[LEAPSECS] current / future state of UT1 access?

[Rob Seaman]

Hi all,

Regarding Demetrios's response to Steve: did astronomers give advice
divergent to what CCIR decided?It isn't obvious how the history of this
rather typical, if somewhat esoteric, technical debate amounts to
"strong emotional bias". I reject the implication that technical
disagreements, at that time or in the current day, are nothing more than
emotion.

It is perhaps telling that Demetrios doesn't address Steve's central
assertion that it was recognized early on that two kinds of time were
needed. Two kinds of time are still needed.

Meanwhile, over the past week or two I have not been able to connect to
NIST's UT1 server:

   
https://www.nist.gov/pml/time-and-frequency-division/time-services/ut1-ntp-time-dissemination

Judah Levine has been very helpful in looking at things on the NIST
side, and Harlan Stenn and Martin Burnicki have been insightful
regarding NTP. Needless to say, this level of expert customer support is
atypical! There is no reason to believe that NIST cannot serve UT1, and
certainly such a brain trust (absent my fumble-fingers) could oil the
gears and get the NTP clock spinning like a top. However, that is not
currently the case from my campus. (We do see two other NTP servers in
the same rack as that NIST UT1 server.)

I'm preparing a paper on pragmatic timekeeping for an upcoming
observatory operations conference and would welcome comments from
anybody who has been using the NIST's UT1 service or any other UT1
service or related internet tables. And those who maintain NTP instances
might try connecting to 128.138.140.50 at the University of Colorado in
Boulder and report on their results.

For many purposes (even in astronomy) UTC currently serves as a proxy
for UT1 and for mean solar time in general. If leap seconds cease that
approximation will no longer be functional and the engineering
requirements and infrastructure for delivering UT1 will be stressed
manyfold. How well does it work now? What investment would be needed to
make it reliably scalable? Absent emotion, what are the proposed best
practices for providing access to the multiple timescales needed?

Many thanks!

Rob Seaman
Lunar and Planetary Laboratory
University of Arizona
--


On 3/16/18 9:16 AM, Matsakis, Demetrios N CIV NAVOBSY, N3TS wrote:
> I was surprised to find phrases in the Lick web pages:  "CCIR ignored the advice that astronomers " and "squelched astronomers who insisted that leap seconds would cause trouble".   
>
> I realize their author is not the only person with a strong emotional bias, but even so I question the tone of these web pages because they are inconsistent with the following:
>
> 1. There was a progression in thought as technology advanced and atomic clocks proved their reliability.
>
> 2. It should be obvious that ephemeris time would need a flywheel system to get practical time to the users, and GMT could be part of that.  Today individual labs realize UTC(k) for the same reason - to flywheel before the monthly computations of UTC are published.  WWVB, GPS, and your local cell towers are all part of the system as well.  (Even so, I think everyone today agrees that Ephemeris time was a mistake.)
>
> 3.  According to references in Nelson et al’s Metrologia article, which was peer-reviewed, it looks to me like the switch to UTC was by universal agreement among the institutions.  The IAU, URSI, CIPM(=CGPM), and CCIR(= ITU) all agreed to the current system in the late 60's, and I would guess that the timing of their resolutions probably depended more on the (generally) 3-year spacing of their general assemblies than anything else.  Note that many of those groups had overlapping membership.  It would however be unusual if all individual members of these bodies ever agreed to any resolution, even if passed "by consensus".
>
> For more trivia, the dynamic  Gernot Winkler of the USNO was both a practical clock man and astronomer.  He was not the only one, and he was a very active member of the IAU who chaired commissions, served on working groups, etc.  He told me personally that he and Essen independently came up with the idea of leap seconds.   He also said a big reason was to win the support of the mariners, who in the pre-GNSS days actually did celestial navigation and who in the pre-internet days could not easily get access to tables that incorporated the difference between UT1 and UTC.
>
>
> ________________________________________
> From: LEAPSECS [leapsecs-bounces at leapsecond.com] on behalf of Steve Allen [sla at ucolick.org]
> Sent: Wednesday, March 14, 2018 12:16 AM
> To: Leap Second Discussion List
> Subject: [Non-DoD Source] [LEAPSECS] D.H. Sadler in 1954
>
> In 1954 D.H. Sadler produced a monograph on the changes in time
> that had been resolved at the 1952 IAU General Assembly.
> His writeup is clearer than almost anything else for the next 60 years.
> It was published in Occasional Notices of the RAS, and it has been hard
> to find until now.
> https://www.ucolick.org/~sla/leapsecs/twokindsoftime.html
> This is one of the series of documents produced starting in 1948 and
> proceeding through the next 20 years where astronomers explained that
> two kinds of time would be needed to satisfy all applications.
>
> --
> Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
> UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
> 1156 High Street               Voice: +1 831 459 3046         Lng -122.06015
> Santa Cruz, CA 95064           http://www.ucolick.org/~sla/   Hgt +250 m
>

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