[LEAPSECS] Ghosts of Leap-seconds past and future

Steve Allen sla at ucolick.org
Tue Dec 28 11:21:34 EST 2010

On 2010 Dec 28, at 04:56, Richard B. Langley wrote:

> Documents demonstrate a clear misunderstanding of the definitions and applications of time scales and system times for internal synchronization

> o Indications that users have the choice between UTC, TAI, UT1, GPS Time for their applications is incorrect

> o UTC is the only international standard time scale, represented by local approximations in time laboratories, that should be used for worldwide time coordination and measurement traceability

> o TAI is not an option for applications needing a continuous reference as it has no means of dissemination, and it is not physically represented by clocks

> o GPS time is not a reference time scale, it is an internal time for GPS system synchronization, as other GNSS system times would be

> o A variety of continuous internal system time scales have proliferated to provide a solution to the problems associated with discontinuities in UTC


> The existence of multiple time scales creates potential problems in operational use as well as conceptual confusion on the proper definition and roles of time references

This is consistent with other presentations by Ron Beard.
It has the usual powerpoint problem of lacking any explanation for
the fiat-like statements. It also contains his ongoing insistence
that the name of the ITU-R approved time scale must remain UTC,
still without explanation for why that should be when the
2003 Colloquium in Torino asserted otherwise.

In other documents the BIPM has expressed dismay with the use of
TAI as a standard time scale. I don't think that they are tasked
nor funded with the distribution of a time scale, but it's still
not clear to me why they oppose its use. The folks who are
setting up the Perl 6 time API (among others) have certainly
not heard that they should not use TAI. The apparent horror
with which the BIPM reacts to the use of GPS time is also not
clear to the folks who have chosen it at a practical solution.

The first sentence says "Documents" demonstrate misunderstanding
Which documents? Who is misunderstanding?
In that sentence I see what may be the root problem of the issue.
By the nature of its charter the ITU-R is incapable of serving
a role of giving guidance. That seems to me what Dave Finkleman
has been starting to do.

Steve Allen <sla at ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855
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