timekeeping on Earth to be held during 2013 May in Charlottesville VA USA.

This question was the subject of the meeting Decoupling Civil Timekeeping from Earth Rotation held during 2011 October in Exton PA USA. The presentations at that meeting resulted in 400 pages of proceedings (also available on CDROM).

Previously, the ITU-R convened a Colloquium on the UTC Time Scale in Torino Italy during 2003 May. At the conclusion of that meeting the invited experts suggested that a solution to the problems of leap seconds in the radio broadcast time scale would be to create a new atomic timescale named TI in about the year 2022. Subsequent to that meeting the delegates to the ITU-R seem to have rejected or ignored the advice given to them by the experts who attended their meeting.

Optical and Infrared Observatories

Study of the bibliography above indicates that no formal survey has ever been performed specifically to ask optical and infrared observatories to consider the schedule and cost implications of discontinuing leap seconds from UTC. The initial URSI survey was published very broadly, and attempts were made to contact observatories. Nevertheless, I believe that this survey was inadequate for several reasons:

• The survey was performed on behalf of URSI Commission J, which is Radio Astronomy.
• The survey was performed before the nature of the cost implications of discontinuing leap seconds had been considered.
• The survey was performed before it had become clear that those who were suggesting changes to UTC were either serious or capable of doing it.

Some older optical and infrared telescopes were built or designed before Stoyko had confirmed that the length of day varied seasonally. Others were not designed to require pointing accuracy of 1 second of time. Often this was because they are manually pointed by a full-time telescope technician -- not by the observer, not by software. Telescopes such as these have never required their control systems to distinguish between UT1 and UTC. Discontinuing leap seconds requires a fundamental change in their operational procedures.

Astronomers should note in particular that the agenda for the meeting in Torino considered financial aspects (costs and opportunities) for several disciplines, but not for astronomy.

A survey of schedule and cost consequences for observatories

A description of costs and consequences

This is an introduction to the survey below.

The survey about schedule and cost

This is an attempt to gather some estimates of the scheduled time and costs which observatories will have to expend if leap seconds are discontinued.

The results of the survey

Here are the data gathered in response to the above survey. The results are sparse. This may be because it is difficult to answer the questions without expending most of the effort required to identify the deficiencies, and this is amplified by the absence of a clear indication of the detailed nature of a change.

Various postings that I have made to the LEAPSECS mailing list

UTC vis-a-vis civil time (2003-02-12) local text/plain, Mail Archive, LEAPSECS subscribers

UTC without leap seconds would deviate from all other forms of "universal" time.

legal time (2003-04-10) local text/plain , LEAPSECS subscribers, (ideas included here)

If UTC switches to leap hours, how far in the future will those occur?
Under the current legal time for the US and UK (which is, effectively, UT2) will lawsuits begin to happen when DUT1 exceeds a few seconds?

UTC is doomed (2003-04-22) local text/plain , LEAPSECS subscribers, (ideas included here)

But it is not doomed anytime soon.

UT and the IAU (2003-05-10) local text/plain , LEAPSECS subscribers, (ideas included here, here, and here)

Universal Time was defined and approved by action of the IAU

will history repeat itself? (2003-05-10) local text/plain , LEAPSECS subscribers, (ideas included here)

In 1970 the CCIR (predecessor of the ITU) was in a similar position with respect to UTC. Rather than create an international and interdisciplinary committee to choose a solution, the CCIR acted unilaterally and imposed a solution on the world with less than 2 years notice.

Polyglot search engine bait

English

leap second, leap seconds

German

Schaltsekunde, Schaltsekunden

French

seconde intercalaire, secondes intercalaires

Spanish

segundo intercalar, segundos intercalares, segundo intercalado, segundos intercalados, segundo adicional, segundos adicionales, segundo extra (tal vez segundo bisiesto, segundos bisiestos)

Italian

secondo intercalare, secondi intercalari

Portuguese

segundo intercalado, segundos intercalados

Swedish

skottsekund, skottsekunder

Icelandic

hlaupasekundum, hlaupasekundur

Danish

skudsekund, skudsekunder

Dutch

schrikkelseconde, schrikkelseconden

Russian

дополнительная секунда, дополнительные секунды